Back contact battery assembly and photovoltaic system

Abstract

The invention relates to the technical field of back contact batteries, in particular to a back contact battery assembly and a photovoltaic system.The back contact battery assembly comprises a battery string, the battery string comprises battery pieces connected in series, and the battery pieces comprise a first battery piece, a second battery piece and a first insulating strip, the first insulating strip is arranged at one end, close to the first battery piece, of the second battery piece, the first bus bar is arranged on one side, back on to the second battery piece, of the first insulating strip, the first insulating strip and the first bus bar are arranged in an extending mode in the second direction, and the first welding strip is used for electrically connecting the first bus bar and the first battery piece. The first insulating strip is provided with an extension section extending out of the first bus bar, the extension section extends out of the second battery piece, and in the thickness direction of the second battery piece, the orthographic projection of the extension section at least partially coincides with the orthographic projection of the first battery piece. According to the invention, the effective light-receiving area of the cell module can be increased, the conversion efficiency of the module is improved, the observed area of the bus bar from one side of the light-receiving surface is smaller and even can be completely hidden, meanwhile, the production difficulty can be effectively reduced, the risks of short circuit, subfissure and fragmentation of the cell piece are reduced, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of back-contact batteries, and in particular to a back-contact battery assembly and a photovoltaic system. Background Art

[0002] In existing back-contact battery modules, the series bus bars between adjacent battery strings in series are usually installed at the edge of the battery module, and the parallel bus bars between adjacent battery strings in parallel are usually installed in the reserved spacing area between the two battery strings. This results in the need to reserve a certain amount of space at the edge of the battery module for placing the series bus bars, and a certain amount of space also needs to be reserved between the two parallel battery strings for placing the parallel bus bars. On the one hand, this reduces the effective light-receiving area of ​​the battery module and affects the module conversion efficiency. On the other hand, it affects the appearance of the battery module.

[0003] In some products, the bus bar is installed in the middle position on the back side of the battery cell, and an insulating strip is set between the bus bar and the battery cell. Although this setting can hide the bus bar, it is necessary to make holes in the insulating strip or replace the bus bar with intermittent insulating blocks so that the bus bar can contact the same polarity welding strip on the battery cell and be insulated from the opposite polarity welding strip on the battery cell. This setting requires high precision in the opening of the insulating strip and the arrangement position of the insulating block. It is difficult to produce and is prone to positional offset when the insulating strip is opened or when the insulating block is laminated. The offset in the width direction can easily cause a short circuit. Summary of the invention

[0004] The purpose of the present invention is to provide a back-contact battery assembly and a photovoltaic system in view of the existing technical status.

[0005] The present invention can increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the bus bar observed from the light-receiving side is smaller and can even be completely hidden, which is more beautiful. At the same time, it can effectively reduce the difficulty of production, reduce the risks of short circuit, hidden cracks and fragments of the battery cell, and improve reliability.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] First, the present invention discloses a back contact battery assembly, comprising:

[0008] A battery string, wherein the battery string includes battery cells connected in series, and the battery cells include a first battery cell and a second battery cell arranged along a first direction,

[0009] A first insulating strip is provided at one end of the second battery cell close to the first battery cell,

[0010] A first bus bar is provided on a side of the first insulating strip facing away from the second battery cell.

[0011] The first insulating bar and the first bus bar are both extended along a second direction, and the first direction is intersected with the second direction.

[0012] a first welding strip, used for electrically connecting the first bus bar and the first battery cell,

[0013] An extension section extending out of the first bus bar is provided at one end of the first insulating strip close to the first battery cell, and the extension section extends out of the second battery cell, and in the thickness direction of the second battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the first battery cell.

[0014] In one embodiment, the first battery cell and the second battery cell are arranged on the same plane.

[0015] In the first direction, the width of the portion of the extension section extending outside the second battery cell is greater than the distance between the first battery cell and the second battery cell.

[0016] In one embodiment, in the first direction, the width of the extension segment is:

[0017] 1mm≤L 1 ≤l 11 +l 12 +l 13 ,

[0018] Where, L 1 is the width of the extension segment in the first direction, l 11 is the distance between the first battery cell and the second battery cell, l 12 is the relative width distance from the edge of the first battery cell close to one end of the second battery cell to the first welding point, the first welding point is used to connect with the first welding strip and is provided at one end of the first battery cell close to the second battery cell, l 13 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

[0019] In one embodiment, in the first direction, the width of the extension segment is:

[0020] 1mm≤L 1 ≤l 11 +l 13 +4mm,

[0021] Where, L 1is the width of the extension segment in the first direction, l 11 is the distance between the first battery cell and the second battery cell, l 13 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

[0022] In one embodiment, an end of the second battery cell close to the first battery cell is at least partially stacked with the first battery cell.

[0023] In the first direction, the width of the extension section is greater than the width of the stacking region between the first battery cell and the second battery cell.

[0024] In one embodiment, the width of the extension section is:

[0025] 1mm≤L 2 ≤l 22 +l 23 -l 21 ,

[0026] Where, L 2 is the width of the extension segment in the first direction, l 21 is the width of the stacking area between the first battery cell and the second battery cell, l 22 is the relative width distance from the edge of the first battery cell close to one end of the second battery cell to the first welding point, the first welding point is used to connect with the first welding strip and is provided at one end of the first battery cell close to the second battery cell, l 23 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

[0027] In one embodiment, the width of the extension section is:

[0028] 1mm≤L 2 ≤l 23 +4mm-l 21 ,

[0029] Where, L 2 is the width of the extension segment in the first direction, l 21 is the width of the stacking area between the first battery cell and the second battery cell, l 23 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

[0030] In one embodiment, the battery assembly includes at least one series-connected battery string group, the same series-connected battery string group includes two battery strings arranged along the second direction and arranged in series with each other, and in the same series-connected battery string group, the same first bus bar extends from the second battery cell in one battery string to the second battery cell in another battery string.

[0031] In one embodiment, a fourth battery cell is provided at one end of each battery string away from the first battery cell, and a third battery cell is provided at one end of the fourth battery cell close to the first battery cell.

[0032] The battery assembly includes a parallel battery string group, and the same parallel battery string group includes at least two battery strings arranged along a first direction and arranged in parallel with each other, and the fourth battery cells in the two battery strings arranged in parallel with each other are arranged adjacent to each other in the first direction,

[0033] The battery assembly further comprises:

[0034] A second insulating strip is provided at an edge of the third battery cell in the battery string, and the second insulating strip is provided at an end of the third battery cell close to the fourth battery cell,

[0035] an intermediate bus bar, used for connecting in parallel two battery strings arranged adjacent to each other in the first direction, the intermediate bus bar being arranged on a side of the second insulating strip facing away from the third battery cell,

[0036] The second insulating strip and the middle bus bar are both extended along the second direction.

[0037] The second welding strip is used to electrically connect the middle bus bar, the fourth battery cell in the battery string, and the fourth battery cell in another battery string adjacent to the battery string in the first direction.

[0038] In one embodiment, an end of the second insulating strip close to the fourth battery cell is provided with an extension section extending outside the middle bus bar, and the extension section extends outside the third battery cell, and in the thickness direction of the third battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth battery cell in the battery string where it is located.

[0039] Secondly, the present invention also discloses a back contact battery assembly, comprising:

[0040] A parallel battery string group, wherein the same parallel battery string group comprises at least two battery strings arranged in a first direction and arranged in parallel with each other, each of the battery strings comprises battery cells connected in series with each other, the battery cells comprise a third battery cell and a fourth battery cell arranged in the first direction, and the fourth battery cells in the two battery strings arranged in parallel with each other are arranged adjacently in the first direction,

[0041] A second insulating strip is provided at an edge of the third battery cell in one of the battery strings, and the second insulating strip is provided at an end of the third battery cell close to the fourth battery cell,

[0042] An intermediate bus bar is used to connect in parallel two battery strings arranged adjacent to each other in the first direction, and the intermediate bus bar is arranged on a side of the second insulating strip facing away from the third battery cell.

