A back contact cell assembly and photovoltaic system

Abstract

This invention relates to the field of solar cell technology, specifically disclosing a back-contact solar cell module and photovoltaic system. The module includes a first cell string electrically connected to a first busbar, a second cell string connected to a second busbar, a first solder strip welded to the first busbar that is closest to the first lead bend of the first busbar and also closest to the first edge of the first cell string, a second solder strip welded to the second busbar that is closest to the second lead bend of the second busbar, and a third solder strip that is closest to the second edge of the second cell string and also closest to the second solder strip. The first lead bend and the second lead bend are symmetrical about a first reference line. The distance between the first reference line and the first solder strip is d1, and the distance between the first reference line and the third solder strip is d2, where d1 > d2. This back-contact solar cell module improves the reliability of the connection between the busbar and the solder strip.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a back-contact battery module and photovoltaic system. Background Technology

[0002] A photovoltaic module includes multiple cell strings, each cell string including multiple cells connected in series. The multiple cell strings are connected to a central busbar by solder strips. The current flowing through the grid lines of the cells is led out to the outside of the photovoltaic module by the lead wires connected to the end of the central busbar.

[0003] Due to space constraints, the cell layout of existing photovoltaic modules has resulted in some solder strips on the intermediate busbars being too close to the lead wires, which can easily lead to poor soldering between the solder strips and the intermediate busbars, affecting the reliability of the photovoltaic modules. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a back contact battery assembly that improves the reliability of the connection between the busbar and the solder strip.

[0005] To solve the above technical problems, the present invention provides a back contact battery assembly, including a battery string, the battery string including battery cells arranged along a first direction, and solder strips arranged on the battery cells along a second direction, wherein the first direction and the second direction are intersected.

[0006] At least two of the battery strings are arranged along the second direction and connected in series to form a series battery string group;

[0007] At least two of the battery strings are arranged along a first direction and connected in parallel to each other to form a parallel battery string group;

[0008] The series battery string group includes an adjacent first battery string and a second battery string. The first battery string is electrically connected to a first busbar, and the second battery string is connected to a second busbar. The first busbar is bent at the first lead bend, and the second busbar is bent at the second lead bend.

[0009] Along the second direction, the edge of the first battery string near the bend of the first lead is the first edge, the edge of the second battery string near the bend of the second lead is the second edge, the solder strip closest to the bend of the first lead among the multiple solder strips welded to the first busbar is the first solder strip, the first solder strip is the solder strip closest to the first edge in the first battery string, the solder strip closest to the bend of the second lead among the multiple solder strips welded to the second busbar is the second solder strip, the solder strip closest to the second edge in the second battery string is the third solder strip, and the second solder strip is the solder strip closest to the third solder strip;

[0010] The first lead bend and the second lead bend are symmetrical about the first reference line. The first reference line extends in the first direction. The distance between the first reference line and the first solder strip is d1, and the distance between the first reference line and the third solder strip is d2, where d1 > d2.

[0011] The back contact battery assembly includes a first component edge and a second component edge disposed along a second direction, with the first battery string located at the first component edge;

[0012] Both the first battery string and the second battery string are connected to the edge bus bar, and the length of the second bus bar is greater than or equal to the length of the edge bus bar.

[0013] As an improvement to the above scheme, the distance between the first battery string and the second battery string is d3, and along the second direction, the distance between the first solder strip and the first edge is d4, where d1 > (1 / 2)d3 + d4.

[0014] As an improvement to the above solution, the distance between the bend of the first lead and the bend of the second lead is 3mm to 15mm.

[0015] As an improvement to the above solution, the back contact battery assembly includes a first component edge and a second component edge along a second direction, with the first battery string located at the first component edge;

[0016] The series battery string group also includes an adjacent third battery string and a fourth battery string. The third battery string is located at the edge of the second component. The third battery string is electrically connected to the third bus bar. The fourth battery string is connected to the fourth bus bar. The third bus bar is bent at the third lead bend. The fourth bus bar is bent at the fourth lead bend.

[0017] Along the second direction, the edge of the third battery string near the bend of the third lead is the third edge, the edge of the fourth battery string near the bend of the fourth lead is the fourth edge, the solder strip closest to the bend of the third lead among the multiple solder strips welded to the third busbar is the fourth solder strip, the solder strip closest to the third edge among the multiple solder strips welded to the third busbar is the fifth solder strip, the fourth solder strip is the solder strip closest to the fifth solder strip, the solder strip closest to the bend of the fourth lead among the multiple solder strips welded to the fourth busbar is the sixth solder strip; the sixth solder strip is the solder strip closest to the fourth edge among the multiple solder strips welded to the fourth busbar.

[0018] The bend of the third lead wire and the bend of the fourth lead wire are symmetrical about the second reference line. The second reference line extends in the first direction. The distance between the second reference line and the sixth solder strip is d5, and the distance between the second reference line and the fifth solder strip is d6, where d5 > d6.

[0019] As an improvement to the above solution, the distance between the end of the first busbar away from the bend of the first lead and the edge of the first component is greater than the distance between the end of the third busbar away from the bend of the third lead and the edge of the second component.

[0020] As an improvement to the above solution, the distance between the two lead bends of the second busbar is greater than the length of the edge busbar.

[0021] As an improvement to the above scheme, the length difference between the first busbar and the third busbar is L1, where L1 < 12 mm.

