Battery assembly and photovoltaic assembly

Abstract

The invention discloses a battery assembly and a photovoltaic assembly. The battery assembly comprises a battery string and a bus bar, the battery string comprises a plurality of battery pieces arranged along a first direction; a plurality of welding parts are arranged on the back surface of the battery piece at intervals, a plurality of back surface welding strips are arranged on the back surface of the battery piece along the first direction, and each back surface welding strip is connected with the plurality of welding parts which are arranged at intervals along the first direction; the bus bar is arranged on the back face of the battery piece in the second direction intersecting with the first direction and located between every two adjacent welding parts in the first direction. According to the embodiment, the problem of subfissure or fragment of the photovoltaic module can be relieved or avoided, and the photovoltaic module can be applied to the photovoltaic module which uses a welding part and a bus bar with relatively large thickness in order to improve the current collection capability; the method only needs to add front and rear pieces on a series welding machine and identify and move the special-shaped pieces of the battery pieces directly welded by the bus bars and the welding strips, does not need to use a new machine table, is convenient and simple to transform, and can be suitable for production and use of photovoltaic modules.

Description

Technical Field

[0001] This invention relates primarily to the field of photovoltaic technology, and specifically to a battery module and a photovoltaic module. Background Technology

[0002] In the photovoltaic module manufacturing sector, the industry is constantly promoting technological innovation to continuously improve power generation efficiency, especially in the cell and module sectors where various efficiency-enhancing solutions have emerged. One key technology is moving the busbars from the front of the cell to the back, replacing the traditional exposed layout with a hidden design.

[0003] However, if the busbar is hidden on the back of the cell, the thickness of the hidden part increases, resulting in stress concentration. In lamination or alternating hot and cold environments, the concentrated stress at the busbar can easily cause microcracks or breakage of the cell. Figure 1 The EL (Electroluminescence) image of the battery module showing microcracks after lamination and aging tests is shown in the image. Figure 1 As shown, after lamination, cracks appeared at the weld positions on both the middle and end busbars on the back of the cell; after aging tests, microcracks appeared at the weld positions on the cell. Summary of the Invention

[0004] This invention provides a battery module and a photovoltaic module that can mitigate or avoid microcracks or cell breakage in photovoltaic modules. It is applicable to photovoltaic modules that use thicker welded sections and busbars to improve current collection capacity. It only requires the addition of front and rear cells and the identification and movement of irregularly shaped cells that are directly welded to the welding strip on the string welding machine. No new machine is required, and the modification is convenient and simple. It can be applied to the production and use of photovoltaic modules.

[0005] According to a first aspect of the present invention, a battery assembly is provided.

[0006] The battery assembly according to an embodiment of the present invention includes: a battery string and a busbar; The battery string includes a plurality of battery cells arranged along a first direction; Multiple welding portions are spaced apart on the back of the battery cell, and multiple back welding strips are arranged on the back of the battery cell along a first direction, with each back welding strip connecting to multiple welding portions spaced apart along the first direction. The busbar is disposed on the back of the battery cell along a second direction intersecting the first direction, and is located between two adjacent welded portions along the first direction.

[0007] Optionally, the back of the solar cell has multiple first main grids arranged along a first direction and multiple first fine grids arranged along a second direction; each first main grid corresponds to multiple welding portions spaced apart along the first direction. Each first main grid has a discontinuity, the two ends of which correspond to two welded portions on both sides of the busbar along the first direction, and the busbar is located at the discontinuity; Optionally, the back of the cell has multiple bridging grid lines connecting two welded portions on both sides of the busbar along the first direction.

[0008] Optionally, the thickness of the bridging grid line is less than the thickness of the first main grid, the width of the bridging grid line is less than or equal to the width of the first main grid, the thickness of the first fine grid is less than or equal to the thickness of the bridging grid line, and the width of the first fine grid is less than or equal to the width of the bridging grid line.

[0009] Optionally, the back side of the solar cell includes a current-collecting region and a non-current-collecting region; the density of the first fine grid in the current-collecting region is greater than the density of the first fine grid in the non-current-collecting region; The busbar area refers to the area on the back of the solar cell where the busbars are located, while the non-busbar area refers to the area on the back of the solar cell other than the busbar area.

[0010] Optionally, each bridging wire includes: A transverse fine grid is provided along a first direction; along the first direction, the transverse fine grid is located between two welding parts on both sides of the busbar along the first direction, and along the second direction, the transverse fine grid is not collinear with the welding parts at the corresponding positions; Two first inclined fine grids are respectively disposed at both ends of the transverse fine grid and connect the transverse fine grid and two welding parts located on both sides of the busbar along the first direction; Optionally, the angle between the first inclined fine grid and the first direction is 5-60°.

[0011] Optionally, the back of the battery cell has multiple second fine grids, which connect the end weld portion located at the edge of a plurality of weld portions spaced apart along the first direction to multiple first fine grids located outside the end weld portion. The outside of the end weld portion refers to the side of the end weld portion away from other weld portions spaced apart along the first direction.

[0012] Optionally, the shape of the second fine grid is a broken line or a diagonal line that is not parallel to the first direction.

[0013] Optionally, the distance between the end weld and the edge of the battery cell along the first direction is 3-10 mm.

[0014] Optionally, the front side of the solar cell has multiple second main grids arranged along the first direction, with the first end of the front solder strip connected to the second main grids and the second end folded to the back side of the solar cell and connected to the busbar.

[0015] Optionally, the battery assembly also includes a first insulating buffer layer located below the busbar and the front solder strip folded to the back of the battery cell. Optionally, the first buffer layer includes: a first non-groove area and a first groove area disposed along the second direction, wherein the first groove area is located on one or both sides of the first non-groove area along the first direction; The first non-groove area corresponds to the busbar; the first groove area corresponds at least to the welded portions located on both sides of the busbar along the first direction, and a plurality of first grooves are provided corresponding one-to-one with the welded portions to expose the welded portions at the corresponding positions. Optionally, the second end of the front solder strip folded to the back of the cell is staggered with the back solder strip and avoids the welding portion exposed by the first slot.

[0016] Optionally, the back solder strip of the battery cell includes a first portion connecting two solder portions located on both sides of the busbar along a first direction, and a second portion other than the first portion, wherein the first portion is connected to the busbar, and: The busbar abuts against the back of the battery cell, or the battery assembly also includes a second insulating buffer layer, which is at least partially located below the busbar; Optionally, the thickness of the second buffer layer is 0.05-0.15 mm.

[0017] Optionally, The second buffer layer is rectangular. The width of the second buffer layer is less than the distance between the two welded parts on both sides of the busbar along the first direction and greater than the width of the busbar along the first direction. The second buffer layer is located below the first part. or, The second buffer includes: a second non-groove area and a second groove area arranged along the second direction, wherein the second groove area is located on one side of the second non-groove area along the first direction; The second slot area is provided with a plurality of second slots at intervals along the second direction and a second slot tongue piece located between two adjacent second slots. The second slots extend to the edge of the second slot area along the direction away from the second non-slot area. The second non-slot area is located above the second part. The second slots avoid the first part and the welding part connected to the first part. The second slot tongue piece is inserted between the busbar and the battery cell along the first direction. Optionally, the spacing between any position on the second buffer layer and the welded part adjacent to any position is greater than or equal to 1 mm.

[0018] According to a second aspect of the present invention, a photovoltaic module is provided, the photovoltaic module including the battery module provided in the first aspect of the present invention.

[0019] The technical solution of the above invention has the following advantages or beneficial effects: By placing the busbar between two adjacent welding portions along the first direction on the back of the solar cell, the busbar can avoid the welding portions on the back of the solar cell when placed on the back of the solar cell. On the one hand, this reduces the overall thickness of the solar cell at the welding portion location. On the other hand, during lamination and high / low temperature cycling, since there is no welding portion below the busbar, even if the encapsulant or busbar deforms due to thermal expansion and contraction, the busbar will not exert concentrated stress on the solar cell through the welding portion. Therefore, the embodiments of the present invention can mitigate or avoid the problem of microcracks or cell breakage in photovoltaic modules, and are applicable to photovoltaic modules that use thicker welding portions and busbars to improve current collection capacity. Since the pattern changes of the solar cell only occur on both sides of the cell string and on the solar cells where the busbar is welded to the welding strip, and not on other solar cells, it is only necessary to add the identification and movement of irregularly shaped solar cells for the front and rear cells and solar cells where the busbar is directly welded to the welding strip on the string welding machine. No new machine is required, the modification is convenient and simple, and it can be applied to the production and use of photovoltaic modules. Attached Figure Description

[0020] The accompanying drawings are provided to better understand the invention and are not intended to unduly limit the scope of the invention. Wherein: Figure 1 EL images showing microcracks in the battery module after lamination and aging tests; Figure 2 This is a schematic diagram illustrating the principle of solving the microcrack problem in battery cells according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the back side of the battery cell in Embodiment 1 of the present invention; Figure 4 This is a cross-sectional schematic diagram of the battery cell in some optional embodiments of the present invention; Figure 5 This is a schematic diagram of the back side of the battery cell in Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of the first buffer layer in some optional embodiments of the present invention; Figure 7 This is a schematic diagram of the first buffer layer in some alternative embodiments of the present invention; Figure 8 This is a schematic diagram of the back side of the battery cell in Embodiment 3 of the present invention; Figure 9 This is a schematic diagram of the second buffer layer in some optional embodiments of the present invention; Figure 10 This is a schematic diagram of the back of the battery cell in Embodiment 4 of the present invention; Figure 11 This is a schematic diagram of the back side of the battery cell in Embodiment 5 of the present invention; Figure 12 This is a schematic diagram of the back side of the battery cell in Embodiment Six of the present invention.