[0043] The second insulating strip and the middle bus bar are both extended along the second direction.

[0044] a second welding strip, for electrically connecting the middle bus bar, the fourth battery cell in the battery string where the middle bus bar is located, and the fourth battery cell in another battery string adjacent to the battery string in the first direction,

[0045] An end of the second insulating strip close to the fourth battery cell is provided with an extension section extending out of the middle bus bar, and the extension section extends outside the third battery cell. In the thickness direction of the third battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth battery cell in the battery string where the extension section is located.

[0046] In one embodiment, in the battery string provided with the second insulating strip, the fourth battery cell and the third battery cell are provided on the same plane.

[0047] In the first direction, the width of the portion of the extension section extending outside the third battery cell is greater than the distance between the fourth battery cell and the third battery cell.

[0048] In one embodiment, in the first direction, the width of the extension section is:

[0049] 1mm≤L 3 ≤l 31 +l 32 +l 33 ,

[0050] Where, L 3 is the width of the extension segment in the first direction, l 31 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the second insulating strip, l 32 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 33It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

[0051] In one embodiment, in the first direction, the width of the extension segment is:

[0052] 1mm≤L 3 ≤l 31 +l 33 +4mm,

[0053] Where, L 3 is the width of the extension segment in the first direction, l 31 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the second insulating strip, l 33 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

[0054] In one embodiment, in the battery string provided with the second insulating strip, one end of the third battery cell close to the fourth battery cell is at least partially stacked with the fourth battery cell.

[0055] In the first direction, the width of the extension section is greater than the width of the stacking region between the third battery cell and the fourth battery cell.

[0056] In one embodiment, in the first direction, the width of the extension section is:

[0057] 1mm≤L 4 ≤l 42 +l 43 -l 41 ,

[0058] Where, L 4 is the width of the extension segment in the first direction, l 41 is the width of the stacking region between the third battery cell and the fourth battery cell, l 42 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 43 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

[0059] In one embodiment, in the first direction, the width of the extension section is:

[0060] 1mm≤L 4 ≤l 43 -l 41 +4mm,

[0061] Where, L 4 is the width of the extension segment in the first direction, l 41 is the width of the stacking region between the third battery cell and the fourth battery cell, l 42 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 43 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

[0062] A photovoltaic system comprises the above-mentioned back-contact battery assembly.

[0063] The beneficial effects of the present invention are:

[0064] 1) On the one hand, the built-in structure of the end bus bar of the present invention can increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the bus bar observed from the light-receiving side is smaller, or even completely hidden, and the overall aesthetics of the battery assembly is better. On the other hand, it can ensure that the first welding strip can be fully fitted and welded with the effective welding position of the first battery cell, avoiding the setting of the first bus bar causing insufficient welding between the first welding strip and the first battery cell and affecting the current collection. During assembly, it is only necessary to place the entire first insulating strip on the end of the second battery cell close to the first battery cell. At the same time, through the setting of the extension section, during the preparation process, it is possible to allow a certain degree of offset of the first insulating strip relative to the first bus bar and the first insulating strip relative to the two battery cells in the width direction, effectively reducing the production accuracy requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, the built-in structure of the end bus bar of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, and has stronger versatility. The stress of the built-in structure of the end bus bar is smaller during lamination, which can reduce the risk of hidden cracks and fragments of the battery cells, and the reliability of the back contact battery assembly is good.

[0065] 2) The intermediate bus bar built-in structure of the present invention, on the one hand, can increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the bus bar observed from the light-receiving side is smaller, or even completely hidden, and the overall aesthetics of the battery assembly is better. On the other hand, it can ensure that the second welding strip can be fully fitted and welded with the effective welding position of the fourth battery cell, avoiding the setting of the intermediate bus bar causing insufficient welding between the second welding strip and the fourth battery cell and affecting the current collection. During assembly, it is only necessary to place the entire second insulating strip on the end of the third battery cell close to the fourth battery cell. At the same time, through the setting of the extension section, during the preparation process, it is possible to allow a certain degree of offset of the second insulating strip relative to the intermediate bus bar and the second insulating strip relative to the two battery cells in the width direction, effectively reducing the production accuracy requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, the intermediate bus bar built-in structure of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, with stronger versatility. The intermediate bus bar built-in structure has less stress during lamination, which can reduce the risk of hidden cracks and fragments of battery cells, and the reliability of the back contact battery assembly is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a schematic structural diagram of a series-connected battery string group (adjacent battery cells are on the same plane, and the extended section is a long strip structure) according to Example 1 of the present invention.

[0067] Figure 2 It is a cross-sectional view of the end busbar built-in structure of Example 1 of the present invention.

[0068] Figure 3 Schematic diagram of the structure of the battery string of Example 1 of the present invention.

[0069] Figure 4 This is a schematic diagram of the structure of the back contact battery assembly of Example 1 of the present invention.

[0070] Figure 5 It is a schematic structural diagram of a parallel battery string group (adjacent battery cells are on the same plane) according to Example 1 of the present invention.

[0071] Figure 6 It is a schematic structural diagram of a series-connected battery string group (adjacent battery cells are stacked) according to Embodiment 2 of the present invention.

[0072] Figure 7 This is a cross-sectional view of an embodiment of the end busbar built-in structure of embodiment 2 of the present invention.

[0073] Figure 8 It is a cross-sectional view of another embodiment of the end busbar built-in structure of embodiment 2 of the present invention.

[0074] Fig. 9It is a cross-sectional view of the end busbar built-in structure of embodiment 3 of the present invention.

[0075] Fig.10 It is a schematic structural diagram of a parallel battery string group (adjacent battery cells are on the same plane) according to Example 3 of the present invention.

[0076] Fig.11 It is a schematic structural diagram of a parallel battery string group (adjacent battery cells are stacked) according to Example 4 of the present invention.

[0077] Fig.12 It is a cross-sectional view of an embodiment of the intermediate bus bar built-in structure of embodiment 4 of the present invention.

[0078] Fig.13 It is a cross-sectional view of another embodiment of the intermediate bus bar built-in structure of embodiment 4 of the present invention. DETAILED DESCRIPTION

[0079] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0080] In the description of the present application, the terms "first", "second", "third", "fourth", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", "third", "fourth", etc. may explicitly or implicitly include one or more of the features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0081] 1) On the one hand, the built-in structure of the end bus bar of the present invention can increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the bus bar observed from the light-receiving side is smaller, or even completely hidden, and the overall aesthetics of the battery assembly is better. On the other hand, it can ensure that the first welding strip can be fully fitted and welded with the effective welding position of the first battery cell, avoiding the setting of the first bus bar causing insufficient welding between the first welding strip and the first battery cell and affecting the current collection. During assembly, it is only necessary to place the entire first insulating strip on the end of the second battery cell close to the first battery cell. At the same time, through the setting of the extension section, during the preparation process, it is possible to allow a certain degree of offset of the first insulating strip relative to the first bus bar and the first insulating strip relative to the two battery cells in the width direction, effectively reducing the production accuracy requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, the built-in structure of the end bus bar of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, and has stronger versatility. The stress of the built-in structure of the end bus bar is smaller during lamination, which can reduce the risk of hidden cracks and fragments of the battery cells, and the reliability of the back contact battery assembly is good.

[0082] 2) The intermediate bus bar built-in structure of the present invention, on the one hand, can increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the bus bar observed from the light-receiving side is smaller, or even completely hidden, and the overall aesthetics of the battery assembly is better. On the other hand, it can ensure that the second welding strip can be fully fitted and welded with the effective welding position of the fourth battery cell, avoiding the setting of the intermediate bus bar causing insufficient welding between the second welding strip and the fourth battery cell and affecting the current collection. During assembly, it is only necessary to place the entire second insulating strip on the end of the third battery cell close to the fourth battery cell. At the same time, through the setting of the extension section, during the preparation process, it is possible to allow a certain degree of offset of the second insulating strip relative to the intermediate bus bar and the second insulating strip relative to the two battery cells in the width direction, effectively reducing the production accuracy requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, the intermediate bus bar built-in structure of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, with stronger versatility. The intermediate bus bar built-in structure has less stress during lamination, which can reduce the risk of hidden cracks and fragments of battery cells, and the reliability of the back contact battery assembly is good.