[0022] As an improvement to the above scheme, the length difference between the second busbar and the fourth busbar is L2, where L2 < L1.

[0023] As an improvement to the above solution, an insulating strip is also included, which is disposed on the back surface of the battery cell along a second direction, and the first busbar and the second busbar are both disposed on the side of the insulating strip away from the battery cell.

[0024] As an improvement to the above solution, the orthographic projection of the first lead bend and the orthographic projection of the second lead bend are located on the same solar cell.

[0025] As an improvement to the above solution, the parallel battery string group includes a first battery string and a fifth battery string, the fifth battery string and the first battery string are connected in parallel through the first busbar, and the first solder strip extends from the first battery string to the fifth battery string along a first direction.

[0026] As an improvement to the above solution, the first welding strip includes a first connecting segment, a bent segment and a second connecting segment connected in sequence. The first connecting segment is connected to the battery cell and the second connecting segment is connected to the first busbar.

[0027] Along the second direction, the distance between the first connecting segment and the first edge is less than the distance between the second connecting segment and the first edge.

[0028] As an improvement to the above scheme, the distance d1 between the first baseline and the first weld strip is the distance between the first connecting segment and the first baseline.

[0029] As an improvement to the above solution, the two ends of the battery cell are a chamfered end and a cut end, respectively, and the chamfered ends of all battery cells in the back contact battery assembly face the same direction.

[0030] As an improvement to the above solution, the first battery string is provided with a first battery cell and a second battery cell arranged along a first direction. The first battery cell is located at the end of the first battery string, the second battery cell is located at the second end of the first battery string, and the first busbar is located at the end of the second battery cell near the first battery cell.

[0031] In addition, the present invention also provides a photovoltaic system comprising the aforementioned back contact battery assembly.

[0032] Implementing this invention has the following beneficial effects:

[0033] This invention discloses a back-contact battery assembly. A first battery string in a series-connected battery string group is connected to a first busbar via multiple solder strips. The first busbar is bent at a first lead bend, and the first solder strip welded to the first busbar is closest to the first lead bend and also closest to the first edge of the first battery string. Simultaneously, a second battery string in the series-connected battery string group is connected to a second busbar via multiple solder strips. The second busbar is bent at a second lead bend, and the second solder strip welded to the second busbar is closest to the second lead bend. Furthermore, the third solder strip on the second battery string is closest to the second edge, and the second solder strip is closest to the third solder strip at the first lead bend. Based on the symmetry of the second lead bend with respect to the first reference line extending along the first direction, the distance d1 between the first reference line and the first solder strip is made greater than the distance d2 between the first reference line and the third solder strip. That is, the symmetrical reference line between the first lead bend and the second lead bend is shifted towards the second battery string, thereby increasing the distance between the first lead bend and the first solder strip, reducing the influence of the first lead bend on the first solder strip closest to the first edge, and reducing the traction and heat effect of the first lead bend on the welding between the first solder strip and the first busbar, avoiding the problem of poor soldering of the solder strip on the first busbar, and improving the reliability of the connection between the first busbar and the solder strip. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a first embodiment of a back contact battery assembly according to the present invention;

[0035] Figure 2 yes Figure 1 A magnified structural diagram of section C;

[0036] Figure 3 This is a schematic diagram of the structure of a second embodiment of a back-contact battery assembly according to the present invention;

[0037] Figure 4 yes Figure 3 A schematic diagram of the enlarged structure of part D;

[0038] Figure 5This is a schematic diagram of the structure of a third embodiment of a back-contact battery assembly of the present invention;

[0039] Figure 6 yes Figure 5 A magnified structural diagram of part E. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0042] In the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" or "a number" means two or more, unless otherwise explicitly specified.

[0043] In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0045] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0046] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0047] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0048] First, see Figure 1 and Figure 2As shown, the present invention provides a first embodiment of a back-contact battery assembly, including a battery string, the battery string including battery cells arranged along a first direction, the battery cells having solder strips arranged along a second direction, wherein the first direction and the second direction are intersected; at least two battery strings are arranged along the second direction and connected in series to form a series battery string group; at least two battery strings are arranged along the first direction and connected in parallel to form a parallel battery string group; the series battery string group includes adjacent first battery string 11 and second battery string 12, the first battery string 11 being electrically connected to a first busbar 21, the second battery string 12 being connected to a second busbar 22, the first busbar 21 being bent at a first lead bend 211, and the second busbar 22 being bent at a second lead bend 221; along the second direction, the edge of the first battery string 11 near the first lead bend 211 is a first edge 111, the second battery string 12 being... The edge of the battery string 12 closest to the second lead bend 221 is the second edge 121. Among the multiple solder strips welded to the first busbar 21, the solder strip closest to the first lead bend 211 is the first solder strip 31. The first solder strip 31 is the solder strip in the first battery string 11 closest to the first edge 111. Among the multiple solder strips welded to the second busbar 22, the solder strip closest to the second lead bend 221 is the second solder strip 32. The solder strip on the second battery string 12 closest to the second edge 121 is the third solder strip 33. The second solder strip 32 is the solder strip closest to the third solder strip 33. The first lead bend 211 and the second lead bend 221 are symmetrical about the first reference line a. The first reference line a extends in the first direction. The distance between the first reference line a and the first solder strip 31 is d1. The distance between the first reference line a and the third solder strip 33 is d2. d1 > d2.