[0021] The attached figures are labeled as follows: 10-Battery cell; 101-Combine area; 102-Non-Combine area; 11-Back solder strip; 12-Welding part; 121-End welding part; 13-First main grid; 14-First fine grid; 15-Transverse fine grid; 16-First inclined fine grid; 17-Second fine grid; 18-Front solder strip; 20-Busbar; 30 - First buffer layer; 31 - First slot area; 311 - First slot; 32 - First non-slot area; 40 - Second buffer layer; 41 - Second slot area; 411 - Second slot; 412 - Second slot tongue; 42 - Second non-slot area. Detailed Implementation

[0022] The exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0023] It should be noted that the terms "upper", "lower", "inner", "outer", "end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the elements referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0024] Unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components.

[0025] In the photovoltaic (PV) module manufacturing sector, the industry is constantly promoting technological innovation to continuously improve power generation efficiency, especially with the emergence of various efficiency-enhancing solutions at the cell and module levels. One key technology is moving the busbars from the front of the cell to the back, replacing the traditional exposed layout with a hidden design. This structure effectively reduces unused space in PV modules, significantly increases the effective light-receiving area, and thus improves incident light utilization and current transmission efficiency. This not only increases the power output per unit area of ​​PV modules but also improves the overall aesthetics, representing an advanced direction in the development of high-efficiency modules and becoming one of the important paths for the industry to break through efficiency bottlenecks.

[0026] To prevent the busbar from squeezing the solar cell during lamination and to provide insulation on the positive electrode side, a buffer insulating pad is typically placed between the busbar and the back of the solar cell. However, placing the busbar and the insulating buffer pad on the back of the solar cell results in an excessively thick corresponding area on the back. Furthermore, since the welded area on the back of the solar cell is relatively thicker than other areas, the increased thickness of the hidden portion when the busbar is concealed on the back of the solar cell leads to stress concentration. In lamination or alternating hot and cold environments, this concentrated stress at the busbar can easily cause microcracks or breakage of the solar cell. If the busbar covers the welded area on the back of the solar cell, the risk of microcracks or breakage is further exacerbated.

[0027] In view of the above-mentioned problems existing in the prior art, embodiments of the present invention provide a battery module and a photovoltaic module. The following are combined with... Figure 2-12 The battery module and photovoltaic module provided in the embodiments of the present invention will be described.

[0028] The battery assembly in this embodiment of the invention includes battery strings and busbars 20. The battery assembly includes one or more battery strings, each battery string including multiple battery cells 10 arranged along a first direction. The battery cells 10 in the same battery string are connected in series via solder strips. Multiple battery strings are connected in series and / or in parallel via solder strips and / or busbars 20. The busbars 20 lead out the current from the battery string assembly. Among the multiple battery cells 10 belonging to the same battery string, the battery cells 10 located at the ends of the battery string along the first direction are end battery cells, and the battery cells 10 located between two end battery cells are intermediate battery cells. A battery string may include one or more intermediate battery cells. Multiple welded portions 12 are spaced apart on the back of the battery cells 10. The number of welded portions 12 can be selectively set according to actual conditions; this embodiment of the invention does not specifically limit this. The multiple welded portions 12 can be arranged in an array, for example, along the first direction and a second direction intersecting the first direction. Among the multiple welded portions 12 spaced apart along the first direction, the welded portions 12 located at the edges are called end welded portions 121. The back side of the battery cell 10 is also provided with multiple back-side solder strips 11 extending along a first direction. These multiple back-side solder strips 11 are disposed along the first direction on the back side of the battery cell 10 and connect to multiple solder portions 12 spaced apart along the first direction, for collecting current from the back side of the battery cell 10. In this embodiment of the invention, X represents the first direction, Y represents the second direction, and Z represents the thickness direction. The first direction intersects the second direction, and the thickness direction intersects both the first and second directions. In this embodiment of the invention, "intersection" refers to non-parallelism.

[0029] The busbar 20 is disposed on the back side of the battery cell 10 along a second direction intersecting the first direction. In the case where the battery assembly includes multiple battery strings, the busbar 20 is connected to the multiple battery strings along the second direction. In this embodiment of the invention, when the busbar 20 is disposed on the back side of the battery cell 10 along the second direction, the busbar 20 is located between two adjacent welded portions 12 along the first direction.

[0030] Figure 2 This is a schematic diagram illustrating the principle of solving the microcrack problem in battery cells according to an embodiment of the present invention. Figure 2 As shown, when the busbar 20 is hidden on the back of the battery cell 10, the thickness of the hidden part increases, leading to stress concentration. In lamination or alternating hot and cold environments, the concentrated stress at the busbar can easily cause microcracks or breakage of the battery cell. If the busbar 20 covers the welded portion 12 on the back of the battery cell 10, on the one hand, the busbar 20 will compress the welded portion 12, and on the other hand, stress is easily concentrated at the welded portion, thereby increasing the risk of microcracks or breakage of the battery cell 10. In this embodiment of the invention, by placing the busbar 20 between two adjacent welded portions 12 along the first direction on the back side of the solar cell 10, the busbar 20 avoids the welded portions 12 on the back side of the solar cell 10. This reduces the thickness of the solar cell at the welded portion 12 location. Furthermore, during lamination and high / low temperature cycling, since there is no welded portion 12 below the busbar 20, even if the encapsulant or the busbar 20 deforms due to thermal expansion and contraction, the busbar 20 will not exert concentrated stress on the solar cell 10 through the welded portion 12. This mitigates or avoids microcracks or cell breakage in the photovoltaic module. This invention is applicable to photovoltaic modules that use thicker welded portions and busbars to improve current collection capacity. In addition, by placing the busbar 20 between two adjacent welded portions 12 along the first direction on the back side of the solar cell 10, this embodiment of the invention transforms the point stress on the solar cell at the location corresponding to the busbar 20 into a line stress on the back solder strip 11, increasing the stress area and making microcracks less likely to occur during lamination or high / low temperature cycling.

[0031] The busbar 20 can be positioned between the two welded portions 12 closest to the back edge of the battery cell 10, such as... Figure 3 and Figure 4 As shown, the busbar 20 is disposed between the first welding portion 12 (i.e., the end welding portion 121) and the second welding portion 12 on the right side of the back surface of the battery cell 10. In practical applications, the busbar 20 can also be disposed in other positions, for example, the busbar 20 can be disposed between the second welding portion 12 and the third welding portion 12 near the edge of the back surface of the battery cell 10 (e.g., Figure 5(As shown), or the busbar 20 may be disposed between the third welded portion 12 and the fourth welded portion 12 near the back edge of the battery cell 10 (not shown), etc. This embodiment of the invention does not specifically limit which two welded portions 12 on the back of the battery cell 10 the busbar 20 is disposed between.

[0032] In this embodiment of the invention, the spacing between the busbar 20 and the adjacent welded portion 12 can be selectively set. Figure 4 and Figure 5 In the optional embodiment shown, L8 represents the distance between the busbar 20 and the adjacent welded portion 12. Increasing the distance L8 between the busbar 20 and the adjacent welded portion 12 helps prevent the busbar 20 from contacting the welded portion 12, thus avoiding the risk of short circuit. In an optional embodiment of the invention, the distance L8 between the busbar 20 and the adjacent welded portion 12 is greater than or equal to 2 mm; for example, the distance L8 between the busbar 20 and the adjacent welded portion 12 is a value such as 2 mm, 2.5 mm, or 3 mm.

[0033] The material of the busbar 20 can be set according to the actual situation. For example, the busbar 20 is a lead-tin alloy solder layer, or the busbar 20 is a tin-plated copper flat strip or a tin-plated copper mesh strip. The embodiments of the present invention do not specifically limit the material of the busbar 20.

[0034] In this embodiment of the invention, the dimension of the busbar 20 along the first direction is referred to as the width of the busbar 20, and the width of the busbar 20 is less than the distance between two adjacent welded portions 12 along the first direction. For example... Figure 2 and Figure 4 As shown, L1 represents the width of the busbar 20, and L2 represents the distance between two adjacent welded portions 12 along the first direction. L1 is less than L2. Increasing the width of the busbar 20 is beneficial to improving the current collection effect of the battery string. However, if the width L1 of the busbar 20 is too large, the distance between the busbar 20 and its adjacent welded portions 12 will be small, which may easily lead to contact between the busbar 20 and its adjacent welded portions 12, resulting in a short circuit risk. The width L1 of the busbar 20 can be selectively set according to the actual situation. For example, the width L1 of the busbar 20 is 5-15mm, such as 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, etc.

[0035] In this embodiment of the invention, the dimension of the busbar 20 along the thickness direction is referred to as the thickness of the busbar 20. For example... Figure 2As shown, H1 represents the thickness of busbar 20. Increasing the thickness of busbar 20 is beneficial to improving the current collection effect of the battery string. However, if the thickness H1 of busbar 20 is too large, it will increase the thickness of the area where busbar 20 is located, causing concentrated stress on the battery cell 10 during lamination and high / low temperature cycling, which may easily lead to microcracks or cell breakage. The thickness H1 of busbar 20 can be selectively set according to actual conditions. For example, the thickness H1 of busbar 20 is 0.08-0.3mm, such as 0.08mm, 0.10mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, etc.

[0036] In this embodiment of the invention, the dimension of the busbar 20 along the second direction is referred to as the length of the busbar 20 (not shown in the figure). The length of the busbar 20 should be at least sufficient to allow the busbar to connect with the corresponding polarity back solder strips 11 distributed along the second direction. Figure 3 In the optional embodiment shown, L3 represents the maximum distance between the various back-side solder strips 11 distributed along the second direction on the back side of the battery cell 10 and corresponding to the polarity of the busbar 20, such as... Figure 3 As shown, the busbar 20 extends along the second direction and connects sequentially with the corresponding back solder strips 11 distributed along the second direction. It further extends outward from the corresponding back solder strip 11 located at the edge of the second direction. In other words, the length of the busbar 20 is greater than the distance L3. By making the length of the busbar 20 greater than the maximum distance L3 between the corresponding back solder strips 11 distributed along the second direction on the back of the battery cell 10, effective contact between the busbar 20 and the corresponding back solder strips 11 on the back of the battery cell 10 can be ensured, which is beneficial for improving the current collection effect of the battery string.

