Back contact battery assembly and photovoltaic system

Abstract

The invention relates to the technical field of back contact batteries, and particularly discloses a back contact battery assembly, which comprises a battery string, a first insulating strip, a first bus bar, a second insulating strip, a second bus bar, a second bus bar, a third bus bar and a fourth bus bar, the first bus bar is arranged on the side, back on to the second battery piece, of the first insulating strip, the first insulating strip and the first bus bar extend in the second direction, the first welding strip is used for being electrically connected with the first bus bar and the first battery piece, and in the first direction, the two ends of the first insulating strip are provided with a first widened section and a second widened section which extend out of the edge of the first bus bar; the first widening section and the second widening section are sequentially arranged in the direction away from the first battery piece, and the width of the second widening section is smaller than that of the first widening section. According to the invention, the effective light-receiving area of the battery assembly can be increased, the conversion efficiency of the assembly can be improved, the observed area of the bus bar from one side of the light-receiving surface is smaller, even the bus bar can be completely hidden and is more beautiful, meanwhile, the production difficulty can be effectively reduced, the risks of short circuit, subfissure and fragmentation of the battery piece are reduced, the reliability is improved, and the double-sided rate of the battery assembly can be ensured.

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 placed at the edge of the battery module, and the parallel bus bars between adjacent battery strings in parallel are usually placed 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 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 cell.

[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 cells, improve reliability, and ensure the bifaciality of the battery assembly.

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

[0007] First, the present invention provides 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] In the first direction, both ends of the first insulating strip are provided with a first widened section and a second widened section extending beyond the edge of the first bus bar, the first widened section and the second widened section are arranged sequentially in a direction away from the first battery cell, and the width of the second widened section is smaller than the width of the first widened section.

[0014] In some embodiments, the first widened section at least partially extends beyond an edge of the second battery sheet.

[0015] In some embodiments, in the first direction, an orthographic projection of the first widened section in the thickness direction of the second battery cell at least partially overlaps with an orthographic projection of the first battery cell in the thickness direction of the second battery cell.

[0016] In some embodiments, in the first direction, the width D of the second widened section is 2 ≥1mm.

[0017] In some embodiments, the first battery cell and the second battery cell are arranged on the same plane, wherein:

[0018] 1mm<D 1 ≤l 11 +l 12 +l 13

[0019] Where D 1 is the width of the first widened section in the first direction, l 11 is the relative width distance between the first bus bar and the edge of the second battery cell close to one end of the first battery cell in the first direction, l 12 is the distance between the first battery cell and the second battery cell, l 13 It 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, and the first welding point is arranged at one end of the first battery cell close to the second battery cell and is used to connect with the first welding strip.

[0020] In some embodiments, an end of the second battery cell close to the first battery cell is at least partially stacked with the first battery cell, wherein:

[0021] 1mm<D 1 ≤l 21 +l 23 -l 22

[0022] Where D 1 is the width of the first widened section in the first direction, l 21 is the relative width distance between the first bus bar and the edge of the second battery cell close to one end of the first battery cell in the first direction, l 22 is the width of the stacking region between the first battery cell and the second battery cell in the first direction, l 23 It 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, and the first welding point is arranged at one end of the first battery cell close to the second battery cell and is used to connect with the first welding strip.

[0023] In some embodiments, the battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge and a second edge arranged along the second direction, and the orthographic projection of the first insulating strip in the thickness direction of the second battery cell falls between the first edge and the second edge.

[0024] In some embodiments, in the first direction, the orthographic projection of the first bus bar in the thickness direction of the second battery cell falls within the second battery cell.

[0025] In some embodiments, 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.

[0026] In some embodiments, 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.

[0027] 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,

[0028] an intermediate bus bar, used for connecting two battery strings arranged adjacent to each other in a first direction in parallel, the intermediate bus bar being arranged on a side of the second insulating strip facing away from the third battery cell,

[0029] The second insulating strip and the middle bus bar are both extended along the second direction.

[0030] 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.

[0031] In some embodiments, in a first direction, both ends of the second insulating strip are provided with a first extension segment and a second extension segment extending beyond the edge of the middle bus bar, the first extension segment and the second extension segment are arranged sequentially in a direction away from the fourth battery cell, the first extension segment at least partially extends beyond the edge of the third battery cell, and the width of the second extension segment is smaller than the width of the first extension segment.

