Back contact solar cell module and system

Abstract

The present disclosure provides a back contact solar cell module and a system. The back contact solar cell module comprises: solar cell strings, which each comprises at least a first solar cell and a second solar cell arranged sequentially in a first direction, the first solar cell being arranged at an end of the corresponding solar cell string; first ribbons, which are arranged on the rear surfaces of the first solar cells; second ribbons, which are arranged on the rear surfaces of the second solar cells; and first busbars, which are arranged on the rear surfaces of the second solar cells.

Description

Back contact battery assembly and system

[0001] Cross-references to related applications

[0002] This disclosure claims Chinese patent application No. 202423322585.7, entitled "Back Contact Battery Module and Photovoltaic System", filed on December 31, 2024, with the State Intellectual Property Office of China, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure pertains to the field of photovoltaic technology, and particularly relates to a back-contact battery module and a photovoltaic system. Background Technology

[0004] In existing back-contact battery modules, the series busbars between adjacent battery strings are usually placed at the edge of the module, while the parallel busbars between adjacent battery strings are usually placed in the reserved gap area between the two battery strings. This requires a certain amount of space to be reserved at the edge of the battery module to place the series busbars, and a certain amount of space to be reserved between the two parallel battery strings to place the parallel busbars. On the one hand, this reduces the effective light-receiving area of ​​the battery module and affects the module's conversion efficiency; on the other hand, it affects the aesthetics of the module.

[0005] In some products, the busbar is installed in the middle of the back of the battery cell, and an insulating strip is set between the busbar and the battery cell. Although this setting can hide the busbar, it requires the insulating strip to be perforated so that the busbar can contact the same polarity solder strip on the battery cell, while insulating it from the opposite polarity solder strip on the battery cell. This setting requires high precision in the perforation and arrangement of the insulating strip, which is difficult to produce and can easily cause short circuits or poor soldering due to positional misalignment when perforating the insulating strip.

[0006] Public content

[0007] This disclosure provides a back-contact battery assembly, which aims to solve the problem that existing insulating strips require hole-making, which has high requirements for the hole-making accuracy and the arrangement accuracy of the insulating strips, making production difficult and prone to short circuits or poor soldering due to positional misalignment during hole-making.

[0008] This disclosure is implemented as follows: a back-contact battery assembly includes: a battery string, the battery string including at least a first battery cell and a second battery cell arranged sequentially along a first direction, the first battery cell being disposed at the end of the battery string; a first solder strip disposed on the back surface of the first battery cell; a second solder strip disposed on the back surface of the second battery cell; a first busbar disposed on the back surface of the second battery cell; and a first insulating strip disposed between the first busbar and the second battery cell, the first insulating strip being used to isolate the second solder strip and the first busbar, both the first insulating strip and the first busbar extending along a second direction, the first direction and the second direction being intersected; wherein, the first solder strip includes a main body segment electrically connected to the first battery cell and an extension segment electrically connected to the first busbar, the extension segment and the second solder strip being spaced apart in the second direction; and the main body segment and the second solder strip being collinear in the first direction.

[0009] In some embodiments, the first solder strip further includes a connecting segment that connects the body segment and the extension segment.

[0010] In some embodiments, the back contact battery assembly satisfies at least one of the following: a smooth transition connection between the main body segment and the connecting segment; or a smooth transition connection between the extension segment and the connecting segment.

[0011] In some embodiments, the connecting segment is bent relative to the main body segment in the second direction.

[0012] In some embodiments, the back contact battery assembly satisfies one of the following: the first solder strip is multiple strips, and in a second direction, the connecting segments of the multiple first solder strips are all bent toward a first side of the main body segment; the connecting segments of the multiple first solder strips are all bent toward a second side of the main body segment; a portion of the connecting segments of the multiple first solder strips is bent toward a first side of the main body segment, and another portion of the connecting segments of the multiple first solder strips is bent toward a second side of the main body segment, with the first side and the second side opposite to each other.

[0013] In some embodiments, the bending angle of the connecting segment relative to the main body segment is greater than or equal to 10° and less than or equal to 70°.

[0014] In some embodiments, the bending angle of the connecting segment relative to the main body segment is greater than or equal to 30° and less than or equal to 60°.