[0037] In this embodiment of the invention, the back surface of the battery cell 10 has multiple first main grids 13 arranged along a first direction and multiple first fine grids 14 arranged along a second direction; each first main grid 13 corresponds to multiple welding portions 12 spaced apart along the first direction, each first main grid 13 has an interruption, the two ends of which correspond to two welding portions 12 on both sides of the busbar 20 along the first direction, and the busbar 20 is disposed at the interruption. On one hand, as... Figure 10 , Figure 11 and Figure 12As shown, a busbar 20 is directly welded to the back solder strip 11 of the battery cell 10. The welding strength between the busbar 20 and the back solder strip 11 is greater than the welding strength between the back solder strip 11 and the main grid 13 of the battery cell. Under thermal stress, the busbar 20 may pull up the back solder strip 11, causing the first main grid 13 at the weld between the back solder strip 11 and the first main grid 13 to be pulled up or even detached from the back of the battery cell 10, resulting in grid breakage. The current in the first fine grid 14 cannot be transmitted to the solder strip, affecting current transmission and increasing the power attenuation of the module. This embodiment of the invention prevents the above situation from occurring by making the first main grid 13 have an interruption and placing the busbar 20 at the interruption, avoiding the risk of grid breakage of the first main grid 13 due to the busbar 20 pulling off the back solder strip 11. On the other hand, by making the first main grid 13 have a discontinuity and placing the busbar 20 at the discontinuity, the thickness of the area where the busbar 20 is located can be further reduced, thus mitigating or avoiding the risk of microcracks or breakage of the battery cell.

[0038] In an optional embodiment of the present invention, the back of the battery cell 10 has multiple bridging grid lines. These bridging grid lines connect two welded portions 12 on both sides of the busbar 20 along a first direction to collect current from the busbar 20 in the bus region 101. That is, multiple bridging grid lines replace the discontinuous first main grid 13. The bridging grid lines extend between and connect the two welded portions 12 at corresponding positions. The extension shape of the bridging grid lines can be selectively configured; for example, the bridging grid lines can extend along a broken line or a curve. The embodiments of the present invention do not specifically limit the extension shape of the bridging grid lines. In the embodiments of the present invention, the dimension of the bridging grid line along the vertical direction (Z-direction) is called the thickness of the bridging grid line, and the dimension of the bridging grid line perpendicular to both the vertical direction (Z-direction) and the extension direction of the bridging grid line is called the width of the bridging grid line. A smaller bridging grid line width means it occupies less light-receiving area, reducing shading losses and improving the short-circuit current and photoelectric conversion efficiency of the solar cell. However, a smaller bridging grid line width also increases the series resistance of the solar cell string. Therefore, a balance needs to be struck between reducing series resistance and minimizing shading losses in the bridging grid line width. The thickness of the bridging grid line determines its cross-sectional area, affecting its resistance and contact resistance. A larger bridging grid line thickness results in a larger cross-sectional area, lower series resistance, and higher fill factor and output power. However, a larger bridging grid line thickness also means a smaller contact area between the bridging grid line and the solar cell, higher contact resistance, and lower fill factor and output power. Therefore, it is necessary to comprehensively consider factors such as the number, width, and thickness of the bridging grid lines to achieve optimal photoelectric conversion efficiency and output power. In some optional embodiments of the present invention, the thickness of the bridging grid line is less than the thickness of the first main grid 13, the width of the bridging grid line is less than or equal to the width of the first main grid 13, the thickness of the first fine grid 14 is less than or equal to the thickness of the bridging grid line, and the width of the first fine grid 14 is less than or equal to the width of the bridging grid line. Since the thickness of the bridging grid line is less than the thickness of the first main grid 13, compared to the scheme where the first main grid 13 is provided at discontinuous locations, replacing the first main grid 13 with a bridging grid line can reduce the overall thickness at the busbar 20.

[0039] In an optional embodiment of the invention, each bridging grid line includes a transverse fine grid 15 and two first inclined fine grids 16. For example... Figure 11 and Figure 12As shown, the transverse fine grid 15 is arranged along a first direction; along the first direction, the transverse fine grid 15 is located between two welding portions 12 on both sides of the busbar along the first direction, and along the second direction, the transverse fine grid 15 is not collinear with the welding portions 12 at the corresponding positions. Two first inclined fine grids 16 are respectively arranged at both ends of the transverse fine grid 15 and connect the transverse fine grid 15 and the two welding portions 12 located on both sides of the busbar 20 along the first direction. Typically, the thickness of the first main grid 13 is 10um-20um, while the thickness of the first inclined fine grid 16 and the transverse fine grid 15 is only less than 10um. In this embodiment of the invention, bridging grid lines are used to replace the first main grid 13, which can further reduce the thickness of the busbar region 101 and mitigate or avoid the risk of microcracks or breakage of the battery cell 20. Furthermore, in the case where the battery assembly includes multiple lateral grids 15 and multiple first inclined grids 16, even if one of the lateral grids 15 and / or the first inclined grids 16 breaks, current can still be transmitted through the other lateral grids 15 and the first inclined grids 16. This can avoid the situation where current cannot be transmitted due to the breakage of the first main grid 13 when there is only one first main grid 13. It can also reduce the risk of the first main grid 13 breaking due to thermal stress when the busbar 20 is directly welded to the back solder strip 11.

[0040] The number of transverse fine grids 15 and the first inclined fine grids 16 can be selectively set according to actual conditions. The first inclined fine grid 16 connects the transverse fine grids 15 and the welding portion 12 adjacent to the busbar region 102. When the transverse fine grids 15 and the welding portion 12 adjacent to the busbar region 102 are not collinear along the first direction, the first inclined fine grid 16 is inclined relative to the first direction, that is, the first inclined fine grid 16 has an angle with the first direction. This angle can be selectively set according to actual conditions. For example, the angle between the first inclined fine grid 16 and the first direction is 5-60°, such as 5°, 15°, 30°, 45°, 60°, etc.

[0041] In this embodiment of the invention, the back surface of the battery cell 10 includes a current-carrying region 101 and a non-current-carrying region 102. The current-carrying region 101 refers to the area on the back surface of the battery cell 10 where the current-carrying strips 20 are located, and the non-current-carrying region 102 refers to the area on the back surface of the battery cell 10 other than the current-carrying region 101, such as... Figure 10 As shown. In an optional embodiment of the present invention, the density of the first fine grid 14 in the merging region 101 is greater than the density of the first fine grid 14 in the non-merging region 102, as... Figure 10 , Figure 11 and Figure 12As shown. In this embodiment of the invention, by increasing the density of the first fine grid 14 in the current-collecting region 101 to be greater than the density of the first fine grid 14 in the non-current-collecting region 102, even if one or more first fine grids 14 in the current-collecting region 101 become detached or break, other first fine grids 14 can still collect current, ensuring normal current transmission and improving the safety of current transmission. Furthermore, for the busbar 20, when transmitting current, if the width of the busbar 20 is too large and there is no buffer layer between the busbar 20 and the solar cell 10, the busbar 20 will contact the first fine grid 14 during the lamination process. If the current transmitted to the busbar 20 by a single first fine grid 14 is too large, it will cause localized overheating on the back of the solar cell 10, increasing series resistance. By densifying the first fine grid 14 in the current-collecting region 101, the localized current in this region can be distributed, reducing localized heat and preventing severe power degradation of the photovoltaic module during use. Furthermore, if the busbar 20 and the first fine grid 14 are not welded together, after lamination, the busbar 20 and the first fine grid 14 will be in a semi-contact state. If current flows through the busbar 20, there will also be current on the first fine grid 14, which may cause an electric arc between the busbar 20 and the first fine grid 14. The occurrence of the electric arc may damage the surface of the solar cell. In this embodiment of the invention, by making the density of the first fine grid 14 in the busbar region 101 greater than the density of the first fine grid 14 in the non-busbar region 102, the denser first fine grid 14 can distribute the current, preventing the formation of an electric arc between the first fine grid 14 and the busbar 20 due to current blockage, avoiding damage to the surface of the solar cell, and reducing the risk of electric arcing. In addition, since the first main grid 13 is replaced by a bridging grid line with a smaller cross-sectional area, the current transmission capacity of the bridging grid line is weaker than that of the first main grid 13. Increasing the density of the first fine grid 14 in the busbar region 101 to distribute the current can reduce the current transmitted by each bridging main grid.

[0042] To ensure the current-carrying capacity of the busbar 20, the busbar 20 needs to have a sufficient width. In order to prevent the two overlapping portions 12 of the busbar 20 from being separated, the distance between the two overlapping portions 12 on both sides of the busbar 20 along the first direction needs to be greater than the width of the busbar 20. Therefore, the width between the two overlapping portions 12, i.e., the current-carrying area 101, is relatively large. In order to improve the current collection efficiency, the density of the first fine grid 14 in the current-carrying area is increased to better transmit and collect current and improve the overall efficiency of the component.

[0043] In this embodiment of the invention, multiple first fine grids 14 near the back edge of the battery cell 10 can be combined via a first main grid 13 or via fine grids. In an optional embodiment of the invention, the back of the busbar 20 has multiple second fine grids 17 for connecting the end weld portions 121 located at the edge of a plurality of weld portions 12 spaced apart along a first direction to a plurality of first fine grids 14 located outside the end weld portions 121, where "outside the end weld portion 121" refers to the side of the end weld portion 121 away from other weld portions. Figure 10-12 In the optional embodiment shown, the second fine grid 17 is an oblique line that is not parallel to the first direction. Those skilled in the art can also set the second fine grid 17 to other shapes according to actual conditions, such as a broken line or a curve. As long as the second fine grid 1 connects the end weld portion 121 located at the edge of the plurality of weld portions 12 spaced apart along the first direction to the plurality of first fine grids 14 located outside the end weld portion 121, the shape of the second fine grid in this embodiment of the invention is not specifically limited. Since the edges are over-pressed during the photovoltaic module lamination process, this embodiment of the application, by using the second fine grid 17 instead of the first main grid 13, can reduce the thickness of the solar cell 10 at the corresponding position, mitigating or avoiding microcracks or breakage at the edges of the photovoltaic module during lamination. In some embodiments, the distance between the end weld portion 121 and the edge of the solar cell along the first direction can be 3-10 mm.