[0032] Secondly, the present invention also provides a back contact battery assembly, comprising:

[0033] 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 connected in series with each other 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,

[0034] 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,

[0035] an intermediate bus bar, used for connecting two battery strings arranged adjacent to each other in a first direction in parallel, 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] 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,

[0038] In the first direction, both ends of the second insulating strip are provided with a first extension segment and a second extension segment extending beyond the edge of the middle bus bar, the first extension segment and the second extension segment are arranged sequentially in a direction away from the fourth battery cell, and the width of the second extension segment is smaller than the width of the first extension segment.

[0039] In some embodiments, the first extension segment at least partially extends beyond the edge of the third battery cell.

[0040] In some embodiments, in the first direction, an orthographic projection of the first extension segment in the thickness direction of the third battery cell at least partially overlaps with an orthographic projection of the fourth battery cell in the thickness direction of the third battery cell.

[0041] In some embodiments, in the first direction, the width d of the second extension segment is 2 ≥1mm.

[0042] In some embodiments, the fourth battery cell and the third battery cell are arranged on the same plane, wherein:

[0043] 1mm<d 1 ≤l 31 +l 32 +l 33

[0044] Where, d 1 is the width of the first extension segment in the first direction, l 31 is the relative width distance between the middle bus bar and the edge of the third battery cell close to one end of the fourth battery cell in the first direction in the battery string provided with the middle bus bar, l 32 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the middle bus bar, l 33 The second welding point is provided on the fourth battery cell in the battery string where the intermediate bus bar is provided, and is provided at one end of the fourth battery cell close to the third battery cell, for connecting to the second welding strip.

[0045] In some embodiments, in the battery string provided with the intermediate bus bar, one end of the third battery cell close to the fourth battery cell is at least partially stacked with the fourth battery cell, wherein:

[0046] 1mm<d 1 ≤l 41 +l 43 -l 42

[0047] Where, d 1 is the width of the first extension segment in the first direction, l 41 is the relative width distance between the middle bus bar and the edge of the third battery cell close to one end of the fourth battery cell in the first direction in the battery string provided with the middle bus bar, l 42is the width of the stacking region between the third battery cell and the fourth battery cell in the first direction, l 43 In the battery string provided with the intermediate bus bar, 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, the second welding point is provided at one end of the fourth battery cell close to the third battery cell, and is used to connect with the second welding strip.

[0048] In some embodiments, the battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge and a second edge arranged along the second direction, and the orthographic projection of the second insulating strip in the thickness direction of the third battery cell falls between the first edge and the second edge.

[0049] A photovoltaic system comprises the above-mentioned back-contact battery assembly.

[0050] The beneficial effects of the present invention are:

[0051] 1) The end busbar built-in structure of the present invention can, on the one hand, increase the effective light-receiving area of ​​the battery assembly and improve the conversion efficiency of the assembly. The area of ​​the busbar observed from the light-receiving side is smaller, and it can even be 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 attached and welded to the effective welding position of the first battery cell, avoiding the installation of the first busbar 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 first insulating strip on the end of the second battery cell close to the first battery cell. At the same time, By setting the first widening section and the second widening section, during the preparation process, it is possible to allow a certain degree of offset in the width direction between the first insulating strip and the first insulating strip and between the two battery cells, effectively reducing the production precision requirements and the risk of short circuit, and ensuring that the battery assembly has a high double-sided rate; furthermore, the end 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, and has stronger versatility. The end 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.

[0052] 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 installation 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 arrangement of the first extension section and the second extension section, during the preparation process, it is possible to allow the second insulating strip to have a certain degree of offset in the width direction relative to the intermediate bus bar and the second insulating strip to have a certain degree of offset in the width direction relative to the two battery cells, effectively reducing the production precision requirements and the risk of short circuit, and ensuring that the battery assembly has a high bifaciality. 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 the battery cells, and the reliability of the back contact battery assembly is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] 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.

[0054] Figure 2 It is a cross-sectional view of the end busbar built-in structure of Example 1 of the present invention.

[0055] Figure 3 Schematic diagram of the structure of the battery string of Example 1 of the present invention.

[0056] Figure 4 This is a schematic diagram of the structure of the back contact battery assembly of Example 1 of the present invention.

[0057] 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.

[0058] Figure 6 This is a cross-sectional view of an embodiment of the end busbar built-in structure of embodiment 2 of the present invention.

[0059] Figure 7 It is a cross-sectional view of another embodiment of the end busbar built-in structure of embodiment 2 of the present invention.

[0060] Figure 8 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.

[0061] Fig. 9It is a cross-sectional view of the end busbar built-in structure of embodiment 3 of the present invention.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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

[0066] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0067] Example 1

[0068] First, see Figures 1 to 3 As shown, this embodiment discloses a back contact battery assembly, including:

[0069] 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, wherein the first battery cell 11 is arranged at an end of the battery string,

[0070] The first insulating strip 21 is disposed at one end of the second battery cell 12 close to the first battery cell 11.