[0049] In this embodiment of the back-contact battery assembly, the first battery string 11 in the series battery string group is connected to the first busbar 21 by multiple solder strips. The first busbar 21 is bent at the first lead bend 211, and the first solder strip 31 welded to the first busbar 21 is closest to the first lead bend 211 and also closest to the first edge 111 of the first battery string 11. Simultaneously, the second battery string 12 in the series battery string group is connected to the second busbar 22 by multiple solder strips. The second busbar 22 is bent at the second lead bend 221, and the second solder strip 32 welded to the second busbar 22 is closest to the second lead bend 221. Furthermore, the third solder strip 33 on the second battery string 12 is closest to the second edge 121, and the second solder strip 32 is closest to the third solder strip 33. Based on the symmetry between the bend 211 and the second lead bend 221 about the first reference line a extending along the first direction, the distance d1 between the first reference line a and the first solder strip 31 is made greater than the distance d2 between the first reference line a and the third solder strip 33. That is, the symmetrical reference line between the first lead bend 211 and the second lead bend is shifted toward the second battery string 12, thereby increasing the distance between the first lead bend 211 and the first solder strip 31, reducing the influence of the first lead bend 211 on the first solder strip 31 closest to the first edge 111, and reducing the stress and heat effect of the first lead bend 211 on the welding between the first solder strip 31 and the first busbar 21, avoiding the problem of poor soldering of the solder strip on the first busbar 21, and improving the reliability of the connection between the first busbar 21 and the solder strip.

[0050] In this embodiment, the first busbar 21, the second busbar 22, and the third busbar 23 and the fourth busbar (hereinafter referred to as the third busbar 23) can be intermediate busbars. The first busbar 21, the second busbar 22, the third busbar 23, and the fourth busbar are all arranged along the second direction. Adjacent intermediate busbars are connected through a junction box, specifically by connecting the bent lead wire to the junction box. In this embodiment, stress residue exists during the lead bending process of the intermediate busbar. The material thickness at the lead bending point becomes uneven due to the stretching of the outer edge and the compression of the inner edge. The closer the solder strip is to the lead bending point, the easier it is for gaps to form between the solder strip and the busbar, resulting in incomplete soldering. Moreover, the closer to the lead bending point, the more concentrated the stress becomes. Under the subsequent welding thermal cycle, component lamination, or thermal expansion and contraction during component use, these residual stresses will gradually be released, leading to solder joint fatigue or even cracking. In this embodiment, the distance between the first lead bending point 211 and the first solder strip 31 is increased, thus reducing the stress impact of the first lead bending point 211 on the welding between the first solder strip 31 and the first busbar 21. During the connection of the first busbar 21 and the second busbar 22 through the junction box, the welding heat when the junction box is connected to the first lead will be transferred along the first lead, and the heat transferred to the first solder strip 31 will decrease as the distance between the first solder strip 31 and the bend 211 of the first lead increases; therefore, when the distance between the bend 211 of the first lead and the first solder strip 31 increases, the welding between the first solder strip 31 and the first busbar 21 is less affected by the heat from the bend 211 of the first lead.

[0051] In some other cases, if the junction box is located at the edge of the assembly, the first busbar 21, the second busbar 22, and the third busbar 23 and the fourth busbar (hereinafter referred to as the third busbar 23 and the fourth busbar) can be end busbars.

[0052] In some embodiments, the first battery string 11 and the second battery string 12 can be arranged in an overlapping manner, that is, along the second direction, the first battery string 11 is partially laid on the second battery string 12, or the second battery string 12 is partially laid on the first battery string 11. In other words, the first battery string 11 and the second battery string 12 coincide in the orthographic projection of the third direction. At this time, there is a relationship between the distance d1 between the first reference line and the first solder strip and the distance d2 between the first reference line and the third solder strip, where d1 > d2. The third direction intersects with the first direction and the second direction.

[0053] For the first battery string 11 and the second battery string 12, the distance between the strings is d3. Along the second direction, the distance between the first solder strip 31 and the first edge 111 is d4. Preferably, d1 > (1 / 2)d3 + d4. Wherein, the distance between the first lead bend 211 and the second lead bend 221 is 3mm to 15mm, d3 is -3mm to 3mm, and d4 is 3mm to 6mm. When d3 is negative, that is, the first battery string 11 and the second battery string 12 adopt an overlapping arrangement, and the overlap size of the first battery string 11 and the second battery string 12 along the second direction is 0~3mm.

[0054] In this embodiment, the busbars are preferably positioned on the back of the solar cell to increase the effective power generation area of ​​the solar cell. Specifically, an insulating strip is provided on the back surface of the solar cell along a second direction, and the first busbar 21 and the second busbar 22 are both located on the side of the insulating strip away from the solar cell.

[0055] The first battery string 11 has a first battery cell 1101 and a second battery cell 1102 arranged along a first direction. The first battery cell 1101 is located at one end of the first battery string 11, and the second battery cell 1102 is located at the next end of the first battery string 11. The first busbar 21 is disposed at one end of the second battery cell 1102 near the first battery cell 1101. Compared to disposing of the first busbar 21 on the first battery cell, disposing of the first busbar 21 on the second battery cell avoids the need to drill holes in the insulating strip, reducing the manufacturing process.