[0044] The front side of the solar cell 10 has multiple second main grids (not shown in the figure) arranged along a first direction. The first end of the front solder strip 18 is connected to the second main grid, and the second end is folded over to the back side of the solar cell 10 and connected to the busbar 20. In practical applications, the second end of the front solder strip 18 can be connected to the busbar 20 first, and then the busbar 20 can be placed on the back side of the solar cell 10; alternatively, the busbar 20 can be placed on the back side of the solar cell 10 first, and then the second end of the front solder strip 18 can be connected to the busbar 20. In this case, the busbar 20 is located between the first welding part (end welding part) and the second welding part to reduce the degree of the front solder strip 18 folded over to the back side of the solar cell, thereby reducing the risk of short circuit caused by the front solder strip 18 contacting the back side of the solar cell, the back solder strip, and / or the welding part. In this embodiment of the invention, the second end of the front solder strip 18 can be placed between the busbar 20 and the solar cell 10, or it can be placed on the side of the busbar 20 away from the solar cell 10 (i.e., the back surface of the busbar 20). In an optional embodiment of the present invention, the second end of the front solder strip 18 and the back solder strip 11 are staggered along the second direction. By staggering the second end of the front solder strip 18 and the back solder strip 11, the risk of short circuit due to contact between the front solder strip 18 and the back solder strip 11 can be avoided. On the other hand, the thickness of the edge of the cell 10 can be reduced, thus mitigating or avoiding microcracks or breakage of the cell 10.

[0045] In an optional embodiment of the invention, the battery assembly further includes an insulating first buffer layer 30, located below the busbar 20 and the front solder strip 18 folded to the back of the battery cell 10. The projected area of ​​the first buffer layer 30 along its thickness direction covers the projected area of ​​the busbar 20 along its thickness direction, the thickness direction intersecting with a first direction and a second direction. Figure 3 As shown, a first buffer layer 30 is disposed between the busbar 20 and the battery cell 10. The first buffer layer 30 extends along the second direction, and the projection area of ​​the first buffer layer 30 along the thickness direction covers the projection area of ​​the busbar 20 along the thickness direction. That is to say, the back of the busbar 20 and the battery cell 10 do not directly abut against each other, but are separated by the first buffer layer 30. By providing the first buffer layer 30 between the busbar 20 and the battery cell 10, on the one hand, it can prevent the front solder strip 18 on the front side of the battery cell 10 from contacting the back solder strip 11 on the back side, thus avoiding a short circuit. On the other hand, it can play a buffering role, preventing the busbar 20 from squeezing the battery cell 10 during lamination and use, and slowing down or preventing microcracks or breakage of the battery cell.

[0046] In this embodiment of the invention, the dimension of the first buffer layer 30 along the first direction is referred to as the width of the first buffer layer 30, and the dimension of the first buffer layer 30 along the second direction is referred to as the length of the first buffer layer 30. In this embodiment of the invention, the projected area of ​​the first buffer layer 30 along the thickness direction covers the projected area of ​​the busbar 20 along the thickness direction. The length of the first buffer layer 30 is greater than or equal to the length of the busbar 20, and the width of the first buffer layer 30 is greater than or equal to the width of the busbar 20. By making the length of the first buffer layer 30 greater than or equal to the length of the busbar 20, and the width of the first buffer layer 30 greater than or equal to the width L1 of the busbar 20, contact between the busbar 20 and the back solder strip 11 can be avoided, and the front solder strip 18 and the back solder strip 11 can be kept insulated, thus avoiding the risk of short circuit.

[0047] Figure 3 This is a schematic diagram of the back side of the battery cell in Embodiment 1 of the present invention. Figure 4 These are cross-sectional schematic diagrams of the battery cells in some optional embodiments of the present invention, such as... Figure 3 and 4As shown, the width of the first buffer layer 30 is greater than the width of the busbar 20, and the first buffer layer 30 extends beyond the busbar 20 in a first direction. Exemplarily, the first buffer layer 30 extends beyond the busbar 20 in the first direction and terminates at the edge of the battery cell 10. This reduces the material consumption of the first buffer layer 30 while maintaining insulation between the front solder strip 18 folded to the back of the battery cell and the back solder strip 11. In an optional embodiment of the invention, the first buffer layer 30 extends beyond the busbar 20 in the first direction and terminates at the bend of the front solder strip 18 on the front side of the battery cell 10. By extending the first buffer layer 30 to the bend of the front solder strip 18, the first buffer layer 30 can alleviate the pressure at the bend during lamination, preventing the pressure at the bend of the front solder strip 18 from being applied to the edge of the battery cell 10, reducing the pressure on the edge of the battery cell 10, thereby mitigating or avoiding the risk of microcracks or cracks in the battery cell 10.

[0048] It should be noted that the above-described limitation on the position of the first buffer layer 30 is only an example. In actual applications, those skilled in the art can make various adaptive settings according to the actual situation, and are not limited to the embodiments listed above. For example, a portion of the first buffer layer 30 can be disposed on the back side of the battery cell 10, and another portion can extend from the back side of the battery cell 10 to the edge of the front side of the battery cell 10, thereby further ensuring that the front solder strip 18 and the back solder strip 11 remain insulated and prevent short circuits.

[0049] In an optional embodiment of the present invention, the width of the first buffer layer 30 is greater than the width of the busbar 20. The width of the first buffer layer 30 can be selectively set according to actual conditions. For example, the width of the first buffer layer 30 is 6-25mm, such as 6mm, 8mm, 10mm, 12mm, 15mm, 20mm, 23mm, 25mm, etc. By making the first buffer layer 30 have a larger width, it can be ensured that the busbar 20 can be completely hidden in the first buffer layer 30, avoiding the risk of short circuit caused by the busbar 20 being exposed on the back of the battery cell 10. By making the first buffer layer 30 have a smaller width, it can be prevented that the first buffer layer 30 covers the adjacent weld portion 12, avoiding the increase in thickness at the location of the adjacent weld portion 12 due to the adjacent weld portion 12 being covered, thereby reducing the concentrated stress at the location of the adjacent weld portion 12 and mitigating or avoiding the risk of microcracks or fragments appearing at the location of the adjacent weld portion 12. The edge of the first buffer layer 30 refers to the edge of the first buffer layer 30 in the direction away from the battery cell 10, and the edge of the busbar 20 refers to the edge of the busbar 20 in the direction away from the battery cell 10. In optional embodiments of the present invention, such as Figure 4As shown, the distance L4 between the edge of the busbar 20 and the edge of the corresponding first buffer layer 30 along the first direction is greater than or equal to 1 mm, for example, L4 can be 1 mm, 2 mm, etc. By ensuring that the distance L4 between the edge of the busbar 20 and the edge of the corresponding first buffer layer 30 along the first direction is greater than or equal to 1 mm, it is possible to ensure that the busbar 20 is laid on the first buffer layer 30, preventing the busbar 20 from being exposed on the battery cell 10 due to laying accuracy issues, avoiding short circuit problems, and reducing the requirements for laying accuracy.

[0050] The thickness of the first buffer layer 30 refers to the dimension of the first buffer layer 30 along the thickness direction. For example... Figure 4 As shown, L5 represents the thickness of the first buffer layer 30. The thickness L5 of the first buffer layer 30 can be selectively set according to actual conditions. For example, the thickness of the first buffer layer 30 is 0.1-0.4 mm, such as 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, etc. By making the first buffer layer 30 have a larger thickness, the buffering effect of the first buffer layer 30 on the battery cell 10 can be increased, further mitigating or avoiding the risk of microcracks or breakage of the battery cell 10. By making the first buffer layer 30 have a smaller thickness, the thickness at the corresponding position of the battery cell 10 can be reduced, thereby reducing the concentrated stress at the edge of the battery cell 10 and mitigating or avoiding the risk of microcracks or breakage of the battery cell 10.

[0051] The first buffer layer 30 can be any elongated strip structure extending along the second direction, such as a rectangular structure extending along the second direction (e.g., ...). Figure 3 (as shown), or a rectangular structure with chamfers, or an elliptical structure, etc. In this case, the first buffer layer 30 can be disposed between the back of the battery cell 10 and the busbar 20, and located between two adjacent welding portions 12 on the back of the battery cell 10. The width of the first buffer layer 30 can be equal to or greater than the width of the busbar 20.

[0052] The first buffer layer 30 can also be a structure with slots. Figure 6 This is a schematic diagram of the first buffer layer in some optional embodiments of the present invention, such as... Figure 6As shown, the first buffer layer 30 includes a first non-slotted area 32 and a first slotted area 31 disposed along a second direction. The first slotted area 31 is located on one or both sides of the first non-slotted area 32 along the first direction. The first non-slotted area 32 corresponds to the busbar 20, and the first slotted area 31 corresponds at least to the welding portions 12 located on both sides of the busbar 20 along the first direction. Multiple first slots 311 are provided, each corresponding to a welding portion 12, to expose the corresponding welding portion 12. The first slotted area 31 and the first non-slotted area 32 are distributed along the first direction X, and extend along the second direction Y, respectively. In the case where the first end of the front solder strip 18 is connected to the second main busbar and the second end is folded to the back of the battery cell 10 and connected to the busbar 20, the second end of the front solder strip 18 folded to the back of the battery cell 10 is staggered with the back solder strip 11 and avoids the welding portions 12 exposed by the first slots 311. By staggering the second end of the front solder strip 18 with the back solder strip 11 and avoiding the welding portion 12 exposed by the first slot 311, on the one hand, the risk of short circuit caused by the contact between the front solder strip 18 and the welding portion 12 on the back of the cell 10 can be avoided, and on the other hand, the thickness of the edge of the cell 10 can be reduced, thus mitigating or avoiding the problem of microcracks or breakage of the cell 10.