[0083] Example 1

[0084] See also Figures 1 to 3 As shown, this embodiment discloses a back contact battery assembly, including:

[0085] A battery string, the battery string includes battery cells connected in series, the battery cells include a first battery cell 11 and a second battery cell 12 arranged along a first direction, the first battery cell 11 is arranged at the end of the battery string,

[0086] The first insulating strip 21 is disposed at one end of the second battery cell 12 close to the first battery cell 11.

[0087] The first bus bar 31 is disposed on the side of the first insulating strip 21 facing away from the second battery cell 12, i.e., the back side of the first insulating strip 21; conversely, the side of the first insulating strip 21 facing the second battery cell 12 is the front side of the first insulating strip 21.

[0088] The first insulating strip 21 and the first bus bar 31 are both extended along the second direction, and the first direction and the second direction are intersected.

[0089] The first welding strip is used to electrically connect the first bus bar 31 and the first battery cell 11.

[0090] An end of the first insulating strip 21 close to the first battery cell 11 is provided with an extension section 211 extending out of the first bus bar 31, and the extension section 211 extends to the outside of the second battery cell 12. In the thickness direction of the second battery cell 12, the orthographic projection of the extension section 211 at least partially overlaps with the orthographic projection of the first battery cell 11, that is, the extension section 211 can cover the edge area of ​​the first battery cell 11 to separate the first bus bar 31 from the edge area of ​​the first battery cell 11.

[0091] It can be understood that the electrical connection method can be welding, bonding through conductive adhesive, etc., but is not limited thereto.

[0092] It is understandable that in a battery string, the battery string may include two battery cells connected in series, three battery cells connected in series, or any other greater number of battery cells. The specific number of battery cells to be connected in series may be determined based on actual usage.

[0093] In the present embodiment, the first bus bar 31 is an end bus bar, and the first battery cell 11 is located at the end of the battery string. For ease of explanation, in the present embodiment, the end where the first battery cell 11 is located is recorded as the tail end of the battery string, that is, in the first direction, the first battery cell 11 is the last battery cell of the battery string, and the second battery cell 12 is the second to last battery cell of the battery string. It is not difficult to understand that the end where the first battery cell 11 is located can also be recorded as the head end of the battery string, which will not be repeated here.

[0094] Optionally, in the same battery string, adjacent battery cells can be connected in series by means of welding strips, conductive adhesive, etc.

[0095] In one embodiment, adjacent battery cells are connected by a series welding ribbon 51. Specifically, the series welding ribbon 51 includes a first series welding ribbon 511 and a second series welding ribbon 512. In a first direction, the first series welding ribbon 511 and the second series welding ribbon 512 are alternately arranged. In a second direction, the first series welding ribbon 511 and the second series welding ribbon 512 are alternately arranged. In a battery string, the Nth battery cell, the N+1th battery cell, and the N+2th battery cell (N is a positive integer greater than 1) are arranged in sequence along the first direction, wherein the positive electrode welding point of the Nth battery cell and the negative electrode welding point of the N+1th battery cell are connected in series through multiple first series welding ribbons 511, and the positive electrode welding point of the N+1th battery cell and the negative electrode welding point of the N+2th battery cell are connected in series through multiple second series welding ribbons 512.

[0096] During assembly, the battery cells in the battery string are connected in series with each other, the first insulating strip 21 is arranged at one end of the second battery cell 12 close to the first battery cell 11, the first bus bar 31 is arranged on the back side of the first insulating strip 21, the main body of the first welding strip is electrically connected to the effective welding position of the first battery cell 11, and the end of the first welding strip close to the second battery cell 12 is electrically connected to the first bus bar 31, thereby enabling the first bus bar 31 to draw the current of the battery string.

[0097] First, in the present invention, the first bus bar 31 is arranged on the second battery cell 12, and the first bus bar 31 and the second battery cell 12 are separated by the first insulating strip 21. On the one hand, there is no need to reserve space on the edge of the battery assembly for placing the bus bar, and the battery assembly can reserve more space for installing the battery cells, so that the effective light-receiving area of ​​the battery assembly is larger and the assembly conversion efficiency is higher. On the other hand, when observing from the light-receiving surface (or "front") of the battery cell, the first insulating strip 21 can block the first bus bar 31 to prevent the first bus bar 31 from being exposed, and the overall aesthetics of the battery assembly is better.

[0098] Secondly, compared to setting the bus bar in the middle position on the back of the battery cell, the first bus bar 31 of the present invention is set at the end of the second battery cell 12 close to the first battery cell 11, and the first welding strip can be fully fitted and welded with the effective welding position of the first battery cell 11, thereby avoiding the installation of the first bus bar 31 causing insufficient welding between the first welding strip and the first battery cell 11 and affecting the current collection. At the same time, after the first welding strip is welded to the first battery cell 11, it can be directly connected to the first bus bar 31 without the need to open holes in the insulating strip or replace it with an intermittently arranged insulating block. During assembly, it is only necessary to place the entire first insulating strip 21 on the end of the second battery cell 12 close to the first battery cell 11, which effectively reduces the production precision requirements and production difficulty, and can avoid short circuits caused by position offset when opening holes in the insulating strip or position offset when laminating the insulating blocks, thereby increasing product yield. At the same time, the first insulating strip 21 of the present invention is provided with an extension section 211, which allows a certain degree of offset in the width direction of the first insulating strip 21 relative to the first bus bar 31 and the first insulating strip 21 relative to the two battery cells during the preparation process, thereby reducing the production precision requirements and production difficulty. On the other hand, the first insulating strip 21 can cover the edges of the second battery cell 12 and the first battery cell 11, thereby not only preventing the first bus bar 31 from contacting the heterogeneous welding strip / heterogeneous grid line on the first battery cell 11 to cause a short circuit, but also preventing the first welding strip from contacting the second battery cell 12. The short circuit caused by the contact of the heterogeneous welding strip / heterogeneous grid line of the cell sheet 12 and the short circuit easily caused by conductive foreign matter such as tin slag in the preparation process can further reduce the risk of short circuit and improve the reliability of the battery assembly. Especially when the battery sheet is cut into half sheets, the cut edge is very likely to cause a short circuit after cutting. The arrangement of the extension section 211 of the present invention can effectively avoid the short circuit easily caused by the cut edge, so that the cut edge of the battery half is arranged on the side of the first bus bar 31 on the battery sheet or on the side of the adjacent battery sheet close to the first bus bar 31, which can also ensure the reliability of the battery assembly.

[0099] Furthermore, when the bus bar is set at the outer edge of the last battery cell in the battery string, that is, when the first battery cell 11 is away from one end of the second battery cell 12, since the outer edge of the last battery cell in the battery string is close to the edge of the battery assembly, the stress there is relatively large during lamination, which is prone to produce defects such as fragments. At the same time, the installation of the bus bar will affect the welding between the first welding strip and the first battery cell 11. The first welding strip cannot be welded to the first battery cell 11 at the position covered by the bus bar, resulting in insufficient welding between the first welding strip and the first battery cell 11 and poor current collection. This situation is particularly serious when the battery assembly is a main grid back contact battery assembly.

[0100] In contrast, the built-in structure of the end bus bar of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, and is more versatile. In addition, the end of the second battery cell 12 close to the first battery cell 11 has less stress during lamination than the outer edge of the last battery cell in the battery string, which can reduce the risk of fragments and cracks and further improve the reliability of the battery assembly.

[0101] In one embodiment, see Figures 1 to 3 As shown, the first battery cell 11 and the second battery cell 12 are arranged on the same plane.

[0102] In the first direction, the width of the portion of the extension section 211 extending outside the second battery cell 12 is greater than the distance between the first battery cell 11 and the second battery cell 12 .