[0056] The orthographic projections of the first lead bend 211 and the second lead bend 221 are preferably located on the same battery cell. In this case, the distance between the first lead bend 211 and the first solder strip 31 and the distance between the second lead bend 221 and the second solder strip 32 are close, which effectively avoids the poor soldering caused by the small gap between one of the busbar leads and the solder strip welded on the busbar.

[0057] The parallel battery string group includes a first battery string 11 and a fifth battery string 15. The fifth battery string 15 is connected in parallel with the first battery string 11 through the first busbar 21. The first solder strip 31 extends from the first battery string 11 to the fifth battery string 15 along a first direction.

[0058] The parallel battery string group includes a first battery string 11 and a fifth battery string 15. The fifth battery string 15 is connected in parallel with the first battery string 11 through a first busbar 21. A first solder strip 31 extends from the first battery string 11 to the fifth battery string 15 along a first direction. Both the first battery string 11 and the fifth battery string 15 are connected in parallel through the first solder strip 31 and the first busbar 21. Correspondingly, other solder strips welded on the first busbar 21 also extend from the first battery string 11 to the fifth battery string 15.

[0059] The parallel battery string group also includes a second battery string 12 and a sixth battery string 16. The sixth battery string 16 is connected in parallel with the second battery string 12 via a second busbar 22. The second solder strip 32 extends from the second battery string 12 to the sixth battery string 16 along a first direction. Both the second battery string 12 and the sixth battery string 16 are connected in parallel via the second solder strip 32 and the second busbar 22. Correspondingly, other solder strips welded on the second busbar 22 also extend from the second battery string 12 to the sixth battery string 16.

[0060] like Figure 3 and Figure 4 In the second embodiment, the end of the first solder strip 31 connected to the first busbar 21 is preferably configured as a bent structure to further increase the distance between the first solder strip 31 and the bend 211 of the first lead wire, thereby preventing incomplete soldering of the solder strip on the first busbar 21. Specifically, the first solder strip 31 includes a first connecting segment 311, a bent segment 312, and a second connecting segment 313 connected in sequence. The first connecting segment 311 is connected to the battery cell, and the second connecting segment 313 is connected to the first busbar 21. Along the second direction, the distance between the first connecting segment 311 and the first edge 111 is less than the distance between the second connecting segment 313 and the first edge 111.

[0061] In this embodiment, the distance d1 between the first baseline a and the first welding strip 31 is the distance between the first connecting segment and the first baseline a.

[0062] Furthermore, the end of the second solder strip 32 connected to the second busbar 22 can be configured as a bent structure. When the bend of the second solder strip 32 is in the same direction as the bend of the first solder strip 31, the first solder strip 31 and the second solder strip 32 can be solder strips with the same structure, which is convenient for production material preparation. In addition, the bend of the second solder strip 32 can be made to be opposite to the bend of the first solder strip 31, so as to increase the distance between the second solder strip 32 and the bend 221 of the second lead wire, and further increase the distance between the first solder strip 31 and the bend 211 of the first lead wire, which can better avoid the problem of poor soldering of the solder strips on the first busbar 21 and the second busbar 22.

[0063] like Figure 5 and Figure 6As shown, in the third embodiment, the back-contact battery assembly includes a first component edge and a second component edge along a second direction; the series battery string group includes adjacent first battery string 11 and second battery string 12, as well as adjacent third battery string 13 and fourth battery string 14, with the first battery string 11 located at the edge of the first component and the third battery string 13 located at the edge of the second component; wherein, the first battery string 11 is electrically connected to the first busbar 21, the second battery string 12 is connected to the second busbar 22, the first busbar 21 is bent at the first lead bend 211, and the second busbar 22 is bent at the second lead bend 221; along the second direction, the first battery string 11 is adjacent to the first busbar 21. The edge near the first lead bend 211 is the first edge 111, and the edge of the second battery string 12 near the second lead bend 221 is the second edge 121. Among the multiple solder strips welded to the first busbar 21, the solder strip closest to the first lead bend 211 is the first solder strip 31, which is the solder strip in the first battery string 11 closest to the first edge 111. Among the multiple solder strips welded to the second busbar 22, the solder strip closest to the second lead bend 221 is the second solder strip 32, and the solder strip on the second battery string 12 closest to the second edge 121 is the third solder strip 33, which is the solder strip in the second battery string 12 closest to the third edge 121. The solder strip 33; the first lead bend 211 and the second lead bend 221 are symmetrical about the first reference line a, the first reference line a extends in the first direction, the distance between the first reference line a and the first solder strip 31 is d1, the distance between the first reference line a and the third solder strip 33 is d2, d1>d2; the third battery string 13 is electrically connected to the third busbar 23, the fourth battery string 14 is connected to the fourth busbar 24, the third busbar 23 is bent at the third lead bend 231, and the fourth busbar 24 is bent at the fourth lead bend 241; along the second direction, the third battery string 13 is close to the third lead bend The edge of the bend 231 is the third edge 131, the edge of the fourth battery string 14 near the bend 241 of the fourth lead is the fourth edge 141, the solder strip closest to the bend 231 of the third lead among the multiple solder strips welded to the third busbar 23 is the fourth solder strip 34, the solder strip closest to the third edge 131 of the third battery string 13 is the fifth solder strip 35, the fourth solder strip 34 is the solder strip closest to the fifth solder strip 35, the solder strip closest to the bend 241 of the fourth lead among the multiple solder strips welded to the fourth busbar 24 is the sixth solder strip 36; the sixth solder strip 36 is the solder strip closest to the fourth edge 141 of the fourth battery string 14;The third lead bend 231 and the fourth lead bend 241 are symmetrical about the second reference line b. The second reference line b extends in the first direction. The distance between the second reference line b and the sixth solder strip 36 is d5, and the distance between the second reference line b and the fifth solder strip 35 is d6, where d5 > d6.

