Back contact cell assembly and system

Abstract

NOT VISIBLE DUE TO STATUS OF PATENT

Description

Back contact cell assembly and system

[0001] Priority information

[0002] The present disclosure claims priority to and the benefit of Chinese Patent Application No. 202421366666.4, filed on June 14, 2024, and Chinese Patent Application No. 202411273475.8 and 202411276522.4, filed on September 11, 2024, to the China National Intellectual Property Office, and incorporates by reference the entire contents of each of the foregoing applications. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of solar cells, and in particular to a back contact cell assembly and a photovoltaic system. BACKGROUND

[0004] Solar cell power generation is a sustainable clean energy source that can convert sunlight into electrical energy using the photovoltaic effect of a semiconductor p-n junction. In the related art, a plurality of back contact cell pieces are subjected to steps such as series welding, lamination, and packaging to form a back contact cell assembly. The back contact cell assembly includes bus bars for series connection, and the bus bars are exposed to affect the appearance of the cell pieces, and the bus bars reduce the light-receiving area of the cell pieces, resulting in poor power generation efficiency.

[0005] In some products, the bus bars are installed at the middle positions of the back surfaces of the cell pieces, and an insulating strip is arranged between the bus bars and the cell pieces. Although this arrangement can hide the bus bars, it is necessary to perform hole processing on the insulating strip or replace the bus bars with insulating blocks arranged intermittently, so that the bus bars can be in contact with the same polarity tab on the cell pieces and be insulated from the reverse polarity tab on the cell pieces. This arrangement requires high precision in hole processing of the insulating strip and arrangement position of the insulating blocks, and is difficult to produce. Position deviation during hole processing of the insulating strip or during lamination of the insulating blocks is likely to occur, and width direction deviation is likely to cause short circuit. SUMMARY

[0006] The present disclosure aims to provide a back contact cell assembly and a photovoltaic system in view of the existing technical situation.

[0007] One of the purposes of the present disclosure is to solve the problem of how to avoid exposure of the bus bars and reduce power generation efficiency. The present disclosure can increase the effective light-receiving area of the cell assembly, improve the conversion efficiency of the assembly, and the area of the bus bars observed from the light-receiving side is smaller, or even completely hidden, which is more aesthetic.

[0008] Meanwhile, the present disclosure can effectively reduce the production difficulty, reduce the risk of cell piece short circuit, hidden crack, and fragmentation, and improve reliability.

[0009] To achieve the above object, the present disclosure adopts the following technical solutions:

[0010] First, the present disclosure provides a back contact battery assembly, comprising:

[0011] A battery string, the battery string comprising a plurality of battery pieces connected in series, the plurality of battery pieces being distributed along a first direction;

[0012] An insulating strip, the insulating strip being arranged on the back light surface of the battery piece along a second direction, wherein the first direction and the second direction are arranged intersectingly; and

[0013] A bus bar, the bus bar being arranged on the side of the insulating strip away from the battery piece along the second direction, the insulating strip covering the surface of the side of the bus bar close to the battery piece;

[0014] The battery string comprises adjacent first and second battery pieces, the insulating strip is arranged on the back light surface of the first battery piece, and the second solder strip is connected to the second battery piece and the bus bar respectively, and the insulating strip blocks the second solder strip and the first battery piece.

[0015] In some embodiments, the insulating strip covers the bus bar in the second direction; and the insulating strip covers and exceeds the bus bar in the first direction.

[0016] In some embodiments, the back contact battery assembly further comprises a solder strip, the solder strip comprising a first solder strip and a second solder strip, the first solder strip being used for connecting adjacent battery pieces, and the second solder strip being used for connecting the battery piece and the bus bar.

[0017] In some embodiments, the second solder strip is arranged on the side of the bus bar away from the insulating strip, or the second solder strip is arranged on the side of the bus bar close to the insulating strip.

[0018] In some embodiments, the first and second battery pieces are arranged at least partially in a stack.

[0019] In some embodiments, when the back light surface of the first battery piece and the light receiving surface of the second battery piece are arranged at least partially in a stack, the insulating strip is connected at least partially to the back light surface of the second battery piece.

[0020] In some embodiments, the battery piece is in a rectangular shape, and the battery piece further comprises a chamfered edge and a cut edge, the chamfered edge and the cut edge being distributed on both sides of the battery piece along the first direction, and the first direction and the second direction are arranged perpendicularly.

[0021] In some embodiments, in the first direction, the chamfered edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece; or in the first direction, the chamfered edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece.

[0022] In some embodiments, the chamfered edge of each cell piece is arranged on the back surface of the cutting edge of the adjacent cell piece.

[0023] Secondly, the disclosure provides a back contact cell assembly, comprising:

[0024] The cell string comprises cell pieces connected in series, and the cell pieces comprise fifth and sixth cell pieces arranged along a first direction,

[0025] The first insulating strip is arranged at one end of the sixth cell piece close to the fifth cell piece,

[0026] The first bus bar is arranged on one side of the first insulating strip away from the sixth cell piece,

[0027] The first insulating strip and the first bus bar are arranged along a second direction, and the first direction and the second direction are arranged crosswise,

[0028] The second solder strip A is used to electrically connect the first bus bar and the fifth cell piece,

[0029] In the first direction, the two ends of the first insulating strip are provided with a first widened section and a second widened section extending beyond the edge of the first bus bar, and the first widened section and the second widened section are arranged in sequence in a direction away from the fifth cell piece, and the width of the second widened section is smaller than the width of the first widened section.

[0030] In some embodiments, the first widened section at least partially extends beyond the edge of the sixth cell piece.

[0031] In some embodiments, in the first direction, the orthogonal projection of the first widened section in the thickness direction of the sixth cell piece at least partially coincides with the orthogonal projection of the fifth cell piece in the thickness direction of the sixth cell piece.

[0032] In some embodiments, in the first direction, the width D2 of the second widened section is greater than or equal to 1mm.

[0033] In some embodiments, the fifth and sixth cell pieces are arranged on the same plane, and 1mm < D1 ≤ l 11 +l 12 +l 13

[0034] In the formula, D1 is the width of the first widened section in the first direction, l 11 is the relative width distance between the first bus bar and the edge of the sixth cell piece close to the fifth cell piece in the first direction, l 12 is the distance between the fifth cell piece and the sixth cell piece, and l 13A relative width distance from an edge of the fifth cell piece close to one end of the sixth cell piece to the first soldering point, the first soldering point being arranged at the fifth cell piece close to one end of the sixth cell piece for connecting with the second soldering ribbon A.

[0035] In some embodiments, the sixth cell piece close to one end of the fifth cell piece is at least partially laminated with the fifth cell piece, wherein 1mm < D1≤ l 21 +l 23 -l 22

[0036] In the formula, D1 is the width of the first widened section in the first direction, l 21 is a relative width distance between the first busbar and an edge of the sixth cell piece close to one end of the fifth cell piece in the first direction, l 22 is a width of a laminated region between the fifth cell piece and the sixth cell piece in the first direction, l 23 A relative width distance from an edge of the fifth cell piece close to one end of the sixth cell piece to the first soldering point, the first soldering point being arranged at the fifth cell piece close to one end of the sixth cell piece for connecting with the second soldering ribbon A.

[0037] In some embodiments, the battery assembly further comprises a front plate, the battery strings are arranged on the front plate, the front plate is arranged with a first edge and a second edge along the second direction, and a projection of the first insulating strip in the thickness direction of the sixth cell piece falls between the first edge and the second edge.

[0038] In some embodiments, a projection of the first busbar in the thickness direction of the sixth cell piece falls within the sixth cell piece in the first direction.

[0039] In some embodiments, the battery assembly comprises at least one series battery string group, the same series battery string group comprises two battery strings arranged along the second direction and arranged in series with each other, and in the same series battery string group, the same first busbar extends from the sixth cell piece in one battery string to the sixth cell piece of another battery string.

[0040] In some embodiments, each battery string is provided with a fourth cell piece away from one end of the fifth cell piece, the fourth cell piece is provided with a third cell piece close to one end of the fifth cell piece,

[0041] The back contact battery assembly further comprises:

[0042] A second insulating strip is arranged at an edge of the third cell piece in one battery string, and the second insulating strip is arranged at one end of the third cell piece close to the fourth cell piece,

[0043] A middle busbar is arranged for parallel connection of two battery strings arranged adjacent to each other in the first direction, the middle busbar is arranged at a side of the second insulating strip away from the third cell piece,

[0044] The second insulation strip and the intermediate busbar are arranged in extension along a second direction,

[0045] The second solder strip B is used for electrically connecting the intermediate busbar, the fourth cell piece in the battery string, and the fourth cell piece in another battery string adjacent to the battery string in the first direction.

[0046] In some embodiments, in the first direction, two ends of the second insulation strip are provided with a first extension segment and a second extension segment extending out of the edge of the intermediate busbar, the first extension segment and the second extension segment are sequentially arranged in a direction away from the fourth cell piece, the first extension segment at least partially extends out of the edge of the third cell piece, and the width of the second extension segment is smaller than the width of the first extension segment.

[0047] Thirdly, the present disclosure also provides a back contact battery assembly, comprising:

[0048] The parallel battery string group comprises at least two battery strings arranged in the first direction and arranged in parallel with each other, each battery string comprises cell pieces arranged in series with each other, the cell pieces arranged in series with each other comprise the third cell piece and the fourth cell piece arranged in the first direction, and the fourth cell pieces in the two battery strings arranged in parallel with each other are arranged adjacent to each other in the first direction,

[0049] The second insulation strip is arranged at the edge of the third cell piece in a battery string, and the second insulation strip is arranged at one end of the third cell piece close to the fourth cell piece,

[0050] The intermediate busbar is used for connecting in parallel the two battery strings arranged adjacent to each other in the first direction, and the intermediate busbar is arranged at one side of the second insulation strip away from the third cell piece,

[0051] The second insulation strip and the intermediate busbar are arranged in extension along a second direction,

[0052] The second solder strip B is used for electrically connecting the intermediate busbar, the fourth cell piece in the battery string where the intermediate busbar is located, and the fourth cell piece in another battery string adjacent to the battery string in the first direction.

[0053] In the first direction, two ends of the second insulation strip are provided with a first extension segment and a second extension segment extending out of the edge of the intermediate busbar, the first extension segment and the second extension segment are sequentially arranged in a direction away from the fourth cell piece, and the width of the second extension segment is smaller than the width of the first extension segment.

[0054] In some embodiments, the first extension segment at least partially extends out of the edge of the third cell piece.

[0055] In some embodiments, in the first direction, the orthogonal projection of the first extension segment in the thickness direction of the third cell piece at least partially coincides with the orthogonal projection of the fourth cell piece in the thickness direction of the third cell piece.

[0056] In some embodiments, the width d2 of the second epitaxial segment in the first direction is ≥ 1 mm.

[0057] In some embodiments, the fourth cell piece and the third cell piece are disposed on the same plane, wherein 1 mm < d1 ≤ l 31 + 32 + 33

[0058] wherein d1 is the width of the first epitaxial segment in the first direction, l 31 is the relative width distance between the middle busbar and the edge of the third cell piece close to the fourth cell piece in the first direction in the battery string with the middle busbar, l 32 is the spacing between the fourth cell piece and the third cell piece in the battery string with the middle busbar, l 33 is the relative width distance between the edge of the fourth cell piece close to the third cell piece and the second soldering point in the battery string with the middle busbar, the second soldering point being disposed on the fourth cell piece in the battery string with the middle busbar and close to the third cell piece, and being used for connecting with the second soldering ribbon B.

[0059] In some embodiments, the edge of the third cell piece close to the fourth cell piece and the fourth cell piece are at least partially laminated in the battery string with the middle busbar, wherein 1 mm < d1 ≤ l 41 + 43 - 42

[0060] wherein d1 is the width of the first epitaxial segment in the first direction, l 41 is the relative width distance between the middle busbar and the edge of the third cell piece close to the fourth cell piece in the first direction in the battery string with the middle busbar, l 42 is the width of the lamination region between the third cell piece and the fourth cell piece in the first direction, l 43 is the relative width distance between the edge of the fourth cell piece close to the third cell piece and the second soldering point in the battery string with the middle busbar, the second soldering point being disposed on the fourth cell piece close to the third cell piece, and being used for connecting with the second soldering ribbon B.

[0061] In some embodiments, the battery assembly further comprises a front plate, the battery string is disposed on the front plate, the front plate is arranged with a first edge and a second edge along the second direction, and the second insulating strip falls between the first edge and the second edge in the orthographic projection of the thickness direction of the third cell piece.

[0062] Fourth, a back contact battery assembly comprises:

[0063] The battery string comprises battery pieces arranged in series, and each battery piece comprises a fifth battery piece and a sixth battery piece arranged along a first direction,

[0064] A first insulating strip is arranged at one end of the sixth battery piece close to the fifth battery piece,

[0065] A first bus bar is arranged at one side of the first insulating strip away from the sixth battery piece,

[0066] The first insulating strip and the first bus bar are arranged along a second direction, and the first direction and the second direction are arranged crossly,

[0067] A second solder strip A is arranged to electrically connect the first bus bar and the fifth battery piece,

[0068] The first insulating strip is provided with an extension segment extending out of the first bus bar at one end close to the fifth battery piece, and the extension segment extends out of the sixth battery piece, and in the thickness direction of the sixth battery piece, the orthographic projection of the extension segment and the orthographic projection of the fifth battery piece at least partially overlap.

[0069] In some embodiments, the fifth battery piece and the sixth battery piece are arranged on the same plane,

[0070] In the first direction, the width of the part of the extension segment extending out of the sixth battery piece is greater than the interval between the fifth battery piece and the sixth battery piece. In some embodiments, in the first direction, the width of the extension segment is: 1mm≤L1≤l 11 +l 12 +l 13 ,

[0071] In the formula, L1 is the width of the extension segment in the first direction, l 11 is the interval between the fifth battery piece and the sixth battery piece, l 12 is the relative width distance from the edge of the fifth battery piece close to the sixth battery piece to the first solder point, the first solder point is arranged to be connected with the second solder strip A, and is arranged at one end of the fifth battery piece close to the sixth battery piece, l 13 is the relative width distance between the edge of the first bus bar close to the fifth battery piece and the edge of the sixth battery piece close to the fifth battery piece.

[0072] In some embodiments, in the first direction, the width of the extension segment is: 1mm≤L1≤l 11 +l 13 +4mm,

[0073] In the formula, L1 is the width of the extension segment in the first direction, l 11 is the interval between the fifth battery piece and the sixth battery piece, l 13a relative width distance between an edge of the fifth cell tab near an end of the fifth cell tab and an edge of the sixth cell tab near an end of the fifth cell tab.

[0074] In some embodiments, an end of the sixth cell tab near the fifth cell tab is at least partially overlapped with the fifth cell tab,

[0075] In the first direction, a width of the epitaxial segment is greater than a width of the overlapped region between the fifth cell tab and the sixth cell tab.

[0076] In some embodiments, the width of the epitaxial segment is: 1mm≤L2≤l 22 +l 23 -l 21 ,

[0077] wherein L2 is a width of the epitaxial segment in the first direction, l 21 is a width of the overlapped region between the fifth cell tab and the sixth cell tab, l 22 is a relative width distance between an edge of the fifth cell tab near an end of the sixth cell tab and a first soldering point for connecting with the second soldering ribbon A, the first soldering point being arranged at the end of the fifth cell tab near the sixth cell tab, l 23 is a relative width distance between an edge of the first bus bar near an end of the fifth cell tab and an edge of the sixth cell tab near an end of the fifth cell tab.

[0078] In some embodiments, the width of the epitaxial segment is: 1mm≤L2≤l 23 +4mm-l 21 ,

[0079] wherein L2 is a width of the epitaxial segment in the first direction, l 21 is a width of the overlapped region between the fifth cell tab and the sixth cell tab, l 23 is a relative width distance between an edge of the first bus bar near an end of the fifth cell tab and an edge of the sixth cell tab near an end of the fifth cell tab.

[0080] In some embodiments, the battery assembly comprises at least one series cell string group, each series cell string group comprising two cell strings arranged in the second direction and connected in series with each other, and in each series cell string group, the sixth cell tab of one cell string and the sixth cell tab of another cell string are connected by the same first bus bar.

[0081] In some embodiments, each cell string is provided with a fourth cell tab at an end away from the fifth cell tab, and the fourth cell tab is provided with a third cell tab at an end near the fifth cell tab,

[0082] The battery assembly comprises parallel battery string groups, each parallel battery string group comprises at least two battery strings arranged along a first direction and connected in parallel with each other, and the fourth cell tab in each of the two battery strings connected in parallel with each other is arranged adjacent to each other in the first direction,

[0083] The back contact battery assembly further comprises:

[0084] The second insulation strip is arranged at the edge of the third cell tab in a battery string, and the second insulation strip is arranged at one end of the third cell tab close to the fourth cell tab,

[0085] The intermediate busbar is arranged at the side of the second insulation strip away from the third cell tab and is used to connect in parallel two battery strings arranged adjacent to each other in the first direction,

[0086] The second insulation strip and the intermediate busbar are both arranged extending along a second direction,

[0087] The second solder strip B is used to electrically connect the intermediate busbar, the fourth cell tab in the battery string, and the fourth cell tab in another battery string adjacent to the battery string in the first direction.

[0088] In some embodiments, the second insulation strip is provided with an extension section extending out of the intermediate busbar at one end close to the fourth cell tab, and the extension section extends out of the third cell tab, and in the thickness direction of the third cell tab, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth cell tab in the battery string where the extension section is located.

[0089] Fifth, the disclosure provides a back contact battery assembly comprising:

[0090] The parallel battery string groups each comprises at least two battery strings arranged along a first direction and connected in parallel with each other, each battery string comprises cell tabs connected in series with each other, the cell tabs comprise a third cell tab and a fourth cell tab arranged along the first direction, and the fourth cell tab in each of the two battery strings connected in parallel with each other is arranged adjacent to each other in the first direction,

[0091] The second insulation strip is arranged at the edge of the third cell tab in a battery string, and the second insulation strip is arranged at one end of the third cell tab close to the fourth cell tab,

[0092] The intermediate busbar is arranged at the side of the second insulation strip away from the third cell tab and is used to connect in parallel two battery strings arranged adjacent to each other in the first direction,

[0093] The second insulation strip and the intermediate busbar are both arranged extending along a second direction,

[0094] The second solder strip B is used to electrically connect the intermediate busbar, the fourth cell tab in the battery string where the intermediate busbar is located, and the fourth cell tab in another battery string adjacent to the battery string in the first direction,

[0095] wherein the second insulation strip is provided with an extension section extending out of the middle busbar at an end of the fourth cell piece, and the extension section extends to outside of the third cell piece, and in the thickness direction of the third cell piece, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth cell piece in the cell string where the extension section is located.

[0096] In some embodiments, in the cell string provided with the second insulation strip, the fourth cell piece and the third cell piece are located on the same plane,

[0097] In the first direction, the width of the portion of the extension section extending out of the third cell piece is greater than the spacing between the fourth cell piece and the third cell piece. In some embodiments, in the first direction, the width of the extension section is: 1mm≤L3≤l 31 + 32 + 33 ,

[0098] wherein L3 is the width of the extension section in the first direction, l 31 is the spacing between the fourth cell piece and the third cell piece in the cell string provided with the second insulation strip, l 32 is the relative width distance from the edge of the fourth cell piece at the end close to the third cell piece to the second soldering point in the cell string provided with the second insulation strip, l 33 is the relative width distance between the edge of the middle busbar at the end close to the fourth cell piece and the edge of the third cell piece at the end close to the fourth cell piece in the cell string provided with the second insulation strip.