[0071] 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).

[0072] 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.

[0073] The first welding strip 41 is used to electrically connect the first bus bar 31 and the first battery cell 11.

[0074] In the first direction, both ends of the first insulating strip 21 are provided with a first widened section 211 and a second widened section 212 extending beyond the edge of the first bus bar 31. The first widened section 211 and the second widened section 212 are arranged in sequence along a direction away from the first battery cell 11, and the width of the second widened section 212 is smaller than the width of the first widened section 211.

[0075] It can be understood that the electrical connection method can be welding, bonding through conductive adhesive, etc., but is not limited thereto.

[0076] 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.

[0077] In the present invention, 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 invention, 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.

[0078] Optionally, in the same battery string, adjacent battery cells can be connected in series by means of welding strips, conductive adhesive, etc.

[0079] 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.

[0080] 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 41 is electrically connected to the effective welding position of the first battery cell 11, and the end of the first welding strip 41 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.

[0081] 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.

[0082] 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 41 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 41 and the first battery cell 11 and affecting the current collection. At the same time, after the first welding strip 41 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.

[0083] At the same time, the first insulating strip 21 of the present invention is provided with a first widening section 211 and a second widening section 212, that is, the first insulating strip 21 has widening portions on both sides in the first direction that extend beyond the edge of the first bus bar 31. The provision of the first widening section 211 and the second widening section 212, on the one hand, 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 second widening section 212 in the first insulating strip 21 of the present invention is smaller than the first widening section 211, that is, in the first direction, the first bus bar 31 is biased relative to the first insulating strip 21, rather than being centrally symmetrically arranged, and this arrangement will form a relatively wide first widening section 211 and a relatively narrow second widening section 212, wherein the relatively wide first widening section 211 is conducive to the first widening section. The wide section 211 can cover more area of ​​the edge of the first battery cell 11 and the edge of the second battery cell 12, thereby better reducing the risk of short circuit caused by the contact between the first bus bar 31 and the heterogeneous welding strip / heterogeneous grid line on the first battery cell 11, reducing the risk of short circuit caused by the contact between the first welding strip 41 and the heterogeneous welding strip / heterogeneous grid line of the second battery cell 12, and reducing the risk of short circuit easily caused by conductive foreign matter such as tin slag during the preparation process, thereby improving the reliability of the battery module; the narrower second widened section 212 can reduce the influence of the second widened section 212 on the double-sidedness of the battery module while ensuring the above-mentioned reduction in production precision requirements and short-circuit risks, thereby ensuring that the battery module has a higher double-sidedness.

[0084] 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 defects such as fragments. At the same time, the installation of the bus bar will affect the welding between the first welding ribbon 41 and the first battery cell 11. The first welding ribbon 41 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 ribbon 41 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.

[0085] 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.

[0086] In some embodiments, see Figure 2As shown, the first widened section 211 at least partially extends to the outside of the edge of the second battery cell 12 .

[0087] Thus, while allowing 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, it is also possible to ensure that the first widened section 211 can cover more area of ​​the edge of the first battery cell 11 and the edge of the second battery cell 12, thereby reducing the risk of short circuit caused by contact between the first bus bar 31, the first welding strip 41 and the heterogeneous welding strip / heterogeneous grid line, thereby improving the reliability of the battery assembly.

[0088] In some embodiments, see Figure 2 As shown, in the first direction, the orthographic projection of the first widened section 211 in the thickness direction of the second battery cell 12 at least partially overlaps with the orthographic projection of the first battery cell 11 in the thickness direction of the second battery cell 12 .

[0089] As a result, the first insulating strip 21 can cover the edges of the second battery cell 12 and the first battery cell 11, thereby preventing not only the first bus bar 31 from contacting the heterogeneous welding strip / heterogeneous grid line on the first battery cell 11 and causing a short circuit, but also preventing the first welding strip 41 from contacting the heterogeneous welding strip / heterogeneous grid line on the second battery cell 12 and causing a short circuit, thereby further reducing the risk of short circuit.

[0090] Especially when the battery cell is cut into half pieces, the cut edge is very likely to cause a short circuit after cutting. The setting of the first widened 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 where the first bus bar 31 is located on the battery cell or on the side of the adjacent battery cell close to the first bus bar 31, which can also ensure the reliability of the battery assembly.

[0091] In some embodiments, see Figure 2 As shown, preferably, in the first direction, the width D of the second widening section 212 is 2 ≥1mm.