[0015] In some embodiments, the epitaxial segment and the second solder strip are arranged in parallel.

[0016] In some embodiments, the spacing between the epitaxial segment and the second solder strip satisfies: 1mm≤L1≤1 / 2D, where L1 is the spacing between the epitaxial segment and the second solder strip in the second direction, and D is the spacing between two adjacent second solder strips.

[0017] In some embodiments, the extension direction of the epitaxial segment intersects with the extension direction of the second solder strip.

[0018] In some embodiments, the minimum spacing between the epitaxial segment and the second solder strip satisfies: 1mm≤L2≤1 / 2D, where L2 is the minimum spacing between the epitaxial segment and the second solder strip in the second direction, and D is the spacing between two adjacent second solder strips.

[0019] In some embodiments, the first battery cell and the second battery cell are disposed on the same plane, and the first battery cell and the second battery cell are disposed at intervals.

[0020] In some embodiments, the distance between the first battery cell and the second battery cell is greater than or equal to 0 and less than or equal to 3 mm.

[0021] In some embodiments, the first and second battery cells are partially overlapped in a first direction.

[0022] In some embodiments, the local overlap distance between the first and second battery cells is greater than 0 and less than or equal to 1.5 mm.

[0023] In some embodiments, the back contact battery assembly further includes a third solder strip extending from the first battery cell to the second battery cell along a first direction, the third solder strip connecting the first battery cell and the second battery cell.

[0024] In some embodiments, there are multiple third solder strips, with at least one first solder strip and one second solder strip disposed between two adjacent third solder strips.

[0025] In some embodiments, a first solder joint is provided at one end of the first battery cell near the second battery cell, and the first solder joint is connected to a first solder strip.

[0026] In some embodiments, the first busbar is disposed at the end of the second battery cell near the first battery cell.

[0027] In some embodiments, the back-contact battery assembly includes at least two sets of battery strings arranged along a second direction, wherein a first insulating strip extends from one of the two sets of battery strings to the other of the two sets of battery strings along the second direction.

[0028] This disclosure allows the first busbar to be concealed on the back surface of the solar cell, increasing the effective light-receiving area of ​​the solar module, improving module conversion efficiency, and enhancing the overall aesthetics of the solar module. Furthermore, since the first busbar is located on the second solar cell, it ensures that the first solder strip can fully adhere to and weld with the effective welding position of the first solar cell, preventing insufficient welding between the first solder strip and the first solar cell that could affect current collection. During assembly, a first insulating strip is placed between the second solar cell and the first busbar for isolation. The first insulating strip does not require holes or additional openings. The staggered arrangement greatly simplifies the processing and installation of the first insulating strip. Furthermore, by electrically connecting the first welding strip to the first busbar via an extended section, and with the extended section and second welding strip spaced apart in the second direction, a certain degree of offset in the first direction is allowed during fabrication. This effectively reduces production precision requirements and manufacturing difficulty, and also significantly lowers the risk of short circuits. Moreover, the staggered arrangement of the extended section and second welding strip reduces the stacking height and stress during lamination, thus reducing the risk of microcracks and fragmentation in the battery cells and improving the reliability of the back-contact battery module.

[0029] A photovoltaic system includes the aforementioned back-contact battery module. The technical effects of this disclosure are the same as those of the aforementioned back-contact battery module, and will not be repeated here. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the structure of the first type of back contact battery assembly disclosed herein.

[0031] Figure 2 is a schematic diagram of the structure of the second type of back contact battery assembly disclosed herein;

[0032] Figure 3 is a magnified schematic diagram of the structure at point A in Figure 2;

[0033] Figure 4 is a structural cross-sectional view of the first type of back contact battery assembly disclosed herein;

[0034] Figure 5 is a structural cross-sectional view of the second type of back-contact battery assembly disclosed herein;

[0035] Figure 6 is a schematic diagram of the structure of the third type of back contact battery assembly currently disclosed.