[0099] In some embodiments, in the first direction, the width of the extension section is: 1mm≤L3≤l 31 + 33 +4mm,

[0100] wherein L3 is the width of the extension section in the first direction, l 31 is the spacing between the fourth cell piece and the third cell piece in the cell string provided with the second insulation strip, l 33 is the relative width distance between the edge of the middle busbar at the end close to the fourth cell piece and the edge of the third cell piece at the end close to the fourth cell piece in the cell string provided with the second insulation strip.

[0101] In some embodiments, in the cell string provided with the second insulation strip, the end of the third cell piece close to the fourth cell piece and the fourth cell piece are at least partially laminated,

[0102] In the first direction, the width of the extension section is greater than the width of the laminated region between the third cell piece and the fourth cell piece.

[0103] In some embodiments, in the first direction, the width of the extension section is: 1mm≤L4≤l42 + l 43 - l 41 ,

[0104] wherein L4 is the width of the extension in the first direction, l 41 is the width of the lamination region between the third cell and the fourth cell, l 42 is the relative width distance from the edge of the fourth cell near the third cell to the second solder in the cell string with the second insulating strip, l 43 is the relative width distance between the edge of the middle busbar near the fourth cell and the edge of the third cell near the fourth cell in the cell string with the second insulating strip.

[0105] In some embodiments, the width of the extension in the first direction is: 1 mm ≤ L4 ≤ l 43 - l 41 + 4 mm,

[0106] wherein L4 is the width of the extension in the first direction, l 41 is the width of the lamination region between the third cell and the fourth cell, l 42 is the relative width distance from the edge of the fourth cell near the third cell to the second solder in the cell string with the second insulating strip, l 43 is the relative width distance between the edge of the middle busbar near the fourth cell and the edge of the third cell near the fourth cell in the cell string with the second insulating strip.

[0107] Sixth, the present disclosure also provides a photovoltaic system comprising the back contact cell module described above.

[0108] The present disclosure has the following beneficial effects:

[0109] 1) In the present disclosure, the busbar is hidden behind the back surface of the plurality of battery pieces, and the busbar cannot be observed from the light receiving surface side, so that the overall color of the front surface of the back contact battery assembly is uniform and beautiful. At the same time, the insulating strip can be arranged between the busbar and the battery piece to avoid short circuit problems. Secondly, compared with arranging the busbar at the middle position of the back surface of the battery piece, the busbar of the present disclosure is arranged at one end of the first battery piece close to the second battery piece, and the second solder strip is arranged on the second battery piece. The second solder strip can be fully matched and welded with the effective welding position of the second battery piece, avoiding the installation of the busbar to cause insufficient welding of the second solder strip and the second battery piece, which affects the collection of current. At the same time, after the second solder strip is welded with the second battery piece, it can be directly connected with the busbar without the need of opening hole treatment of the insulating strip or replacing it with an intermittently arranged insulating block. During assembly, only the insulating strip needs to be placed at one end of the first battery piece close to the second battery piece, effectively reducing the production precision requirement and production difficulty, and avoiding short circuit caused by position deviation of the insulating strip when opening hole or position deviation of the insulating block when laminating, thereby increasing the product yield.

[0110] 2) The end busbar built-in structure of the present disclosure can increase the effective light receiving area of the battery assembly and improve the conversion efficiency of the assembly. The area of the busbar observed from the light receiving surface side is smaller, and even can be completely hidden, so that the overall appearance of the battery assembly is better. On the other hand, it can ensure that the second solder strip A can be fully matched and welded with the effective welding position of the fifth battery piece, avoiding the installation of the first busbar to cause insufficient welding of the second solder strip A and the fifth battery piece, which affects the collection of current. During assembly, only the first insulating strip needs to be placed at one end of the sixth battery piece close to the fifth battery piece. At the same time, through the arrangement of the first widening section and the second widening section, during the preparation process, a certain degree of deviation of the first insulating strip relative to the first busbar and the first insulating strip relative to the two battery pieces in the width direction can be allowed, effectively reducing the production precision requirement and short circuit risk, and ensuring that the battery assembly has a high double-sided rate. Furthermore, the end busbar built-in structure of the present disclosure can be applied to back contact battery assemblies with main grid and back contact battery assemblies without main grid, and has stronger universality. When laminating the end busbar built-in structure, the stress is smaller, which can reduce the risk of battery piece cracking and fragmentation, and the reliability of the back contact battery assembly is good.

[0111] 3) The intermediate busbar built-in structure of the present disclosure can increase the effective light receiving area of the battery assembly, improve the conversion efficiency of the assembly, and the area of the busbar observed from the light receiving side is smaller, and even can be completely hidden, the overall appearance of the battery assembly is better; on the other hand, it can ensure that the second solder strip B can be fully matched and welded with the effective welding position of the fourth battery piece, avoid the installation of the intermediate busbar to cause insufficient welding of the second solder strip B and the fourth battery piece, and affect the current collection, and only one whole second insulating strip needs to be placed on the end of the third battery piece close to the fourth battery piece during assembly, at the same time, through the setting of the first extension section and the second extension section, a certain degree of offset of the second insulating strip relative to the intermediate busbar and the two battery pieces in the width direction can be allowed during the preparation process, effectively reducing the production precision requirement and short circuit risk, and ensuring that the battery assembly has a high double-sided rate; furthermore, the intermediate busbar built-in structure of the present disclosure can be applied to the main grid back contact battery assembly and the main grid back contact battery assembly, and has stronger universality, smaller stress during lamination of the intermediate busbar built-in structure, and can reduce the risk of battery piece hidden crack and fragment, and the reliability of the back contact battery assembly is good.

[0112] 4) The end busbar built-in structure of the present disclosure can increase the effective light receiving area of the battery assembly, improve the conversion efficiency of the assembly, and the area of the busbar observed from the light receiving side is smaller, and even can be completely hidden, the overall appearance of the battery assembly is better; on the other hand, it can ensure that the second solder strip A can be fully matched and welded with the effective welding position of the fifth battery piece, avoid the setting of the first busbar to cause insufficient welding of the second solder strip A and the fifth battery piece, and affect the current collection, and only one whole first insulating strip needs to be placed on the end of the sixth battery piece close to the fifth battery piece during assembly, at the same time, through the setting of the extension section, a certain degree of offset of the first insulating strip relative to the first busbar and the two battery pieces in the width direction can be allowed during the preparation process, effectively reducing the production precision requirement and production difficulty, and effectively reducing the short circuit risk; furthermore, the end busbar built-in structure of the present disclosure can be applied to the main grid back contact battery assembly and the main grid back contact battery assembly, and has stronger universality, smaller stress during lamination of the end busbar built-in structure, and can reduce the risk of battery piece hidden crack and fragment, and the reliability of the back contact battery assembly is good.

[0113] 5)The built-in structure of the middle busbar of the present disclosure can increase the effective light receiving area of the battery assembly, improve the conversion efficiency of the assembly, and the area of the busbar observed from the light receiving side is smaller, and even can be completely hidden, and the overall appearance of the battery assembly is better; on the other hand, it can ensure that the second solder strip B can be fully matched and welded with the effective welding position of the fourth battery piece, avoid the setting of the middle busbar to cause insufficient welding of the second solder strip B and the fourth battery piece, and affect the collection of current, and only the second insulating strip needs to be placed at one end of the third battery piece close to the fourth battery piece during assembly, and at the same time, through the setting of the extension section, the second insulating strip can be allowed to offset in the width direction relative to the middle busbar and the two battery pieces during the preparation process, effectively reducing the production precision requirement and production difficulty, and effectively reducing the short circuit risk; further, the built-in structure of the middle busbar of the present disclosure can be applied to the main grid back contact battery assembly and the main grid back contact battery assembly, and the universality is stronger, the stress is smaller when the built-in structure of the middle busbar is laminated, the risk of battery piece hidden crack and fragment can be reduced, and the reliability of the back contact battery assembly is good. BRIEF DESCRIPTION OF DRAWINGS

[0114] FIG. 1 is a structural schematic diagram of a back contact battery assembly provided by an embodiment of the present disclosure.

[0115] FIG. 2 is a schematic diagram of a cross-sectional structure of a back contact battery assembly provided by an embodiment of the present disclosure.

[0116] FIG. 3 is a schematic diagram of another cross-sectional structure of a back contact battery assembly provided by an embodiment of the present disclosure.

[0117] FIG. 4 is a schematic diagram of another structure of a back contact battery assembly provided by an embodiment of the present disclosure.

[0118] FIG. 5 is a schematic diagram of another structure of a back contact battery assembly provided by an embodiment of the present disclosure.

[0119] FIG. 6 is a schematic diagram of a photovoltaic system provided by an embodiment of the present disclosure.

[0120] FIG. 7 is a schematic diagram of a series battery string provided by an embodiment of the present disclosure.

[0121] FIG. 8 is a schematic diagram of a cross-sectional structure of an end busbar built-in structure provided by an embodiment of the present disclosure.

[0122] FIG. 9 is a schematic diagram of a battery string provided by an embodiment of the present disclosure.

[0123] FIG. 10 is a schematic diagram of another structure of a back contact battery assembly provided by an embodiment of the present disclosure.

[0124] Figure 11 is a schematic diagram of a structure of parallel battery string groups (adjacent battery pieces in the same plane) according to an embodiment of the present disclosure.

[0125] Figure 12 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0126] Figure 13 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0127] Figure 14 is a schematic diagram of a structure of series battery string groups (adjacent battery pieces exist in a stack) according to an embodiment of the present disclosure.

[0128] Figure 15 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0129] Figure 16 is a schematic diagram of a structure of parallel battery string groups (adjacent battery pieces exist in a stack) according to an embodiment of the present disclosure.

[0130] Figure 17 is a schematic diagram of a cross-sectional structure of a middle busbar built-in structure according to an embodiment of the present disclosure.

[0131] Figure 18 is a schematic diagram of another cross-sectional structure of a middle busbar built-in structure according to an embodiment of the present disclosure.

[0132] Figure 19 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0133] Figure 20 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0134] Figure 21 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0135] Figure 22 is a schematic diagram of another cross-sectional structure of an end busbar built-in structure according to an embodiment of the present disclosure.

[0136] Figure 23 is a schematic diagram of another cross-sectional structure of a middle busbar built-in structure according to an embodiment of the present disclosure.

[0137] Figure 24 is a schematic diagram of another cross-sectional structure of a middle busbar built-in structure according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0138] In order to make the purposes, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the drawings and embodiments. The examples of the embodiments are shown in the drawings, wherein the same or similar notations denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present disclosure, and should not be understood as limiting the present disclosure. In addition, it should be understood that the specific embodiments described herein are only used to explain the present disclosure and should not be used to limit the present disclosure.

[0139] In the description of the present disclosure, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present disclosure and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present disclosure.

[0140] In the description of the present disclosure, the terms "first", "second", "third", "fourth" and the like are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second", "third", "fourth" and the like can explicitly or implicitly include one or more of the features. In the description of the present disclosure, the meaning of "a plurality of" or "several" is two or more, unless otherwise explicitly specified and limited.

[0141] In the description of the present disclosure, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0142] In the present disclosure, unless explicitly specified and limited, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "under" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0143] The following disclosure provides many different embodiments or examples for implementing different structures of the present disclosure. In order to simplify the disclosure of the present disclosure, the components and arrangements of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present disclosure. In addition, the present disclosure can repeatedly refer to reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which in itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present disclosure provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0144] In the related art, the bus bar is exposed, which affects the appearance of the battery piece, and the bus bar reduces the light receiving area of the battery piece, and the power generation efficiency is poor. In the present disclosure, the bus bar is hidden behind the back light of the plurality of battery pieces, and the bus bar cannot be observed from the light receiving side, so that the overall color of the front surface of the back contact battery assembly is uniform and beautiful. At the same time, the insulating strip can be arranged between the bus bar and the battery piece to avoid short circuit problems.

[0145] Secondly, compared with arranging the bus bar at the middle position of the back of the battery piece, the bus bar of the present disclosure is arranged at one end of the first battery piece close to the second battery piece, and the second solder strip is arranged on the second battery piece. The second solder strip can fully match and weld with the effective welding position of the second battery piece, avoiding the installation of the bus bar to cause insufficient welding of the second solder strip with the second battery piece, which affects the collection of current. At the same time, after the second solder strip is welded with the second battery piece, it can be directly connected with the bus bar, without the need to process the insulating strip for hole opening or replace it with an insulating block arranged intermittently. During assembly, only the insulating strip needs to be placed at one end of the first battery piece close to the second battery piece, effectively reducing the production precision requirement and production difficulty, and avoiding short circuit caused by position deviation of the insulating strip during hole opening or position deviation of the insulating block during lamination, and increasing the product yield.

[0146] The present disclosure will be further described below in conjunction with the drawings and embodiments:

[0147] Embodiment one

[0148] Referring to FIG. 1, FIG. 2 and FIG. 3, the back contact battery assembly 1100 provided by the present disclosure includes a battery string 110, an insulation strip 120 and a bus bar 130, the battery string 110 includes a plurality of series-connected battery pieces 111, the plurality of battery pieces 111 are distributed along a first direction, the insulation strip 120 is arranged on the back light surface 1113 of the battery piece 111 along a second direction, wherein the first direction and the second direction are arranged intersectingly, the bus bar 130 is arranged on the side of the insulation strip 120 away from the battery piece 111 along the second direction, and the insulation strip 120 covers the surface of the side of the bus bar 130 close to the battery piece 111;

[0149] The battery string 110 includes a first battery piece 1111 and a second battery piece 1112 adjacent to each other, the insulation strip 120 is arranged on the back light surface 1113 of the first battery piece 1111, and the second solder strip 142 is connected to the second battery piece 1112 and the bus bar 130 respectively, and the insulation strip 120 blocks the second solder strip 142 and the first battery piece 1111.

[0150] In the embodiment, the insulation strip 120 and the bus bar 130 are both arranged along the second direction, wherein the insulation strip 120 covering the bus bar 130 means that the projection of the bus bar 130 is completely located inside the insulation strip 120 from the direction of the back light surface 1113 of the battery piece 111, or in other words, the insulation strip 120 can completely block the bus bar 130 from being exposed from the direction of the light receiving surface 1114 of the battery piece 111. At the same time, the bus bar 130 and the insulation strip 120 can be arranged on the back light surface 1113 of the battery piece 111, avoiding affecting the light receiving surface 1114 of the battery piece 111, so that the light receiving surface 1114 of the battery piece 111 is larger and the power generation efficiency is higher.

[0151] Wherein, the specifications of the first battery piece 1111 and the second battery piece 1112 can be the same or different, and the structures of the first battery piece 1111 and the second battery piece 1112 can be the same or different. The specific relationship between the first battery piece 1111 and the second battery piece 1112 is not limited herein.

[0152] It can be understood that the "first" and "second" in the first battery piece 1111 and the second battery piece 1112 are relative concepts, which refer to the difference between two back contact batteries. For example, in the examples of FIG. 2 and FIG. 3, the left back contact battery is marked as the first battery piece 1111, and the right back contact battery is marked as the second battery piece 1112.

[0153] The bus bar 130 is arranged on the first battery piece 1111, and the bus bar 130 and the first battery piece 1111 are separated by the insulating strip 120. On the one hand, the edge of the battery assembly does not need to reserve space for placing the bus bar 130, and the battery assembly can reserve more space for installing the battery piece 111, so that the effective light receiving area of the battery assembly is larger, and the conversion efficiency of the assembly is higher. On the other hand, from the light receiving surface direction of the battery piece 111, the insulating strip 120 can shield the bus bar 130, so as to avoid the exposure of the bus bar 130, and the overall appearance of the battery assembly is better. At the same time, the insulating strip 120 can be arranged between the bus bar 130 and the battery piece, so as to avoid the short circuit problem.

[0154] In addition, compared with arranging the bus bar at the middle position of the back surface of the battery piece, the bus bar 130 of the present disclosure is arranged at one end of the first battery piece 1111 close to the second battery piece 1112, and the second solder strip 142 is arranged on the second battery piece 1112. The second solder strip 142 can be fully matched and welded with the effective welding position of the second battery piece 1112, so as to avoid the insufficient welding of the second solder strip 142 and the second battery piece 1112 caused by the installation of the bus bar 130, thereby affecting the current collection. At the same time, after the second solder strip 142 is welded with the second battery piece 1112, the second solder strip 142 can be directly connected with the bus bar 130, without the need of opening holes in the insulating strip 120 or replacing the insulating strip 120 with an insulating block arranged in sections. During assembly, only the insulating strip 120 needs to be placed at one end of the first battery piece 1111 close to the second battery piece 1112, so as to effectively reduce the production precision requirement and production difficulty, and avoid the short circuit caused by the position deviation of the insulating strip 120 when the holes are opened or the position deviation of the insulating block when laminated, thereby increasing the product yield.

[0155] The insulating strip 120 of the present embodiment is a long strip similar in shape to the bus bar 130. Compared with the conventional insulating component which needs to be prepared by means of slotting, section distribution, punching and the like, the insulating strip 120 of the present embodiment has a simpler process and can save production time. The long strip-shaped insulating strip 120 also has the characteristics of simpler placement operation, lower requirement for fine operation of equipment, higher production yield and the like. In this way, the overall equipment and production cost of the whole back contact battery assembly 1100 can be minimized, and the assembly reliability is better.

[0156] Optionally, in the present embodiment, the bus bar 130 can be a middle bus bar located at the middle position of the battery string 110. The bus bar 130 can also be an end bus bar located at the end of the battery string 110. The specific position and specific form of the bus bar 130 are not limited here, so as to meet various needs.

[0157] In the embodiment, the plurality of back contact cells in the back contact cell assembly 1100 can be sequentially connected in series to form a cell string 110, so as to realize the series connection of the current output, for example, the series connection of the cell pieces 111 can be realized by means of the welding strip 140 (bus bar 130, interconnection strip), conductive back plate, etc.

[0158] It can be understood that in such an embodiment, the back contact cell assembly 1100 can further include a frame, a back plate, photovoltaic glass, and a film. The film can be filled between the front and back surfaces of the back contact cell and the photovoltaic glass, the adjacent cell pieces 111, etc., and can be a transparent adhesive with good light transmission performance and aging resistance, for example, the film can be an EVA film or a POE film, which can be selected according to actual conditions, and is not limited herein.

[0159] The photovoltaic glass can be covered on the film on the front surface of the back contact cell. The photovoltaic glass can be super white glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, the light transmittance of the super white glass can be more than 92%, which can protect the back contact cell without affecting the efficiency of the back contact cell as much as possible. Meanwhile, the film can bond the photovoltaic glass and the back contact cell together, and the presence of the film can seal and insulate the back contact cell and prevent water and moisture.

[0160] The back plate can be attached to the film on the back surface of the back contact cell. The back plate can protect and support the back contact cell, has reliable insulation, water resistance, and aging resistance, and can have multiple choices, which can be tempered glass, organic glass, aluminum alloy TPT composite film, etc., and can be set according to actual conditions, which is not limited herein. The whole of the back plate, the back contact cell, the film, and the photovoltaic glass can be arranged on the frame, which is the main external support structure of the whole back contact cell assembly 1100, and can stably support and install the back contact cell assembly 1100, for example, the back contact cell assembly 1100 can be installed at the desired installation position through the frame.

[0161] In one example, when the bus bar 130 is an end bus bar, the welding strip 140 to be welded with the bus bar 130 extends to the second last row of cell pieces 111, and the insulating strip 120 and the bus bar 130 are both arranged at the position of the second last row of cell pieces 111 close to the last row of cell pieces 111. The width of the insulating strip 120 is greater than the width of the bus bar 130. The edge of the insulating strip 120 exceeds the lamination gap and cannot cover the effective welding position of the last row of cell pieces 111.