[0064] In this embodiment, the first battery string 11 is disposed at the edge of the first component of the back-contact battery assembly, and the third battery string 13 is disposed at the edge of the second component of the back-contact battery assembly. The first battery string 11 in the series battery string group is connected to the first busbar 21 by multiple solder strips. The first busbar 21 is bent at the first lead bend 211, and the first solder strip 31 welded to the first busbar 21 is closest to the first lead bend 211 and also closest to the first edge 111 of the first battery string 11. At the same time, the third battery string 13 in the series battery string group... The second battery string 12 is connected to the second busbar 22 via multiple solder strips. The second busbar 22 is bent at the second lead bend 221. The second solder strip 32, which is welded to the second busbar 22, is closest to the second lead bend 221. The third solder strip 33 is the one closest to the second edge 121 on the second battery string 12. The second solder strip 32 is closest to the third solder strip 33. Based on the symmetry between the first lead bend 211 and the second lead bend 221 about the first reference line a extending along the first direction, the first reference line a is aligned with... The distance d1 between the first solder strip 31 and the first lead bend 211 is greater than the distance d2 between the first reference line a and the third solder strip 33. This means the symmetrical reference line between the first lead bend 211 and the second lead bend is offset towards the second battery string 12. This increases the distance between the first lead bend 211 and the first solder strip 31, reducing the impact of the first lead bend 211 on the first solder strip 31 closest to the first edge 111. Consequently, the stress and heat impact of the first lead bend 211 on the welding between the first solder strip 31 and the first busbar 21 is reduced, avoiding... To avoid the problem of poor soldering on the solder strips of the first busbar 21, the reliability of the connection between the first busbar 21 and the solder strips can be improved. Similarly, the third battery string 13 in the series battery string group is connected to the third busbar 23 through multiple solder strips. The third busbar 23 is bent at the third lead bend 231. The fourth solder strip 34, which is welded to the third busbar 23, is closest to the third lead bend 231. The fifth solder strip 35 is closest to the third edge 131 on the third battery string 13. The fourth solder strip 34 is closest to the fifth solder strip 35.Simultaneously, the fourth battery string 14 in the series battery string group is connected to the fourth busbar 24 through multiple solder strips. The fourth busbar 24 is bent at the fourth lead bend 241. The sixth solder strip 36, which is welded to the fourth busbar 24, is closest to the fourth lead bend 241 and also closest to the fourth edge 141 of the fourth battery string 14. Based on the symmetry between the third lead bend 231 and the fourth lead bend 241 about the second reference line b extending along the first direction, the distance d5 between the second reference line b and the sixth solder strip 36 is greater than the distance between the second reference line b and the fifth solder strip 36. The distance d6, i.e., the symmetrical baseline between the third lead bend 231 and the fourth lead bend, is shifted towards the third battery string 13. This increases the distance between the fourth lead bend 241 and the sixth solder strip 36, reducing the impact of the fourth lead bend 241 on the sixth solder strip 36, which is closest to the fourth edge 141. The stress and heat effects of the fourth lead bend 241 on the welding between the sixth solder strip 36 and the fourth busbar 24 are reduced, avoiding the problem of incomplete soldering on the solder strips of the fourth busbar 24, and improving the reliability of the connection between the fourth busbar 24 and the solder strips.

[0065] The length difference between the first busbar 21 and the third busbar 23 is L1, where L1 < 12mm. This avoids an excessive length difference between the first busbar 21 and the third busbar 23, which could lead to the first busbar 21 extending excessively towards the edge of the first component, resulting in an excessively small distance between the first busbar 21 and the edge of the first component, or the third busbar 23 extending excessively towards the edge of the second component, resulting in an excessively small distance between the third busbar 23 and the edge of the second component, thus increasing the risk of short circuits.

[0066] More preferably, the length difference between the second bus 22 and the fourth bus 24 is L2. If L2 = L1, then the second bus 22 or the fourth bus 24 needs to be extended further, which would increase the short-circuit risk of the two long buses. In this embodiment, it is preferable to make L2 < L1 to avoid excessive extension of the second bus 22 toward the fourth bus 24, thereby reducing the short-circuit risk of the two long buses.

[0067] With the first battery string 11 located at the edge of the first component and the third battery string 13 located at the edge of the second component, in this embodiment, the distance between the end of the first busbar 21 furthest from the first lead bend 211 and the edge of the first component is greater than the distance between the end of the third busbar 23 furthest from the third lead bend 231 and the edge of the second component. This shortens the length of the first busbar 21 and reduces the risk of microcracks at the component edge.

[0068] Both the first battery string 11 and the second battery string 12 are connected to the first edge busbar 41, which connects two adjacent battery strings in the second direction. In this embodiment, the second busbar 22 connects two adjacent battery strings in the second direction, and the length of the second busbar 22 is greater than or equal to the length of the first edge busbar 41. Because the first edge busbar 41 is closer to the edge of the back-contact battery assembly, it is subject to stronger constraints than the second busbar 22. This ensures that the length of the first edge busbar 41 is not greater than that of the second busbar 22 located in the middle, effectively preventing microcracks in the battery cells caused by excessive internal stress in the first edge busbar 41.