[0103] As a result, the extension section 211 can reserve a sufficient width, allowing the first insulating strip 21 to be offset to a certain extent in the width direction relative to the first bus bar 31 and the first insulating strip 21 relative to the two battery cells during the preparation process, thereby reducing the production precision requirements and production difficulty. On the other hand, the extension section 211 can extend to cover the edge area of ​​the first battery cell 11 and the edge area of ​​the second battery cell 12, which can avoid the first bus bar 31 from contacting the anisotropic welding strip / anisotropic grid line on the first battery cell 11 and causing a short circuit, and can also avoid the first welding strip from contacting the anisotropic welding strip / anisotropic grid line of the second battery cell 12 and causing a short circuit, further reducing the risk of short circuits and improving the reliability of battery components.

[0104] In one embodiment, see Figure 2 As shown, in the first direction, the width of the extension section 211 is:

[0105] 1mm≤L 1 ≤l 11 +l 12 +l 13 ,

[0106] Where, L 1 is the width of the extension section 211 in the first direction, l 11 is the distance between the first battery cell 11 and the second battery cell 12, l 12 is the relative width distance from the edge of the first battery cell 11 close to the second battery cell 12 to the first welding point 61. The first welding point 61 is used to connect with the first welding strip and is provided at the end of the first battery cell 11 close to the second battery cell 12. 13 It is the relative width distance between the edge of the first bus bar 31 close to one end of the first battery cell 11 and the edge of the second battery cell 12 close to one end of the first battery cell 11 .

[0107] Understandable, 11 +l13 >1mm,l 11 <1mm, therefore, L 1 ≥1mm, which can ensure that the extension section 211 can extend to cover the edge area of ​​the first battery cell 11 and the edge area of ​​the second battery cell 12, while reserving sufficient offset space 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 allowing the first insulating strip 21 to be slightly offset in the width direction relative to the first bus bar 31 and the first insulating strip 21 relative to the two battery cells.

[0108] When the width of the extension section 211 is too small, the risk of short circuit increases and the reliability of the battery assembly decreases. As the width of the extension section 211 increases, the reliability of the battery assembly increases. The displacement deviation of the first insulating strip 21 relative to the first bus bar 31 and the first insulating strip 21 relative to the two battery cells in the width direction allowed in the preparation process increases, and the production accuracy requirement decreases. However, when the width of the extension section 211 is too large, it will affect the full welding between the first welding strip and the effective welding position on the first battery cell 11, the current collection effect will decrease, and the bifaciality of the battery assembly will be affected. It can be understood that the first welding point 61 is located at the edge of the effective welding position of the first battery cell 11 closest to the second battery cell 12 (that is, the edgemost connection point of the first welding strip 41 on the first battery cell 11). The first welding point 61 can be a grid line or a pad. In the present invention, by controlling 1mm≤L 1 ≤l 11 +l 12 +l 13 , ensuring that the extended section 211 of the first insulating strip 21 can extend to cover the edge area of ​​the first battery cell 11 and the edge area of ​​the second battery cell 12, 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 first welding strip.

[0109] In one embodiment, see Figure 2 As shown, in the first direction, the width of the extension section 211 is:

[0110] 1mm≤L 1 ≤l 11 +l 13 +4mm,

[0111] Where, L 1 is the width of the extension section 211 in the first direction, l 11 is the distance between the first battery cell 11 and the second battery cell 12, l 13 It is the relative width distance between the edge of the first bus bar 31 close to one end of the first battery cell 11 and the edge of the second battery cell 12 close to one end of the first battery cell 11 .

[0112] Within this range, while allowing for offset errors in the preparation process, it is possible to ensure that the extended segment 211 of the first insulating strip 21 can extend to cover the edge areas of the first battery cell 11 and the second battery cell 12, thereby further improving the reliability and production yield of the battery assembly. At the same time, unnecessary material waste will not occur, and even if the first insulating strip 21 is offset during production and preparation, it can ensure that the sufficient welding of the first welding strip will not be affected, thereby effectively reducing the production precision.

[0113] In one embodiment, see Figure 1 and Figure 4 As shown, the battery assembly includes at least one series battery string group 100, and the same series battery string group 100 includes two battery strings arranged along the second direction and connected in series with each other. In the same series battery string group 100, the same first bus bar 31 extends from the second battery cell 12 in one battery string to the second battery cell 12 in another battery string.

[0114] Furthermore, the first welding strip includes a first positive welding strip and a first negative welding strip. The same first bus bar 31 is electrically connected to the first positive welding strip in one battery string and to the first negative welding strip in another battery string, so that adjacent battery strings are connected in series.

[0115] Exemplarily, the same series battery string group 100 includes a first battery string 10A and a second battery string 10B, and the first welding strip includes a first positive electrode welding strip and a first negative electrode welding strip. In the same series battery string group 100, the same first bus bar 31 extends from the second battery cell 12 in the first battery string 10A to the second battery cell 12 in the second battery string 10B, and in the first battery string 10A, the first bus bar 31 is electrically connected to the first positive electrode welding strip on the first battery cell 11, and in the second battery string 10B, the first bus bar 31 is electrically connected to the first negative electrode welding strip on the first battery cell 11.

[0116] Among them, in one embodiment, the battery assembly includes a parallel battery string group 200, and the same parallel battery string group 200 includes at least two battery strings arranged along a first direction and arranged in parallel with each other, and a spacing area is set between the two battery strings arranged in parallel with each other, and an intermediate bus bar 32 is provided in the spacing area. The intermediate bus bar 32 is used to connect two battery strings adjacent to each other in the first direction in parallel, that is, the end bus bar built-in structure of the present invention can cooperate with the conventional intermediate bus bar 32 installation structure.

[0117] In another more preferred embodiment, see Figures 4 to 5 As shown, each battery string is provided with a fourth battery cell 14 at one end away from the first battery cell 11, and a third battery cell 13 is provided at one end of the fourth battery cell 14 close to the first battery cell 11.

[0118] The battery assembly includes a parallel battery string group 200, and the same parallel battery string group 200 includes at least two battery strings arranged along a first direction and arranged in parallel with each other, and the fourth battery cells 14 in the two battery strings arranged in parallel with each other are arranged adjacent to each other in the first direction.

[0119] The battery assembly also includes:

[0120] The second insulating strip 22 is disposed at the edge of the third battery cell 13 in a battery string, and the second insulating strip 22 is disposed at one end of the third battery cell 13 close to the fourth battery cell 14.

[0121] The middle bus bar 32 is used to connect two battery strings arranged adjacent to each other in the first direction in parallel. The middle bus bar 32 is arranged on the side of the second insulating strip 22 facing away from the third battery cell 13.

[0122] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0123] The second welding strip 42 is used to electrically connect the middle bus bar 32 , the fourth battery cell 14 in the battery string, and the fourth battery cell 14 in another battery string adjacent to the battery string in the first direction.

[0124] For example, see Figures 4 to 5 As shown, for the convenience of explanation, the third battery string 20A and the fourth battery string 20B connected in parallel in the same parallel battery string group 200 are taken as an example, wherein the third battery string 20A is the battery string where the middle bus bar 32 is located:

[0125] The third battery cell 13 in the third battery string 20A is recorded as the third battery cell 13A, the fourth battery cell 14 is recorded as the fourth battery cell 14A, the third battery cell 13 in the fourth battery string 20B is recorded as the third battery cell 13B, the fourth battery cell 14 is recorded as the fourth battery cell 14B, the third battery string 20A and the fourth battery string 20B are arranged along the first direction, the fourth battery cell 14A and the fourth battery cell 14B are adjacently arranged in the first direction,

[0126] The battery assembly also includes:

[0127] The second insulating strip 22 is disposed at the edge of the third battery cell 13A in the third battery string 20A, and the second insulating strip 22 is disposed at one end of the third battery cell 13A close to the fourth battery cell 14A.

[0128] The middle bus bar 32 is used to connect the third battery string 20A and the fourth battery string 20B in parallel. The middle bus bar 32 is arranged on the side of the second insulating strip 22 facing away from the third battery cell 13.