[0162] In another example, when the busbar 130 is a middle busbar, the solder strip 140 to be welded with the busbar 130 extends to the second last row of the battery sheet 111 of the power generation unit, and the insulating strip 120 and the busbar 130 are both arranged at the position of the second last row of the battery sheet 111 close to the last row of the battery sheet 111. The width of the insulating strip 120 is greater than the width of the busbar 130. The edge of the insulating strip 120 exceeds the lamination gap, and cannot cover the effective welding position of the last row of the battery sheet 111.

[0163] It can be understood that in the battery string 110, the battery string 110 can include two battery sheets 111 in series, three battery sheets 111 in series, or other more battery sheets 111 in series, and the number of battery sheets 111 to be connected in series can be determined according to actual use.

[0164] In the embodiments of the present disclosure, the size and type of the busbar 130 and the insulating strip 120 are not limited, and only the insulating strip 120 needs to cover the busbar 130 to meet different needs.

[0165] Embodiment two

[0166] Referring to FIG. 1, in some optional embodiments, the insulating strip 120 covers the busbar 130 in the second direction, and the insulating strip 120 covers and exceeds the busbar 130 in the first direction.

[0167] In this way, the first direction and the second direction can determine the plane where the back surface 1113 of the battery sheet 111 is located, so that when the insulating strip 120 and the busbar 130 are attached to the back surface 1113 of the battery sheet 111, the insulating strip 120 can isolate the busbar 130 and the battery sheet 111 to which the insulating strip 120 is attached, to avoid short circuit between the two.

[0168] Embodiment three

[0169] Referring to FIG. 1, FIG. 2 and FIG. 3, in some optional embodiments, the back contact battery assembly 1100 further includes a solder strip 140, the solder strip 140 includes a first solder strip 141 and a second solder strip 142, the first solder strip 141 is used to connect adjacent battery sheets 111, and the second solder strip 142 is used to connect the battery sheet 111 and the busbar 130.

[0170] In the embodiments of the present disclosure, the solder strip 140 can be used to connect two adjacent battery pieces 111, and can also be used to connect an adjacent battery piece 111 and the bus bar 130. That is, the solder strip 140 used to connect two adjacent battery pieces 111 is the first solder strip 141, and the solder strip 140 used to connect a battery piece 111 and the bus bar 130 is the second solder strip 142. The first solder strip 141 is used to electrically connect adjacent battery pieces 111, and the first solder strip 141 is used to electrically connect adjacent battery pieces 111 and the bus bar 130.

[0171] Specifically, the solder strip 140 can include a copper core and a tin layer covering the copper core. The tin layer can cover all or part of the surface of the copper core. For example, the tin layer can cover all the surfaces of the copper core facing the battery piece 111 and all the surfaces of the copper core away from the battery piece 111, and not cover the side surface of the copper core. For another example, the tin layer covers all the surfaces of the copper core.

[0172] Optionally, in the embodiments of the present disclosure, the specific type of the tin layer is not limited to meet various needs. For example, the tin layer can be a tin single layer, and can also be a tin alloy layer. The tin alloy layer includes but is not limited to at least one of a SnPb layer, a SnBi layer, and a SnAg layer.

[0173] In addition, in the embodiments of the present disclosure, the size and type of the solder strip 140 are not limited to meet different needs.

[0174] Embodiment Four

[0175] Referring to FIGS. 2 and 3, in some optional embodiments, the second solder strip 142 is arranged on the side of the bus bar 130 away from the insulating strip 120, or the second solder strip 142 is arranged on the side of the bus bar 130 close to the insulating strip 120.

[0176] In one embodiment, the second solder strip 142 is arranged on the side of the bus bar 130 away from the insulating strip 120, so that it is more convenient to weld the second solder strip 142, and the end of the second solder strip 142 can be directly welded on the exposed surface of the bus bar 130.

[0177] In another embodiment, the second solder strip 142 is arranged on the side of the bus bar 130 close to the insulating strip 120, and at this time, the end of the second solder strip 142 can be clamped between the bus bar 130 and the insulating strip 120, so that the bus bar 130 can be more stably connected with the second solder strip 142. In addition, the second solder strip 142 is arranged on the side of the bus bar 130 close to the insulating strip 120, that is, the end of the second solder strip 142 is arranged between the bus bar 130 and the insulating strip 120, so that the height difference between the second solder strip 142 and the battery piece 111 is smaller, and the welding effect between the second solder strip 142 and the battery piece 111 is better.

[0178] Embodiment Five

[0179] Referring to FIG. 1, FIG. 2 and FIG. 3, in some alternative embodiments, the first cell sheet 1111 and the second cell sheet 1112 are at least partially laminated together.

[0180] In this way, the back contact battery assembly 1100 can have a larger light receiving surface 1114, and the gap between the first cell sheet 1111 and the second cell sheet 1112 does not expose the components such as the solder strip 140 and the bus bar 130.

[0181] In the embodiments of the present disclosure, the specific positions of the first cell sheet 1111 and the second cell sheet 1112 are not limited to meet different needs. In one embodiment, the edges of the first cell sheet 1111 and the second cell sheet 1112 are at least partially laminated together; in another embodiment, the second cell sheet 1112 can be spaced apart from the first cell sheet 1111. The spacing between the second cell sheet 1112 and the first cell sheet 1111 is within a suitable range, which can avoid the small operating space and the difficulty of welding caused by too small spacing, and can also avoid the waste of component space and the increase of cost caused by too large spacing.

[0182] Embodiment six

[0183] Referring to FIG. 1 and FIG. 2, in some alternative embodiments, when the back light surface 1113 of the first cell sheet 1111 and the light receiving surface 1114 of the second cell sheet 1112 are at least partially laminated together, the insulating strip 120 is at least partially connected to the back light surface 1113 of the second cell sheet 1112.

[0184] In this embodiment, the back light surface 1113 of the first cell sheet 1111 and the light receiving surface 1114 of the second cell sheet 1112 are laminated together, so that there is no gap between the first cell sheet 1111 and the second cell sheet 1112. The insulating strip 120 is arranged on the back light surface 1113 of the first cell sheet 1111, and the edge portion of the insulating strip 120 close to the second cell sheet 1112 is attached to the back light surface 1113 of the second cell sheet 1112. At this time, the solder strip 140 located on the back light surface 1113 of the second cell sheet 1112 can be blocked by the insulating strip 120, so that the solder strip 140 can be stably connected with the bus bar 130, and the short circuit between the first cell sheet 1111 and the solder strip 140 or the bus bar 130 is avoided.

[0185] In other embodiments, the light receiving surface 1114 of the first cell sheet 1111 and the back light surface 1113 of the second cell sheet 1112 can also be at least partially laminated together, which is not limited here.

[0186] Embodiment seven

[0187] Referring to FIG. 1, FIG. 4 and FIG. 5, in some optional embodiments, the battery piece 111 is rectangular, and the battery piece 111 further comprises a chamfered edge 1115 and a cut edge 1116, both of which are distributed on two sides of the battery piece 111 along a first direction, and the first direction and the second direction are perpendicular.

[0188] The insulation strip 120 and the bus bar 130 can both be rectangular, at this time, the first direction and the second direction can be perpendicular directions, so that the small rectangle of the bus bar 130 is located inside the large rectangle of the insulation strip 120. The battery piece 111 can comprise parallel chamfered edges 1115 and cut edges 1116, and the extension directions of the chamfered edges 1115 and the cut edges 1116 are both the second direction, and the chamfered edge 1115 is an edge with chamfers at both ends.

[0189] In the embodiments of the present disclosure, the positions of the chamfered edges 1115 and the cut edges 1116 are not limited to meet different needs. In one embodiment, the battery piece 111 can be distributed up and down, that is, the first direction is a vertical up-and-down direction, at this time, the battery piece 111 can be distributed in a form that the chamfered edge 1115 is on the top and the cut edge 1116 is on the bottom; or the battery piece 111 can be distributed in a form that the cut edge 1116 is on the top and the chamfered edge 1115 is on the bottom.

[0190] In the present embodiment, the preparation process of the battery piece 111 is not limited to meet different needs. For example, the battery piece 111 can be cut from a large rectangular battery piece 111, and chamfers can be formed on the four corners before cutting, and then cut along the middle position to form two shaped battery pieces 111, which have parallel chamfered edges 1115 and cut edges 1116.

[0191] Embodiment Eight

[0192] Referring to FIG. 4 and FIG. 5, in some optional embodiments, in the first direction, the chamfered edge 1115 of the battery piece 111 is arranged together with the chamfered edge 1115 of the adjacent battery piece 111, and the cut edge 1116 of the battery piece 111 is arranged together with the cut edge 1116 of the adjacent battery piece 111; or

[0193] In the first direction, the chamfered edge 1115 of the battery piece 111 is arranged together with the cut edge 1116 of the adjacent battery piece 111, and the cut edge 1116 of the battery piece 111 is arranged together with the chamfered edge 1115 of the adjacent battery piece 111.

[0194] In one embodiment, the adjacent battery pieces 111 are symmetrically arranged, and in the direction from left to right, the first battery piece 111 has the chamfered edge 1115 placed on the left side and the cut edge 1116 placed on the right side; the first battery piece 111 has the cut edge 1116 placed on the left side and the chamfered edge 1115 placed on the right side; the third battery piece 111 has the chamfered edge 1115 placed on the left side and the cut edge 1116 placed on the right side, and so on. In this way, the battery piece 111 is easier to position, and the position of the welding strip 140, the bus bar 130 and the insulating strip 120 can be determined according to the placement direction of the battery piece 111.

[0195] In another embodiment, the battery pieces 111 are placed in the same way, and in the direction from left to right, the chamfered edge 1115 is placed on the left side and the cut edge 1116 is placed on the right side. The plurality of battery pieces 111 are sequentially overlapped together, and at this time, the cut edge 1116 of the left side battery piece 111 is arranged together with the chamfered edge 1115 of the adjacent right side battery piece 111. Of course, in this embodiment, left and right are relative concepts, and the chamfered edge 1115 can also be placed on the right side and the cut edge 1116 can be placed on the left side. In this way, the installation of the battery piece 111 is more convenient.

[0196] Example Nine

[0197] In one embodiment, as shown in FIG. 4, the chamfered edge 1115 of the battery piece 111 is stacked on the back light surface on the side of the cut edge 1116 of the adjacent battery piece 111, and the chamfered edge 1115 of the above-mentioned adjacent battery piece 111 is stacked on the back light surface 1113 on the side of the cut edge 1116 of the other battery piece 111 adjacent thereto.

[0198] That is, from the direction of the light receiving surface of the battery piece 111, the chamfered edge 1115 of any battery piece 111 is stacked on the back light surface on the side of the cut edge 1116 of the battery piece 111 adjacent thereto.

[0199] As the battery assembly is in the laminating process, the compression direction of the battery assembly is from the back light surface 1113 of the battery piece 111 to the light receiving surface 1114. When the adjacent battery pieces 111 are locally stacked on each other, if the cutting edge 1116 side of the battery piece 111 is pressed on the back light surface 1113 of the chamfered edge 1115 of the adjacent battery piece 111, the area of the cutting edge 1116 side of the battery piece 111 pressed on the upper side at the corner position will be in a suspended state due to the lack of support from the lower side. In the laminating process, the battery piece 111 will be unevenly stressed, which will increase the risk of battery piece 111 fragmentation, hidden cracks, etc. By stacking the chamfered edge 1115 of the battery piece 111 on the back light surface of the cutting edge 1116 side of the adjacent battery piece 111, and stacking the chamfered edge 1115 of the adjacent battery piece 111 on the back light surface 1113 of the cutting edge 1116 side of the battery piece 111, the chamfered edge 1115 of the battery piece 111 pressed on the upper side is evenly stressed, and there is no suspended area, which can effectively reduce the risk of such fragmentation, hidden cracks, etc., and improve the yield of the product and the reliability of the battery assembly.

[0200] Example Ten

[0201] Referring to FIG. 6, the photovoltaic system 1200 provided by the embodiments of the present disclosure includes the back contact battery assembly 1100 of any of the above embodiments.

[0202] In the back contact battery assembly 1100 and the photovoltaic system 1200 of the embodiments of the present disclosure, the back contact battery assembly 1100 includes a battery string 110, an insulating strip 120, and a busbar 130. The battery string 110 includes a plurality of battery pieces 111 connected in series, and the plurality of battery pieces 111 are distributed along a first direction. The insulating strip 120 is arranged on the back light surface 1113 of the battery piece 111 along a second direction, wherein the first direction and the second direction are arranged at an intersection. The busbar 130 is arranged on the side of the insulating strip 120 away from the battery piece 111 along the second direction, and the insulating strip 120 covers the busbar 130. In this way, the busbar 130 is hidden behind the back light surface 1113 of the plurality of battery pieces 111, and the busbar 130 cannot be observed from the light receiving surface 1114 side, so that the overall front surface of the back contact battery assembly 1100 is uniformly and aesthetically colored. At the same time, the insulating strip 120 can be arranged between the busbar 130 and the battery piece 111 to avoid short circuit problems.

[0203] In the embodiment, the photovoltaic system 1200 can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus that generates power by using solar energy, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system 1200 are not limited to this, that is, the photovoltaic system 1200 can be applied in all fields that need to generate power by using solar energy. Taking a photovoltaic power generation system network as an example, the photovoltaic system 1200 can include a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of cell assemblies, for example, a plurality of cell assemblies can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected to the combiner box, the combiner box can combine the currents generated by the photovoltaic arrays, the combined currents flow through the inverter to convert into alternating current required by a power grid, and then the alternating current is connected to a power network to realize solar power supply.

[0204] Embodiment eleven

[0205] Referring to FIGS. 7-9, the embodiment discloses a back contact cell assembly, comprising:

[0206] a cell string, the cell string comprising cell pieces connected in series with each other, the cell pieces comprising a fifth cell piece 211 and a sixth cell piece 212 arranged along a first direction, wherein the fifth cell piece 211 is arranged at an end of the cell string;

[0207] a first insulating strip 221 arranged at one end of the sixth cell piece 212 close to the fifth cell piece 211;

[0208] a first bus bar 231 arranged at a side of the first insulating strip 221 away from the sixth cell piece 212 (i.e., the back of the first insulating strip 221, and vice versa, the side of the first insulating strip 221 facing the sixth cell piece 212 is the front of the first insulating strip 221), the first insulating strip 221 and the first bus bar 231 are both arranged extending along a second direction, and the first direction and the second direction are arranged intersecting each other;

[0209] a second solder strip A 241 for electrically connecting the first bus bar 231 and the fifth cell piece 211;

[0210] wherein in the first direction, both ends of the first insulating strip 221 are provided with a first widened section 2211 and a second widened section 2212 extending out of the edge of the first bus bar 231, the first widened section 2211 and the second widened section 2212 are arranged in sequence in a direction away from the fifth cell piece 211, and the width of the second widened section 2212 is smaller than the width of the first widened section 2211.

[0211] It can be understood that the electrical connection mode can be welding, bonding through conductive glue, etc., but is not limited thereto.

[0212] It can be understood that in the battery string, the battery string can include two battery pieces in series, three battery pieces in series, or other more battery pieces in series, and the number of battery pieces in series can be determined according to actual use.

[0213] In the present disclosure, the first bus bar 231 is an end bus bar, and the fifth battery piece 211 is located at the end of the battery string. For the convenience of description, in the present disclosure, the end where the fifth battery piece 211 is located is recorded as the tail end of the battery string, that is, in the first direction, the fifth battery piece 211 is the last battery piece of the battery string, and the sixth battery piece 212 is the second last battery piece of the battery string. It is not difficult to understand that the end where the fifth battery piece 211 is located can also be recorded as the head end of the battery string, which will not be described here.

[0214] Optionally, in the same battery string, adjacent battery pieces can be connected in series by means of welding strips, conductive glue, etc.

[0215] In an embodiment, adjacent battery pieces are connected by a series welding strip 251 (in other embodiments, for example, in embodiment one, it is referred to as a "first welding strip"). Specifically, the series welding strip 251 includes a first series welding strip 2511 and a second series welding strip 2512. In the first direction, the first series welding strip 2511 and the second series welding strip 2512 are arranged alternately, and in the second direction, the first series welding strip 2511 and the second series welding strip 2512 are arranged alternately. In a battery string, the Nth battery piece, the N+1th battery piece, and the N+2th battery piece (N is a positive integer greater than 1) are arranged in the first direction in sequence, wherein the positive electrode welding point of the Nth battery piece and the negative electrode welding point of the N+1th battery piece are connected in series by a plurality of first series welding strips 2511, and the positive electrode welding point of the N+1th battery piece and the negative electrode welding point of the N+2th battery piece are connected in series by a plurality of second series welding strips 2512.

[0216] During assembly, each battery piece in the battery string is connected in series with each other, the first insulating strip 221 is arranged at one end of the sixth battery piece 212 close to the fifth battery piece 211, the first bus bar 231 is arranged at the back of the first insulating strip 221, the main body of the second welding strip A 241 is electrically connected with the effective welding position of the fifth battery piece 211, and one end of the second welding strip A 241 close to the sixth battery piece 212 is electrically connected with the first bus bar 231, so that the first bus bar 231 can lead out the current of the battery string.

[0217] Firstly, in the present disclosure, the first bus bar 231 is arranged on the sixth cell piece 212, and the first bus bar 231 and the sixth cell piece 212 are separated by the first insulation strip 221. On the one hand, the edge of the battery assembly does not need to reserve space for placing the bus bar, and the battery assembly can reserve more space for installing the cell piece, so that the effective light receiving area of the battery assembly is larger, and the conversion efficiency of the assembly is higher. On the other hand, from the direction of the light receiving surface (or "front surface") of the cell piece, the first insulation strip 221 can shield the first bus bar 231 to avoid the first bus bar 231 from being exposed, and the overall appearance of the battery assembly is better.

[0218] Secondly, compared with arranging the bus bar at the middle position of the back surface of the cell piece, the first bus bar 231 of the present disclosure is arranged at one end of the sixth cell piece 212 close to the fifth cell piece 211, and the second solder strip A 241 can fully match and weld with the effective welding position of the fifth cell piece 211, avoiding the installation of the first bus bar 231 to cause insufficient welding of the second solder strip A 241 with the fifth cell piece 211, thereby affecting the collection of current. At the same time, after the second solder strip A 241 is welded with the fifth cell piece 211, it can be directly connected with the first bus bar 231, without the need of punching the insulation strip or replacing it with an intermittently arranged insulation block. During assembly, only the first insulation strip 221 needs to be placed at one end of the sixth cell piece 212 close to the fifth cell piece 211, effectively reducing the production precision requirement and production difficulty, and avoiding short circuit caused by position deviation when the insulation strip is punched or position deviation when the insulation block is laminated, thereby increasing the product yield.

[0219] Meanwhile, the first insulation strip 221 of the present disclosure is provided with a first widened section 2211 and a second widened section 2212, that is, the first insulation strip 221 has a widened section beyond the edge of the first bus bar 231 on both sides in the first direction. The provision of the first widened section 2211 and the second widened section 2212, on the one hand, allows the first insulation strip 221 to have a certain degree of offset in the width direction relative to the first bus bar 231 and the two battery pieces during preparation, thereby reducing the production precision requirement and production difficulty; on the other hand, the second widened section 2212 of the first insulation strip 221 of the present disclosure is smaller than the first widened section 2211, that is, in the first direction, the first bus bar 231 is offset relative to the first insulation strip 221, rather than being centrally symmetric, which forms a relatively wide first widened section 2211 and a relatively narrow second widened section 2212. The relatively wide first widened section 2211 is conducive to covering more area of the edges of the fifth battery piece 211 and the sixth battery piece 212, thereby better reducing the risk of short circuit caused by the contact between the first bus bar 231 and the heterogeneous solder strip or heterogeneous grid line on the fifth battery piece 211, the risk of short circuit caused by the contact between the second solder strip A241 and the heterogeneous solder strip or heterogeneous grid line of the sixth battery piece 212, and the risk of short circuit caused by the conductive foreign matter such as tin dross during preparation, thereby improving the reliability of the battery assembly. The relatively narrow second widened section 2212 can reduce the influence of the second widened section 2212 on the double-sided rate of the battery assembly while ensuring the above-mentioned reduction in production precision requirement and short circuit risk, thereby ensuring that the battery assembly has a high double-sided rate.