[0069] In some cases, the distance between the two lead bends at both ends of the second busbar 22 is greater than the length of the first edge busbar 41, which can further reduce the occurrence of microcracks.

[0070] Accordingly, the third battery string 13 and the fourth battery string 14 are both connected to the second edge bus bar 42. The second edge bus bar 42 connects two adjacent battery strings in the second direction. In this embodiment, the fourth bus bar 24 connects two adjacent battery strings in the second direction. The length of the fourth bus bar 24 is greater than or equal to the length of the second edge bus bar 42.

[0071] Similarly, in some cases, the distance between the two lead bends at both ends of the fourth busbar 24 is greater than the length of the second edge busbar 42, which can further reduce the occurrence of microcracks.

[0072] When the back-contact battery assembly has four battery strings arranged along the second direction, the second busbar 22 and the fourth busbar 24 are formed as one unit. When the back-contact battery assembly has more than four battery strings arranged along the second direction, it is preferable to set the second busbar 22 and the fourth busbar 24 as busbars of equal length to facilitate production material preparation.

[0073] In this embodiment, the busbars are preferably positioned on the back of the solar cell to increase the effective power generation area of ​​the solar cell. Specifically, a first insulating strip 51 is provided on the back surface of the solar cell along a second direction, and the first busbar 21, the second busbar 22, the third busbar 23, and the fourth busbar 24 are all located on the side of the first insulating strip 51 away from the solar cell. A second insulating strip 52 is provided on the back surface of the solar cell along a second direction, and the first edge busbar 41 and the second edge busbar 42 are both located on the side of the second insulating strip 52 away from the solar cell.

[0074] The first battery string 11 is provided with a first battery cell 1101 and a second battery cell 1102 arranged along a first direction. The first battery cell 1101 is located at the end of the first battery string 11, and the second battery cell 1102 is located at the next end of the first battery string 11. The first busbar 21 is provided at the end of the second battery cell 1102 near the first battery cell 1101.

[0075] The orthographic projections of the first lead bend 211 and the second lead bend 221 are both located on the same solar cell, while the orthographic projections of the third lead bend 231 and the fourth lead bend 241 are both located on another solar cell. At this time, the distances between the first lead bend 211 and the first solder strip 31, the second lead bend 221 and the second solder strip 32 are close, and the distances between the third lead bend 231 and the fourth solder strip 34, and the fourth lead bend 241 and the sixth solder strip 36 are close, effectively avoiding incomplete soldering caused by excessively small spacing between one of the busbar leads and the solder strips welded to the busbar.

[0076] The parallel battery string group includes a first battery string 11 and a fifth battery string 15. The fifth battery string 15 is connected in parallel with the first battery string 11 through a first busbar 21. A first solder strip 31 extends from the first battery string 11 to the fifth battery string 15 along a first direction. Both the first battery string 11 and the fifth battery string 15 are connected in parallel through the first solder strip 31 and the first busbar 21. Correspondingly, other solder strips welded on the first busbar 21 also extend from the first battery string 11 to the fifth battery string 15.

[0077] The parallel battery string group also includes a second battery string 12 and a sixth battery string 16. The sixth battery string 16 is connected in parallel with the second battery string 12 via a second busbar 22. The second solder strip 32 extends from the second battery string 12 to the sixth battery string 16 along a first direction. Both the second battery string 12 and the sixth battery string 16 are connected in parallel via the second solder strip 32 and the second busbar 22. Correspondingly, other solder strips welded on the second busbar 22 also extend from the second battery string 12 to the sixth battery string 16.

[0078] The parallel battery string group also includes the third battery string 13 and the seventh battery string 17. The seventh battery string 17 is connected in parallel with the third battery string 13 through the third busbar 23. The fourth solder strip 34 extends from the third battery string 13 to the seventh battery string 17 along a first direction. Both the third battery string 13 and the seventh battery string 17 are connected in parallel through the fourth solder strip 34 and the third busbar 23. Correspondingly, other solder strips welded on the third busbar 23 also extend from the third battery string 13 to the seventh battery string 17.

[0079] The parallel battery string group also includes the fourth battery string 14 and the eighth battery string 18. The eighth battery string 18 is connected in parallel with the fourth battery string 14 through the third busbar 23. The sixth solder strip 36 extends from the third battery string 13 to the seventh battery string 17 along the first direction. The fourth battery string 14 and the eighth battery string 18 are both connected in parallel through the sixth solder strip 36 and the fourth busbar 24. Correspondingly, other solder strips welded on the fourth busbar 24 also extend from the fourth battery string 14 to the eighth battery string 18.

[0080] Accordingly, the fifth battery string 15 and the sixth battery string 16 are both connected to the third edge busbar 43, and the seventh battery string 17 and the eighth battery string 18 are both connected to the fourth edge busbar 44. A third insulating strip 53 is provided on the back surface of the battery cell along the second direction. The third edge busbar 43 and the fourth edge busbar 44 can be positioned on the side of the third insulating strip 53 away from the battery cell, thereby increasing the effective power generation area of ​​the battery cell.