[0092] When the second widened section 212 is too small, the amount of deviation allowed for the first insulating strip 21 during the preparation process is small, which leads to the need to improve the production precision requirements. When the width of the second widened section 212 of this embodiment is controlled to be ≥1mm, sufficient deviation space can be reserved for the horizontal tolerance of the equipment placement during the preparation process and the tolerance of the bus bar deviation during the lamination process, thereby reducing the production precision requirements.

[0093] In some embodiments, see Figure 2 As shown, the first battery cell 11 and the second battery cell 12 are arranged on the same plane, wherein:

[0094] 1mm<D 1 ≤l11 +l 12 +l 13

[0095] Where D 1 is the width of the first widening section 211 in the first direction, l 11 is the relative width distance between the first bus bar 31 and the edge of the second battery cell 12 close to one end of the first battery cell 11 in the first direction, l 12 is the distance between the first battery cell 11 and the second battery cell 12, l 13 It 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 provided at the end of the first battery cell 11 close to the second battery cell 12 for connecting with the first welding strip 41 .

[0096] Understandable, 11 +l 12 >1mm,l 11 <1mm, therefore, control D 1 >1mm, which can ensure that the first widened 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.

[0097] It can be understood that the first welding point 61 is located at the edge of the first battery cell 11 closest to the second battery cell 12 at the effective welding position of the first battery cell 11 (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 gate line or a pad, but is not limited to this.

[0098] When the width of the first widened section 211 is too small, the risk of short circuit increases and the reliability of the battery assembly decreases. As the width of the first widened 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 during the preparation process increases, and the production accuracy requirement decreases. However, when the width of the first widened section 211 is too large, it will affect the full welding between the first welding strip 41 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 this embodiment, 1mm<D 1 ≤l 11 +l 12 +l 13, ensuring that on the basis of allowing a certain deviation in the preparation process of the first insulating strip 21, the first widened section 211 of the first insulating strip 21 can still be extended to cover more edge areas of the first battery cell 11 and the second battery cell 12, further improving the reliability and production yield of the battery assembly, reducing the production precision requirements, and at the same time, avoiding affecting the sufficient welding between the first welding strip 41 and the effective welding position on the first battery cell 11, and will not cause unnecessary material waste and loss of bifaciality.

[0099] In one embodiment, in the first direction, one end of the first bus bar 31 close to the first battery cell 11 extends to outside the edge of the second battery cell 12 .

[0100] In another more preferred embodiment, see Figure 2 As shown, in the first direction, the orthographic projection of the first bus bar 31 in the thickness direction of the second battery cell 12 falls within the second battery cell 12 , that is, the first bus bar 31 is disposed within the edge of the second battery cell 12 .

[0101] In some embodiments, see Figure 1 , Figure 3 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.

[0102] Furthermore, the first welding strip 41 includes a first positive welding strip 411 and a first negative welding strip 412. The same first bus bar 31 is electrically connected to the first positive welding strip 411 in one battery string and is electrically connected to the first negative welding strip 412 in another battery string, so that adjacent battery strings are connected in series.

[0103] 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 41 includes a first positive electrode welding strip 411 and a first negative electrode welding strip 412. 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 411 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 412 on the first battery cell 11.

[0104] 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.

[0105] In another more preferred embodiment, see Figure 1 , 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.

[0106] 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.

[0107] 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.

[0108] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0109] 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.

[0110] 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:

[0111] 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,

[0112] The battery assembly also includes:

[0113] 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.

[0114] 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.

[0115] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0116] 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.

[0117] 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 .

[0118] On the one hand, the built-in structure of the intermediate bus bar 32 of the present invention can 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 make the overall appearance of the battery assembly better; 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, it is only necessary to place the entire first insulating strip 21 at one end of the third battery cell 13 close to the fourth battery cell 14. Furthermore, the built-in structure of the intermediate 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 intermediate 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.

[0119] 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.

[0120] In some embodiments, see Figure 4 and Figure 5 As shown, in the first direction, both ends of the second insulating strip 22 are provided with a first extension section 221 and a second extension section 222 extending to the edge of the middle bus bar 32, and the first extension section 221 and the second extension section 222 are arranged in sequence along a direction away from the fourth battery cell 14, and the first extension section 221 at least partially extends to the edge of the third battery cell 13, and the width of the second extension section 222 is smaller than the width of the first extension section 221.