[0053] Each first slot 311 can correspond to one welding part 12, that is, each first slot 311 only exposes one welding part 12 at its corresponding position, such as Figure 8 As shown, each first slot 311 can also correspond to multiple welded portions 12. For example, each first slot 311 exposes two or more welded portions 12 at its corresponding position. Furthermore, by setting the first slot 311, all welded portions 12 within the projection area of ​​the first buffer layer 30 can be exposed, or only some welded portions 12 within the projection area of ​​the first buffer layer 30 can be exposed, while welded portions 12 at other positions remain unexposed. Therefore, in this embodiment of the invention, the number of first slots 311 spaced along the second direction on the first slot area 31 can be selectively set according to actual conditions. Figure 6 In the optional embodiment shown, nine first slots 311 are spaced apart along the second direction on the first slot area 31. Figure 8In the optional embodiment shown, nine first slots 311 spaced apart along the second direction on the first slot area 31 expose nine weld portions 12 spaced apart along the second direction on the back edge of the battery cell 10. By exposing the weld portions 12 at corresponding positions using the first slots 311 in the first slot area 31 of the first buffer layer 30, the weld portions 12 near the back edge of the battery cell 10 and the back solder strips 11 above the weld portions 12 can be exposed in the first slots 311 of the first buffer layer 30. That is, the first buffer layer 30 will not apply pressure to the weld portions 12 on the back edge of the battery cell 10, thereby reducing or avoiding the risk of microcracks or breakage of the battery cell 10 due to concentrated stress at the weld portions 12 on the back edge of the battery cell 10.

[0054] The shape of the first slot 311 on the first slot area 31 can be selectively set according to actual conditions. For example, the first slot 311 on the first slot area 31 can be a rectangular, circular, elliptical, polygonal, or other structure with a closed outline located on the first slot area 31. Figure 6 and Figure 8 As shown, the first slot 311 on the first slot area 31 is a rectangular structure with a closed outline. The first slot 311 on the first slot area 31 can also be a shape without a closed outline. For example, the first slot 311 on the first slot area 31 extends to the edge of the first slot area 31 in a direction away from the first non-slot area 32. Figure 7 This is a schematic diagram of the first buffer layer in some optional embodiments of the present invention, such as... Figure 7As shown, the first slot 311 on the first slot area 31 extends to the edge of the first slot area 31 in a direction away from the first non-slot area 32. Each first slot 311 is an open rectangular opening, and nine first slots 311 are spaced apart along the second direction on the first slot area 31. When the first buffer layer 30 with open rectangular openings 311 is laid on the back of the battery cell 10, the nine open rectangular openings spaced apart along the second direction on the first slot area 31 expose the nine welding portions 12 spaced apart along the second direction on the back edge of the battery cell 10. In this embodiment, the first buffer layer 30 has a comb-like structure. In practical application, the first buffer layer 30 with the comb-like structure can be laid on the back of the battery cell 10 first, and then the busbar 20 can be placed on the first buffer layer 30. Because the first buffer layer 30 has a comb-like structure, it is easy to avoid the welding part at the corresponding position during laying, which is convenient for laying. In practical application, the busbar 20, which is connected to the front welding strip 12 and bent to the back of the battery cell 10, can also be lifted at a certain angle, and then the first buffer layer 30 with the comb-like structure can be inserted between the battery cell 10 and the busbar 20. The operation is simple. It can be seen that by setting the first slot as an open opening, the first buffer layer 30 can avoid the welding part 12 at the corresponding position during the laying process, which can improve the laying efficiency of the first buffer layer 30. It should be noted that, although Figure 7 The first slot 311 shown is an open rectangular opening, but this is only an example. Those skilled in the art can also set other shapes of open openings, such as open arc-shaped openings, open polygonal openings, etc.

[0055] When the first buffer layer 30 has a slotted structure, the width of the first buffer layer 30 can be greater than the width of the busbar 20, and may even be greater than the distance between the two welded portions 12 on both sides of the busbar 20 along the first direction. For example, the first buffer layer 30 spans one or more welded portions 12 along the first direction. Figure 8 In the optional embodiment shown, the first buffer layer 30 spans a weld portion 12 along the first direction. In an optional embodiment of the invention, the width of the first non-groove area 32 is greater than the width of the first groove area 31, thus preventing the busbar 20 from contacting the weld portion on the back of the battery cell 10, thereby avoiding the risk of a short circuit. The width of the first groove area 31 along the first direction is greater than the width of the busbar 20 along the first direction, and the distance between the busbar 20 and the first groove area 31 along the first direction can be selectively set. Figure 8In the optional embodiment shown, L6 represents the distance between the busbar 20 and the first slot area 31 along the first direction. For example, the distance L6 between the busbar 20 and the first slot area 31 along the first direction is greater than or equal to 1 mm; for example, the distance L6 between the end busbar 21 and the first slot area 31 along the first direction can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, etc. By setting the distance L6 between the busbar 20 and the first slot area 31 along the first direction to be greater than or equal to 1 mm, the precision requirements for the placement of the busbar 20 and the battery cell 10 can be reduced, the difficulty of laying the busbar 20 and the first buffer layer 30 can be reduced, and the risk of short circuit due to contact between the busbar 20 and the back solder strip 11 on the back of the battery cell 10 can be avoided.

[0056] In some embodiments, the busbar 20 can be connected to the back solder strip 11 of the battery cell 10. In this case, the busbar 20 can abut against the back of the battery cell 10. That is, no buffer layer with a buffering effect is provided between the busbar 20 and the back of the battery cell 10. This can reduce the thickness of the battery cell at the location of the busbar 20 and avoid the busbar 20 applying concentrated stress to the battery cell 10 due to excessive thickness at the location of the busbar 20, thereby mitigating or avoiding microcracks or breakage of the battery cell 10.

[0057] In some alternative embodiments of the present invention, the battery assembly further includes an insulating second buffer layer 40, which is at least partially located below the busbar 20, and the projection area of ​​the second buffer layer 40 along the thickness direction may cover part or all of the projection area of ​​the intermediate busbar 22 along the thickness direction.

[0058] In this embodiment of the invention, the dimension of the second buffer layer 40 along the first direction is referred to as the width of the second buffer layer 40, and the dimension of the second buffer layer 40 along the second direction is referred to as the length of the second buffer layer 40. In this embodiment of the invention, the length of the second buffer layer 40 may be less than, equal to, or greater than the length of the busbar 20, and the width of the second buffer layer 40 may be less than, equal to, or greater than the width of the busbar 20. In an optional embodiment of the invention, the projected area of ​​the second buffer layer 40 along the thickness direction may cover the projected area of ​​the busbar 20 along the thickness direction, the length of the second buffer layer 40 is greater than or equal to the length of the busbar 20, and the width of the second buffer layer 40 is greater than or equal to the width of the busbar 20. If the busbar 20 abuts against the back of the battery cell 10, the busbar 20 is directly welded to the back solder strip 11 on the back of the battery cell 10. There is no buffer layer between the busbar 20 and the back solder strip 11 to cushion the pressure. The pressure exerted by the back solder strip 11 on the battery cell 10 is linear, making it more prone to microcracks or breakage due to the pressure from the back solder strip 11. This embodiment, by placing the second buffer layer at least partially below the busbar 20, transforms the pressure from the back solder strip 11 on the battery cell 10 from linear pressure to surface pressure. This increases the stress area, making it less prone to microcracks during lamination or high / low temperature cycling.

[0059] The thickness of the second buffer layer 40 refers to its dimension along the thickness direction. The thickness of the second buffer layer 40 can be selectively set according to actual conditions. For example, the thickness of the second buffer layer 40 is 0.05-0.15 mm, such as 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm, 0.15 mm, etc. By making the second buffer layer 40 have a larger thickness, the buffering effect of the second buffer layer 40 on the battery cell 10 can be increased, further mitigating or avoiding the risk of microcracks or breakage of the battery cell 10. By making the second buffer layer 40 have a smaller thickness, the thickness at the corresponding position of the battery cell 10 can be reduced, thereby reducing the concentrated stress at the edge of the battery cell 10 and mitigating or avoiding the risk of microcracks or breakage of the battery cell 10.

[0060] The back solder strip 11 of the battery cell 10 includes a first portion connecting two solder portions 12 located on both sides of the busbar 20 along a first direction, and a second portion other than the first portion. The first portion is connected to the busbar 20. The second buffer layer 40 can be any elongated strip structure extending along a second direction, such as a rectangular structure (not shown in the figure) extending along the second direction, a rectangular structure with chamfers, or an elliptical structure. In this case, the second buffer layer 40 can be disposed between the back side of the battery cell 10 and the busbar 20, and located between two adjacent solder portions 12 on the back side of the battery cell 10. For example, the second buffer layer 40 is rectangular, and the width of the second buffer layer 40 is less than the distance between the two solder portions 12 located on both sides of the busbar 20 along the first direction, but greater than the width of the busbar 20 along the first direction. The second buffer layer 40 is located below the first portion of the back solder strip 11. This solution is applicable to the case where the first main grid 13 is disconnected at the busbar 20. Since there is no first main grid 13 here, the first part of the back solder strip 11 is not fixed to the battery cell 10. The first part can be slightly lifted to form a gap between the first part and the battery cell, and then the rectangular second buffer layer 40 can be inserted from the end along the second direction between the first part and the battery cell 10.