[0220] Furthermore, when the bus bar is arranged at the outer edge of the last battery piece of the battery string, that is, at the end of the fifth battery piece 211 away from the sixth battery piece 212, since the outer edge of the last battery piece of the battery string is close to the edge of the battery assembly, the stress at this position is large during lamination, which is prone to produce fragments and other defects. Meanwhile, the installation of the bus bar can affect the welding between the second solder strip A241 and the fifth battery piece 211. The second solder strip A241 cannot be welded to the fifth battery piece 211 at the position covered by the bus bar, which results in insufficient welding between the second solder strip A241 and the fifth battery piece 211, poor current collection, and this situation is particularly serious when the battery assembly is a back contact battery assembly without a main grid.

[0221] In contrast, the built-in structure of the end bus bar of the present disclosure can be applied to back contact battery assemblies with a main grid and back contact battery assemblies without a main grid, and has stronger universality. Moreover, the end of the sixth battery piece 212 close to the fifth battery piece 211 has smaller stress during lamination than the outer edge of the last battery piece of the battery string, which can reduce the risk of fragments and cracks, thereby further improving the reliability of the battery assembly.

[0222] In some embodiments, referring to FIG. 8, the first widened section 2211 extends at least partially beyond the edge of the sixth cell piece 212. Thus, on the basis of allowing a certain degree of offset in the width direction in the preparation process of the first insulating strip 221 relative to the first bus bar 231 and the first insulating strip 221 relative to two cell pieces, it can also ensure that the first widened section 2211 can cover more area of the edge of the fifth cell piece 211 and the edge of the sixth cell piece 212, thereby reducing the risk of short circuit caused by contact between the first bus bar 231, the second solder strip A 241 and the heterogeneous solder strip or heterogeneous grid line, and improving the reliability of the battery assembly.

[0223] In some embodiments, referring to FIG. 8, in the first direction, the orthogonal projection of the first widened section 2211 in the thickness direction of the sixth cell piece 212 at least partially overlaps the orthogonal projection of the fifth cell piece 211 in the thickness direction of the sixth cell piece 212.

[0224] Thus, the first insulating strip 221 can cover the edges of the sixth cell piece 212 and the fifth cell piece 211, which not only can avoid short circuit caused by contact between the first bus bar 231 and the heterogeneous solder strip or heterogeneous grid line on the fifth cell piece 211, but also can avoid short circuit caused by contact between the second solder strip A 241 and the heterogeneous solder strip or heterogeneous grid line of the sixth cell piece 212, further reducing the risk of short circuit.

[0225] Especially when the cell piece is cut into a half piece, the cutting edge is extremely easy to cause short circuit after cutting. The arrangement of the first widened section 2211 of the present disclosure can effectively avoid short circuit caused by the cutting edge, so that the cutting edge of the battery half piece is arranged on the side of the first bus bar 231 of the cell piece or the side of the adjacent cell piece close to the first bus bar 231, and the reliability of the battery assembly can also be ensured.

[0226] In some embodiments, referring to FIG. 8, optionally, in the first direction, the width D2 of the second widened section 2212 is ≥1mm.

[0227] When the second widened section 2212 is too small, the amount of offset allowed by the first insulating strip 221 in the preparation process is small, thereby resulting in the need to improve the production precision requirement. When the width of the second widened section 2212 of the present embodiment is controlled to be ≥1mm, sufficient offset space can be reserved for the horizontal tolerance of the equipment placement in the preparation process and the tolerance of the bus bar offset in the lamination process, thereby reducing the production precision requirement.

[0228] In some embodiments, referring to FIG. 8, the fifth cell piece 211 and the sixth cell piece 212 are arranged on the same plane, wherein 1mm 11 +l 12 +l 13

[0229] D1 is the width of the first widened section 2211 in the first direction, l 11 l is the relative width distance between the first bus bar 231 and the edge of the fifth cell tab 211 close to the sixth cell tab 212 in the first direction, l 12 l is the distance between the fifth cell tab 211 and the sixth cell tab 212, l 13 l is the relative width distance between the edge of the fifth cell tab 211 close to the sixth cell tab 212 and the first soldering point 261, the first soldering point 261 is arranged on the fifth cell tab 211 close to the sixth cell tab 212 for connecting with the second soldering tape A 241.

[0230] It can be understood that, l 11 + l 12 > 1 mm, l 11 < 1 mm, therefore, controlling D1 > 1 mm, can reserve enough offset space for the equipment placement horizontal tolerance in the preparation process and the tolerance of bus bar offset in the lamination process, thereby allowing a small amount of offset in the width direction of the first insulating strip 221 relative to the first bus bar 231 and the first insulating strip 221 relative to the two cell tabs.

[0231] It can be understood that the first soldering point 261 is located on the edge of the fifth cell tab 211 closest to the sixth cell tab 212 (i.e. the most edge connection point of the second soldering tape A 241 on the fifth cell tab 211), and the first soldering point 261 can be a grid line, a soldering pad, but is not limited thereto.

[0232] When the width of the first widened section 2211 is too small, the short circuit risk increases and the reliability of the battery assembly decreases, as the width of the first widened section 2211 increases, the reliability of the battery assembly increases, the displacement deviation of the first insulating strip 221 relative to the first bus bar 231 and the first insulating strip 221 relative to the two cell tabs in the width direction is increased in the preparation process, and the production precision requirement is reduced, but when the width of the first widened section 2211 is too large, it will affect the sufficient welding between the second soldering tape A 241 and the effective welding position on the fifth cell tab 211, the current collection effect decreases, and it will affect the double-sided rate of the battery assembly, in the embodiment, control 1 mm < D1 ≤ l 11 + l 12 + l 13, ensure that there is a certain offset in the preparation of the first insulating strip 221, on the basis of which the first widened section 2211 of the first insulating strip 221 can still be guaranteed to extend more to cover the edge region of the fifth cell piece 211 and the edge region of the sixth cell piece 212, further improving the reliability and production yield of the battery assembly, reducing the production precision requirement, at the same time, can avoid affecting the sufficient welding between the second welding strip A241 and the effective welding position on the fifth cell piece 211, and will not cause unnecessary material waste and double-sided rate loss.

[0233] In one embodiment, in the first direction, the first bus bar 231 extends to the edge of the sixth cell piece 212 outside the one end of the fifth cell piece 211.

[0234] In another embodiment, as shown in FIG. 8, in the first direction, the orthographic projection of the first bus bar 231 in the thickness direction of the sixth cell piece 212 falls within the sixth cell piece 212, that is, the first bus bar 231 is arranged within the edge of the sixth cell piece 212.

[0235] In some embodiments, as shown in FIGS. 7, 9 and 10, the battery assembly includes at least one series cell string group 2100, which includes two cell strings arranged in the second direction and connected in series with each other in the same series cell string group 2100, and in the same series cell string group 2100, the same first bus bar 231 extends from the sixth cell piece 212 in one cell string to the sixth cell piece 212 of another cell string.

[0236] Optionally, the second welding strip A241 includes a first positive electrode welding strip 2411 and a first negative electrode welding strip 2412, the same first bus bar 231 is electrically connected with the first positive electrode welding strip 2411 in one cell string and electrically connected with the first negative electrode welding strip 2412 in another cell string, so as to form series connection between adjacent cell strings.

[0237] For example, the same series cell string group 2100 includes a first cell string 210A and a second cell string 210B, the second welding strip A241 includes a first positive electrode welding strip 2411 and a first negative electrode welding strip 2412, in the same series cell string group 2100, the same first bus bar 231 extends from the sixth cell piece 212 in the first cell string 210A to the sixth cell piece 212 of the second cell string 210B, and in the first cell string 210A, the first bus bar 231 is electrically connected with the first positive electrode welding strip 2411 on the fifth cell piece 211, and in the second cell string 210B, the first bus bar 231 is electrically connected with the first negative electrode welding strip 2412 on the fifth cell piece 211.

[0238] In one embodiment, the battery assembly includes a parallel battery string group 2200, the same parallel battery string group 2200 includes at least two battery strings arranged in the first direction and arranged in parallel with each other, and a spacing area is arranged between the two battery strings arranged in parallel with each other, and the spacing area is provided with an intermediate busbar 232, and the intermediate busbar 232 is used to connect the two battery strings arranged adjacent in the first direction in parallel, that is, the end busbar built-in structure of the present disclosure can cooperate with the conventional intermediate busbar 232 mounting structure.

[0239] In another embodiment, as shown in FIGS. 10 and 11, each battery string is provided with a fourth cell tab 214 away from one end of the fifth cell tab 211, and the fourth cell tab 214 is provided with a third cell tab 213 close to one end of the fifth cell tab 211;

[0240] The back contact battery assembly further includes:

[0241] A second insulating strip 222 is arranged at the edge of the third cell tab 213 in a battery string, and the second insulating strip 222 is arranged at one end of the third cell tab 213 close to the fourth cell tab 214;

[0242] An intermediate busbar 232 is used to connect two battery strings arranged adjacent in the first direction in parallel, and the intermediate busbar 232 is arranged at the side of the second insulating strip 222 away from the third cell tab 213, and the second insulating strip 222 and the intermediate busbar 232 are arranged in extension in the second direction;

[0243] The second solder strip B242 is used to electrically connect the intermediate busbar 232, the fourth cell tab 214 in the battery string, and the fourth cell tab 214 in another battery string adjacent to the battery string in the first direction.

[0244] For example, for the convenience of description, the third battery string 220A and the fourth battery string 220B in the same parallel battery string group 2200 are taken as an example, wherein the third battery string 220A is the battery string where the intermediate busbar 232 is located.

[0245] The third cell tab 213 in the third battery string 220A is denoted as the third cell tab 213A, and the fourth cell tab 214 is denoted as the fourth cell tab 214A. The third cell tab 213 in the fourth battery string 220B is denoted as the third cell tab 213B, and the fourth cell tab 214 is denoted as the fourth cell tab 214B. The third battery string 220A and the fourth battery string 220B are arranged in the first direction, and the fourth cell tab 214A and the fourth cell tab 214B are arranged adjacent in the first direction;

[0246] The back contact battery assembly further includes:

[0247] The second insulation strip 222 is arranged at the edge of the third cell tab 213A in the third cell string 220A, and the second insulation strip 222 is arranged at one end of the third cell tab 213A close to the fourth cell tab 214A;

[0248] The intermediate busbar 232 is used to connect the third cell string 220A and the fourth cell string 220B in parallel, and the intermediate busbar 232 is arranged at the side of the second insulation strip 222 away from the third cell tab 213. Both the second insulation strip 222 and the intermediate busbar 232 are arranged in the second direction;

[0249] The second welding strip B242 is used to electrically connect the intermediate busbar 232, the fourth cell tab 214A and the fourth cell tab 214B, that is, the same second welding strip B242 extends from the fourth cell tab 214B to the fourth cell tab 214A and the intermediate busbar 232 in sequence.

[0250] Optionally, the second welding strip B242 includes a second positive electrode welding strip 2421 and a second negative electrode welding strip 2422, and the fourth cell tab 214A, the fourth cell tab 214B and the intermediate busbar 232 are electrically connected by the second positive electrode welding strip 2421 or the second negative electrode welding strip 2422.

[0251] On the one hand, the intermediate busbar 232 built-in structure of the present disclosure can increase the effective light receiving area of the battery module, improve the conversion efficiency of the module, avoid the exposure of the intermediate busbar 232, and make the overall appearance of the battery module better. On the other hand, it can ensure that the second welding strip B242 can fully match and weld with the effective welding position of the fourth cell tab 214, avoid the installation of the intermediate busbar 232 causing insufficient welding of the second welding strip B242 and the fourth cell tab 214, and affect the current collection. When assembling, only the first insulation strip 221 needs to be placed at one end of the third cell tab 213 close to the fourth cell tab 214. Furthermore, the intermediate busbar 232 built-in structure of the present disclosure can be applied to the main grid back contact battery module and the non-main grid back contact battery module, and has stronger universality, smaller stress when laminating, and can reduce the risk of cell tab cracking and fragmentation, and the reliability of the back contact battery module is good.

[0252] The end busbar built-in structure of the present disclosure cooperates with the intermediate busbar 232 built-in structure of the present disclosure to increase the effective light receiving area of the battery module, improve the conversion efficiency of the module, and make the overall appearance and reliability of the battery module better. It effectively reduces the production precision requirement and production difficulty, and improves the production efficiency.

[0253] In some embodiments, referring to FIG. 10 and FIG. 11, in the first direction, the two ends of the second insulation strip 222 are provided with a first extension segment 2221 and a second extension segment 2222 extending out of the edge of the middle bus bar 232, the first extension segment 2221 and the second extension segment 2222 are sequentially arranged in the direction away from the fourth cell tab 214, the first extension segment 2221 at least partially extends out of the edge of the third cell tab 213, and the width of the second extension segment 2222 is smaller than the width of the first extension segment 2221.

[0254] By providing the first extension segment 2221 and the second extension segment 2222 of the second insulation strip 222, on the one hand, it allows the second insulation strip 222 to have a certain degree of offset in the width direction relative to the middle bus bar 232 and the two cell tabs during the manufacturing process, thereby reducing the production precision requirement and production difficulty; on the other hand, a relatively wide first extension segment 2221 and a relatively narrow second extension segment 2222 are formed on the second insulation strip 222, wherein the relatively wide first extension segment 2221 is conducive to covering more areas of the edge of the fourth cell tab 214A and the edge of the third cell tab 213A, thereby better reducing the risk of short circuit caused by the contact between the middle bus bar 232 and the heterogeneous solder strip or heterogeneous grid line on the fourth cell tab 214A, and the risk of short circuit caused by the contact between the second solder strip B242 and the heterogeneous solder strip or heterogeneous grid line of the third cell tab 213A, thereby improving the reliability of the battery assembly.

[0255] In some embodiments, referring to FIG. 10, the battery assembly further includes a front plate, and the battery string is arranged on the front plate, the front plate is arranged with a first edge 271 and a second edge 272 in the second direction, and the orthogonal projection of the first insulation strip 221 in the thickness direction of the sixth cell tab 212 falls between the first edge 271 and the second edge 272.

[0256] If the first insulation strip 221 exceeds the first edge 271 or the second edge 272, the material layers such as the adhesive film, the front plate, and the back plate of the battery assembly cannot be fully compounded, especially in the edge area, which causes external moisture to easily enter the inside of the battery assembly, thereby affecting the reliability of the battery assembly.

[0257] The embodiment also discloses a photovoltaic system including the back contact battery assembly.

[0258] Embodiment Twelve

[0259] The difference between this embodiment and embodiment eleven is that, as shown in FIGS. 12-14, the sixth cell piece 212 is at least partially laminated with the fifth cell piece 211 near one end of the fifth cell piece 211, that is, the fifth cell piece 211 and the sixth cell piece 212 are arranged in a laminated manner, and there is no gap between the two cells. Here, 1mm < D1≤ l 21 +l 23 -l 22

[0260] where D1 is the width of the first widened section 2211 in the first direction, l 21 is the relative width distance between the first bus bar 231 and the edge of the sixth cell piece 212 near the fifth cell piece 211 in the first direction, l 22 is the width of the laminated region between the fifth cell piece 211 and the sixth cell piece 212 in the first direction, l 23 is the relative width distance between the edge of the fifth cell piece 211 near the sixth cell piece 212 and the first solder point 261, and the first solder point 261 is arranged at the edge of the fifth cell piece 211 near the sixth cell piece 212 and is used to connect with the second solder strip A241.

[0261] In one embodiment, as shown in FIG. 12, the side of the sixth cell piece 212 facing away from the first insulating strip 221 is at least partially laminated with the fifth cell piece 211.

[0262] In another embodiment, as shown in FIG. 13, the side of the sixth cell piece 212 facing the first insulating strip 221 is at least partially laminated with the fifth cell piece 211.

[0263] It can be understood that, l 21 +l 22 >1mm, l 21 <1mm, so that D1>1mm is controlled, which can ensure that the first widened section 2211 can extend to cover the edge region of the fifth cell piece 211 and the edge region of the sixth cell piece 212, while reserving sufficient offset space for the equipment placement horizontal tolerance in the preparation process and the tolerance of the bus bar offset in the lamination process, thereby allowing a small degree of offset of the first insulating strip 221 relative to the first bus bar 231 and the first insulating strip 221 relative to the two cell pieces in the width direction.

[0264] When the width of the first widened section 2211 is too small, the short circuit risk increases, the reliability of the battery assembly decreases, and as the width of the first widened section 2211 increases, the reliability of the battery assembly increases, the displacement deviation of the first insulating strip 221 relative to the first bus bar 231 and the first insulating strip 221 relative to the two battery pieces in the width direction during the preparation process is increased, and the production precision requirement is reduced, but when the width of the first widened section 2211 is too large, it will affect the sufficient welding between the second solder strip A 241 and the effective welding position on the fifth battery piece 211, the current collection effect decreases, and it will affect the double-sided rate of the battery assembly. In the embodiment, 1mm < D1 ≤ l 21 +l 22 +l 23 , on the basis of allowing a certain offset during the preparation of the first insulating strip 221, it is still possible to ensure that the first widened section 2211 of the first insulating strip 221 can extend to cover the edge region of the fifth battery piece 211 and the edge region of the sixth battery piece 212, further improving the reliability and production yield of the battery assembly, reducing the production precision requirement, at the same time, it can avoid affecting the sufficient welding between the second solder strip A 241 and the effective welding position on the fifth battery piece 211, and will not cause unnecessary material waste and double-sided rate loss.

[0265] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the back contact battery described above can refer to the corresponding structure and implementation principle in the foregoing embodiment thirteen, which will not be repeated here.

[0266] Embodiment thirteen

[0267] Referring to FIGS. 11 and 15, the present embodiment discloses a back contact battery assembly, comprising:

[0268] The parallel battery string group 2200 includes at least two battery strings arranged along the first direction and arranged in parallel with each other, each battery string including battery pieces connected in series with each other, the battery pieces connected in series with each other including a third battery piece 213 and a fourth battery piece 214 arranged along the first direction, the fourth battery piece 214 being arranged at an end of the battery string, and the fourth battery pieces 214 in the two battery strings arranged in parallel with each other being arranged adjacent to each other in the first direction;

[0269] The second insulating strip 222 is arranged at the edge of the third battery piece 213 in a battery string, and the second insulating strip 222 is arranged at one end of the third battery piece 213 close to the fourth battery piece 214;

[0270] The intermediate bus bar 232 is used to connect two battery strings arranged adjacent to each other in the first direction in parallel, and the intermediate bus bar 232 is arranged on the side of the second insulation strip 222 away from the third battery sheet 213, and the second insulation strip 222 and the intermediate bus bar 232 are arranged in extension in the second direction;

[0271] The second welding strip B242 is used to electrically connect the intermediate bus bar 232, the fourth battery sheet 214 in the battery string where the intermediate bus bar 232 is located, and the fourth battery sheet 214 in another battery string adjacent to the battery string in the first direction;

[0272] Wherein, in the first direction, the two ends of the second insulation strip 222 are provided with a first extension segment 2221 and a second extension segment 2222 extending to the outside of the edge of the intermediate bus bar 232, and the first extension segment 2221 and the second extension segment 2222 are arranged in sequence in the direction away from the fourth battery sheet 214, and the width of the second extension segment 2222 is smaller than the width of the first extension segment 2221.