[0121] By setting the first extension section 221 and the second extension section 222 of the second insulating strip 22, on the one hand, the second insulating strip 22 is allowed to have a certain degree of deviation 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 requirement and production difficulty; on the other hand, a relatively wide first extension section 221 and a relatively narrow second extension section 222 are formed on the second insulating strip 22, wherein the relatively wide first extension section 221 is conducive to the first extension section 221 being able to cover more fourth battery cells 14 A edge area and the edge area of ​​the third battery cell 13A, thereby better reducing the risk of short circuit caused by the contact between the middle bus bar 32 and the heterogeneous welding strip / heterogeneous grid line on the fourth battery cell 14A, and reducing the risk of short circuit caused by the contact between the second welding strip 42 and the heterogeneous welding strip / heterogeneous grid line on the third battery cell 13A, thereby improving the reliability of the battery component; the narrower second extension segment 222 can reduce the influence of the second extension segment 222 on the double-sidedness of the battery component while ensuring the above-mentioned reduction in production precision requirements and short-circuit risks, thereby ensuring that the battery component has a higher double-sidedness.

[0122] In some embodiments, see Figure 4 As shown, the battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge 71 and a second edge 72 arranged along the second direction, and the orthographic projection of the first insulating strip 21 in the thickness direction of the second battery cell 12 falls between the first edge 71 and the second edge 72.

[0123] If the first insulating strip 21 extends beyond the first edge 71 or the second edge 72, the adhesive film, front plate, back plate and other material layers of the battery assembly cannot be fully compounded, especially in the edge area, causing external water vapor to easily invade the interior of the battery assembly, affecting the reliability of the battery assembly.

[0124] This embodiment also discloses a photovoltaic system, including the above-mentioned back-contact battery assembly.

[0125] Example 2

[0126] The difference between this embodiment and embodiment 1 is that, see Figures 6 to 8 As shown, the 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, that is, the first battery cell 11 and the second battery cell 12 are stacked, and there is no gap between the two batteries, wherein,

[0127] 1mm<D 1 ≤l 21 +l 23 -l 22

[0128] Where D 1is the width of the first widening section 211 in the first direction, l 21 is the relative width distance between the first bus bar 31 and the edge of the second battery cell 12 close to one end of the first battery cell 11 in the first direction, l 22 is the width of the stacking region between the first battery cell 11 and the second battery cell 12 in the first direction, l 23 It 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 provided at the end of the first battery cell 11 close to the second battery cell 12 for connecting with the first welding strip 41 .

[0129] In one embodiment, see Figure 7 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 .

[0130] In another embodiment, see Figure 8 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 .

[0131] Understandable, 21 +l 22 >1mm,l 21 <1mm, therefore, control D 1 >1mm, which can ensure that the first widened 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.

[0132] When the width of the first widened section 211 is too small, the risk of short circuit increases and the reliability of the battery assembly decreases. As the width of the first widened 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 during the preparation process increases, and the production accuracy requirement decreases. However, when the width of the first widened section 211 is too large, it will affect the full welding between the first welding strip 41 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 this embodiment, 1mm<D 1 ≤l 21 +l 22 +l 23, ensuring that on the basis of allowing a certain deviation in the preparation process of the first insulating strip 21, the first widened section 211 of the first insulating strip 21 can still be extended 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, reducing the production precision requirements, and at the same time, avoiding affecting the sufficient welding between the first welding ribbon 41 and the effective welding position on the first battery cell 11, and will not cause unnecessary material waste and loss of bifaciality.

[0133] 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.

[0134] Example 3

[0135] See also Figures 9 and 10 As shown, this embodiment discloses a back contact battery assembly, including:

[0136] 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, and the battery cells connected in series with each other 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 arranged adjacent to each other in the first direction,

[0137] 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.

[0138] 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.

[0139] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0140] 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.

[0141] In the first direction, the two ends of the second insulating strip 22 are provided with a first extension section 221 and a second extension section 222 extending beyond the edge of the middle bus bar 32. The first extension section 221 and the second extension section 222 are arranged in sequence along the direction away from the fourth battery cell 14, and the width of the second extension section 222 is smaller than the width of the first extension section 221.

[0142] 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:

[0143] 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,

[0144] The battery assembly also includes:

[0145] 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.

[0146] 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.

[0147] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0148] 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.

[0149] An end of the second insulating strip 22 close to the fourth battery cell 14A is provided with an extension section extending beyond the edge of the third battery cell 13A, and in the thickness direction of the third battery cell 13A, the orthographic projection of the extension section at least partially overlaps with the orthographic projection of the fourth battery cell 14A.

[0150] 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.

[0151] 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:

[0152] 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,

[0153] The battery assembly also includes:

[0154] 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.

[0155] 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.

[0156] The second insulating strip 22 and the middle bus bar 32 are both extended along the second direction.

[0157] 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 center bus bar in sequence.