[0061] The second buffer layer 40 can also be a structure with slots. Figure 9 This is a schematic diagram of the second buffer layer in some optional embodiments of the present invention, such as... Figure 9 As shown, the second buffer layer 40 includes: a second non-slotted area 42 and a second slotted area 41 disposed along a second direction, the second slotted area 41 being located on one side of the second non-slotted area 42 along a first direction; a plurality of second slots 411 are disposed at intervals along the second direction on the second slotted area 41 and a second tongue piece 412 located between two adjacent second slots 411, the second slots 411 extending to the edge of the second slotted area 41 along a direction away from the second non-slotted area 42, the second non-slotted area 42 being located above the second part of the back solder strip 11, the second slots 411 avoiding the first part of the back solder strip 11 and the welding part 12 connected to the first part of the back solder strip 11, and the second tongue piece 412 being inserted between the busbar 20 and the battery cell 10 along the first direction. Figure 10 This is a schematic diagram of the back of the battery cell in some alternative embodiments of the present invention, such as... Figure 10 As shown, the second slot area 41 and the second non-slot area 42 are distributed along the first direction X, and the second slot area 41 and the second non-slot area 42 extend along the second direction Y, respectively. Each second slot 411 can correspond to a welding part 12 on a back solder strip 11, that is, each second slot 411 only exposes one welding part 12 on a back solder strip 11 at its corresponding position, such as... Figure 10As shown. Each second slot 411 can also correspond to multiple welded portions 12 on a back solder strip 11. For example, each second slot 411 exposes two or more welded portions 12 on a back solder strip 11 at its corresponding position. Each second slot 411 can also correspond to multiple welded portions 12 on two or more back solder strips 11, wherein one or more welded portions 12 on each back solder strip 11 can be exposed. Furthermore, all welded portions 12 in the projection area of ​​the second buffer layer 40 can be exposed by setting the second slot 411, or only some welded portions 12 in the projection area of ​​the second buffer layer 40 can be exposed, while welded portions 12 at other positions are not exposed. Thus, in this embodiment of the invention, the number of second slots 411 spaced apart along the second direction on the second slot area 41 can be selectively set according to actual conditions. Figure 9 In the optional embodiment shown, nine second slots 411 are spaced apart along a second direction on the second slot area 41. Figure 10 In the optional embodiment shown, nine second slots 411 spaced apart along the second direction on the second slot area 41 expose nine weld portions 12 spaced apart along the second direction on the back edge of the battery cell 10. By exposing the weld portions 12 at corresponding positions using the second slots 411 in the second slot area 41 of the second buffer layer 40, the weld portions 12 located in the projection area of ​​the busbar 20 along the thickness direction and the back weld strip 11 above the weld portions 12 can be exposed in the second slots 411 of the second buffer layer 40. That is, the second buffer layer 40 will not apply pressure to the weld portions 12 on the back edge of the battery cell 10, thereby mitigating or avoiding the risk of microcracks or breakage of the battery cell 10 due to concentrated stress at the weld portions 12 on the back edge of the battery cell 10.

[0062] The second slot tongue 412 between two adjacent second slots 411 on the second slot area 41 is located between the busbar 20 and the battery cell 10. The second slot 411 between two adjacent second slot tongues 412 corresponds to the back solder strip 11. The second non-slot area 42 is located outside the busbar area. Figure 9 This is a schematic diagram of the second buffer layer in some optional embodiments of the present invention, such as... Figure 9 As shown, the second slots 411 on the second slot area 41 extend to the edge of the second slot area 41 in a direction away from the second non-slot area 42. Each second slot 411 is an open rectangular opening, and nine second slots 411 are spaced apart along the second direction on the second slot area 41. When the second buffer layer 40 with open rectangular openings 411 is laid on the back of the battery cell 10, the nine open rectangular openings spaced apart along the second direction on the second slot area 41 expose the nine welding portions 12 spaced apart along the second direction on the back edge of the battery cell 10, as shown. Figure 10As shown. In this embodiment, the second buffer layer 40 has a comb-like structure. In actual application, the second buffer layer 40 with the comb-like structure can be laid on the back of the battery cell 10 first, and then the busbar 20 can be placed on the second buffer layer 40. Since the second buffer layer 40 has a comb-like structure, it is easy to avoid the welding part at the corresponding position during laying, which is convenient for laying. In actual application, the busbar 20 can also be opened at a certain angle, and the second tongue piece 412 of the second slot area 41 of the second buffer layer 40 with the comb-like structure can be inserted between the battery cell 10 and the busbar 20 along the first direction. The second slot 411 of the second slot area 41 corresponds to the first part of the back welding strip 11 and the welding part 12 connected to the first part to avoid the first part and the welding part 12 connected to the first part. The operation is simple. It can be seen that by setting the second slot as an open opening, the second buffer layer 40 can avoid the welding part 12 at the corresponding position during the laying process, which can improve the laying efficiency of the second buffer layer 40. It should be noted that, although Figure 9 The second slot 411 shown is an open rectangular opening, but this is only an example. Those skilled in the art can also set other shapes of open openings, such as open arc-shaped openings, open polygonal openings, etc.

[0063] When the second buffer layer 40 has a slotted structure, the second non-slotted area 42 of the second buffer layer 40 is located in the non-confluence region 102. Therefore, the overall width of the second buffer layer 40 can be greater than the width of the busbar 20, and even greater than the distance between the two welded portions 12 on both sides of the busbar 20 along the first direction. For example, the second buffer layer 40 spans one or more welded portions 12 along the first direction. Figure 10In the optional embodiment shown, the second buffer layer 40 spans a weld portion 12 along the first direction. In an optional embodiment of the invention, there is no contact between any position on the second buffer layer 40 and the weld portion 12 adjacent to that position; that is, the distance between any position on the second buffer layer 40 and the weld portion 12 adjacent to that position is greater than 0. The distance between any position on the second buffer layer 40 and the weld portion 12 adjacent to that position can be selectively set, as long as it does not affect the welding of the weld portion 12 and the back solder strip 11. For example, the distance between any position on the second buffer layer 40 and the weld portion 12 adjacent to that position is greater than or equal to 1 mm, such as 1 mm, 1.5 mm, 2.0 mm, 2.5 mm, etc. By ensuring that any position on the second buffer layer 40 does not abut against the adjacent weld portion 12, the thickness of the corresponding position of the battery cell can be prevented from increasing due to the second buffer layer 40 covering the weld portion 12, thus mitigating or avoiding the risk of microcracks or breakage of the battery cell 10. By ensuring that the distance between any position on the second buffer layer 40 and the adjacent weld portion 12 is greater than or equal to 1 mm, the precision requirements for the placement of the busbar 20 and the battery cell 10 can be reduced, the difficulty of laying the busbar 20 and the second buffer layer 40 can be reduced, and the thickness of the corresponding position of the battery cell 10 can be avoided due to the second buffer layer 40 covering the weld portion 12.

[0064] In this embodiment of the invention, the end welding portion 121 near the back edge of the battery cell 10 is at a certain distance from the back edge of the battery cell 10; that is, no welding portion 12 is provided on the back edge of the battery cell 10. Figure 4In the optional embodiment shown, L7 represents the distance along the first direction between the end weld portion 121 near the back edge of the battery cell 10 and the back edge of the battery cell 10. The distance L7 can be selectively set according to actual conditions. For example, the distance L7 along the first direction between the end weld portion 121 near the back edge of the battery cell 10 and the back edge of the battery cell 10 is 3-10 mm, such as 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc. If there is residual plating on the back edge of the battery cell 10, and the distance L7 between the end weld portion 121 and the back edge of the battery cell 10 is too small, the end weld portion 121 can easily contact the plating passivation area of ​​the battery cell 10, making it easy to be removed during the plating removal process, affecting the welding stability of the back solder strip 11 and the power generation performance of the battery cell. In this embodiment of the invention, by setting the distance L7 between the end welding portion 121 near the back edge of the battery cell 10 and the back edge of the battery cell 10 along the first direction to 3-10 mm, the above-mentioned situation can be avoided on the one hand, and the breakage can be prevented when connecting the next battery cell with the welding strip on the other hand.

[0065] It should be noted that the various solder strips mentioned in the embodiments of the present invention, such as front solder strips and back solder strips, can be selected in terms of shape and material according to actual conditions. The embodiments of the present invention do not specifically limit the shape and material of the solder strips. In some optional embodiments, the cross-sectional shape of the solder strip can be circular, elliptical, rectangular, trapezoidal or other polygonal shapes. The cross-section of the solder strip mentioned here refers to the outline of the solder strip obtained by cutting the solder strip along a direction perpendicular to the extension direction of the solder strip. For example, when the cross-sectional shape of the welding strip is circular, the diameter of the welding strip is 0.1-0.26 mm, such as 0.10 mm, 0.15 mm, 0.20 mm, 0.23 mm, 0.26 mm, etc.; when the cross-sectional shape of the welding strip is rectangular or trapezoidal, the length of the longer of the two parallel sides of the cross-section of the welding strip is called the width of the welding strip, and the distance between the two parallel sides is called the thickness of the welding strip. Then the width of the welding strip is 0.1-0.5 mm, such as 0.10 mm, 0.20 mm, 0.30 mm, 0.40 mm, 0.50 mm, etc., and the thickness of the welding strip is 0.1-0.3 mm, such as 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, etc.

[0066] This invention, by placing the busbar between two adjacent welded portions along a first direction on the back of the solar cell, avoids the welded portions on the back of the cell when the busbar is placed. This reduces the thickness of the solar cell at the welded portion location. Furthermore, during lamination and high / low temperature cycling, since there is no welded portion below the busbar, even if the encapsulant or the busbar deforms due to thermal expansion and contraction, the busbar will not exert concentrated stress on the solar cell through the welded portion. Therefore, this invention can mitigate or avoid microcracks or cell breakage in photovoltaic modules and is applicable to photovoltaic modules that use thicker welded portions and busbars to improve current collection capacity. Since the pattern changes of the solar cell only occur on both sides of the cell string and on the cells where the busbar is welded to the solder strip, and not on other cells, only the identification and movement of irregularly shaped cells for the front and rear cells and cells where the busbar is directly welded to the solder strip needs to be added to the string welding machine. No new machine is required, making the modification convenient and simple, and applicable to the production and use of photovoltaic modules.