[0129] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0130] The second welding ribbon 42 is used to electrically connect the middle bus bar 32 , the fourth battery cell 14A and the fourth battery cell 14B. That is, the same second welding ribbon 42 extends from the fourth battery cell 14B to the fourth battery cell 14A and the middle bus bar 32 in sequence.

[0131] Furthermore, the second welding strip 42 includes a second positive electrode welding strip 421 and a second negative electrode welding strip 422 , and the fourth battery cell 14A, the fourth battery cell 14B and the middle bus bar 32 are electrically connected via the second positive electrode welding strip 421 or the second negative electrode welding strip 422 .

[0132] The internal structure of the intermediate bus bar 32 of the present invention can, on the one hand, increase the effective light receiving area of ​​the battery assembly, improve the conversion efficiency of the assembly, avoid the exposure of the intermediate bus bar 32, and improve the overall aesthetics of the battery assembly; on the other hand, it can ensure that the second welding strip 42 can be fully attached and welded to the effective welding position of the fourth battery cell 14, and avoid the installation of the intermediate bus bar 32 causing insufficient welding between the second welding strip 42 and the fourth battery cell 14 and affecting the current collection. During assembly, only the second insulating strip 22 needs to be placed on the end of the third battery cell 13 close to the fourth battery cell 14. By setting the extension section 221, the second insulating strip 22 is allowed to be offset to a certain extent in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells during the preparation process, which effectively reduces the production precision requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, the built-in structure of the middle bus bar 32 of the present invention can be applied to battery assemblies with main grid back contact and battery assemblies without main grid back contact, and has stronger versatility. The built-in structure of the middle bus bar 32 has less stress during lamination, which can reduce the risk of hidden cracks and fragments of battery cells, and the reliability of the back contact battery assembly is good.

[0133] The built-in structure of the end bus bar of the present invention cooperates with the built-in structure of the middle bus bar 32 of the present invention to increase the effective light-receiving area of ​​the battery assembly, improve the conversion efficiency of the assembly, improve the overall aesthetics and reliability of the battery assembly, effectively reduce the production precision requirements and production difficulty, and improve production efficiency.

[0134] In one embodiment, see Figures 4 to 5 As shown, an end of the second insulating strip 22 close to the fourth battery cell 14 is provided with an extension section 221 extending out of the middle bus bar 32, and the extension section 221 extends to the outside of the third battery cell 13, and in the thickness direction of the third battery cell 13, the orthographic projection of the extension section 221 at least partially overlaps with the orthographic projection of the fourth battery cell 14 in the battery string where it is located.

[0135] That is, an end of the second insulating strip 22 close to the fourth battery cell 14A is provided with an extension section 221 extending out of the middle bus bar 32, and the extension section 221 extends to the outside of the third battery cell 13A, and in the thickness direction of the third battery cell 13A, the orthographic projection of the extension section 221 at least partially overlaps with the orthographic projection of the fourth battery cell 14A.

[0136] The second insulating strip 22 of the present invention is provided with an extension section 221. On the one hand, it allows the second insulating strip 22 to be offset to a certain extent in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells during the preparation process, thereby reducing the production precision requirements and production difficulty. On the other hand, the second insulating strip 22 can cover the edges of the third battery cell 13 and the fourth battery cell 14, thereby not only avoiding the middle bus bar 32 and the heterogeneous welding strip / heterogeneous grid line on the fourth battery cell 14 from contacting to cause a short circuit, but also avoiding the second welding strip 42 and the heterogeneous welding strip / heterogeneous grid line on the third battery cell 13 from contacting to cause a short circuit, further reducing the risk of short circuit and improving the reliability of the battery assembly. In particular, when the battery cell is cut into half pieces, the cut edge is very likely to cause a short circuit after cutting. The provision of the extension section 221 of the present invention can effectively avoid the short circuit easily caused by the cut edge, so that the cut edge of the battery half is arranged on the side of the middle bus bar 32 on the battery cell or on the side of the adjacent battery cell close to the middle bus bar 32, which can also ensure the reliability of the battery assembly.

[0137] Furthermore, the present invention provides a photovoltaic system, comprising the above-mentioned back-contact cell assembly.

[0138] In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, rooftop power stations, water power stations, etc., and can also be applied to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar street lights, solar cars, solar buildings, etc. Of course, it can be understood that the application scenarios of the photovoltaic system are not limited to this, that is to say, the photovoltaic system can be applied in all fields that require solar energy to generate electricity. Taking the photovoltaic power generation system network as an example, the photovoltaic system may include a photovoltaic array, a junction box and an inverter. The photovoltaic array may be an array combination of multiple battery components. For example, multiple battery components can form multiple photovoltaic arrays. The photovoltaic array is connected to the junction box. The junction box can converge the current generated by the photovoltaic array. The converged current flows through the inverter and is converted into the alternating current required by the mains power grid, and then connected to the mains network to realize solar power supply.

[0139] Example 2

[0140] The difference between this embodiment and embodiment 1 is that, see Figures 6 to 8 As shown, one end of the second battery cell 12 close to the first battery cell 11 is at least partially stacked with the first battery cell 11.

[0141] In the first direction, the width of the extension section 211 is greater than the width of the stacking region between the first battery cell 11 and the second battery cell 12 .

[0142] That is, the first battery cell 11 and the second battery cell 12 are stacked, and there is no gap between the two batteries.

[0143] In one embodiment, see Figure 8 As shown, the side of the second battery cell 12 facing away from the first insulating strip 21 is at least partially stacked with the first battery cell 11 .

[0144] In another embodiment, see Figure 7 As shown, the side of the second battery cell 12 facing the first insulating strip 21 is at least partially stacked with the first battery cell 11 .

[0145] In one embodiment, preferably, the width of the extension section 211 is:

[0146] 1mm≤L 2 ≤l 22 +l 23 -l 21 ,

[0147] Where, L 2 is the width of the extension section 211 in the first direction, l 21 is the width of the stacking region between the first battery cell 11 and the second battery cell 12, l 22 is the relative width distance from the edge of the first battery cell 11 close to the second battery cell 12 to the first welding point 61. The first welding point 61 is used to connect with the first welding strip and is provided at the end of the first battery cell 11 close to the second battery cell 12. 23 It is the relative width distance between the edge of the first bus bar 31 close to one end of the first battery cell 11 and the edge of the second battery cell 12 close to one end of the first battery cell 11 .

[0148] Understandable, 21 +l 23 >1mm,l 21 <1mm, therefore, L 2 ≥1mm, which can ensure that the extension section 211 can extend to cover the edge area of ​​the first battery cell 11 and the edge area of ​​the second battery cell 12, while reserving sufficient offset space 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 allowing the first insulating strip 21 to have a small offset in the width direction relative to the first bus bar 31 during the preparation process.

[0149] When the width of the extension section 211 is too small, the risk of short circuit increases and the reliability of the battery assembly decreases. As the width of the extension section 211 increases, the reliability of the battery assembly increases. The displacement deviation of the first insulating strip 21 relative to the first bus bar 31 and the first insulating strip 21 relative to the two battery cells in the width direction allowed in the preparation process increases, and the production accuracy requirement decreases. However, when the width of the extension section 211 is too large, it will affect the full welding between the first welding strip and the effective welding position on the first battery cell 11, the current collection effect will decrease, and it will affect the bifaciality of the battery assembly. In the present invention, by controlling 1mm≤L 2 ≤l 22 +l 23 -l 21 , ensuring that the extended section 211 of the first insulating strip 21 can extend to cover the edge area of ​​the first battery cell 11 and the edge area of ​​the second battery cell 12, 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 first welding strip.

[0150] In one embodiment, preferably, the width of the extension section 211 is:

[0151] 1mm≤L 2 ≤l 23 +4mm-l 21 ,

[0152] Where, L 2 is the width of the extension section 211 in the first direction, l 21 is the width of the stacking region between the first battery cell 11 and the second battery cell 12, l 23 It is the relative width distance between the edge of the first bus bar 31 close to one end of the first battery cell 11 and the edge of the second battery cell 12 close to one end of the first battery cell 11 .