[0273] For example, for the convenience of description, the third battery string 220A and the fourth battery string 220B in the same parallel battery string group 2200 are taken as an example, wherein the third battery string 220A is the battery string where the intermediate bus bar 232 is located;

[0274] The third battery sheet 213 in the third battery string 220A is denoted as the third battery sheet 213A, and the fourth battery sheet 214 is denoted as the fourth battery sheet 214A. The third battery sheet 213 in the fourth battery string 220B is denoted as the third battery sheet 213B, and the fourth battery sheet 214 is denoted as the fourth battery sheet 214B. The third battery string 220A and the fourth battery string 220B are arranged in the first direction, and the fourth battery sheet 214A and the fourth battery sheet 214B are arranged adjacent to each other in the first direction;

[0275] The battery assembly further comprises:

[0276] The second insulation strip 222 is arranged at the edge of the third battery sheet 213A in the third battery string 220A, and the second insulation strip 222 is arranged at one end of the third battery sheet 213A close to the fourth battery sheet 214A;

[0277] The intermediate bus bar 232 is used to connect the third battery string 220A and the fourth battery string 220B in parallel, and the intermediate bus bar 232 is arranged on the side of the second insulation strip 222 away from the third battery sheet 213, and the second insulation strip 222 and the intermediate bus bar 232 are arranged in extension in the second direction;

[0278] The second welding strip B242 is used to electrically connect the middle busbar 232, the fourth cell piece 214A and the fourth cell piece 214B, that is, the same second welding strip B242 extends from the fourth cell piece 214B to the fourth cell piece 214A and the middle busbar 232 in sequence.

[0279] In some embodiments, the second insulating strip 222 is provided with an extension section extending out of the edge of the third cell piece 213A at one end close to the fourth cell piece 214A, and in the thickness direction of the third cell piece 213A, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth cell piece 214A. In yet some embodiments, the middle busbar 232 is provided with an extension section at one end close to the fourth cell piece 214A, the extension section extends out of the edge of the second insulating strip 222 in the first direction and is electrically connected with the second welding strip B242, and the connection between the extension section and the second welding strip B242 forms a joint end.

[0280] In this way, in assembly, each cell piece in the cell string is connected in series, the second insulating strip 222 is arranged at one end of the third cell piece 213A close to the fourth cell piece 214A, the middle busbar 232 is arranged on the back of the second insulating strip 222, the main body of the second welding strip B242 is electrically connected with the effective welding position of the fourth cell piece 214A and the effective welding position of the fourth cell piece 214B respectively, and the one end of the second welding strip B242 close to the third cell piece 213A is electrically connected with the middle busbar 232, thereby enabling the middle busbar 232 to be connected in parallel with the third cell string 220A and the fourth cell string 220B.

[0281] Firstly, in the embodiments of the present disclosure, the middle busbar 232 is arranged on the third cell piece 213A, and the middle busbar 232 is separated from the third cell piece 213A by the second insulating strip 222, on the one hand, the edge of the battery assembly does not need to reserve space for placing the busbar, and the battery assembly can reserve more space for installing cell pieces, so that the effective light receiving area of the battery assembly is larger, and the conversion efficiency of the assembly is higher, on the other hand, from the direction of the light receiving surface (or front surface) of the cell piece, the second insulating strip 222 can shield the middle busbar 232, and the overall appearance of the battery assembly is better.

[0282] Secondly, compared with the bus bar arranged at the middle position of the back surface of the battery piece, the middle bus bar 232 of the embodiment of the present disclosure is arranged at one end of the third battery piece 213A close to the fourth battery piece 214A, the second welding strip B242 extends to the fourth battery piece 214A after being connected with the effective welding position of the fourth battery piece 214B, and can be fully matched and welded with the effective welding position of the fourth battery piece 214A, avoiding that the installation of the middle bus bar 232 causes insufficient welding between the second welding strip B242 and the fourth battery piece 214A, thereby affecting the current collection, at the same time, after being welded with the fourth battery piece 214A and the fourth battery piece 214B, the second welding strip B242 can be directly connected with the middle bus bar 232, without the need of opening holes in the insulation strip or replacing it with an insulation block arranged intermittently, and only the second insulation strip 222 needs to be placed at one end of the third battery piece 213A close to the fourth battery piece 214A during assembly, thereby effectively reducing the production precision requirement and production difficulty, and avoiding short circuit caused by position deviation when the insulation strip is opened or position deviation when the insulation block is laminated, thereby increasing the product yield.

[0283] At the same time, the second insulation strip 222 of the embodiment of the present disclosure is provided with a first extension segment 2221 and a second extension segment 2222, that is, the second insulation strip 222 has widened portions beyond the edges of the middle bus bar 232 on both sides in the first direction. The first extension segment 2221 and the second extension segment 2222 are arranged on both sides of the second insulation strip 222, on one hand, allowing a certain degree of deviation of the second insulation strip 222 in the width direction during the preparation process with respect to the middle bus bar 232 and the two battery pieces, thereby reducing the production precision requirement and production difficulty, and on the other hand, the second extension segment 2222 of the second insulation strip 222 of the embodiment of the present disclosure is smaller than the first extension segment 2221, that is, in the first direction, the middle bus bar 232 is arranged to deviate from the center with respect to the second insulation strip 222, rather than being arranged in a central symmetry, which forms a relatively wide first extension segment 2221 and a relatively narrow second extension segment 2222, wherein the relatively wide first extension segment 2221 is conducive to covering more areas of the edges of the fourth battery piece 214A and the third battery piece 213A, thereby better reducing the risk of short circuit caused by the contact between the middle bus bar 232 and the heterogeneous welding strip or heterogeneous grid line on the fourth battery piece 214A, and the risk of short circuit caused by the contact between the second welding strip A241 and the heterogeneous welding strip or heterogeneous grid line of the third battery piece 213A, thereby improving the reliability of the battery assembly.

[0284] Furthermore, when the busbar is arranged at the outer edge of the last cell tab of the cell string, i.e. at the end of the fourth cell tab 214A away from the third cell tab 213A, since the stress at the outer edge of the last cell tab of the cell string is large when laminated, fragments and other defects are prone to occur, and meanwhile, the installation of the busbar can affect the welding between the second welding ribbon B242 and the fourth cell tab 214A. The second welding ribbon B242 cannot be welded to the fourth cell tab 214A at the position covered by the busbar, resulting in insufficient welding between the second welding ribbon B242 and the fourth cell tab 214A, poor current collection, and this situation is particularly serious when the battery assembly is a back contact battery assembly without a main grid.

[0285] In contrast, the built-in structure of the intermediate busbar 232 in the embodiments of the present disclosure can be applied to back contact battery assemblies with a main grid and back contact battery assemblies without a main grid, and has stronger universality. On the one hand, the end of the third cell tab 213A close to the fourth cell tab 214A has smaller stress than the outer edge of the last cell tab of the cell string when laminated, thereby further reducing the risk of cell tab cracking and fragments and improving the reliability of the back contact battery assembly.

[0286] In some embodiments, referring to FIG. 15, the first extension segment 2221 extends at least partially to the outside of the edge of the third cell tab 213.

[0287] Thus, on the basis of allowing a certain degree of offset in the width direction of the second insulating strip 222 relative to the intermediate busbar 232 and the second insulating strip 222 relative to the two cell tabs during preparation, it can also be ensured that the first widened segment 2211 can cover more area of the edge of the fourth cell tab 214A and the edge of the third cell tab 213A, thereby reducing the risk of short circuit caused by contact between the intermediate busbar 232, the second welding ribbon A241 and the female welding ribbon or female grid line, and improving the reliability of the battery assembly.

[0288] In some embodiments, referring to FIG. 15, in the first direction, the orthogonal projection of the first extension segment 2221 in the thickness direction of the third cell tab 213 at least partially coincides with the orthogonal projection of the fourth cell tab 214 in the thickness direction of the third cell tab 213.

[0289] Thus, the second insulating strip 222 can cover the edges of the third cell tab 213A and the fourth cell tab 214A, thereby not only avoiding short circuit caused by contact between the intermediate busbar 232 and the female welding ribbon or female grid line on the fourth cell tab 214A, but also avoiding short circuit caused by contact between the second welding ribbon B242 and the female welding ribbon or female grid line of the third cell tab 213A, further reducing the risk of short circuit.

[0290] Especially when the battery piece is cut into a half piece, the cutting edge is extremely easy to cause short circuit after cutting. The first extension section 2221 can effectively avoid the short circuit caused by the cutting edge, so that the cutting edge of the battery half piece is arranged on the side of the middle bus bar 232 on the battery piece or the side of the adjacent battery piece close to the middle bus bar 232, and the reliability of the battery assembly can be ensured.

[0291] In some embodiments, as shown in FIG. 15, in the first direction, the width d2 of the second extension section 2222 is greater than or equal to 1 mm.

[0292] When the second extension section 2222 is too small, the second insulating strip 222 allows a small amount of offset during the preparation process, thereby causing the production precision requirement to be improved. When the width of the second extension section 2222 is greater than or equal to 1 mm, the second extension section 2222 can reserve sufficient offset space for the equipment placement level tolerance and the bus bar lead-out hole lamination offset tolerance during the preparation process, thereby reducing the production precision requirement.

[0293] In some embodiments, as shown in FIG. 15, the fourth battery piece 214 and the third battery piece 213 are arranged on the same plane, and 1 mm < d1 ≤ l 31 +l 32 +l 33

[0294] In the formula, d1 is the width of the first extension section 2221 in the first direction, l 31 is the relative width distance between the middle bus bar 232 and the edge of the third battery piece 213 close to the fourth battery piece 214 in the first direction in the battery string provided with the middle bus bar 232, l 32 is the spacing between the fourth battery piece 214 and the third battery piece 213 in the battery string provided with the middle bus bar 232, l 33 is the relative width distance between the edge of the fourth battery piece 214 close to the third battery piece 213 and the second soldering point 262 in the battery string provided with the middle bus bar 232, and the second soldering point 262 is arranged on the fourth battery piece 214 in the battery string provided with the middle bus bar 232 and is arranged on the fourth battery piece 214 close to the third battery piece 213, and is used for being connected with the second soldering strip B242.

[0295] It can be understood that the second soldering point 262 is located on the edge of the fourth battery piece 214A closest to the third battery piece 213 (that is, the connection point of the most edge of the second soldering strip B242 on the fourth battery piece 214A), and the second soldering point 262 can be a grid line, a soldering pad, but is not limited thereto.

[0296] It can be understood that l 31 +l 32 > 1 mm, l31 Therefore, controlling d1>1mm, it is able to ensure that the first extension segment 2221 is able to extend to cover the edge area of the fourth cell piece 214A and the edge area of the third cell piece 213A, while reserving sufficient offset space for the equipment placement level tolerance in the preparation process and the busbar lead-out hole lamination offset tolerance, thereby being able to allow a small degree of offset in the width direction of the second insulation strip 222 relative to the middle busbar 232 and the second insulation strip 222 relative to the two cell pieces.

[0297] When the width of the first extension segment 2221 is too small, the short circuit risk increases, and the reliability of the battery assembly decreases. As the width of the first extension segment 2221 becomes larger, the reliability of the battery assembly increases, the displacement deviation in the width direction of the second insulation strip 222 relative to the middle busbar 232 and the second insulation strip 222 relative to the two cell pieces is allowed in the preparation process, and the production precision requirement decreases. However, when the width of the first extension segment 2221 is too large, it will affect the sufficient welding between the second solder strip B242 and the effective welding position on the fourth cell piece 214A, the current collection effect decreases, and the double-sided rate of the battery assembly is affected. In the embodiment, 1mm 31 + 32+33 On the basis of allowing a certain offset of the second insulation strip 222 in the preparation process, it is still able to ensure that the first extension segment 2221 of the second insulation strip 222 is able to extend to cover the edge area of the third cell piece 213A and the edge area of the fourth cell piece 214A, further improving the reliability and production yield of the battery assembly, reducing the production precision requirement, while being able to avoid affecting the sufficient welding between the second solder strip B242 and the effective welding position on the fourth cell piece 214A, and not causing unnecessary material waste and double-sided rate loss.

[0298] In some embodiments, the battery assembly further includes a front plate, the cell string is arranged on the front plate, the front plate is arranged with a first edge and a second edge along the second direction, and the orthogonal projection of the second insulation strip 222 in the thickness direction of the third cell piece 213 falls between the first edge and the second edge.

[0299] If the second insulation strip 222 exceeds the first edge or the second edge, the material layers such as the adhesive film, the front plate, and the back plate of the battery assembly cannot be fully compounded, especially in the edge area, which causes external moisture to easily enter the inside of the battery assembly, affecting the reliability of the battery assembly.

[0300] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the back contact battery described above can refer to the corresponding structure and implementation principle in the foregoing embodiment thirteen, which will not be described herein.

[0301] Embodiment fourteen

[0302] The difference between this embodiment and embodiment thirteen is that, as shown in FIGS. 16-18, in the battery string provided with the intermediate busbar 232, the third battery sheet 213 is at least partially laminated with the fourth battery sheet 214 at the end close to the fourth battery sheet 214, that is, the third battery sheet 213A and the fourth battery sheet 214A are provided in a laminated manner without a gap between the two battery sheets, wherein 1mm < d1≤l 41 +l 43 -l 42

[0303] In the formula, d1 is the width of the first extension section 2221 in the first direction, l 41 is the relative width distance between the intermediate busbar 232 and the edge of the third battery sheet 213 close to the fourth battery sheet 214 in the first direction in the battery string provided with the intermediate busbar 232, l 42 is the width of the laminated area between the third battery sheet 213 and the fourth battery sheet 214 in the first direction, l 43 is the relative width distance between the edge of the fourth battery sheet 214 close to the third battery sheet 213 and the second soldering point 262 in the battery string provided with the intermediate busbar 232, the second soldering point 262 is arranged at the end of the fourth battery sheet 214 close to the third battery sheet 213 and is used for connecting with the second soldering strip B242.

[0304] In an embodiment, as shown in FIG. 17, the third battery sheet 213A is at least partially laminated with the fourth battery sheet 214A on the side facing the first insulating strip 221.

[0305] In another embodiment, as shown in FIG. 18, the third battery sheet 213A is at least partially laminated with the fourth battery sheet 214A on the side facing away from the second insulating strip 222.

[0306] It can be understood that l 41 +l 42 >1mm, l 41 <1mm, so that d1>1mm is controlled, which can reserve sufficient offset space for the equipment placement horizontal tolerance in the preparation process and the lamination offset tolerance of the busbar lead-out hole, thereby allowing a small amount of offset in the width direction between the second insulating strip 222 and the intermediate busbar 232 and between the second insulating strip 222 and the two battery sheets.

[0307] When the width of the first extension section 2221 is too small, the short circuit risk increases, the reliability of the battery assembly decreases, as the width of the first extension section 2221 becomes larger, the reliability of the battery assembly increases, the displacement deviation of the second insulating strip 222 relative to the middle bus bar 232 and the second insulating strip 222 relative to the two battery pieces in the width direction is increased during the preparation process, and the production precision requirement is reduced, but when the width of the first extension section 2221 is too large, it will affect the sufficient welding between the second solder strip B242 and the effective welding position on the fourth battery piece 214A, the current collection effect decreases, and it will affect the double-sided rate of the battery assembly. In the embodiment, 1mm < d1≤l 41 +l 42 +l 43 , ensure that on the basis of allowing a certain offset during the preparation of the second insulating strip 222, the first extension section 2221 of the second insulating strip 222 can still extend to cover the edge area of the third battery piece 213A and the edge area of the fourth battery piece 214A, further improve the reliability and production yield of the battery assembly, reduce the production precision requirement, at the same time, can avoid affecting the sufficient welding between the second solder strip B242 and the effective welding position on the fourth battery piece 214A, and will not cause unnecessary material waste and double-sided rate loss.

[0308] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the back contact battery described above can refer to the corresponding structure and implementation principle in the foregoing embodiment eleven, embodiment twelve and embodiment thirteen, which will not be repeated here.

[0309] Embodiment fifteen

[0310] Referring to FIGS. 7, 9 and 19, the embodiment discloses a back contact battery assembly, comprising:

[0311] A battery string, the battery string comprising battery pieces connected in series with each other, the battery pieces comprising a fifth battery piece 311 and a sixth battery piece 312 arranged along a first direction, the fifth battery piece 311 being arranged at an end of the battery string;

[0312] A first insulating strip 321 arranged at one end of the sixth battery piece 312 close to the fifth battery piece 311;

[0313] A first bus bar 331 arranged at a side of the first insulating strip 321 away from the sixth battery piece 312, i.e. the back surface of the first insulating strip 321, and vice versa, the side of the first insulating strip 321 facing the sixth battery piece 312 being the front surface of the first insulating strip 321, the first insulating strip 321 and the first bus bar 331 both extending along a second direction, the first direction and the second direction being arranged transversely;

[0314] The second welding strip A341 is used for electrically connecting the first bus bar 331 and the fifth battery piece 311.

[0315] The first insulating strip 321 is provided with an extension segment 3211 extending out of the first bus bar 331 at one end close to the fifth battery piece 311, and the extension segment 3211 extends to outside the sixth battery piece 312. In the thickness direction of the sixth battery piece 312, the orthographic projection of the extension segment 3211 at least partially overlaps the orthographic projection of the fifth battery piece 311, that is, the extension segment 3211 can cover the edge region of the fifth battery piece 311 to separate the first bus bar 331 and the edge region of the fifth battery piece 311.

[0316] It can be understood that the electrically connecting manner can be welding, bonding through conductive glue, etc., but is not limited thereto.

[0317] It can be understood that in the battery string, the battery string can include two battery pieces in series, three battery pieces in series, or other more battery pieces in series, and the number of battery pieces to be connected in series can be determined according to actual use.

[0318] In the embodiment, the first bus bar 331 is an end bus bar, and the fifth battery piece 311 is located at the end of the battery string. For the convenience of description, in the embodiment, the end where the fifth battery piece 311 is located is recorded as the tail end of the battery string, that is, in the first direction, the fifth battery piece 311 is the last battery piece of the battery string, and the sixth battery piece 312 is the second last battery piece of the battery string. It can be understood that the end where the fifth battery piece 311 is located can also be recorded as the head end of the battery string, which is not described herein.

[0319] Optionally, in the same battery string, the adjacent battery pieces can be connected in series through welding strips, conductive glue, etc.

[0320] In an embodiment, the adjacent battery pieces are connected through series welding strips 351. Specifically, the series welding strip 351 includes a first series welding strip 3511 and a second series welding strip 3512. In the first direction, the first series welding strip 3511 and the second series welding strip 3512 are arranged alternately, and in the second direction, the first series welding strip 3511 and the second series welding strip 3512 are arranged alternately. In one battery string, the Nth battery piece, the N+1th battery piece, and the N+2th battery piece (N is a positive integer greater than 1) are arranged in sequence along the first direction. The positive electrode welding point of the Nth battery piece and the negative electrode welding point of the N+1th battery piece are connected in series through a plurality of first series welding strips 3511, and the positive electrode welding point of the N+1th battery piece and the negative electrode welding point of the N+2th battery piece are connected in series through a plurality of second series welding strips 3512.

[0321] In assembly, each battery piece in the battery string is connected in series with each other, the first insulating strip 321 is arranged at one end of the sixth battery piece 312 close to the fifth battery piece 311, the first bus bar 331 is arranged at the back of the first insulating strip 321, the main body of the second solder strip A 341 is electrically connected with the effective welding position of the fifth battery piece 311, and one end of the second solder strip A 341 close to the sixth battery piece 312 is electrically connected with the first bus bar 331, so that the first bus bar 331 can lead out the current of the battery string.

[0322] Firstly, in the embodiments of the present disclosure, the first bus bar 331 is arranged on the sixth battery piece 312, and the first bus bar 331 is separated from the sixth battery piece 312 by the first insulating strip 321. On the one hand, the edge of the battery assembly does not need to reserve space for placing the bus bar, and the battery assembly can reserve more space for installing the battery piece, so that the effective light receiving area of the battery assembly is larger, and the conversion efficiency of the assembly is higher. On the other hand, from the direction of the light receiving surface (or the front surface) of the battery piece, the first insulating strip 321 can shield the first bus bar 331 to avoid the first bus bar 331 from being exposed, and the overall appearance of the battery assembly is better.