[0067] According to a second aspect of the present invention, a photovoltaic module is provided, the photovoltaic module including the battery module provided in the first aspect of the present invention. Specifically, the photovoltaic module according to the present invention includes at least a front cover plate, a front encapsulant film, a battery module, a back encapsulant film, and a back cover plate stacked sequentially.

[0068] The front cover can be made of glass with high light transmittance, such as low-iron tempered patterned glass. The front cover can be conventional flat glass, and its shape is not limited in this embodiment; it can be square, round, or other shapes, as long as it achieves the purpose of this embodiment. Alternatively, the front cover can be irregularly shaped glass, such as curved glass. This embodiment does not limit the curvature angle of the curved glass; it can be set according to actual conditions, such as 5°, 10°, 15°, 20°, or other degrees. The thickness of the front cover can be set according to actual conditions, ranging from 1.6-3.2mm. For example, the thickness of the front cover can be 1.6mm, 2.7mm, 3mm, 3.1mm, or 3.2mm; this embodiment does not specifically limit this. The material and shape of the back cover can be the same as or different from the front cover.

[0069] The front adhesive film is located on the front of the cell string in the solar module, and the back adhesive film is located on the back of the cell string. By applying front and back adhesive films to the front and back of the cell string respectively, the corrosion of environmental factors such as moisture and oxygen can be effectively prevented, thus preventing the external environment from affecting the performance of the solar module, improving the reliability of the photovoltaic module and extending its service life. In addition, the front and back adhesive films can also bond the front cover plate, the cell module, and the back cover plate together, providing a certain degree of adhesive strength. The thickness of the front adhesive film and / or the back adhesive film can range from 0.3 to 0.5 mm; specifically, the thickness of the front adhesive film and / or the back adhesive film can be 0.3 mm, 0.4 mm, 0.45 mm, or 0.5 mm.

[0070] The areas of the front and / or back adhesive films can be set according to actual conditions. In this embodiment of the invention, the area of ​​the front adhesive film refers to its projected area along the thickness direction; the area of ​​the back adhesive film refers to its projected area along the thickness direction. For example, the projected areas of the front and / or back adhesive films are the same as the projected areas of the battery strings in the battery assembly, and the projections of the front and / or back adhesive films along the thickness direction coincide with the projections of the battery strings along the thickness direction in the battery assembly, so that the front and / or back adhesive films exactly cover the battery strings in the battery assembly. For example, the projected area of ​​the front and / or back films is slightly larger than the area of ​​the cell string, and the projected area of ​​the front and / or back films along the thickness direction is slightly larger than the projected area of ​​the cell string along the thickness direction. Thus, even when the cell string is completely covered, some of the film extends beyond the cell string, meaning the edges of the front and / or back films extend beyond the edges of the cell string they cover. This overhang design ensures that the film at least covers the first end of the front solder strip connected to the cell. After covering the film, it can be heated to increase its adhesion, thereby using the film to fix the first end of the front solder strip to the second main grid on the front of the cell, preventing the first end of the front solder strip from shifting or deforming relative to the cell, which helps improve the reliability of the photovoltaic module.

[0071] The front and / or back adhesive films can be made of ethylene-vinyl acetate copolymer (EVA film), polyvinyl octene copolymer elastomer (POE film), or polyvinyl butyral (PVB film). Among these, ethylene-vinyl acetate copolymer (EVA film) offers advantages such as excellent adhesion, low melting temperature, good melt flow and flexibility, low cost, and ease of application. The introduction of vinyl acetate monomers into the EVA molecular chain reduces high crystallinity, improving toughness, impact resistance, filler compatibility, and heat-sealing performance. The molecular structure of polyvinyl octene copolymer elastomer (POE film) gives it excellent mechanical properties, rheological properties, and UV resistance, as well as good affinity with polyolefins, good low-temperature toughness, and a high performance-to-price ratio. Polyvinyl butyral (PVB film) offers high transparency, cold resistance, impact resistance, and UV radiation resistance, and exhibits good adhesion to metals, glass, wood, ceramics, and fiber products. The front and / or back films can also be EP encapsulation films or EPE encapsulation films. Among them, the EP encapsulation film is an EVA / POE laminated film, which is made by co-extrusion blown film of EVA resin and POE resin. It solves problems such as slippage and additive precipitation, while effectively improving the resistance to humid heat aging of the encapsulation film, and has a wider range of lamination process applications and high encapsulation yield. The EPE encapsulation film is an EVA / POE / EVA laminated film, which is formed by co-extrusion encapsulation of three layers of EVA-POE-EVA. The EPE encapsulation film is manufactured by extruding EVA and POE resin through a co-extrusion process, which combines the good processing performance of EVA with the good anti-PID (Potential Induced Degradation) performance and moisture resistance of POE.

[0072] This invention modifies the back metal coating of the solar cell by placing the busbar between two adjacent welded portions along the first direction on the back of the cell. This allows the busbar to avoid the welded portions on the back of the cell, reducing the cell thickness at the welded portion location. Furthermore, during lamination and high / low temperature cycling, the absence of a welded portion beneath the busbar prevents material deformation due to thermal expansion and contraction, thus avoiding concentrated stress on the cell through the welded portion. Therefore, this invention can mitigate or avoid microcracks or cell breakage in photovoltaic modules and is applicable to photovoltaic modules using thicker welded portions and busbars to improve current collection capacity. Since the cell pattern changes only occur on both sides of the cell string and on cells where the busbar is welded to the strip, and not on other cells, only the identification and movement of irregularly shaped cells (front and rear cells, and cells directly welded to the strip) need to be added to the string welding machine. No new machine is required, making the modification simple and convenient, and suitable for the production and use of photovoltaic modules.

[0073] In summary, the present invention provides the following technical solution: Technical solution 1. A battery assembly, comprising: a battery string and a busbar 20; The battery string includes a plurality of battery cells 10 arranged along a first direction; Multiple welding portions 12 are spaced apart on the back side of the battery cell 10, and multiple back welding strips 11 are disposed on the back side of the battery cell 10 along a first direction, with each back welding strip 11 connecting to the multiple welding portions 12 spaced apart along the first direction. The busbar 20 is disposed on the back side of the battery cell 10 along a second direction intersecting the first direction, and is located between two adjacent welded portions 12 along the first direction.

[0074] Technical Solution 2. According to the battery assembly of Technical Solution 1, the back side of the battery cell 10 has a plurality of first main grids 13 arranged along a first direction and a plurality of first fine grids 14 arranged along a second direction; each first main grid 13 corresponds to a plurality of welding portions 12 spaced apart along the first direction. Each first main grid has a discontinuity, the two ends of which correspond to two welded portions 12 on both sides of the busbar 20 along the first direction, and the busbar 20 is disposed at the discontinuity.

[0075] Technical Solution 3. According to the battery assembly of Technical Solution 2, the back side of the battery cell 10 has a plurality of bridging grid lines connecting two welded portions 12 on both sides of the busbar 20 along a first direction.

[0076] Technical Solution 4. According to the battery assembly of Technical Solution 3, the thickness of the bridging grid line is less than the thickness of the first main grid, the width of the bridging grid line is less than or equal to the width of the first main grid, the thickness of the first fine grid 14 is less than or equal to the thickness of the bridging grid line, and the width of the first fine grid 14 is less than or equal to the width of the bridging grid line.

[0077] Technical Solution 5. According to any one of the technical solutions 2-4, the back side of the battery cell 10 includes a current-collecting region 101 and a non-current-collecting region 102; the density of the first fine grid 14 in the current-collecting region 101 is greater than the density of the first fine grid 14 in the non-current-collecting region 102. The current-carrying area 101 refers to the area on the back of the battery cell 10 where the current-carrying strip 20 is located, and the non-current-carrying area 102 refers to the area on the back of the battery cell 10 other than the current-carrying area 101.

[0078] Technical Solution 6. According to the battery assembly of any one of Technical Solutions 3-5, each bridging grid line includes: A transverse fine grid 15 is provided along a first direction; along the first direction, the transverse fine grid 15 is located between two welding portions 12 on both sides of the busbar along the first direction, and along the second direction, the transverse fine grid 15 is not collinear with the welding portion 12 at the corresponding position; The first inclined fine grid 16 is respectively disposed at both ends of the transverse fine grid 15 and connects the transverse fine grid 15 and the two welding parts 12 located on both sides of the busbar 20 along the first direction; Technical Solution 7. According to the battery assembly of Technical Solution 6, the angle between the first inclined fine grid 16 and the first direction is 5-60°.

[0079] Technical Solution 8. According to any one of the technical solutions 2-4, the battery assembly has a plurality of second fine grids 17 on the back side of the battery cell 10, and the end weld portion 121 located at the edge of the plurality of weld portions 12 spaced apart along the first direction is connected to a plurality of first fine grids 14 located outside the end weld portion 121. The outside of the end weld portion 121 refers to the side of the end weld portion 121 away from the other weld portions spaced apart along the first direction.

[0080] Technical Solution 9. According to the battery assembly of Technical Solution 8, the shape of the second fine grid 17 is a broken line or an oblique line that is not parallel to the first direction.

[0081] Technical Solution 10. According to the battery assembly of Technical Solution 8, the distance between the end weld portion 121 and the edge of the battery cell 10 along the first direction is 3-10mm.

[0082] Technical Solution 11. The battery assembly according to any one of the technical solutions of claims 1-10, wherein the front side of the battery cell 10 has a plurality of second main grids arranged along a first direction, the first end of the front solder strip 18 is connected to the second main grids, and the second end is folded to the back side of the battery cell 10 and connected to the busbar 20.