[0153] Within this range, while allowing for offset errors in the preparation process, it is possible to ensure that the extended segment 211 of the first insulating strip 21 can extend to cover the edge areas of the first battery cell 11 and the second battery cell 12, thereby further improving the reliability and production yield of the battery assembly. At the same time, unnecessary material waste will not occur, and even if the first insulating strip 21 is offset during production and preparation, it can ensure that the sufficient welding of the first welding strip will not be affected, thereby effectively reducing the production precision.

[0154] 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 aforementioned embodiment 1, and will not be repeated here.

[0155] Example 3

[0156] See also Figures 9 and 10 As shown, this embodiment discloses a back contact battery assembly, including:

[0157] A parallel battery string group 200, wherein the same parallel battery string group 200 includes at least two battery strings arranged in a first direction and arranged in parallel with each other, each battery string includes battery cells connected in series, the battery cells include a third battery cell 13 and a fourth battery cell 14 arranged in the first direction, the fourth battery cell 14 is arranged at the end of the battery string, and the fourth battery cells 14 in the two battery strings arranged in parallel are adjacently arranged in the first direction,

[0158] The second insulating strip 22 is disposed at the edge of the third battery cell 13 in a battery string, and the second insulating strip 22 is disposed at one end of the third battery cell 13 close to the fourth battery cell 14.

[0159] The middle bus bar 32 is used to connect two battery strings arranged adjacent to each other in the first direction in parallel. The middle bus bar 32 is arranged on the side of the second insulating strip 22 facing away from the third battery cell 13.

[0160] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0161] The second welding strip 42 is used to electrically connect the middle bus bar 32, the fourth battery cell 14 in the battery string where the middle bus bar 32 is located, and the fourth battery cell 14 in another battery string adjacent to the battery string in the first direction.

[0162] An end of the second insulating strip 22 close to the fourth battery cell 14 is provided with an extension section 221 extending out of the middle bus bar 32, and the extension section 221 extends to the outside of the third battery cell 13, and in the thickness direction of the third battery cell 13, the orthographic projection of the extension section 221 at least partially overlaps with the orthographic projection of the fourth battery cell 14 in the battery string where it is located.

[0163] For example, for ease of explanation, the third battery string 20A and the fourth battery string 20B connected in parallel in the same parallel battery string group 200 are taken as an example, wherein the third battery string 20A is the battery string where the middle bus bar 32 is located:

[0164] The third battery cell 13 in the third battery string 20A is recorded as the third battery cell 13A, the fourth battery cell 14 is recorded as the fourth battery cell 14A, the third battery cell 13 in the fourth battery string 20B is recorded as the third battery cell 13B, the fourth battery cell 14 is recorded as the fourth battery cell 14B, the third battery string 20A and the fourth battery string 20B are arranged along the first direction, the fourth battery cell 14A and the fourth battery cell 14B are adjacently arranged in the first direction,

[0165] The battery assembly also includes:

[0166] The second insulating strip 22 is disposed at the edge of the third battery cell 13A in the third battery string 20A, and the second insulating strip 22 is disposed at one end of the third battery cell 13A close to the fourth battery cell 14A.

[0167] The middle bus bar 32 is used to connect the third battery string 20A and the fourth battery string 20B in parallel. The middle bus bar 32 is arranged on the side of the second insulating strip 22 facing away from the third battery cell 13.

[0168] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0169] The second welding strip 42 is used to electrically connect the middle bus bar 32, the fourth battery cell 14A and the fourth battery cell 14B. That is, the same second welding strip 42 extends from the fourth battery cell 14B to the fourth battery cell 14A and the middle bus bar 32 in sequence.

[0170] An extension section 221 extending out of the middle bus bar 32 is provided at one end of the second insulating strip 22 close to the fourth battery cell 14A, and the extension section 221 extends to the outside of the third battery cell 13A, and in the thickness direction of the third battery cell 13A, the orthographic projection of the extension section 221 at least partially overlaps with the orthographic projection of the fourth battery cell 14A.

[0171] During assembly, the battery cells in the battery string are connected in series with each other, the second insulating strip 22 is arranged at one end of the third battery cell 13A close to the fourth battery cell 14A, the intermediate bus bar 32 is arranged on the back of the second insulating strip 22, the main body of the second welding strip 42 is electrically connected to the effective welding position of the fourth battery cell 14A and the effective welding position of the fourth battery cell 14B respectively, and the end of the second welding strip 42 close to the third battery cell 13A is electrically connected to the intermediate bus bar 32, thereby enabling the intermediate bus bar 32 to connect the third battery string 20A and the fourth battery string 20B in parallel.

[0172] First, in the present invention, the middle bus bar 32 is arranged on the third battery cell 13A, and the middle bus bar 32 and the third battery cell 13A are separated by the second insulating strip 22. On the one hand, there is no need to reserve space on the edge of the battery assembly for placing the bus bar, and the battery assembly can reserve more space for installing the battery cells, so that the effective light-receiving area of ​​the battery assembly is larger and the assembly conversion efficiency is higher. On the other hand, when observing from the light-receiving surface (or "front") of the battery cell, the second insulating strip 22 can block the middle bus bar 32 to prevent the middle bus bar 32 from being exposed, and the overall aesthetics of the battery assembly is better.

[0173] Secondly, compared to setting the bus bar in the middle position on the back of the battery cell, the intermediate bus bar 32 of the present invention is set at one end of the third battery cell 13A close to the fourth battery cell 14A, and the second welding strip 42 extends to the fourth battery cell 14A after being connected to the effective welding position of the fourth battery cell 14B, and can be fully fitted and welded with the effective welding position of the fourth battery cell 14A, thereby avoiding the installation of the intermediate bus bar 32 causing insufficient welding between the second welding strip 42 and the fourth battery cell 14A, thereby affecting the current collection. At the same time, after the second welding strip 42 is welded to the fourth battery cell 14A and the fourth battery cell 14B, it can be directly connected to the intermediate bus bar 32 without the need to perform hole processing on the insulating strip or replace it with an intermittently arranged insulating block. During assembly, it is only necessary to place the entire second insulating strip 22 on one end of the third battery cell 13A close to the fourth battery cell 14A, thereby effectively reducing the production precision requirements and production difficulty, and can avoid short circuits caused by position offset when the insulating strip is opened or the insulating block is laminated, thereby increasing product yield. At the same time, the second insulating strip 22 of the present invention is provided with an extension section 221. On the one hand, the second insulating strip 22 is allowed to be offset to a certain extent in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells during the preparation process, thereby reducing the production precision requirements and production difficulty. On the other hand, the second insulating strip 22 can cover the edges of the third battery cell 13 and the fourth battery cell 14, thereby not only avoiding the middle bus bar 32 and the heterogeneous welding strip / heterogeneous grid line on the fourth battery cell 14 from contacting to cause a short circuit, but also avoiding the second welding strip 42 and the heterogeneous welding strip / heterogeneous grid line on the third battery cell 13 from contacting to cause a short circuit, further reducing the risk of short circuit and improving the reliability of the battery assembly. In particular, when the battery cell is cut into half pieces, the cutting edge is very likely to cause a short circuit after cutting. The setting of the extension section 221 of the present invention can effectively avoid the short circuit easily caused by the cutting edge, so that the cutting edge of the battery half is arranged on the side where the middle bus bar 32 is located on the battery cell or on the side of the adjacent battery cell close to the middle bus bar 32, which can also ensure the reliability of the battery assembly.

[0174] Furthermore, when the bus bar is set at the outer edge of the last battery cell in the battery string, that is, when the fourth battery cell 14A is away from one end of the third battery cell 13A, the stress at the outer edge of the last battery cell in the battery string is relatively large when it is laminated, which is prone to produce defects such as fragments. At the same time, the installation of the bus bar will affect the welding between the second welding ribbon 42 and the fourth battery cell 14A. The second welding ribbon 42 cannot be welded to the fourth battery cell 14A at the position covered by the bus bar, resulting in insufficient welding between the second welding ribbon 42 and the fourth battery cell 14A and poor current collection. This situation is particularly serious when the battery module is a main grid back contact battery module.