[0158] An extension section is provided at one end of the middle bus bar 32 close to the fourth battery cell 14A. The extension section extends in the first direction to the edge of the second insulating strip 22 and is electrically connected to the second welding strip 42 . The connection between the extension section and the second welding strip 42 forms a joint end.

[0159] 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.

[0160] 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, and the overall aesthetics of the battery assembly is better.

[0161] 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.

[0162] At the same time, the second insulating strip 22 of the present invention is provided with a first extension section 221 and a second extension section 222, that is, the second insulating strip 22 has widened portions on both sides in the first direction that extend beyond the edge of the middle bus bar 32. The provision of the first extension section 221 and the second extension section 222, on the one hand, allows a certain degree of offset in the width direction 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 during the preparation process, thereby reducing the production accuracy requirements and production difficulty; on the other hand, the second extension section 222 in the second insulating strip 22 of the present invention is smaller than the first extension section 221, that is, in the first direction, the middle bus bar 32 is offset relative to the second insulating strip 22, rather than being centrally symmetrically arranged. This arrangement will form a relatively wide first extension section 221 and a relatively narrow second extension section 222, wherein the relatively wide first extension section 221 and the relatively narrow second extension section 222 are relatively narrower than the second extension section 221. The extension segment 221 helps the first extension segment 221 to cover more area of ​​the edge of the fourth battery cell 14A and the edge of the third battery cell 13A, thereby better reducing the risk of short circuit caused by the contact between the intermediate bus bar 32 and the heterogeneous welding strip / heterogeneous grid line on the fourth battery cell 14A, and reducing the risk of short circuit caused by the contact between the first welding strip 41 and the heterogeneous welding strip / heterogeneous grid line on the third battery cell 13A, thereby improving the reliability of the battery module; the narrower second extension segment 222 can reduce the influence of the second extension segment 222 on the bifaciality of the battery module while ensuring the above-mentioned reduction in production precision requirements and short circuit risks, thereby ensuring that the battery module has a higher bifaciality.

[0163] 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.

[0164] In contrast, the built-in structure of the intermediate bus bar 32 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 of the battery cells and improving the reliability of the back-contact battery assembly.

[0165] In some embodiments, see Fig. 9 As shown, the first extension segment 221 at least partially extends to the outside of the edge of the third battery cell 13 .

[0166] Thus, while allowing a certain degree of offset in the width direction 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 during the preparation process, it is also possible to ensure that the first widened section 211 can cover more of the edge of the fourth battery cell 14A and the edge of the third battery cell 13A, thereby reducing the risk of short circuit caused by contact between the middle bus bar 32, the first welding strip 41 and the heterogeneous welding strip / heterogeneous grid line, thereby improving the reliability of the battery assembly.

[0167] In some embodiments, see Fig. 9 As shown, in the first direction, the orthographic projection of the first extension segment 221 in the thickness direction of the third battery cell 13 at least partially overlaps with the orthographic projection of the fourth battery cell 14 in the thickness direction of the third battery cell 13 .

[0168] As a result, the second insulating strip 22 can cover the edges of the third battery cell 13A and the fourth battery cell 14A, thereby not only avoiding a short circuit caused by contact between the intermediate bus bar 32 and the heterogeneous welding strip / heterogeneous grid line on the fourth battery cell 14A, but also avoiding a short circuit caused by contact between the second welding strip 42 and the heterogeneous welding strip / heterogeneous grid line of the third battery cell 13A, thereby further reducing the risk of short circuit.

[0169] Especially when the battery cell is cut into half pieces, the cut edge is very likely to cause a short circuit after cutting. The setting of the first widened 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 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.

[0170] In some embodiments, see Fig. 9 As shown, in the first direction, the width d of the second extension section 222 is 2 ≥1mm.

[0171] When the second extension segment 222 is too small, the amount of deviation allowed for the second insulating strip 22 during the preparation process is small, which results in the need to improve the production precision requirements. In this embodiment, when the width of the second extension segment 222 is controlled to be ≥1 mm, sufficient deviation space can be reserved for the equipment placement horizontal tolerance and the bus bar lead-out hole lamination deviation tolerance during the preparation process, thereby reducing the production precision requirements.

[0172] In some embodiments, see Fig. 9 As shown, the fourth battery cell 14 and the third battery cell 13 are arranged on the same plane, wherein,

[0173] 1mm<d 1 ≤l 31 +l 32 +l33

[0174] Where, d 1 is the width of the first extension section 221 in the first direction, l 31 is the relative width distance between the middle bus bar 32 and the edge of the third battery cell 13 close to the fourth battery cell 14 in the first direction in the battery string provided with the middle bus bar 32, l 32 is the distance between the fourth battery cell 14 and the third battery cell 13 in the battery string provided with the middle bus bar 32, l 33 It 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 intermediate bus bar 32. The second welding point 62 is arranged on the fourth battery cell 14 in the battery string where the intermediate bus bar 32 is located, and is arranged at one end of the fourth battery cell 14 close to the third battery cell 13, for connecting to the second welding strip 42.