[0323] Secondly, compared with arranging the bus bar at the middle position of the back surface of the battery piece, the first bus bar 331 of the embodiment of the present disclosure is arranged at one end of the sixth battery piece 312 close to the fifth battery piece 311, and the second solder strip A 341 can be fully matched and welded with the effective welding position of the fifth battery piece 311, avoiding the installation of the first bus bar 331 from affecting the welding between the second solder strip A 341 and the fifth battery piece 311, and affecting the current collection. At the same time, after the second solder strip A 341 is welded with the fifth battery piece 311, it can be directly connected with the first bus bar 331 without the need of punching the insulating strip or replacing it with an intermittently arranged insulating block. When assembling, only the first insulating strip 321 needs to be placed at one end of the sixth battery piece 312 close to the fifth battery piece 311, effectively reducing the production precision requirement and production difficulty, and avoiding short circuit caused by position deviation when the insulating strip is punched or when the insulating block is laminated, and increasing the product yield. At the same time, the first insulating strip 321 of the present application is provided with an extension segment 3211, which allows a certain degree of deviation in the width direction of the first insulating strip 321 relative to the first bus bar 331 and the two battery pieces during preparation, reduces the production precision requirement and production difficulty, and on the other hand, the first insulating strip 321 can cover the edges of the sixth battery piece 312 and the fifth battery piece 311, thereby not only avoiding the contact between the first bus bar 331 and the male solder strip or male grid line on the fifth battery piece 311 to cause short circuit, but also avoiding the contact between the second solder strip A 341 and the male solder strip or male grid line of the sixth battery piece 312 to cause short circuit and the short circuit easily caused by conductive foreign matter such as tin dregs during preparation, further reducing the risk of short circuit and improving the reliability of the battery assembly. Especially when the battery piece is cut into a half piece, the cutting edge is extremely easy to cause short circuit after cutting. The extension segment 3211 of the embodiment of the present disclosure can effectively avoid the short circuit easily caused by the cutting edge, so that the cutting edge of the battery half piece is arranged on the side of the battery piece where the first bus bar 331 is located or on the side of the adjacent battery piece close to the first bus bar 331, and the reliability of the battery assembly can also be ensured.

[0324] Furthermore, when the bus bar is arranged at the outer edge of the last battery piece of the battery string, that is, at one end of the fifth battery piece 311 away from the sixth battery piece 312, since the outer edge of the last battery piece of the battery string is close to the edge of the battery assembly, the stress at this position is large during lamination, and fragments and other defects are easily generated. At the same time, the installation of the bus bar will affect the welding between the second solder strip A 341 and the fifth battery piece 311. The second solder strip A 341 cannot be welded with the fifth battery piece 311 at the position covered by the bus bar, resulting in insufficient welding between the second solder strip A 341 and the fifth battery piece 311, poor current collection, and this situation is particularly serious when the battery assembly is a main grid back contact battery assembly.

[0325] In contrast, the end busbar built-in structure of the embodiment of the present disclosure can be applied to both the back contact cell assembly with a main grid and the back contact cell assembly without a main grid, and has stronger versatility. In addition, the stress of the sixth cell piece 312 near one end of the fifth cell piece 311 compared to the outer edge of the last cell piece of the cell string is smaller during lamination, which can reduce the risk of broken pieces and cracked pieces and further improve the reliability of the cell assembly.

[0326] In an embodiment, referring to FIGS. 7, 9 and 19, the fifth cell piece 311 and the sixth cell piece 312 are arranged on the same plane. In the first direction, the width of the part of the epitaxial segment 3211 extending out of the sixth cell piece 312 is greater than the spacing between the fifth cell piece 311 and the sixth cell piece 312.

[0327] Therefore, the epitaxial segment 3211 can reserve sufficient width to allow a certain degree of offset in the width direction between the first insulating strip 321 and the first busbar 331 and between the first insulating strip 321 and the two cell pieces during the preparation process, thereby reducing the production precision requirement and production difficulty. On the other hand, the epitaxial segment 3211 can extend to cover the edge region of the fifth cell piece 311 and the edge region of the sixth cell piece 312, which can avoid the short circuit caused by the contact between the first busbar 331 and the female solder strip or female grid line on the fifth cell piece 311, and also avoid the short circuit caused by the contact between the second solder strip A341 and the female solder strip or female grid line of the sixth cell piece 312, thereby further reducing the short circuit risk and improving the reliability of the cell assembly.

[0328] In an embodiment, referring to FIG. 19, in the first direction, the width of the epitaxial segment 3211 is: 1mm≤L1≤l 11 +l 12 +l 13 ,

[0329] In the formula, L1 is the width of the epitaxial segment 3211 in the first direction, l 11 is the spacing between the fifth cell piece 311 and the sixth cell piece 312, l 12 is the relative width distance from the edge of the fifth cell piece 311 near one end of the sixth cell piece 312 to the first solder joint 361, which is used to connect with the second solder strip A341 and is arranged on the fifth cell piece 311 near one end of the sixth cell piece 312, l 13 is the relative width distance between the edge of the first busbar 331 near one end of the fifth cell piece 311 and the edge of the sixth cell piece 312 near one end of the fifth cell piece 311.

[0330] It can be understood that l 11 +l 13 >1mm, l 11Therefore, L1≥1mm, which can ensure that the extension of the epitaxial segment 3211 covers the edge area of the fifth cell piece 311 and the edge area of the sixth cell piece 312, and at the same time, reserve sufficient offset space for the equipment placement level tolerance in the preparation process and the tolerance of the busbar offset in the lamination process, thereby allowing a small amount of offset in the width direction of the first insulating strip 321 relative to the first busbar 331 and the first insulating strip 321 relative to the two cell pieces.

[0331] When the width of the epitaxial segment 3211 is too small, the short circuit risk increases, and the reliability of the battery assembly decreases. As the width of the epitaxial segment 3211 increases, the reliability of the battery assembly increases, the displacement deviation of the first insulating strip 321 relative to the first busbar 331 and the first insulating strip 321 relative to the two cell pieces in the width direction is allowed in the preparation process, and the production precision requirement decreases. However, when the width of the epitaxial segment 3211 is too large, it will affect the sufficient welding between the second solder strip A341 and the effective welding position on the fifth cell piece 311, the current collection effect decreases, and the double-sided rate of the battery assembly is affected. It can be understood that the first welding point 361 is located at the edge of the fifth cell piece 311 closest to the edge of the sixth cell piece 312 (that is, the connection point of the second solder strip A341 at the edge of the fifth cell piece 311), and the first welding point 361 can be a grid line, a pad, and the like. In the embodiment of the present disclosure, by controlling 1mm≤L1≤l 11 +l 12 +l 13 , it is ensured that the extension of the epitaxial segment 3211 of the first insulating strip 321 covers the edge area of the fifth cell piece 311 and the edge area of the sixth cell piece 312, further improves the reliability and production yield of the battery assembly, at the same time, does not cause unnecessary material waste, and can avoid affecting the sufficient welding of the second solder strip A341.

[0332] In an embodiment, as shown in FIG. 19, in the first direction, the width of the epitaxial segment 3211 is: 1mm≤L1≤l 11 +l 13 +4mm,

[0333] In the formula, L1 is the width of the epitaxial segment 3211 in the first direction, l 11 is the distance between the fifth cell piece 311 and the sixth cell piece 312, l 13 is the relative width distance between the edge of the first busbar 331 close to one end of the fifth cell piece 311 to the edge of the sixth cell piece 312 close to one end of the fifth cell piece 311.

[0334] Within this range, the extension of the extension section 3211 of the first insulating strip 321 can still cover the edge regions of the fifth and sixth cell pieces 311 and 312, and the reliability and production yield of the battery assembly can be further improved, without causing unnecessary material waste, and even if the first insulating strip 321 is offset, the full welding of the second solder strip A341 can still be ensured, and the production precision can be effectively reduced.

[0335] In an embodiment, referring to FIGS. 7 and 10, the battery assembly includes at least one series battery string group 3100, the same series battery string group 3100 includes two battery strings arranged in the second direction and connected in series with each other, and in the same series battery string group 3100, the sixth cell piece 312 in one battery string and the sixth cell piece 312 in another battery string are connected by the same first bus bar 331.

[0336] Optionally, the second solder strip A341 includes a first positive electrode solder strip 3411 and a first negative electrode solder strip 3412, the same first bus bar 331 is electrically connected with the first positive electrode solder strip 3411 in one battery string and electrically connected with the first negative electrode solder strip 3412 in another battery string, so as to form a series connection between the adjacent battery strings.

[0337] For example, the same series battery string group 3100 includes a first battery string 310A and a second battery string 310B, the second solder strip A341 includes a first positive electrode solder strip 3411 and a first negative electrode solder strip 3412, in the same series battery string group 3100, the same first bus bar 331 extends from the sixth cell piece 312 in the first battery string 310A to the sixth cell piece 312 in the second battery string 310B, and in the first battery string 310A, the first bus bar 331 is electrically connected with the first positive electrode solder strip 3411 on the fifth cell piece 311, and in the second battery string 310B, the first bus bar 331 is electrically connected with the first negative electrode solder strip 3412 on the fifth cell piece 311.

[0338] In an embodiment, the battery assembly includes a parallel battery string group 3200, the same parallel battery string group 3200 includes at least two battery strings arranged in the first direction and connected in parallel with each other, and a spacing region is arranged between the two battery strings connected in parallel with each other, and the spacing region is provided with an intermediate bus bar 332, and the intermediate bus bar 332 is used to connect the two battery strings arranged in the first direction in parallel with each other, that is, the end bus bar built-in structure of the embodiment of the present disclosure can cooperate with the conventional intermediate bus bar 332 mounting structure.

[0339] In another embodiment, referring to FIG. 10 and FIG. 11, each battery string is provided with a fourth cell tab 314 away from one end of a fifth cell tab 311, the fourth cell tab 314 is provided with a third cell tab 313 close to one end of the fifth cell tab 311, and the battery module comprises parallel battery string groups 3200, each parallel battery string group 3200 comprises at least two battery strings arranged in the first direction and connected in parallel with each other, and the fourth cell tab 314 in the two battery strings connected in parallel with each other is arranged adjacent in the first direction;

[0340] The battery module further comprises:

[0341] A second insulating strip 322 is arranged at the edge of the third cell tab 313 in a battery string, and the second insulating strip 322 is arranged at one end of the third cell tab 313 close to the fourth cell tab 314;

[0342] A middle bus bar 332 is arranged for connecting in parallel two battery strings arranged adjacent in the first direction, and the middle bus bar 332 is arranged at the side of the second insulating strip 322 away from the third cell tab 313;

[0343] The second insulating strip 322 and the middle bus bar 332 are arranged extending in the second direction;

[0344] A second solder strip B342 is arranged for electrically connecting the middle bus bar 332, the fourth cell tab 314 in a battery string, and the fourth cell tab 314 in another battery string adjacent to the battery string in the first direction.

[0345] For example, referring to FIG. 10 and FIG. 11, for the convenience of description, taking the third battery string 320A and the fourth battery string 320B connected in parallel in the same parallel battery string group 3200 as an example, wherein the third battery string 320A is the battery string where the middle bus bar 332 is arranged:

[0346] The third cell tab 313 in the third battery string 320A is denoted as the third cell tab 313A, the fourth cell tab 314 is denoted as the fourth cell tab 314A, the third cell tab 313 in the fourth battery string 320B is denoted as the third cell tab 313B, and the fourth cell tab 314 is denoted as the fourth cell tab 314B, the third battery string 320A and the fourth battery string 320B are arranged in the first direction, and the fourth cell tab 314A and the fourth cell tab 314B are arranged adjacent in the first direction;

[0347] The battery module further comprises:

[0348] A second insulating strip 322 is arranged at the edge of the third cell tab 313A in the third battery string 320A, and the second insulating strip 322 is arranged at one end of the third cell tab 313A close to the fourth cell tab 314A;

[0349] The intermediate busbar 332 is used to connect the third battery string 320A and the fourth battery string 320B in parallel, and is arranged on the side of the second insulation strip 322 away from the third battery sheet 313.

[0350] The second insulation strip 322 and the intermediate busbar 332 are arranged in the second direction.

[0351] The second solder strip B342 is used to electrically connect the intermediate busbar 332, the fourth battery sheet 314A and the fourth battery sheet 314B, that is, the same second solder strip B342 extends from the fourth battery sheet 314B to the fourth battery sheet 314A and the intermediate busbar 332 in sequence.

[0352] Optionally, the second solder strip B342 includes a second positive electrode solder strip 3421 and a second negative electrode solder strip 3422, and the fourth battery sheet 314A, the fourth battery sheet 314B and the intermediate busbar 332 are electrically connected by the second positive electrode solder strip 3421 or the second negative electrode solder strip 3422.

[0353] On the one hand, the intermediate busbar 332 built-in structure of the embodiment of the present disclosure can increase the effective light receiving area of the battery module, improve the conversion efficiency of the module, avoid the exposure of the intermediate busbar 332, and the overall aesthetics of the battery module is better; on the other hand, it can ensure that the second solder strip B342 can fully match and weld with the effective welding position of the fourth battery sheet 314, avoid the installation of the intermediate busbar 332 causing insufficient welding of the second solder strip B342 and the fourth battery sheet 314 to affect the current collection, and only need to place the second insulation strip 322 at one end of the third battery sheet 313 close to the fourth battery sheet 314 during assembly. At the same time, through the arrangement of the extension section 3221, the second insulation strip 322 can be offset relative to the intermediate busbar 332 and the second insulation strip 322 relative to the two battery sheets in the width direction during preparation, effectively reducing the production precision requirement and production difficulty, and effectively reducing the risk of short circuit. Furthermore, the intermediate busbar 332 built-in structure of the embodiment of the present disclosure can be applied to the main grid back contact battery module and the main grid back contact battery module, and has higher universality, smaller stress during lamination, lower risk of battery sheet cracking and fragmentation, and better reliability of the back contact battery module.

[0354] The end busbar built-in structure of the embodiment of the present disclosure cooperates with the intermediate busbar 332 built-in structure of the embodiment of the present disclosure, which can increase the effective light receiving area of the battery module, improve the conversion efficiency of the module, and the overall aesthetics and reliability of the battery module are better, effectively reducing the production precision requirement and production difficulty, and improving the production efficiency.

[0355] In an embodiment, referring to FIG. 10 and FIG. 11, the second insulation strip 322 is provided with an extension segment 3221 extending out of the middle busbar 332 at one end close to the fourth cell 314, and the extension segment 3221 extends out of the third cell 313, and in the thickness direction of the third cell 313, the orthographic projection of the extension segment 3221 at least partially overlaps the orthographic projection of the fourth cell 314 in the cell string where the extension segment 3221 is located.

[0356] That is, the second insulation strip 322 is provided with an extension segment 3221 extending out of the middle busbar 332 at one end close to the fourth cell 314A, and the extension segment 3221 extends out of the third cell 313A, and in the thickness direction of the third cell 313A, the orthographic projection of the extension segment 3221 at least partially overlaps the orthographic projection of the fourth cell 314A.

[0357] The second insulation strip 322 of the embodiment of the present disclosure is provided with the extension segment 3221, which on one hand allows a certain degree of offset in the width direction of the second insulation strip 322 relative to the middle busbar 332 and the two cells during the manufacturing process, thereby reducing the production precision requirement and production difficulty, and on the other hand, the second insulation strip 322 can cover the edges of the third cell 313 and the fourth cell 314, thereby not only avoiding the short circuit caused by the contact between the middle busbar 332 and the female solder strip or female grid line on the fourth cell 314, but also avoiding the short circuit caused by the contact between the second solder strip B342 and the female solder strip or female grid line of the third cell 313, further reducing the short circuit risk and improving the reliability of the battery module. Especially when the cell is cut into a half, the cutting edge is extremely easy to cause short circuit after cutting. The provision of the extension segment 3221 of the embodiment of the present disclosure can effectively avoid the short circuit easily caused by the cutting edge, so that the cutting edge of the battery half can be arranged on the side of the cell where the middle busbar 332 is located or the side of the adjacent cell close to the middle busbar 332, and the reliability of the battery module can also be ensured.

[0358] Furthermore, the embodiment of the present disclosure provides a photovoltaic system comprising the above-mentioned back contact battery module.

[0359] In the embodiment, the photovoltaic system can be applied in a photovoltaic power station, such as a ground power station, a roof power station, a water surface power station, etc., and can also be applied in a device or apparatus using solar energy to generate power, such as a user solar power source, a solar street lamp, a solar car, a solar building, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is, the photovoltaic system can be applied in all fields requiring solar energy to generate power. Taking a photovoltaic power generation system network as an example, the photovoltaic system can include a photovoltaic array, a combiner box and an inverter, the photovoltaic array can be an array combination of a plurality of cell assemblies, for example, a plurality of cell assemblies can form a plurality of photovoltaic arrays, the photovoltaic array is connected to the combiner box, the combiner box can combine the current generated by the photovoltaic array, the combined current flows through the inverter to convert into alternating current required by a power grid, and then is connected to a power network to realize solar power supply.

[0360] Embodiment sixteen

[0361] The difference between the embodiment and the embodiment fifteen is that, as shown in FIG. 14, FIG. 20 and FIG. 21, the sixth cell piece 312 is at least partially laminated with the fifth cell piece 311 at one end of the fifth cell piece 311,

[0362] In the first direction, the width of the epitaxial segment 3211 is greater than the width of the lamination region between the fifth cell piece 311 and the sixth cell piece 312.

[0363] That is, the fifth cell piece 311 and the sixth cell piece 312 are arranged in a laminated manner, and there is no gap between the two cells.

[0364] In an embodiment, as shown in FIG. 21, the side of the sixth cell piece 312 away from the first insulating strip 321 is at least partially laminated with the fifth cell piece 311.

[0365] In another embodiment, as shown in FIG. 20, the side of the sixth cell piece 312 toward the first insulating strip 321 is at least partially laminated with the fifth cell piece 311.

[0366] In an embodiment, optionally, the width of the epitaxial segment 3211 is: 1mm≤L2≤l 22 +l 23 -l 21 ,

[0367] In the formula, L2 is the width of the epitaxial segment 3211 in the first direction, l 21 is the width of the lamination region between the fifth cell piece 311 and the sixth cell piece 312, l 22The relative width distance is from the edge of the fifth cell tab 311 close to one end of the sixth cell tab 312 to the first soldering point 361, which is used for connecting with the second soldering ribbon A341 and is arranged at the fifth cell tab 311 close to one end of the sixth cell tab 312, l 23 The relative width distance is between the edge of the first bus bar 331 close to one end of the fifth cell tab 311 and the edge of the sixth cell tab 312 close to one end of the fifth cell tab 311.

[0368] It can be understood that, l 21 + l 23 > 1 mm, l 21 < 1 mm, thus, L2≥1 mm, which can reserve sufficient offset space for the equipment placement horizontal tolerance in the preparation process and the tolerance of the bus bar offset in the lamination process, thereby allowing the first insulating strip 321 to have a small degree of offset in the width direction relative to the first bus bar 331 in the preparation process.