[0036] Explanation of reference numerals in the attached drawings: 100, battery string; 101, first battery cell; 102, second battery cell; 200, first welding strip; 201, main body segment; 202, extension segment; 203, connecting segment; 300, second welding strip; 400, first busbar; 500, first insulating strip; 600, third welding strip; 700, first weld point. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. Examples of 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 this disclosure, and should not be construed as limiting this disclosure. Furthermore, it should be understood that the specific embodiments described herein are merely for explaining this disclosure and are not intended to limit this disclosure.

[0038] In the description of this disclosure, 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 disclosure and simplifying the description, and are not intended to 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 disclosure.

[0039] 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 features. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" 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 disclosure according to the specific circumstances.

[0041] In this disclosure, 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 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 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.

[0042] The following disclosure provides numerous different embodiments or examples for implementing various structures of this disclosure. 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 disclosure. Furthermore, at least one of the reference numerals and 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 arrangements discussed. In addition, various specific examples of processes and materials are provided in this disclosure, but those skilled in the art will recognize at least one of other processes and materials used.

[0043] As shown in Figures 1 and 2, in this embodiment of the present disclosure, a back-contact battery assembly includes a battery string 100, which includes at least a first battery cell 101 and a second battery cell 102 arranged sequentially along a first direction. It is understood that the battery string 100 may include two battery cells connected in series, three battery cells connected in series, or a greater number of battery cells. The specific number of battery cells to be connected in series can be determined according to the actual usage, and this disclosure does not impose any limitations on this. Furthermore, the grid lines on the battery cells are not shown in the figures. The grid lines on the battery cells can be arranged according to the actual situation; for example, they can be on battery cells with main grids or on battery cells without main grids. Understandably, when the battery cell is a cell with a main grid, a first main grid line is set on the first battery cell 101 at the position corresponding to the first solder strip 200, and a corresponding second main grid line is set on the second battery cell 102 at the position corresponding to the second solder strip 300; when the battery cell is a cell without a main grid, a corresponding welding point can be set on the first battery cell 101 at the position corresponding to the first solder strip 200, and a corresponding welding point can be set on the second battery cell 102 at the position corresponding to the second solder strip 300.

[0044] The first battery cell 101 is located at the end of the battery string 100. For ease of explanation, in this embodiment, the end where the first battery cell 101 is located is referred to as the tail end of the battery string 100. That is, in the first direction, the first battery cell 101 is the last battery cell of the battery string 100, and the second battery cell 102 is the penultimate battery cell of the battery string 100. It is easy to understand that the end where the first battery cell 101 is located can also be referred to as the head end of the battery string 100, in which case the second battery cell 102 is the second positive battery cell of the battery string 100. This will not be elaborated further here. It should be noted that when the first battery cell 101 is located at the tail end of the battery string 100, the first busbar 400 can be used for series connection between adjacent battery strings 100 in the second direction; when the first battery cell 101 is located at the head end of the battery string 100, the first busbar 400 can be used for parallel connection between adjacent battery strings 100 in the first direction. In this case, the first busbar 400 is equivalent to the intermediate busbar in the battery assembly.

[0045] In some embodiments, a first solder strip 200 is disposed on the backlight surface of a first battery cell 101, a second solder strip 300 is disposed on the backlight surface of a second battery cell 102, a first busbar 400 is disposed on the backlight surface of a second battery cell 102, and a first insulating strip 500 is disposed between the first busbar 400 and the second battery cell 102. The first insulating strip 500 is used to isolate the second solder strip 300 and the first busbar 400. Both the first insulating strip 500 and the first busbar 400 extend along a second direction, and the first direction and the second direction are intersected. Firstly, in this embodiment, the first busbar 400 is disposed on the second battery cell 102, and the first busbar 400 and the second battery cell 102 are separated by a first insulating strip 500. On the one hand, the edge of the back contact battery assembly no longer needs to reserve space for placing the busbar, and the battery assembly can reserve more space to install the battery cell, so that the effective light-receiving area of ​​the battery assembly is larger and the conversion efficiency of the assembly is higher. On the other hand, when viewed from the light-receiving surface (or "front") of the battery cell, the first insulating strip 500 can block the first busbar 400, preventing the first busbar 400 from being exposed, and the overall aesthetics of the battery assembly are better.