[0175] It can be understood that the second welding point 62 is located at the edge of the fourth battery cell 14A closest to the third battery cell 13A at the effective welding position of the fourth battery cell 14A (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 gate line or a pad, but is not limited to this.

[0176] Understandable, 31 +l 32 >1mm,l 31 <1mm, therefore, control d 1 >1mm, which can ensure that the first 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.

[0177] When the width of the first 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 first 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 first 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. In this embodiment, 1mm<d 1 ≤l 31 +l 32 + 33, ensuring that on the basis of allowing a certain offset in the preparation process of the second insulating strip 22, the first extension section 221 of the second insulating strip 22 can still be extended to cover more of the edge area of ​​the third battery cell 13A and the edge area of ​​the fourth battery cell 14A, further improving the reliability and production yield of the battery assembly, reducing the production precision requirements, and at the same time, avoiding affecting the sufficient welding between the second welding strip 42 and the effective welding position on the fourth battery cell 14A, and will not cause unnecessary material waste and loss of bifaciality.

[0178] In some embodiments, the battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge and a second edge arranged along the second direction, and the orthographic projection of the second insulating strip 22 in the thickness direction of the third battery cell 13 falls between the first edge and the second edge.

[0179] If the second insulating strip 22 extends beyond the first edge or the second edge, the adhesive film, front plate, back plate and other material layers of the battery assembly cannot be fully compounded, especially in the edge area, causing external water vapor to easily invade the interior of the battery assembly, affecting the reliability of the battery assembly.

[0180] 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.

[0181] Example 4

[0182] The difference between this embodiment and embodiment 3 is that, see Figures 11 to 13 As shown, in the battery string provided with the middle bus bar 32, the 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, that is, the third battery cell 13A and the fourth battery cell 14A are stacked, and there is no gap between the two batteries, wherein,

[0183] 1mm<d 1 ≤l 41 +l 43 -l 42

[0184] Where, d 1 is the width of the first extension section 221 in the first direction, l 41 is the relative width distance between the middle bus bar 32 and the edge of the third battery cell 13 close to the fourth battery cell 14 in the first direction in the battery string provided with the middle bus bar 32, l 42 is the width of the stacking region between the third battery cell 13 and the fourth battery cell 14 in the first direction, l 43In a battery string with an intermediate bus bar 32 , 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 is provided. The second welding point 62 is provided at one end of the fourth battery cell 14 close to the third battery cell 13 for connecting to the second welding strip 42 .

[0185] Among them, see Fig.12 As shown, in one 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.

[0186] See also Fig.13 As shown, in another 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.

[0187] Understandable, 41 +l 42 >1mm,l 41 <1mm, therefore, control d 1 >1mm, which can ensure that the first 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.

[0188] When the width of the first 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 first 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 first 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. In this embodiment, 1mm<d 1 ≤l 41 +l 42 +l 43 , ensuring that on the basis of allowing a certain offset in the preparation process of the second insulating strip 22, the first extension section 221 of the second insulating strip 22 can still be extended to cover more of the edge area of ​​the third battery cell 13A and the edge area of ​​the fourth battery cell 14A, further improving the reliability and production yield of the battery assembly, reducing the production precision requirements, and at the same time, avoiding affecting the sufficient welding between the second welding strip 42 and the effective welding position on the fourth battery cell 14A, and will not cause unnecessary material waste and loss of bifaciality.

[0189] 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 structures and implementation principles in the aforementioned embodiments 1, 2 and 3, and will not be repeated here.

[0190] 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, In the first direction, both ends of the first insulating strip are provided with a first widened section and a second widened section extending beyond the edge of the first bus bar, the first widened section and the second widened section are arranged sequentially in a direction away from the first battery cell, and the width of the second widened section is smaller than the width of the first widened section.

2. A back contact battery assembly according to claim 1, characterized in that: The first widened section at least partially extends outside the edge of the second battery cell.

3. A back contact battery assembly according to claim 2, characterized in that: In the first direction, an orthographic projection of the first widened section in the thickness direction of the second battery cell at least partially overlaps with an orthographic projection of the first battery cell in the thickness direction of the second battery cell.

4. A back contact battery assembly according to claim 1, characterized in that: In the first direction, the width D2 of the second widened section is ≥1 mm.