[0369] When the width of the epitaxial segment 3211 is too small, the short circuit risk increases and the reliability of the battery assembly decreases. As the width of the epitaxial segment 3211 increases, the reliability of the battery assembly increases, the displacement deviation of the first insulating strip 321 in the width direction relative to the first bus bar 331 and the first insulating strip 321 relative to the two cell tabs in the preparation process increases, and the production precision requirement decreases. However, when the width of the epitaxial segment 3211 is too large, it will affect the sufficient welding between the second soldering ribbon A341 and the effective welding position on the fifth cell tab 311, the current collection effect decreases, and the double-sided rate of the battery assembly is affected. In the embodiment of the present disclosure, by controlling 1mm≤L2≤l 22 + l 23 - l 21 , it is ensured that the epitaxial segment 3211 of the first insulating strip 321 can extend to cover the edge area of the fifth cell tab 311 and the edge area of the sixth cell tab 312, further improving the reliability and production yield of the battery assembly, while not causing unnecessary material waste and avoiding affecting the sufficient welding of the second soldering ribbon A341.

[0370] In an embodiment, the width of the epitaxial segment 3211 is: 1mm≤L2≤l 23 + 4 mm - l 21 ,

[0371] In the formula, L2 is the width of the epitaxial segment 3211 in the first direction, l 21 is the width of the lamination area between the fifth cell tab 311 and the sixth cell tab 312, l 23The relative width distance between the edge of the first bus bar 331 close to the first end of the fifth cell tab 311 and the edge of the sixth cell tab 312 close to the first end of the fifth cell tab 311.

[0372] Within this range, the extension of the extension section 3211 of the first insulating strip 321 can still cover the edge regions of the fifth cell tab 311 and the sixth cell tab 312, thereby further improving the reliability and production yield of the battery assembly, while not causing unnecessary material waste, and even if the first insulating strip 321 is offset during production, it can still ensure that the sufficient welding of the second solder strip A341 is not affected, thereby effectively reducing the production precision.

[0373] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the back contact battery described above can refer to the corresponding structure and implementation principle in the foregoing embodiment seventeen, which will not be described here.

[0374] Embodiment seventeen

[0375] Referring to FIGS. 11 and 22, the embodiment discloses a back contact battery assembly, comprising:

[0376] The parallel cell string group 3200 comprises at least two cell strings arranged along the first direction and connected in parallel with each other, each cell string comprising cell tabs connected in series with each other, the cell tabs comprising a third cell tab 313 and a fourth cell tab 314 arranged along the first direction, the fourth cell tab 314 being arranged at an end of the cell string, and the fourth cell tabs 314 in the two cell strings arranged in parallel with each other being arranged adjacent to each other in the first direction;

[0377] The second insulating strip 322 is arranged at the edge of the third cell tab 313 in a cell string, and the second insulating strip 322 is arranged at one end of the third cell tab 313 close to the fourth cell tab 314;

[0378] The intermediate bus bar 332 is used to connect in parallel two cell strings arranged adjacent to each other in the first direction, and the intermediate bus bar 332 is arranged at a side of the second insulating strip 322 away from the third cell tab 313;

[0379] The second insulating strip 322 and the intermediate bus bar 332 are both arranged extending along the second direction;

[0380] The second solder strip B342 is used to electrically connect the intermediate bus bar 332, the fourth cell tab 314 in the cell string where the intermediate bus bar 332 is arranged, and the fourth cell tab 314 in another cell string adjacent to the cell string in the first direction;

[0381] The second insulation strip 322 is provided with an extension section 3221 protruding out of the middle busbar 332 at an end close to the fourth cell tab 314, and the extension section 3221 extends out of the third cell tab 313, and in the thickness direction of the third cell tab 313, the orthographic projection of the extension section 3221 at least partially overlaps the orthographic projection of the fourth cell tab 314 in the battery string where the extension section 3221 is located.

[0382] For example, for ease of illustration, the third battery string 320A and the fourth battery string 320B in parallel in the same parallel battery string group 3200 are taken as examples, wherein the third battery string 320A is the battery string where the middle busbar 332 is located;

[0383] The third cell tab 313 in the third battery string 320A is denoted as the third cell tab 313A, and the fourth cell tab 314 is denoted as the fourth cell tab 314A. The third cell tab 313 in the fourth battery string 320B is denoted as the third cell tab 313B, and the fourth cell tab 314 is denoted as the fourth cell tab 314B. The third battery string 320A and the fourth battery string 320B are arranged along the first direction, and the fourth cell tab 314A and the fourth cell tab 314B are arranged adjacent to each other in the first direction.

[0384] The battery assembly further comprises:

[0385] The second insulation strip 322 is provided at the edge of the third cell tab 313A in the third battery string 320A, and the second insulation strip 322 is provided at an end of the third cell tab 313A close to the fourth cell tab 314A. The middle busbar 332 is used to connect the third battery string 320A and the fourth battery string 320B in parallel, and the middle busbar 332 is provided at the side of the second insulation strip 322 away from the third cell tab 313. The second insulation strip 322 and the middle busbar 332 are both arranged to extend along the second direction.

[0386] The second welding strip B342 is used to electrically connect the middle busbar 332, the fourth cell tab 314A, and the fourth cell tab 314B, that is, the same second welding strip B342 extends from the fourth cell tab 314B to the fourth cell tab 314A and the middle busbar 332 in sequence.

[0387] The second insulation strip 322 is provided with an extension section 3221 protruding out of the middle busbar 332 at an end close to the fourth cell tab 314A, and the extension section 3221 extends out of the third cell tab 313A, and in the thickness direction of the third cell tab 313A, the orthographic projection of the extension section 3221 at least partially overlaps the orthographic projection of the fourth cell tab 314A.

[0388] In assembly, each of the battery pieces in the battery string is connected in series with each other, the second insulating strip 322 is arranged at one end of the third battery piece 313A close to the fourth battery piece 314A, the intermediate bus bar 332 is arranged at the back of the second insulating strip 322, the main body of the second solder strip B342 is respectively electrically connected with the effective welding position of the fourth battery piece 314A and the effective welding position of the fourth battery piece 314B, and one end of the second solder strip B342 close to the third battery piece 313A is electrically connected with the intermediate bus bar 332, so that the intermediate bus bar 332 can be connected in parallel with the third battery string 320A and the fourth battery string 320B.

[0389] Firstly, in the embodiments of the present disclosure, the intermediate bus bar 332 is arranged on the third battery piece 313A, and the intermediate bus bar 332 is separated from the third battery piece 313A by the second insulating strip 322. On the one hand, the edge of the battery assembly does not need to reserve space for placing the bus bar, and the battery assembly can reserve more space for installing the battery piece, so that the effective light receiving area of the battery assembly is larger, and the conversion efficiency of the assembly is higher. On the other hand, from the direction of the light receiving surface (or the front surface) of the battery piece, the second insulating strip 322 can shield the intermediate bus bar 332, so as to avoid the exposure of the intermediate bus bar 332, and the overall appearance of the battery assembly is better.

[0390] Secondly, compared with arranging the bus bar at the middle position of the back surface of the battery piece, the middle bus bar 332 of the embodiment of the present disclosure is arranged at one end of the third battery piece 313A close to the fourth battery piece 314A, the second welding strip B342 extends to the fourth battery piece 314A after being connected with the effective welding position of the fourth battery piece 314B, and can be fully matched and welded with the effective welding position of the fourth battery piece 314A, avoiding the installation of the middle bus bar 332 from affecting the welding of the second welding strip B342 and the fourth battery piece 314A, thereby affecting the current collection. At the same time, after being welded with the fourth battery piece 314A and the fourth battery piece 314B, the second welding strip B342 can be directly connected with the middle bus bar 332, without the need of punching the insulating strip or replacing it with an insulating block arranged intermittently. When assembling, only the whole second insulating strip 322 needs to be placed at one end of the third battery piece 313A close to the fourth battery piece 314A, thereby effectively reducing the production precision requirement and production difficulty, avoiding short circuit caused by the position deviation of the insulating strip when being punched or the position deviation of the insulating block when being laminated, and increasing the product yield. At the same time, the second insulating strip 322 of the embodiment of the present disclosure is provided with an extension section 3221, which can allow a certain degree of deviation of the second insulating strip 322 relative to the middle bus bar 332 and the second insulating strip 322 relative to the two battery pieces in the width direction during the preparation process, thereby reducing the production precision requirement and production difficulty. On the other hand, the second insulating strip 322 can cover the edges of the third battery piece 313 and the fourth battery piece 314, thereby not only avoiding the contact between the middle bus bar 332 and the male welding strip or the male grid line on the fourth battery piece 314 to cause short circuit, but also avoiding the contact between the second welding strip B342 and the male welding strip or the male grid line of the third battery piece 313 to cause short circuit, thereby further reducing the short circuit risk and improving the reliability of the battery assembly. Especially when the battery piece is cut into a half piece, the cutting edge is extremely easy to cause short circuit after cutting. The provision of the extension section 3221 of the embodiment of the present disclosure can effectively avoid the short circuit easily caused by the cutting edge, so that the cutting edge of the battery half piece is arranged on the side of the battery piece where the middle bus bar 332 is located or on the side of the adjacent battery piece close to the middle bus bar 332, and the reliability of the battery assembly can also be ensured.

[0391] Furthermore, when the bus bar is arranged at the outer edge of the last battery piece of the battery string, i.e. at one end of the fourth battery piece 314A away from the third battery piece 313A, since the stress at the outer edge of the last battery piece of the battery string is large during lamination, it is easy to produce fragments and other defects. At the same time, the installation of the bus bar can affect the welding between the second welding strip B342 and the fourth battery piece 314A. The second welding strip B342 cannot be welded with the fourth battery piece 314A at the position covered by the bus bar, resulting in insufficient welding between the second welding strip B342 and the fourth battery piece 314A, poor current collection, which is particularly serious when the battery assembly is a main grid back contact battery assembly.

[0392] In contrast, the built-in structure of the middle busbar in the embodiments of the present disclosure can be applied to both the back contact cell assembly with a main grid and the back contact cell assembly without a main grid, and has stronger versatility. On the one hand, the one end of the third cell piece 313A close to the fourth cell piece 314A has less stress than the outer edge of the last cell piece of the cell string during lamination, thereby further reducing the risk of cell piece cracking and fragmentation and improving the reliability of the back contact cell assembly.

[0393] In an embodiment, as shown in FIG. 22, in the cell string provided with the second insulation strip 322, the fourth cell piece 314 and the third cell piece 313 are arranged on the same plane. In the first direction, the width of the extension segment 3221 extending out of the part of the third cell piece 313 is greater than the spacing between the fourth cell piece 314 and the third cell piece 313.

[0394] Thus, the extension segment 3221 can reserve sufficient width to allow a certain degree of offset in the width direction between the second insulation strip 322 and the middle busbar 332 and between the second insulation strip 322 and the two cell pieces during the production process, thereby reducing the production precision requirement and production difficulty. On the other hand, the extension segment 3221 can extend to cover the edge region of the fourth cell piece 314A and the edge region of the third cell piece 313A, thereby avoiding the contact between the middle busbar 332 and the male solder strip or the male grid line on the fourth cell piece 314A to cause short circuit, and also avoiding the contact between the second solder strip B342 and the male solder strip or the male grid line of the third cell piece 313A to cause short circuit, thereby further reducing the risk of short circuit and improving the reliability of the cell assembly.

[0395] In an embodiment, as shown in FIG. 22, in the first direction, the width of the extension segment 3221 is: 1mm≤L3≤l 31 +l 32 +l 33 ,

[0396] wherein L3 is the width of the extension segment 3221 in the first direction, l 31 is the spacing between the fourth cell piece 314 and the third cell piece 313 in the cell string provided with the second insulation strip 322, l 32 is the relative width distance from the edge of the one end of the fourth cell piece 314 close to the third cell piece 313 to the second solder joint 362 in the cell string provided with the second insulation strip 322, l 33 is the relative width distance between the edge of the one end of the middle busbar 332 close to the fourth cell piece 314 and the edge of the one end of the third cell piece 313 close to the fourth cell piece 314.

[0397] It can be understood that l 31 +l33 >1mm, l 31 <1mm, therefore, controlling L3≥1mm, can ensure that the extension section 3221 can extend to cover the edge area of the fourth cell tab 314A and the edge area of the third cell tab 313A, while reserving sufficient offset space for the equipment placement level tolerance and the busbar lead hole lamination offset tolerance in the preparation process, thereby allowing a small amount of offset in the width direction between the second insulating strip 322 and the intermediate busbar 332 and between the second insulating strip 322 and the two cell tabs.

[0398] When the width of the extension section 3221 is too small, the risk of short circuit increases, and the reliability of the battery assembly decreases. As the width of the extension section 3221 increases, the reliability of the battery assembly increases, the allowable displacement deviation in the width direction between the second insulating strip 322 and the intermediate busbar 332 and between the second insulating strip 322 and the two cell tabs in the preparation process increases, and the production precision requirement decreases. However, when the width of the extension section 3221 is too large, it will affect the sufficient welding between the second solder strip B342 and the effective welding position on the fourth cell tab 314A, the current collection effect decreases, and it will affect the double-sided rate of the battery assembly. It can be understood that the second solder point 362 is located at the edge of the fourth cell tab 314A closest to the third cell tab 313A (i.e., the connection point of the second solder strip B342 at the edge of the fourth cell tab 314A), and the second solder point 362 can be a grid line or a pad. In the embodiments of the present disclosure, by controlling 1mm≤L3≤l 31 +1 32 +1 33 , it can still ensure that the extension section 3221 of the second insulating strip 322 can extend to cover the edge area of the fourth cell tab 314A and the edge area of the third cell tab 313A on the basis of allowing offset errors in the preparation process, further improving the reliability and production yield of the battery assembly, while not causing unnecessary material waste and avoiding affecting the sufficient welding of the second solder strip B342.

[0399] In one embodiment, in the first direction, the width of the extension section 3221 is: 1mm≤L3≤l 31 +1 33 +4mm,

[0400] wherein L3 is the width of the extension section 3221 in the first direction, l 31 is the distance between the fourth cell tab 314 and the third cell tab 313 in the battery string provided with the second insulating strip 322, l 33 is the relative width distance between the edge of the end of the intermediate busbar 332 close to the fourth cell tab 314 and the edge of the end of the third cell tab 313 close to the fourth cell tab 314 in the battery string provided with the second insulating strip 322.

[0401] Within this range, the extension section 3221 of the second insulating strip 322 can still cover the edge region of the fourth cell tab 314A and the edge region of the third cell tab 313A, allowing for an offset error in the preparation process, further improving the reliability and production yield of the battery assembly, without causing unnecessary material waste, and ensuring that the full welding of the second solder strip B is not affected even if the first insulating strip 321 is offset, effectively reducing the production precision.

[0402] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the structure and implementation principle of the back contact cell described above can refer to the corresponding structure and implementation principle in the aforementioned embodiment seventeen, which will not be repeated here.

[0403] Embodiment eighteen

[0404] The difference between this embodiment and embodiment seventeen is that, as shown in FIGS. 16, 23 and 24, in the battery string provided with the second insulating strip 322, the end of the third cell tab 313 close to the fourth cell tab 314 is at least partially laminated with the fourth cell tab 314,

[0405] In the first direction, the width of the extension section 3221 is greater than the width of the lamination region between the third cell tab 313 and the fourth cell tab 314.

[0406] That is, the third cell tab 313A and the fourth cell tab 314A are arranged in a laminated manner, and there is no gap between the two cells.

[0407] In one embodiment, the side of the third cell tab 313A facing away from the second insulating strip 322 is at least partially laminated with the fourth cell tab 314A.

[0408] In another embodiment, the side of the third cell tab 313A facing the first insulating strip 321 is at least partially laminated with the fourth cell tab 314A.

[0409] In one embodiment, as shown in FIGS. 23 and 24, in the first direction, the width of the extension section 3221 is: 1mm≤L4≤l 42 +l 43 -l 41 ,

[0410] In the formula, L4 is the width of the extension section 3221 in the first direction, l 41 is the width of the lamination region between the third cell tab 313 and the fourth cell tab 314, l 42In the battery string with the second insulating strip 322, the relative width distance from the edge of the one end of the fourth cell tab 314 close to the third cell tab 313 to the second welding point 362, l 43 In the battery string with the second insulating strip 322, the relative width distance between the edge of the one end of the middle busbar 332 close to the fourth cell tab 314 and the edge of the one end of the third cell tab 313 close to the fourth cell tab 314.

[0411] It can be understood that, l 41 + l 43 > 1 mm, l 41 < 1 mm, therefore, controlling L4≥1 mm, can ensure that the extension section 3221 can extend to cover the edge area of the fourth cell tab 314A and the edge area of the third cell tab 313A, and at the same time, reserve sufficient offset space for the equipment placement horizontal tolerance in the preparation process and the busbar lead hole lamination offset tolerance, thereby allowing the second insulating strip 322 to exist a small amount of offset in the width direction relative to the middle busbar 332 and the second insulating strip 322 relative to the two cell tabs.

[0412] In an embodiment, referring to FIG. 23 and FIG. 24, in the first direction, the width of the extension section 3221 is: 1 mm≤L4≤l 43 - l 41 + 4 mm,

[0413] In the formula, L4 is the width of the extension section 3221 in the first direction, l 41 l is the width of the lamination area between the third cell tab 313 and the fourth cell tab 314, 42 In the battery string with the second insulating strip 322, the relative width distance from the edge of the one end of the fourth cell tab 314 close to the third cell tab 313 to the second welding point 362, l 43 In the battery string with the second insulating strip 322, the relative width distance between the edge of the one end of the middle busbar 332 close to the fourth cell tab 314 and the edge of the one end of the third cell tab 313 close to the fourth cell tab 314.

[0414] In the description of the present specification, the description of the terms "some embodiments", "exemplary", "example", or "for example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present disclosure. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0415] The above merely describes the preferred embodiments of the present disclosure and is not intended to limit the present disclosure in any form. Although the present disclosure has been disclosed as the above preferred embodiments, it is not intended to limit the present disclosure. Any person skilled in the art can make some changes or modifications to the above-mentioned technical content as equivalent embodiments with slight changes or modifications within the scope of the technical solutions of the present disclosure without departing from the technical solutions of the present disclosure. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present disclosure are still within the scope of the present disclosure.

Claims

1. A back contact solar cell assembly, wherein, The battery string comprises a plurality of battery pieces connected in series, and a plurality of the battery pieces are distributed along a first direction. An insulation strip is arranged on the back surface of the battery piece along a second direction, wherein the first direction and the second direction are arranged intersectingly. A bus bar is arranged on the side of the insulation strip away from the battery piece along the second direction, and the surface of the bus bar close to the battery piece is covered by the insulation strip. The battery string comprises a first battery piece and a second battery piece arranged adjacently, the insulation strip is arranged on the back surface of the first battery piece, and a second solder strip is arranged for connecting the second battery piece and the bus bar respectively, and the insulation strip blocks the second solder strip and the first battery piece. The insulation strip covers the bus bar along the second direction, and covers and exceeds the bus bar along the first direction. The back contact battery assembly further comprises a solder strip, the solder strip comprises a first solder strip and the second solder strip, the first solder strip is used for connecting the adjacent battery pieces, and the second solder strip is used for connecting the battery piece and the bus bar.

2. The back contact solar cell assembly of claim 1, wherein, The second solder strip is arranged on the side of the bus bar away from the insulation strip, or the second solder strip is arranged on the side of the bus bar close to the insulation strip.

3. The back contact solar cell assembly of claim 1, wherein, The first battery piece and the second battery piece are arranged at least partially in a stack.

4. The back contact solar cell assembly of claim 3, wherein, When the back surface of the first battery piece and the light receiving surface of the second battery piece are arranged at least partially in a stack, the insulation strip is arranged at least partially on the back surface of the second battery piece.

5. The back contact solar cell assembly of claim 1, wherein, The battery piece is in a rectangular shape, and the battery piece further comprises a chamfered edge and a cut edge, the chamfered edge and the cut edge are arranged on both sides of the battery piece along the first direction, and the first direction and the second direction are arranged perpendicularly.

6. The back contact solar cell assembly of claim 5, wherein, In the first direction, the chamfered edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece; or in the first direction, the chamfered edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece.