[0046] Secondly, compared to when the first busbar 400 is placed on the back of the first battery cell 101, as a possible scenario, the first solder strip 200 cannot be soldered to the first battery cell 101 at the position covered by the first busbar 400, resulting in insufficient soldering between the first solder strip 200 and the first battery cell 101 and poor current collection. In this embodiment, the first busbar 400 is disposed on the backlight surface of the second battery cell 102. The first solder ribbon 200 can fully adhere to and weld with the effective welding position of the first battery cell 101, avoiding insufficient welding between the first solder ribbon 200 and the first battery cell 101 due to the installation of the first busbar 400, which would affect the current collection. At the same time, after the first solder ribbon 200 is welded to the first battery cell 101, it can be directly connected to the first busbar 400 without the need to open the insulating strip (first insulating strip 500). During assembly, only the first insulating strip 500 needs to be placed on the second battery cell 102 as a whole, which effectively reduces the production precision requirements and production difficulty, and can avoid short circuits caused by positional displacement when the insulating strip (first insulating strip 500) is opened, thereby increasing the product yield. Preferably, the first busbar 400 is disposed at the end of the second battery cell 102 near the first battery cell 101. In this way, the extension 202 (as shown in Figure 3) can be electrically connected to the first busbar 400 by extending to the edge of the second battery cell 102 near the first battery cell 101. This reduces the extension length of the extension 202 of the first solder strip 200, saves solder strip material, and thus reduces costs. Since the first solder strip 200 needs to be isolated from the second battery cell 102, the width requirement of the first insulating strip 500 is also reduced. The first insulating strip 500 only needs to insulate the edge area of ​​the second battery cell 102.

[0047] In this embodiment of the disclosure, the first direction is the horizontal direction, which is also the width direction of the battery cell, and the second direction is the vertical direction, which is also the length direction of the battery cell. The first direction and the second direction are perpendicular to each other.

[0048] As shown in Figure 3, in this embodiment of the present disclosure, the first solder strip 200 includes a main body segment 201 electrically connected to the first battery cell 101 and an extension segment 202 electrically connected to the first busbar 400. In a second direction, the extension segment 202 and the second solder strip 300 are spaced apart; in a first direction, the main body segment 201 and the second solder strip 300 are collinearly arranged. That is, the extension segment 202 of the first solder strip 200 is staggered relative to the main body segment 201, so that the extension segment 202 extending to the second battery cell 102 does not overlap with the second solder strip 300 on the second battery cell 102 in the thickness direction of the first busbar 400. This avoids the problem of excessive stress caused by partial overlap of the extension segment 202 and the second solder strip 300 on the first busbar 400, reducing the risk of microcracks in the battery cell during the lamination process. Furthermore, the collinear arrangement of the main body segment 201 and the second solder strip 300 in the first direction makes the solder strip wiring simpler and clearer, reducing wiring difficulty and complexity.

[0049] Understandably, due to existing manufacturing processes (such as process errors), the main body segment 201 and the second solder strip 300 may not be geometrically collinear. For example, the main body segment 201 and the second solder strip 300 may be misaligned by within 1 mm along the length of the first busbar 400, or the main body segment 201 may have a small angle (e.g., 0.5°) of inclination relative to the second solder strip 300, which can also be considered as collinearity. The electrical connection method may be welding, bonding with conductive adhesive, etc., but is not limited to these.

[0050] This disclosure allows the first busbar to be concealed on the back surface of the solar cell, increasing the effective light-receiving area of ​​the solar module, improving module conversion efficiency, and enhancing the overall aesthetics of the solar module. Furthermore, since the first busbar is located on the second solar cell, it ensures that the first solder strip can fully adhere to and weld with the effective welding position of the first solar cell, preventing insufficient welding between the first solder strip and the first solar cell that could affect current collection. During assembly, a first insulating strip is placed between the second solar cell and the first busbar for isolation. The first insulating strip does not require holes or additional openings. The arrangement greatly simplifies the processing and installation of the first insulating strip. At the same time, by setting the first welding strip as an extension segment and electrically connecting it to the first busbar, and by setting the extension segment and the second welding strip alternately in the second direction, a certain degree of offset of the first insulating strip in the first direction can be allowed during the manufacturing process, which effectively reduces the production accuracy requirements and production difficulty, and can effectively reduce the risk of short circuit. Furthermore, due to the staggered arrangement of the extension segment and the second welding strip, the stacking height is reduced, and the stress during lamination is smaller, which can reduce the risk of microcracks and fragmentation of the battery cells, and improve the reliability of the back contact battery module.