[0083] Technical Solution 12. According to the battery assembly of Technical Solution 11, the battery assembly further includes an insulating first buffer layer 30, the first buffer layer 30 being located below the busbar 20 and the front solder strip 18 folded to the back of the battery cell 10.

[0084] Technical Solution 13. According to the battery assembly of Technical Solution 12, the first buffer layer 30 includes: a first non-groove area 32 and a first groove area 31 disposed along a second direction, wherein the first groove area 31 is located on one or both sides of the first non-groove area 32 along the first direction. The first non-groove area 32 corresponds to the busbar 20; the first groove area 31 corresponds at least to the welding portions 12 located on both sides of the busbar 20 along the first direction, and a plurality of first grooves 311 are provided corresponding one-to-one with the welding portions 12 to expose the welding portions 12 at the corresponding positions. Technical Solution 14. According to any one of the technical solutions 11-13, the second end of the front welding strip 18 folded to the back of the battery cell 10 is staggered with the back welding strip 11 and avoids the welding part 12 exposed by the first slot 311.

[0085] Technical Solution 15. According to any one of the technical solutions 1-14, the battery assembly on the back of the battery cell 10 includes a first portion connecting two welding portions 12 located on both sides of the busbar 20 along a first direction, and a second portion other than the first portion. The first portion is connected to the busbar 20, wherein: The busbar 20 abuts against the back of the battery cell 10, or the battery assembly further includes an insulating second buffer layer 40, which is at least partially located below the busbar 20; Technical Solution 16. According to the battery assembly in Technical Solution 15, the thickness of the second buffer layer 40 is 0.05-0.15mm.

[0086] Technical Solution 17. The battery assembly according to Technical Solution 15 or Technical Solution 16, The second buffer layer 40 is rectangular. The width of the second buffer layer 40 is less than the distance between the two welded portions 12 located on both sides of the busbar 20 along the first direction, and greater than the width of the busbar 20 along the first direction. The second buffer layer 40 is located below the first portion. or, The second buffer 40 includes: a second non-groove area 42 and a second groove area 41 disposed along a second direction, wherein the second groove area 41 is located on one side of the second non-groove area 42 along the first direction; The second slot area 41 is provided with a plurality of second slots 411 spaced apart along the second direction and a second slot tongue 412 located between two adjacent second slots 411. The second slots 411 extend to the edge of the second slot area 41 along a direction away from the second non-slot area 42. The second non-slot area 42 is located above the second part. The second slots 411 avoid the first part and the welding part 12 connected to the first part. The second slot tongue 412 is inserted between the busbar 20 and the battery cell 10 along the first direction. Technical Solution 18. According to the battery assembly of Technical Solution 17, the distance between any position on the second buffer layer 40 and the welded portion 12 adjacent to that position is greater than or equal to 1 mm.

[0087] Technical Solution 19. A photovoltaic module, comprising a battery module provided by any one of the technical solutions 1-18.

[0088] In this embodiment of the invention, by modifying the back metal coating of the solar cell and placing the busbar between two adjacent welded portions along the first direction on the back of the solar cell, the busbar can avoid the welded portions on the back of the solar cell when placed. This reduces the thickness of the solar cell at the welded portion location. Furthermore, during lamination and high / low temperature cycling, since there is no welded portion below the busbar, even if the encapsulant or busbar deforms due to thermal expansion and contraction, the busbar will not exert concentrated stress on the solar cell through the welded portion. Therefore, this embodiment of the invention can mitigate or avoid microcracks or cell breakage in photovoltaic modules and is applicable to photovoltaic modules that use thicker welded portions and busbars to improve current collection capacity. Since the pattern changes of the solar cell only occur on both sides of the cell string and on the solar cells where the busbar is welded to the solder strip, and not on other solar cells, only the identification and movement of irregularly shaped solar cells and those directly welded to the solder strip need to be added to the string welding machine. No new machine is required, making the modification convenient and simple, and applicable to the production and use of photovoltaic modules.

[0089] The above steps are provided only to help understand the method, structure, and core ideas of this invention. Those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A battery assembly, characterized in that, include: Battery string and busbar (20); The battery string includes a plurality of battery cells (10) arranged along a first direction; The back of the battery cell (10) is provided with a plurality of welding portions (12) spaced apart, and a plurality of back welding strips (11) are provided on the back of the battery cell (10) along the first direction, and each of the back welding strips (11) connects to the plurality of welding portions (12) spaced apart along the first direction. The busbar (20) is disposed on the back side of the battery cell (10) along a second direction intersecting the first direction, and is located between two adjacent welded portions (12) along the first direction.

2. The battery assembly according to claim 1, characterized in that, The back of the battery cell (10) has multiple first main grids (13) arranged along the first direction and multiple first fine grids (14) arranged along the second direction; each first main grid (13) corresponds to a plurality of welding portions (12) arranged at intervals along the first direction. Each of the first main grids has a discontinuity, the two ends of the discontinuity corresponding to the two welded portions (12) on both sides of the busbar (20) along the first direction, and the busbar (20) is disposed at the discontinuity; Optionally, the back of the battery cell (10) has multiple bridging grid lines connecting the two welding portions (12) on both sides of the busbar (20) along the first direction; Optionally, the thickness of the bridging grid line is less than the thickness of the first main grid, and the width of the bridging grid line is less than or equal to the width of the first main grid; the thickness of the first fine grid (14) is less than or equal to the thickness of the bridging grid line, and the width of the first fine grid (14) is less than or equal to the width of the bridging grid line.

3. The battery assembly according to claim 2, characterized in that, The back side of the battery cell (10) includes a current-collecting region (101) and a non-current-collecting region (102); the density of the first fine grid (14) in the current-collecting region (101) is greater than the density of the first fine grid (14) in the non-current-collecting region (102); The current-carrying area (101) refers to the area on the back of the battery cell (10) where the current-carrying strip (20) is located, and the non-current-carrying area (102) refers to the area on the back of the battery cell (10) other than the current-carrying area (101).

4. The battery assembly according to claim 2, characterized in that, Each of the aforementioned bridging wires includes: A transverse fine grid (15) is provided along the first direction; along the first direction, the transverse fine grid (15) is located between the two welded portions (12) on both sides of the busbar along the first direction, and along the second direction, the transverse fine grid (15) and the welded portion (12) at the corresponding position are not collinear 101; Two first inclined fine grids (16) are respectively disposed at both ends of the transverse fine grid (15) and connect the transverse fine grid (15) and the two welded portions (12) located on both sides of the busbar (20) along the first direction. Optionally, the angle between the first inclined fine grid (16) and the first direction is 5-60°.

5. The battery assembly according to claim 2, characterized in that, The back of the battery cell (10) has multiple second fine grids (17), and the end weld (121) located at the edge of the multiple weld portions (12) spaced apart along the first direction is connected to multiple first fine grids (14) located outside the end weld (121). The outside of the end weld (121) refers to the side of the end weld (121) away from the other weld portions spaced apart along the first direction. Optionally, the shape of the second fine grid (17) is a broken line or a diagonal line that is not parallel to the first direction; Optionally, the distance between the end weld (121) and the edge of the battery cell (10) along the first direction is 3-10 mm.

6. The battery assembly according to any one of claims 1-5, characterized in that, The front side of the battery cell (10) has multiple second main grids arranged along the first direction. The first end of the front solder strip (18) is connected to the second main grid, and the second end is folded to the back side of the battery cell (10) and connected to the busbar (20).

7. The battery assembly according to claim 6, characterized in that, The battery assembly also includes an insulating first buffer layer (30) located below the busbar (20) and the front solder strip (18) folded to the back of the battery cell (10). Optionally, the first buffer layer (30) includes a first non-groove area (32) and a first groove area (31) disposed along the second direction, wherein the first groove area (31) is located on one or both sides of the first non-groove area (32) along the first direction. The first non-groove area (32) corresponds to the busbar (20); the first groove area (31) corresponds at least to the welded portions (12) located on both sides of the busbar (20) along the first direction, and a plurality of first grooves (311) are provided corresponding to the welded portions (12) to expose the welded portions (12) at the corresponding positions. Optionally, the second end of the front solder strip (18) folded to the back of the battery cell (10) is staggered with the back solder strip (11) and avoids the weld portion (12) exposed by the first slot (311).

8. The battery assembly according to claims 1-5, characterized in that, The back solder strip (11) of the battery cell (10) includes a first portion connecting two solder portions (12) located on both sides of the busbar (20) along the first direction, and a second portion other than the first portion. The first portion is connected to the busbar (20), wherein: The busbar (20) abuts against the back of the battery cell (10), or the battery assembly further includes a second buffer layer (40) with insulation, the second buffer layer being at least partially located below the busbar (20); Optionally, the thickness of the second buffer layer (40) is 0.05-0.15 mm.

9. The battery assembly according to claim 8, characterized in that, The second buffer layer (40) is rectangular. The width of the second buffer layer (40) is less than the distance between the two welded portions (12) on both sides of the busbar (20) along the first direction and greater than the width of the busbar (20) along the first direction. The second buffer layer (40) is located below the first part. or, The second buffer (40) includes: a second non-groove area (42) and a second groove area (41) disposed along the second direction, wherein the second groove area (41) is located on one side of the second non-groove area (42) along the first direction; The second slot area (41) is provided with a plurality of second slots (411) spaced apart along the second direction and a second tongue piece (412) located between two adjacent second slots (411). The second slots (411) extend to the edge of the second slot area (41) in a direction away from the second non-slot area (42). The second non-slot area (42) is located above the second part. The second slots (411) avoid the first part and the welding part (12) connected to the first part. The second tongue piece (412) is inserted between the busbar (20) and the battery cell (10) along the first direction. Optionally, the distance between any position on the second buffer layer (40) and the weld (12) adjacent to the arbitrary position is greater than or equal to 1 mm.

10. A photovoltaic module comprising the battery module according to any one of claims 1-9.

Images