5. 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, wherein: 1mm<D1≤l 11 +l 12 +l 13 Wherein, D1 is the width of the first widened section in the first direction, l 11 is the relative width distance between the first bus bar and the edge of the second battery cell close to one end of the first battery cell in the first direction, l 12 is the distance between the first battery cell and the second battery cell, l 13 It 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, and the first welding point is arranged at one end of the first battery cell close to the second battery cell and is used to connect with the first welding strip.

6. A back contact battery assembly according to claim 1, characterized in that: An end of the second battery cell close to the first battery cell is at least partially stacked with the first battery cell, wherein: 1mm<D1≤l 21 +l 23 -l 22 Wherein, D1 is the width of the first widened section in the first direction, l 21 is the relative width distance between the first bus bar and the edge of the second battery cell close to one end of the first battery cell in the first direction, l 22 is the width of the stacking region between the first battery cell and the second battery cell in the first direction, l 23 It 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, and the first welding point is arranged at one end of the first battery cell close to the second battery cell and is used to connect with the first welding strip.

7. A back contact battery assembly according to claim 1, characterized in that: The battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge and a second edge arranged along the second direction, and the orthographic projection of the first insulating strip in the thickness direction of the second battery sheet falls between the first edge and the second edge.

8. A back contact battery assembly according to claim 1, characterized in that: In the first direction, the orthographic projection of the first bus bar in the thickness direction of the second battery cell falls within the second battery cell.

9. 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.

10. 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. 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, used for connecting two battery strings arranged adjacent to each other in a first direction in parallel, the intermediate bus bar being 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.

11. A back contact battery assembly according to claim 10, characterized in that: In the first direction, both ends of the second insulating strip are provided with a first extension segment and a second extension segment extending beyond the edge of the middle bus bar, the first extension segment and the second extension segment are arranged in sequence along a direction away from the fourth battery cell, the first extension segment at least partially extends beyond the edge of the third battery cell, and the width of the second extension segment is smaller than the width of the first extension segment.

12. 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 connected in series with each other 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, used for connecting two battery strings arranged adjacent to each other in a first direction in parallel, the intermediate bus bar being 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, In the first direction, both ends of the second insulating strip are provided with a first extension segment and a second extension segment extending beyond the edge of the middle bus bar, the first extension segment and the second extension segment are arranged sequentially in a direction away from the fourth battery cell, and the width of the second extension segment is smaller than the width of the first extension segment.

13. A back contact battery assembly according to claim 12, characterized in that: The first extension segment at least partially extends beyond the edge of the third battery cell.

14. A back contact battery assembly according to claim 13, characterized in that: In the first direction, the orthographic projection of the first extension segment in the thickness direction of the third battery cell at least partially overlaps with the orthographic projection of the fourth battery cell in the thickness direction of the third battery cell.

15. A back contact battery assembly according to claim 12, characterized in that: In the first direction, the width d2 of the second extension segment is ≥1 mm.

16. A back contact battery assembly according to claim 12, characterized in that: The fourth battery cell and the third battery cell are arranged on the same plane, wherein: 1mm<d1≤l 31 +l 32 +l 33 Wherein, d1 is the width of the first extension segment in the first direction, l 31 is the relative width distance between the middle bus bar and the edge of the third battery cell close to one end of the fourth battery cell in the first direction in the battery string provided with the middle bus bar, l 32 is the distance between the fourth battery cell and the third battery cell in the battery string provided with the middle bus bar, l 33 The second welding point is provided on the fourth battery cell in the battery string where the intermediate bus bar is provided, and is provided at one end of the fourth battery cell close to the third battery cell, for connecting to the second welding strip.

17. A back contact battery assembly according to claim 12, characterized in that: In the battery string provided with the intermediate bus bar, one end of the third battery cell close to the fourth battery cell is at least partially stacked with the fourth battery cell, wherein: 1mm<d1≤l 41 +l 43 -l 42 Wherein, d1 is the width of the first extension segment in the first direction, l 41 is the relative width distance between the middle bus bar and the edge of the third battery cell close to one end of the fourth battery cell in the first direction in the battery string provided with the middle bus bar, l 42 is the width of the stacking region between the third battery cell and the fourth battery cell in the first direction, l 43 In the battery string provided with the intermediate bus bar, 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, the second welding point is provided at one end of the fourth battery cell close to the third battery cell, and is used to connect with the second welding strip.

18. A back contact battery assembly according to claim 12, characterized in that: The battery assembly also includes a front plate, the battery string is arranged on the front plate, the front plate has a first edge and a second edge arranged along the second direction, and the orthographic projection of the second insulating strip in the thickness direction of the third battery cell falls between the first edge and the second edge.

19. 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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