[0051] As shown in Figure 3, the first solder strip 200 further includes a connecting segment 203, which connects the main body segment 201 and the epitaxial segment 202. The connecting segment 203 enables electrical conduction between the main body segment 201 and the epitaxial segment 202, allowing the main body segment 201 to transfer charge carriers on the first battery cell 101 through the connecting segment 203 to the epitaxial segment 202 and then into the first busbar 400, thus completing the collection of charge carriers on the first battery cell 101. Preferably, the back contact battery assembly satisfies at least one of the following: the main body segment 201 and the connecting segment 203 are smoothly connected; the epitaxial segment 202 and the connecting segment 203 are smoothly connected. More specifically, in this embodiment of the present disclosure, the main body segment 201 and the connecting segment 203 are smoothly connected, and the extension segment 202 and the connecting segment 203 are also smoothly connected. The connecting segment 203 is bent relative to the main body segment 201, and the extension segment 202 is bent relative to the connecting segment 203. This is equivalent to the first welding strip 200 being continuously bent to form the connecting segment 203 and the extension segment 202. The first welding strip 200 is prone to stress concentration at the bending point, and the smooth transition design can effectively disperse these stresses, reducing the risk of the first welding strip 200 breaking or falling off due to stress concentration. The smoothly transitioned connection part has better appearance and can improve the overall visual effect and texture of the product.

[0052] The first welding strip 200, which has a main body segment 201, a connecting segment 203, and an extension segment 202, can be formed by integrally stamping a single welding strip, or it can be formed by splicing multiple welding strips together. This disclosure does not impose any limitations on this. Preferably, the first welding strip 200 is integrally stamped, which eliminates redundant processes such as welding during its manufacture, reduces labor costs, and avoids issues such as incomplete welds and burrs caused by manual welding.

[0053] In this embodiment, the connecting segment 203 has a line segment or bend shape. This is not specifically limited in this disclosure; it is sufficient that the extension segment 202 and the second welding strip 300 are spaced apart along the length of the first busbar 400. Preferably, the connecting segment 203 is a straight line segment structure to avoid strength reduction caused by repeated bending of the welding strip, which could easily lead to breakage or detachment.

[0054] As shown in Figure 4, in other embodiments, a first insulating strip 500 is disposed between the first busbar 400 and the second battery cell 102. The first insulating strip 500 is used to isolate the second solder ribbon 300 and the first busbar 400. Since the first solder ribbon 200 has a portion extending to the second battery cell 102, it can be understood that the first insulating strip 500 is also used for isolation between the first solder ribbon 200 and the second battery cell 102. Specifically, the first insulating strip 500 may be disposed at the end of the second battery cell 102 near the first battery cell 101. Optionally, the first insulating strip 500 may cover the edges of the second battery cell 102 and the first battery cell 101. This allows for a certain degree of offset in the width direction of the first insulating strip 500 relative to the first busbar 400 and relative to the two battery cells during the manufacturing process, reducing the requirements for production precision and the difficulty of production. On the other hand, it can avoid short circuits caused by contact between the first busbar 400 and the irregular solder strip (or irregular grid line) on the first battery cell 101, as well as short circuits caused by contact between the first solder strip 200 and the irregular solder strip (or irregular grid line) on the second battery cell 102, and short circuits that are easily caused by conductive foreign matter such as solder dross during the manufacturing process, further reducing the risk of short circuits and improving the reliability of the battery module.

[0055] In contrast, the first solder strip 200 in this embodiment can be applied to both battery modules with and without main grid back contact, making it more versatile. Furthermore, the first busbar 400 is located at the end of the second cell 102 near the first cell 101, which results in less stress during lamination compared to the outer edge of the first cell 101. This reduces the risk of fragmentation and cracking, further improving the reliability of the battery module.