[0175] In contrast, the intermediate bus bar built-in structure of the present invention can be applied to both main-grid back-contact battery assemblies and non-main-grid back-contact battery assemblies, and is more versatile. Moreover, on the one hand, the end of the third battery cell 13A close to the fourth battery cell 14A has less stress during lamination than the outer edge of the last battery cell in the battery string, thereby further reducing the risk of hidden cracks and fragments in the battery cells and improving the reliability of the back-contact battery assembly.

[0176] In one embodiment, see Fig. 9 As shown, in the battery string provided with the second insulating strip 22, the fourth battery cell 14 and the third battery cell 13 are provided on the same plane.

[0177] In the first direction, the width of the portion of the extension section 221 extending from the third battery cell 14 is greater than the distance between the fourth battery cell 14 and the third battery cell 13 .

[0178] As a result, the extension section 221 can reserve a sufficient width, allowing the second insulating strip 22 to be offset to a certain extent in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells during the preparation process, thereby reducing the production precision requirements and production difficulty. On the other hand, the extension section 221 can extend to cover the edge area of ​​the fourth battery cell 14A and the edge area of ​​the third battery cell 13A, which can avoid the middle bus bar 32 and the anisotropic welding strip / anisotropic grid line on the fourth battery cell 14A from contacting and causing a short circuit, and can also avoid the second welding strip 42 and the anisotropic welding strip / anisotropic grid line on the third battery cell 13A from contacting and causing a short circuit, further reducing the risk of short circuits and improving the reliability of battery components.

[0179] In one embodiment, see Fig. 9 As shown, in the first direction, the width of the extension section 221 is:

[0180] 1mm≤L 3 ≤l 31 +l 32 +l 33 ,

[0181] Where, L 3 is the width of the extension section 221 in the first direction, l 31 is the distance between the fourth battery cell 14 and the third battery cell 13 in the battery string provided with the second insulating strip 22, l 32 is the relative width distance from the edge of the fourth battery cell 14 close to one end of the third battery cell 13 to the second welding point 62 in the battery string provided with the second insulating strip 22, l 33 It is the relative width distance between the edge of the middle bus bar 32 close to one end of the fourth battery cell 14 and the edge of the third battery cell 13 close to one end of the fourth battery cell 14 in the battery string provided with the second insulating strip 22 .

[0182] Understandable, 31 +l 33 >1mm,l 31 <1mm, therefore, control L 3 ≥1mm, which can ensure that the extension section 221 can extend to cover the edge area of ​​the fourth battery cell 14A and the edge area of ​​the third battery cell 13A, while reserving sufficient offset space for the horizontal tolerance of the equipment placement in the preparation process and the lamination offset tolerance of the bus bar lead-out hole position, thereby allowing the second insulating strip 22 to be slightly offset in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells.

[0183] When the width of the extension section 221 is too small, the risk of short circuit increases and the reliability of the battery assembly decreases. As the width of the extension section 221 increases, the reliability of the battery assembly increases. The displacement deviation of the second insulating strip 22 relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells in the width direction allowed in the preparation process increases, and the production accuracy requirement decreases. However, when the width of the extension section 221 is too large, it will affect the full welding between the second welding strip 42 and the effective welding position on the fourth battery cell 14A, the current collection effect will decrease, and it will affect the bifaciality of the battery assembly. It can be understood that the second welding point 62 is located at the edge of the effective welding position of the fourth battery cell 14A closest to the third battery cell 13A (that is, the edgemost connection point of the second welding strip 42 on the fourth battery cell 14A). The second welding point 62 can be a grid line or a pad. In the present invention, by controlling 1mm≤L 3 ≤l 31 +l 32 +l 33 On the basis of allowing the offset error in the preparation process, it can still ensure that the extended section 221 of the second insulating strip 22 can extend to cover the edge area of ​​the fourth battery cell 14A and the edge area of ​​the third battery cell 13A, further improving the reliability and production yield of the battery assembly. At the same time, it will not cause unnecessary waste of materials and can avoid affecting the sufficient welding of the second welding strip 42.

[0184] In one embodiment, in the first direction, the width of the extension section 221 is:

[0185] 1mm≤L 3 ≤l 31 +l 33 +4mm,

[0186] Where, L 3 is the width of the extension section 221 in the first direction, l 31 is the distance between the fourth battery cell 14 and the third battery cell 13 in the battery string provided with the second insulating strip 22, l 33It is the relative width distance between the edge of the middle bus bar 32 close to one end of the fourth battery cell 14 and the edge of the third battery cell 13 close to one end of the fourth battery cell 14 in the battery string provided with the second insulating strip 22 .

[0187] Within this range, while allowing for offset errors in the preparation process, it is possible to ensure that the extended segment 221 of the second insulating strip 22 can extend to cover the edge area of ​​the fourth battery cell 14A and the edge area of ​​the third battery cell 13A, thereby further improving the reliability and production yield of the battery assembly. At the same time, unnecessary material waste will not occur, and even if the first insulating strip 21 is offset during production and preparation, it can ensure that the sufficient welding of the second welding strip will not be affected, thereby effectively reducing the production precision.

[0188] 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 aforementioned embodiment 1, and will not be repeated here.

[0189] Example 4

[0190] The difference between this embodiment and embodiment 3 is that, see Figures 11 to 13 As shown, in the battery string provided with the second insulating strip 22, one end of the third battery cell 13 close to the fourth battery cell 14 is at least partially stacked with the fourth battery cell 14.

[0191] In the first direction, the width of the extension section 221 is greater than the width of the stacking region between the third battery cell 13 and the fourth battery cell 14 .

[0192] That is, the third battery cell 13A and the fourth battery cell 14A are stacked, and there is no gap between the two batteries.

[0193] In one embodiment, the side of the third battery cell 13A facing away from the second insulating strip 22 is at least partially stacked with the fourth battery cell 14A.

[0194] In another embodiment, the side of the third battery cell 13A facing the first insulating strip 21 is at least partially stacked with the fourth battery cell 14A.

[0195] In one embodiment, see Figure 12 to Figure 13 As shown, in the first direction, the width of the extension section 221 is:

[0196] 1mm≤L 4 ≤l 42 +l 43 -l 41 ,

[0197] Where, L 4 is the width of the extension section 221 in the first direction, l41 is the width of the stacking region between the third battery cell 13 and the fourth battery cell 14, l 42 is the relative width distance from the edge of the fourth battery cell 14 close to one end of the third battery cell 13 to the second welding point 62 in the battery string provided with the second insulating strip 22, l 43 It is the relative width distance between the edge of the middle bus bar 32 close to one end of the fourth battery cell 14 and the edge of the third battery cell 13 close to one end of the fourth battery cell 14 in the battery string provided with the second insulating strip 22 .

[0198] Understandable, 41 +l 43 >1mm,l 41 <1mm, therefore, control L 4 ≥1mm, which can ensure that the extension section 221 can extend to cover the edge area of ​​the fourth battery cell 14A and the edge area of ​​the third battery cell 13A, while reserving sufficient offset space for the horizontal tolerance of the equipment placement in the preparation process and the lamination offset tolerance of the bus bar lead-out hole position, thereby allowing the second insulating strip 22 to be slightly offset in the width direction relative to the middle bus bar 32 and the second insulating strip 22 relative to the two battery cells.

[0199] In one embodiment, see Figure 12 to Figure 13 As shown, in the first direction, the width of the extension section 221 is:

[0200] 1mm≤L 4 ≤l 43 -l 41 +4mm,

[0201] Where, L 4 is the width of the extension section 221 in the first direction, l 41 is the width of the stacking region between the third battery cell 13 and the fourth battery cell 14, l 42 is the relative width distance from the edge of the fourth battery cell 14 close to one end of the third battery cell 13 to the second welding point 62 in the battery string provided with the second insulating strip 22, l 43 It is the relative width distance between the edge of the middle bus bar 32 close to one end of the fourth battery cell 14 and the edge of the third battery cell 13 close to one end of the fourth battery cell 14 in the battery string provided with the second insulating strip 22 .