[0081] Preferably, the end of the first solder strip 31 connected to the first busbar 21 and the end of the sixth solder strip 36 connected to the fourth busbar 24 are both configured with a bent structure to further increase the distance between the first solder strip 31 and the bend 211 of the first lead, and the distance between the sixth solder strip 36 and the bend 241 of the fourth lead, thus preventing incomplete soldering of the solder strips on the first busbar 21 and the fourth busbar 24. Specifically, the first solder strip 31 and the sixth solder strip 36 each include a first connecting segment, a bent segment, and a second connecting segment connected in sequence. For the first solder strip 31 on the first busbar 21, the first connecting segment is connected to the battery cell, and the second connecting segment is connected to the first busbar 21; along the second direction, the distance between the first connecting segment and the first edge 111 is less than the distance between the second connecting segment and the first edge 111. In this embodiment, the distance d1 between the first reference line a and the first solder strip 31 is the distance between the first connecting segment and the first reference line a. For the sixth solder strip 36 on the fourth busbar 24, the first connecting segment is connected to the battery cell, and the second connecting segment is connected to the fourth busbar 24; along the second direction, the distance between the first connecting segment and the fourth edge 141 is less than the distance between the second connecting segment and the fourth edge 141. In this embodiment, the distance d5 between the second reference line b and the sixth solder strip 36 is the distance between the first connecting segment and the second reference line b.

[0082] In addition, the end of the second welding strip 32 connected to the second busbar 22 can be configured as a bent structure, and the end of the fourth welding strip 34 connected to the third busbar 23 can be configured as a bent structure. When the bends of the second solder strip 32, the fourth solder strip 34, and the sixth solder strip 36 are all aligned with the bend of the first solder strip 31, all solder strips 31, 32, 34, and 36 can be made of the same structure, facilitating production material preparation. Furthermore, the bends of the second solder strip 32 and 31 can be made opposite in direction, as can the bends of the fourth and sixth solder strips 34 and 36. This increases the distance between the second solder strip 32 and the second lead bend 221, the distance between the fourth solder strip 34 and the third lead bend 231, and further increases the distance between the first solder strip 31 and the first lead bend 211, and the distance between the sixth solder strip 36 and the fourth lead bend 241. This better avoids the problem of incomplete soldering on the solder strips of the first busbar 21, second busbar 22, third busbar 23, and fourth busbar 24.

[0083] For all cells in the back-contact battery assembly, each cell is divided into two halves, specifically half-cell A and half-cell B, which are formed by splitting a whole cell. When the whole cell is slicing, half-cell A and half-cell B have the same grid polarity along the first direction. After slicing, the two ends of the cell are chamfered and cut, respectively, along the first direction. By rotating one of the half-cells, A or B, by 180° (i.e., inverting one half-cell), and alternating the arrangement of half-cells A and B along the first direction, the back-contact battery assembly of this embodiment can achieve the same chamfered orientation for all cells, forming a uniformly arranged assembly with good appearance consistency.

[0084] It should be noted that, in Figure 5 and Figure 6 In the back-contact battery assembly shown, each battery string uses half-cell A arranged alternately along the first direction and half-cell B arranged in an inverted manner. In order to more intuitively show that the half-cell B in the back-contact battery assembly is arranged in an inverted manner, the inverted letter B is used in the figure for display.

[0085] Furthermore, since all the chamfered ends of the cells face the same direction, the cell strings do not need to be rotated 180° alternately when arranging them, which simplifies the cell string arrangement, avoids the risk of strings falling off, and helps improve production efficiency.

[0086] Furthermore, the present invention also discloses an embodiment of a photovoltaic system, which includes the aforementioned back contact battery assembly.

[0087] In this embodiment of the photovoltaic system, since the first solder strip 31 in the back contact cell module is closest to the first edge 111 of the first cell string 11 and the first solder strip 31 is closest to the first lead bend 211, the second solder strip 32 is closest to the second lead bend 221, and the third solder strip 33 is closest to the second edge 121 and the second solder strip 32 is closest to the third solder strip 33, and the first lead bend 211 and the second lead bend 221 are symmetrical about the first reference line a extending along the first direction, and the distance d1 between the first reference line a and the first solder strip 31 is greater than the distance d2 between the first reference line a and the third solder strip 33, the problem of poor soldering on the solder strips of the first busbar 21 can be avoided, the reliability of the connection between the first busbar 21 and the solder strips can be improved, and the life of the photovoltaic system can be extended.