7. The back contact solar cell assembly of claim 1, wherein, The chamfered edge of each battery piece is arranged on the back surface of the side of the adjacent battery piece where the cut edge is located.

8. The back contact solar cell assembly of claim 7, wherein, The battery string comprises a plurality of battery pieces connected in series, and a plurality of the battery pieces are distributed along a first direction.

9. The back contact solar cell assembly of claim 8, wherein, An insulation strip is arranged on the back surface of the battery piece along a second direction, wherein the first direction and the second direction are arranged intersectingly.

10. A back contact solar cell assembly wherein, A bus bar is arranged on the side of the insulation strip away from the battery piece along the second direction, and the surface of the bus bar close to the battery piece is covered by the insulation strip. The battery string comprises a first battery piece and a second battery piece arranged adjacently, the insulation strip is arranged on the back surface of the first battery piece, and a second solder strip is arranged for connecting the second battery piece and the bus bar respectively, and the insulation strip blocks the second solder strip and the first battery piece. The insulation strip covers the bus bar along the second direction, and covers and exceeds the bus bar along the first direction. The back contact battery assembly further comprises a solder strip, the solder strip comprises a first solder strip and the second solder strip, the first solder strip is used for connecting the adjacent battery pieces, and the second solder strip is used for connecting the battery piece and the bus bar. The second solder strip is arranged on the side of the bus bar away from the insulation strip, or the second solder strip is arranged on the side of the bus bar close to the insulation strip. The first battery piece and the second battery piece are arranged at least partially in a stack. When the back surface of the first battery piece and the light receiving surface of the second battery piece are arranged at least partially in a stack, the insulation strip is arranged at least partially on the back surface of the second battery piece. The battery piece is in a rectangular shape, and the battery piece further comprises a chamfered edge and a cut edge, the chamfered edge and the cut edge are arranged on both sides of the battery piece along the first direction, and the first direction and the second direction are arranged perpendicularly. In the first direction, the chamfered edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece; or in the first direction, the chamfered edge of the battery piece is arranged in abutment with the cut edge of the adjacent battery piece, and the cut edge of the battery piece is arranged in abutment with the chamfered edge of the adjacent battery piece. The chamfered edge of each battery piece is arranged on the back surface of the side of the adjacent battery piece where the cut edge is located. The battery string comprises a plurality of battery pieces connected in series, and a plurality of the battery pieces are distributed along a first direction. A first insulation strip is arranged on the end of the sixth battery piece close to the fifth battery piece. A first bus bar is arranged on the side of the first insulation strip away from the sixth battery piece, and the first insulation strip and the first bus bar are arranged extending along a second direction, wherein the first direction and the second direction are arranged intersectingly. A second solder strip A is arranged for electrically connecting the first bus bar and the fifth battery piece. In the first direction, two ends of the first insulating strip are provided with a first widened section and a second widened section extending out of the edge of the first bus bar, the first widened section and the second widened section are sequentially arranged in a direction away from the fifth battery piece, and the width of the second widened section is less than the width of the first widened section.

11. The back contact solar cell assembly of claim 10, wherein, The first widened section at least partially extends out of the edge of the sixth battery piece.

12. The back contact solar cell assembly of claim 11, wherein, In the first direction, the orthogonal projection of the first widened section in the thickness direction of the sixth battery piece at least partially overlaps the orthogonal projection of the fifth battery piece in the thickness direction of the sixth battery piece.

13. The back contact solar cell assembly of claim 10, wherein, In the first direction, the width D2 of the second widened section is greater than or equal to 1 mm.

14. The back contact solar cell assembly of claim 10, wherein, The fifth battery piece and the sixth battery piece are arranged on the same plane, wherein 1mm < D1 ≤ l 11 +l 12 +l 13 wherein D1 is the width of the first widened section in the first direction, l 11 is the relative width distance between the first busbar and the edge of the fifth cell piece near the end of the sixth cell piece in the first direction, l 12 is the spacing between the fifth cell piece and the sixth cell piece, l 13 is the relative width distance from the edge of the fifth cell piece near the end of the sixth cell piece to the first soldering point, which is provided on the fifth cell piece near the end of the sixth cell piece for connecting with the second soldering strip A.

15. The back contact solar cell assembly of claim 10, wherein, The sixth cell piece is at least partially laminated with the fifth cell piece near one end of the fifth cell piece, wherein 1mm < D1 ≤ l 21 + l 23 - l 22 wherein D1 is the width of the first widened section in the first direction, l 21 is the relative width distance between the first busbar and the edge of the fifth cell piece near the end of the sixth cell piece in the first direction, l 22 is the width of the lamination region between the fifth cell piece and the sixth cell piece in the first direction, l 23 is the relative width distance from the edge of the fifth cell piece near the end of the sixth cell piece to the first soldering point, which is provided on the fifth cell piece near the end of the sixth cell piece for connecting with the second soldering strip A.

16. The back contact solar cell assembly of claim 10, wherein, The battery assembly further comprises a front plate, the battery string is arranged on the front plate, the front plate is arranged with a first edge and a second edge in a second direction, and the orthogonal projection of the first insulating strip in the thickness direction of the sixth battery piece falls between the first edge and the second edge.

17. The back contact solar cell assembly of claim 10, wherein, The orthogonal projection of the first bus bar in the thickness direction of the sixth battery piece falls within the sixth battery piece.

18. The back contact solar cell assembly of claim 10, wherein, The battery assembly comprises at least one series battery string group, the same series battery string group comprises two battery strings arranged in the second direction and arranged in series with each other, and in the same series battery string group, the first bus bar extends from the sixth battery piece in one battery string to the sixth battery piece in another battery string.

19. The back contact solar cell assembly of claim 10, wherein, Each battery string is provided with a fourth battery piece away from one end of the fifth battery piece, and the fourth battery piece is provided with a third battery piece close to one end of the fifth battery piece. The back contact battery assembly further comprises: A second insulating strip is arranged at the edge of the third battery piece in one battery string, and the second insulating strip is arranged at one end of the third battery piece close to the fourth battery piece. An intermediate bus bar is used to be connected in parallel with two battery strings arranged adjacent to each other in the first direction, the intermediate bus bar is arranged on the side of the second insulating strip away from the third battery piece, and the second insulating strip and the intermediate bus bar are arranged in the second direction. A second solder strip B is used to electrically connect the intermediate bus bar, the fourth battery piece in the battery string, and the fourth battery piece in another battery string adjacent to the battery string in the first direction.

20. The back contact solar cell assembly of claim 19, wherein, In the first direction, two ends of the second insulating strip are provided with a first extended section and a second extended section extending out of the edge of the intermediate bus bar, the first extended section and the second extended section are sequentially arranged in a direction away from the fourth battery piece, the first extended section at least partially extends out of the edge of the third battery piece, and the width of the second extended section is less than the width of the first extended section.

21. A back contact solar cell assembly wherein, Comprise: A parallel battery string group, the same parallel battery string group comprises at least two battery strings arranged in the first direction and arranged in parallel with each other, each battery string comprises battery pieces connected in series with each other, the battery pieces connected in series with each other comprise a third battery piece and a fourth battery piece arranged in the first direction, and the fourth battery pieces in the two battery strings arranged in parallel with each other are arranged adjacent to each other in the first direction. A second insulation strip is arranged at an edge of the third battery piece in one of the battery strings, and the second insulation strip is arranged at one end of the third battery piece close to the fourth battery piece; An intermediate bus bar is arranged in parallel with two battery strings arranged adjacent to each other in the first direction, and the intermediate bus bar is arranged at a side of the second insulation strip away from the third battery piece, and the second insulation strip and the intermediate bus bar are arranged in extension in the second direction; A second welding strip B is arranged to electrically connect the intermediate bus bar, the fourth battery piece in the battery string where the intermediate bus bar is arranged, and the fourth battery piece in another battery string adjacent to the battery string in the first direction; In the first direction, two ends of the second insulation strip are provided with a first extension segment and a second extension segment extending out of the edge of the intermediate bus bar, and the first extension segment and the second extension segment are arranged in sequence in a direction away from the fourth battery piece, and the width of the second extension segment is smaller than the width of the first extension segment.

22. The back contact solar cell assembly of claim 21, wherein, The first extension segment at least partially extends out of the edge of the third battery piece.

23. The back contact solar cell assembly of claim 22, wherein, In the first direction, the orthogonal projection of the first extension segment in the thickness direction of the third battery piece at least partially overlaps the orthogonal projection of the fourth battery piece in the thickness direction of the third battery piece.

24. The back contact solar cell assembly of claim 21, wherein, In the first direction, the width d2 of the second extension segment is greater than or equal to 1 mm.

25. The back contact solar cell assembly of claim 21, wherein, The fourth cell piece and the third cell piece are arranged on the same plane, wherein 1mm < d1 ≤ l 31 + l 32 + l 33 wherein d1 is a width of the first epitaxial segment in the first direction, l 31 is a relative width distance between the middle busbar and an edge of the fourth cell piece near an end of the third cell piece in the battery string with the middle busbar, l 32 is a spacing between the fourth cell piece and the third cell piece in the battery string with the middle busbar, l 33 is a relative width distance between an edge of the fourth cell piece near an end of the third cell piece to a second soldering point in the battery string with the middle busbar, the second soldering point being provided on the fourth cell piece in the battery string with the middle busbar and near the end of the third cell piece for connecting with the second soldering tape B.

26. The back contact solar cell assembly of claim 21, wherein, In the battery string provided with the intermediate busbar, the third battery piece is at least partially laminated with the fourth battery piece at one end close to the fourth battery piece, wherein 1mm < d1 ≤ l 41 + l 43 - l 42 wherein d1 is a width of the first epitaxial segment in the first direction, l 41 is a relative width distance between the middle busbar and an edge of the third cell piece near an end of the fourth cell piece in the first direction in the battery string with the middle busbar, l 42 is a width of a lamination region between the third cell piece and the fourth cell piece in the first direction, l 43 is a relative width distance between an edge of the fourth cell piece near an end of the third cell piece and a second soldering point in the battery string with the middle busbar, the second soldering point being provided on the fourth cell piece near the end of the third cell piece for connecting with the second soldering tape B.

27. The back contact solar cell assembly of claim 21, wherein, The battery assembly further comprises a front plate, and the battery strings are arranged on the front plate, and the front plate is arranged with a first edge and a second edge in the second direction, and the orthogonal projection of the second insulation strip in the thickness direction of the third battery piece falls between the first edge and the second edge.

28. A back contact solar cell assembly wherein, Comprise: A battery string comprises battery pieces connected in series, and the battery pieces comprise a fifth battery piece and a sixth battery piece arranged in a first direction; A first insulation strip is arranged at one end of the sixth battery piece close to the fifth battery piece; A first bus bar is arranged at a side of the first insulation strip away from the sixth battery piece, and the first insulation strip and the first bus bar are arranged in extension in a second direction, and the first direction and the second direction are arranged crosswise; A second welding strip A is arranged to electrically connect the first bus bar and the fifth battery piece; The first insulation strip is provided with an extension segment extending out of the first bus bar at one end close to the fifth battery piece, and the extension segment extends out of the sixth battery piece, and in the thickness direction of the sixth battery piece, the orthogonal projection of the extension segment at least partially overlaps the orthogonal projection of the fifth battery piece.

29. The back contact solar cell assembly of claim 28, wherein, The fifth battery piece and the sixth battery piece are arranged on the same plane; In the first direction, the width of the part of the extension segment extending out of the sixth battery piece is greater than the spacing between the fifth battery piece and the sixth battery piece.

30. The back contact solar cell assembly of claim 29, wherein, In the first direction, the width of the epitaxial segment is: 1 mm ≤ L1 ≤ l 11 + l 12 + l 13 , wherein L1 is the width of the epitaxial segment in the first direction, l 11 is the spacing between the fifth and sixth cell pieces, l 12 is the relative width distance from the edge of the fifth cell piece near the end of the sixth cell piece to the first solder point, which is used to connect with the second solder strip A and is located on the fifth cell piece near the end of the sixth cell piece, l 13 is the relative width distance between the edge of the first busbar near the end of the fifth cell piece and the edge of the sixth cell piece near the end of the fifth cell piece.

31. The back contact solar cell assembly of claim 29, wherein, In the first direction, the width of the epitaxial segment is: 1 mm ≤ L1 ≤ l 11 + l 13 + 4 mm, wherein L1 is the width of the epitaxial segment in the first direction, l 11 is the spacing between the fifth and sixth cell pieces, l 13 is the relative width distance between the edge of the first busbar proximate one end of the fifth cell piece to the edge of the sixth busbar proximate one end of the fifth cell piece.

32. The back contact solar cell assembly of claim 28, wherein, The end of the sixth battery piece close to the fifth battery piece at least partially overlaps the fifth battery piece; In the first direction, the width of the extension segment is greater than the width of the overlapping region between the fifth battery piece and the sixth battery piece.

33. The back contact solar cell assembly of claim 32, wherein, The width of the epitaxial segment is: 1 mm ≤ L2 ≤ l 22 + l 23 - l 21 , wherein L2 is the width of the epitaxial segment in the first direction, l 21 is the width of the lamination region between the fifth and sixth cell pieces, l 22 is the relative width distance from the edge of the fifth cell piece near the end of the sixth cell piece to the first solder point for connection with the second solder ribbon A, and located on the fifth cell piece near the end of the sixth cell piece, l 23 is the relative width distance between the edge of the first busbar near the end of the fifth cell piece and the edge of the sixth cell piece near the end of the fifth cell piece.

34. The back contact solar cell assembly of claim 32, wherein, The width of the epitaxial segment is: 1mm≤L2≤l 23 +4mm−l 21 , wherein L2 is the width of the epitaxial segment in the first direction, l 21 is the width of the lamination region between the fifth and sixth cell pieces, l 23 is the relative width distance between the edge of the first busbar proximate the one end of the fifth cell piece and the edge of the sixth busbar proximate the one end of the fifth cell piece.

35. The back contact solar cell assembly of claim 28, wherein, The battery assembly comprises at least one series battery string group, each series battery string group comprises two battery strings arranged in a second direction and connected in series, and the sixth battery piece of one battery string and the sixth battery piece of another battery string in the same series battery string group are connected by the same first bus bar.

36. The back contact solar cell assembly of claim 28, wherein, Each battery string is provided with a fourth battery piece at one end away from the fifth battery piece, and the fourth battery piece is provided with a third battery piece at one end close to the fifth battery piece. The battery assembly comprises at least one parallel battery string group, each parallel battery string group comprises at least two battery strings arranged in a first direction and connected in parallel, and the fourth battery pieces of the two battery strings arranged in parallel are arranged adjacent to each other in the first direction. The back contact battery assembly further comprises: A second insulating strip is arranged at the edge of the third battery piece in one battery string, and the second insulating strip is arranged at one end of the third battery piece close to the fourth battery piece. A middle bus bar is arranged for connecting two battery strings arranged adjacent to each other in the first direction in parallel, the middle bus bar is arranged at one side of the second insulating strip away from the third battery piece, and the second insulating strip and the middle bus bar are arranged in extension in the second direction. A second solder strip B is arranged for electrically connecting the middle bus bar, the fourth battery piece in the battery string, and the fourth battery piece in another battery string adjacent to the battery string in the first direction.

37. The back contact solar cell assembly of claim 36, wherein, The second insulating strip is provided with an extension section extending out of the middle bus bar at one end close to the fourth battery piece, and the extension section extends out of the third battery piece, and the orthogonal projection of the extension section in the thickness direction of the third battery piece at least partially overlaps with the orthogonal projection of the fourth battery piece in the battery string where the extension section is arranged.

38. A back contact solar cell assembly wherein, The battery assembly comprises at least one parallel battery string group, each parallel battery string group comprises at least two battery strings arranged in a first direction and connected in parallel, each battery string comprises battery pieces connected in series, the battery pieces comprise third battery pieces and fourth battery pieces arranged in the first direction, and the fourth battery pieces of the two battery strings arranged in parallel are arranged adjacent to each other in the first direction. A second insulating strip is arranged at the edge of the third battery piece in one battery string, and the second insulating strip is arranged at one end of the third battery piece close to the fourth battery piece. A middle bus bar is arranged for connecting two battery strings arranged adjacent to each other in the first direction in parallel, the middle bus bar is arranged at one side of the second insulating strip away from the third battery piece, and the second insulating strip and the middle bus bar are arranged in extension in the second direction. A second solder strip B is arranged for electrically connecting the middle bus bar, the fourth battery piece in the battery string where the middle bus bar is arranged, and the fourth battery piece in another battery string adjacent to the battery string in the first direction. ​ The second insulation strip is provided with an extension section extending out of the middle busbar near one end of the fourth cell piece, and the extension section extends to outside the third cell piece. In the thickness direction of the third cell piece, the orthographic projection of the extension section at least partially overlaps the orthographic projection of the fourth cell piece in the cell string where the extension section is located.

39. The back contact solar cell assembly of claim 38, wherein, In the cell string provided with the second insulation strip, the fourth cell piece and the third cell piece are located on the same plane. In the first direction, the width of the part of the extension section extending out of the third cell piece is greater than the spacing between the fourth cell piece and the third cell piece.

40. The back contact solar cell assembly of claim 39, wherein, In the first direction, the width of the extension section is: 1 mm ≤ L3≤ l 31 + l 32 + l 33 , wherein L3 is the width of the extension in the first direction, l 31 is the distance between the fourth cell tab and the third cell tab in the battery string provided with the second insulating strip, l 32 is the relative width distance from the edge of the fourth cell tab near the end of the third cell tab to the second solder point in the battery string provided with the second insulating strip, l 33 is the relative width distance between the edge of the middle busbar near the end of the fourth cell tab and the edge of the third cell tab near the end of the fourth cell tab in the battery string provided with the second insulating strip.

41. The back contact solar cell assembly of claim 40, wherein, In the first direction, the width of the extension section is: 1 mm ≤ L3 ≤ l 31 + l 33 + 4 mm, wherein L3 is the width of the extension in the first direction, l 31 is the distance between the fourth cell tab and the third cell tab in the battery string provided with the second insulating strip, l 33 is the relative width distance between the edge of the intermediate busbar close to the fourth cell tab end and the edge of the third cell tab close to the fourth cell tab end in the battery string provided with the second insulating strip.

42. The back contact solar cell assembly of claim 38, wherein, In the cell string provided with the second insulation strip, the third cell piece is at least partially laminated with the fourth cell piece near one end of the fourth cell piece, In the first direction, the width of the extension section is greater than the width of the lamination region between the third cell piece and the fourth cell piece.

43. The back contact solar cell assembly of claim 42, wherein, In the first direction, the width of the extension section is: 1 mm ≤ L4≤ l 42 + l 43 - l 41 , wherein L4 is the width of the extension section in the first direction, l 41 is the width of the lamination region between the third and fourth cell pieces, l 42 is the relative width distance from the edge of the fourth cell piece near the third cell piece to the second solder point in the cell string provided with the second insulation strip, l 43 is the relative width distance between the edge of the middle busbar near the fourth cell piece and the edge of the third cell piece near the fourth cell piece in the cell string provided with the second insulation strip.

44. The back contact solar cell assembly of claim 42, wherein, In the first direction, the width of the extension is: 1 mm ≤ L4≤ l 43 - 1 41 + 4 mm, wherein L4 is the width of the extension section in the first direction, l 41 is the width of the lamination region between the third and fourth cell pieces, l 42 is the relative width distance from the edge of the fourth cell piece near the third cell piece to the second solder point in the cell string provided with the second insulation strip, l 43 is the relative width distance between the edge of the middle busbar near the fourth cell piece and the edge of the third cell piece near the fourth cell piece in the cell string provided with the second insulation strip.

45. A photovoltaic system, wherein, A back contact cell module comprising a back contact cell module according to any one of claims 1 to 44.