[0202] 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 aforementioned embodiments 1 and 3, and will not be repeated here.

[0203] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the field can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A back contact battery assembly, characterized in that: include: A battery string, wherein the battery string includes battery cells connected in series, and the battery cells include a first battery cell and a second battery cell arranged along a first direction, A first insulating strip is provided at one end of the second battery cell close to the first battery cell, A first bus bar is provided on a side of the first insulating strip facing away from the second battery cell. The first insulating bar and the first bus bar are both extended along a second direction, and the first direction is intersected with the second direction. a first welding strip, used for electrically connecting the first bus bar and the first battery cell, An extension section extending out of the first bus bar is provided at one end of the first insulating strip close to the first battery cell, and the extension section extends out of the second battery cell. In the thickness direction of the second battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the first battery cell.

2. A back contact battery assembly according to claim 1, characterized in that: The first battery cell and the second battery cell are arranged on the same plane. In the first direction, the width of the portion of the extension section extending outside the second battery cell is greater than the distance between the first battery cell and the second battery cell.

3. A back contact battery assembly according to claim 2, characterized in that: In the first direction, the width of the extension segment is: 1mm≤L1≤l 11 +l 12 +l 13 , Wherein, L1 is the width of the extension segment in the first direction, l 11 is the distance between the first battery cell and the second battery cell, l 12 is the relative width distance from the edge of the first battery cell close to one end of the second battery cell to the first welding point, the first welding point is used to connect with the first welding strip and is provided at one end of the first battery cell close to the second battery cell, l 13 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

4. A back contact battery assembly according to claim 2, characterized in that: In the first direction, the width of the extension segment is: 1mm≤L1≤l 11 +l 13 +4mm, Wherein, L1 is the width of the extension segment in the first direction, l 11 is the distance between the first battery cell and the second battery cell, l 13 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

5. A back contact battery assembly according to claim 1, characterized in that: One end of the second battery cell close to the first battery cell is at least partially stacked with the first battery cell, In the first direction, the width of the extension section is greater than the width of the stacking region between the first battery cell and the second battery cell.

6. A back contact battery assembly according to claim 5, characterized in that: The width of the extension section is: 1mm≤L2≤l 22 +l 23 -L 21 , Wherein, L2 is the width of the extension segment in the first direction, l 21 is the width of the stacking area between the first battery cell and the second battery cell, l 22 is the relative width distance from the edge of the first battery cell close to one end of the second battery cell to the first welding point, the first welding point is used to connect with the first welding strip and is provided at one end of the first battery cell close to the second battery cell, l 23 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

7. A back contact battery assembly according to claim 5, characterized in that: The width of the extension section is: 1mm≤L2≤l 23 +4mm-l 21 , Wherein, L2 is the width of the extension segment in the first direction, l 21 is the width of the stacking area between the first battery cell and the second battery cell, l 23 It is the relative width distance between the edge of the first bus bar close to one end of the first battery cell and the edge of the second battery cell close to one end of the first battery cell.

8. A back contact battery assembly according to claim 1, characterized in that: The battery assembly includes at least one series-connected battery string group, and the same series-connected battery string group includes two battery strings arranged along the second direction and arranged in series with each other. In the same series-connected battery string group, the same first bus bar extends from the second battery cell in one battery string to the second battery cell in another battery string.

9. A back contact battery assembly according to claim 1, characterized in that: A fourth battery cell is disposed at one end of each battery string away from the first battery cell, and a third battery cell is disposed at one end of the fourth battery cell close to the first battery cell. The battery assembly includes a parallel battery string group, and the same parallel battery string group includes at least two battery strings arranged along a first direction and arranged in parallel with each other, and the fourth battery cells in the two battery strings arranged in parallel with each other are arranged adjacent to each other in the first direction, The battery assembly also includes: A second insulating strip is provided at an edge of the third battery cell in one of the battery strings, and the second insulating strip is provided at an end of the third battery cell close to the fourth battery cell, An intermediate bus bar is used to connect in parallel two battery strings arranged adjacent to each other in the first direction, and the intermediate bus bar is arranged on a side of the second insulating strip facing away from the third battery cell. The second insulating strip and the middle bus bar are both extended along the second direction. The second welding strip is used to electrically connect the middle bus bar, the fourth battery cell in the battery string, and the fourth battery cell in another battery string adjacent to the battery string in the first direction.

10. A back contact battery assembly according to claim 9, characterized in that: An end of the second insulating strip close to the fourth battery cell is provided with an extension section extending out of the middle bus bar, and the extension section extends outside the third battery cell. In the thickness direction of the third battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth battery cell in the battery string where the extension section is located.

11. A back contact battery assembly, characterized in that: include: A parallel battery string group, wherein the same parallel battery string group comprises at least two battery strings arranged in a first direction and arranged in parallel with each other, each of the battery strings comprises battery cells connected in series with each other, the battery cells comprise a third battery cell and a fourth battery cell arranged in the first direction, and the fourth battery cells in the two battery strings arranged in parallel with each other are arranged adjacently in the first direction, A second insulating strip is provided at an edge of the third battery cell in one of the battery strings, and the second insulating strip is provided at an end of the third battery cell close to the fourth battery cell, An intermediate bus bar is used to connect in parallel two battery strings arranged adjacent to each other in the first direction, and the intermediate bus bar is arranged on a side of the second insulating strip facing away from the third battery cell. The second insulating strip and the middle bus bar are both extended along the second direction. a second welding strip, for electrically connecting the middle bus bar, the fourth battery cell in the battery string where the middle bus bar is located, and the fourth battery cell in another battery string adjacent to the battery string in the first direction, An end of the second insulating strip close to the fourth battery cell is provided with an extension section extending out of the middle bus bar, and the extension section extends outside the third battery cell. In the thickness direction of the third battery cell, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth battery cell in the battery string where the extension section is located.

12. A back contact battery assembly according to claim 11, characterized in that: In the battery string provided with the second insulating strip, the fourth battery cell and the third battery cell are provided on the same plane, In the first direction, the width of the portion of the extension section extending outside the third battery cell is greater than the distance between the fourth battery cell and the third battery cell.

13. A back contact battery assembly according to claim 12, characterized in that: In the first direction, the width of the extension section is: 1mm≤L3≤l 31 +l 32 +l 33 , Wherein, L3 is the width of the extension segment in the first direction, l 31 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the second insulating strip, l 32 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 33 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

14. A back contact battery assembly according to claim 13, characterized in that: In the first direction, the width of the extension section is: 1mm≤L3≤l 31 +l 33 +4mm, Wherein, L3 is the width of the extension segment in the first direction, l 31 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the second insulating strip, l 33 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

15. A back contact battery assembly according to claim 11, characterized in that: In the battery string provided with the second insulating strip, one end of the third battery cell close to the fourth battery cell is at least partially stacked with the fourth battery cell, In the first direction, the width of the extension section is greater than the width of the stacking region between the third battery cell and the fourth battery cell.

16. A back contact battery assembly according to claim 15, characterized in that: In the first direction, the width of the extension section is: 1mm≤L4≤l 42 +l 43 -L 41 , Wherein, L4 is the width of the extension segment in the first direction, l 41 is the width of the stacking region between the third battery cell and the fourth battery cell, l 42 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 43 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

17. A back contact battery assembly according to claim 15, characterized in that: In the first direction, the width of the extension section is: 1mm≤L4≤l 43 -l 41 +4mm, Wherein, L4 is the width of the extension segment in the first direction, l 41 is the width of the stacking region between the third battery cell and the fourth battery cell, l 42 is the relative width distance from the edge of the fourth battery cell close to one end of the third battery cell to the second welding point in the battery string provided with the second insulating strip, l 43 It is the relative width distance between the edge of the middle bus bar close to one end of the fourth battery cell and the edge of the third battery cell close to one end of the fourth battery cell in the battery string provided with the second insulating strip.

18. A photovoltaic system, characterized in that: Comprising a back contact battery assembly according to any one of claims 1 to 18.

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