[0088] The photovoltaic system of this embodiment can be applied in all fields that require solar power generation. Taking a photovoltaic power generation system grid as an example, the photovoltaic system may include a photovoltaic array, a combiner box, and an inverter. The photovoltaic array may be an array combination of multiple back-contact battery modules. For example, multiple back-contact battery modules can form multiple photovoltaic arrays. The photovoltaic array is connected to the combiner box, which can collect the current generated by the photovoltaic array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to realize solar power supply.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A back-contact battery assembly, characterized in that, include A battery string, the battery string comprising battery cells arranged along a first direction, wherein solder strips are arranged on the battery cells along a second direction, wherein the first direction and the second direction are intersecting; At least two of the battery strings are arranged along the second direction and connected in series to form a series battery string group; At least two of the battery strings are arranged along a first direction and connected in parallel to each other to form a parallel battery string group; The series battery string group includes an adjacent first battery string and a second battery string. The first battery string is electrically connected to a first busbar, and the second battery string is connected to a second busbar. The first busbar is bent at the first lead bend, and the second busbar is bent at the second lead bend. Along the second direction, the edge of the first battery string near the bend of the first lead is the first edge. The edge of the second battery string near the bend of the second lead is the second edge. The solder strip closest to the bend of the first lead among the multiple solder strips welded to the first busbar is the first solder strip. The first solder strip is the solder strip closest to the first edge in the first battery string. The solder strip closest to the bend of the second lead among the multiple solder strips welded to the second busbar is the second solder strip. The solder strip closest to the second edge on the second battery string is the third solder strip. The second solder strip is the solder strip closest to the third solder strip. The first lead bend and the second lead bend are symmetrical about the first reference line. The first reference line extends in the first direction. The distance between the first reference line and the first solder strip is d1, and the distance between the first reference line and the third solder strip is d2, where d1 > d2. The back contact battery assembly includes a first component edge and a second component edge disposed along a second direction, with the first battery string located at the first component edge; Both the first battery string and the second battery string are connected to the edge bus bar, and the length of the second bus bar is greater than or equal to the length of the edge bus bar.

2. The back contact battery assembly according to claim 1, characterized in that, The distance between the first battery string and the second battery string is d3, and the distance between the first solder strip and the first edge along the second direction is d4, where d1 > (1 / 2)d3 + d4.

3. The back contact battery assembly according to claim 1 or 2, characterized in that, The distance between the bend of the first lead and the bend of the second lead is 3mm to 15mm.

4. The back contact battery assembly according to claim 1, characterized in that, The back contact battery assembly includes a first component edge and a second component edge disposed along a second direction, with the first battery string located at the first component edge; The series battery string group also includes an adjacent third battery string and a fourth battery string. The third battery string is located at the edge of the second component. The third battery string is electrically connected to the third bus bar. The fourth battery string is connected to the fourth bus bar. The third bus bar is bent at the third lead bend. The fourth bus bar is bent at the fourth lead bend. Along the second direction, the edge of the third battery string near the bend of the third lead is the third edge, the edge of the fourth battery string near the bend of the fourth lead is the fourth edge, the solder strip closest to the bend of the third lead among the multiple solder strips welded to the third busbar is the fourth solder strip, the solder strip closest to the third edge among the multiple solder strips welded to the third busbar is the fifth solder strip, the fourth solder strip is the solder strip closest to the fifth solder strip, the solder strip closest to the bend of the fourth lead among the multiple solder strips welded to the fourth busbar is the sixth solder strip; the sixth solder strip is the solder strip closest to the fourth edge among the multiple solder strips welded to the fourth busbar. The bend of the third lead wire and the bend of the fourth lead wire are symmetrical about the second reference line. The second reference line extends in the first direction. The distance between the second reference line and the sixth solder strip is d5, and the distance between the second reference line and the fifth solder strip is d6, where d5 > d6.

5. The back contact battery assembly according to claim 4, characterized in that, The distance between the end of the first busbar away from the bend of the first lead and the edge of the first component is greater than the distance between the end of the third busbar away from the bend of the third lead and the edge of the second component.

6. The back contact battery assembly according to claim 1, characterized in that, The distance between the two lead bends of the second busbar is greater than the length of the edge busbar.

7. The back contact battery assembly according to claim 4, characterized in that, The length difference between the first busbar and the third busbar is L1, where L1 < 12 mm.

8. The back contact battery assembly according to claim 7, characterized in that, The length difference between the second busbar and the fourth busbar is L2, where L2 < L1.

9. The back contact battery assembly according to claim 1, characterized in that, It also includes an insulating strip, which is disposed along the second direction on the back surface of the battery cell, and the first busbar and the second busbar are both disposed on the side of the insulating strip away from the battery cell.

10. The back contact battery assembly according to claim 9, characterized in that, The orthographic projection of the first lead bend and the orthographic projection of the second lead bend are located on the same solar cell.

11. The back contact battery assembly according to claim 9, characterized in that, The first battery string has a first battery cell and a second battery cell arranged along a first direction. The first battery cell is located at one end of the first battery string, and the second battery cell is located at the next end of the first battery string. The first busbar is located at the end of the second battery cell near the first battery cell.

12. The back contact battery assembly according to claim 9 or 11, characterized in that, The parallel battery string group includes a first battery string and a fifth battery string. The fifth battery string is connected in parallel with the first battery string through the first busbar. The first solder strip extends from the first battery string to the fifth battery string along a first direction.

13. The back contact battery assembly according to claim 1, characterized in that, The first welding strip includes a first connecting segment, a bent segment, and a second connecting segment connected in sequence. The first connecting segment is connected to the battery cell, and the second connecting segment is connected to the first busbar. Along the second direction, the distance between the first connecting segment and the first edge is less than the distance between the second connecting segment and the first edge.

14. The back contact battery assembly according to claim 13, characterized in that, The distance d1 between the first baseline and the first weld strip is the distance between the first connecting segment and the first baseline.

15. The back contact battery assembly according to claim 1, characterized in that, The two ends of the battery cell are a chamfered end and a cut end, respectively, and the chamfered ends of all battery cells in the back contact battery assembly face the same direction.

16. A photovoltaic system, characterized in that, Includes the back contact battery assembly according to any one of claims 1 to 15.

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