[0056] For example, the thickness of the first busbar 400 can be between 0.06 mm and 0.3 mm, and the width can be between 8 mm and 20 mm. The material of the first busbar 400 can be tin-plated copper busbar, conductive copper foil, or aluminum-based copper strip.

[0057] For example, the first insulating strip 500 may be an insulating adhesive, or a non-conductive tape or insulating film, such as a PET or PI tape with acrylic or silicone, or a PET or PI substrate coated with ethylene-vinyl acetate copolymer or hot melt adhesive on one or both sides. It is understood that the first insulating strip 500 may contain one of the following materials: ethylene-vinyl acetate copolymer, resin material, polyimide, polypropylene or polyethylene, and may also contain an acrylic adhesive layer.

[0058] It should be noted that the thickness of the first insulating strip 500 cannot be too thick or too thin. If the first insulating strip 500 is too thin, it is inconvenient to apply, easily deformed by pulling, and there is a risk of breakage during long-term insulation. If it is too thick, it will increase the height difference, generate greater stress during the lamination process, easily cause fragmentation, and increase the risk of poor soldering. Based on this, in this embodiment, the thickness of the first insulating strip 500 can be set between 0.05 mm and 0.8 mm. In this way, the first insulating strip 500 is neither too thin nor too thick. For example, the thickness of the first insulating strip 500 can be one of 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, and 0.8 mm.

[0059] The width of the first insulating strip 500 is greater than or equal to the width of the first busbar 400. If the width of the first insulating strip 500 is too narrow, the first busbar 400 will be exposed, posing a risk of short circuit due to contact between the first busbar 400 and the dissimilar electrode area or dissimilar solder strip.

[0060] Furthermore, there are multiple first solder ribbons 200, which are spaced apart along the second direction on the backlight surface of the first battery cell 101. There are also multiple second solder ribbons 300, which are spaced apart along the second direction on the backlight surface of the second battery cell 102. The multiple first solder ribbons 200 and the multiple second solder ribbons 300 are arranged in a one-to-one correspondence.

[0061] In the second direction, the connecting segment 203 is bent relative to the main body segment 201. Specifically, an angle is formed between the main body segment 201 and the connecting segment 203, which limits the bending direction of the connecting segment 203, so that the connecting segment 203 makes way for the second welding strip 300 when it bends. The angle formed between the main body segment 201 and the connecting segment 203 can be selected according to actual needs, and will not be described in detail here.

[0062] Further, the bending angle of the connecting segment 203 relative to the main body segment 201 is greater than or equal to 10° and less than or equal to 70°. Preferably, the bending angle of the connecting segment 203 relative to the main body segment 201 is greater than or equal to 30° and less than or equal to 60°. In such embodiments, the bending angle of the connecting segment 203 relative to the main body segment 201 can be any value between 30° and 60°. For example, the bending angle of the connecting segment 203 relative to the main body segment 201 can be 30°, 40°, 50°, or 60°, and there is no specific limitation here. When the bending angle of the connecting segment 203 relative to the main body segment 201 is within this range, the metal material of the first welding strip 200 will not reduce its strength due to excessive deformation, and it can be more easily and precisely processed by mechanical or automated equipment. The first welding strip 200 can be bent to the required curvature using less force, thereby improving production efficiency.

[0063] In this embodiment of the present disclosure, the back contact battery assembly satisfies at least one of the following: there are multiple first solder strips 200, and in a second direction, the connecting segments 203 of the multiple first solder strips 200 are all bent toward the first side of the main body segment 201; the connecting segments 203 of the multiple first solder strips 200 are all bent toward the second side of the main body segment 201; a portion of the connecting segments 203 of the multiple first solder strips 200 are bent toward the first side of the main body segment 201, and another portion of the connecting segments 203 of the multiple first solder strips 200 are bent toward the second side of the main body segment 201, with the first side and the second side opposite to each other. That is, the connecting segments 203 of the multiple first solder strips 200 can be arranged in the same direction or in different directions relative to the main body segment 201, and the bending direction of the connecting segments 203 of the first solder strips 200 relative to the main body segment 201 of the first solder strips 200 can be selected according to actual needs to adapt to different process equipment and production processes.

[0064] In some embodiments, the epitaxial segment 202 and the second solder strip 300 are arranged in parallel. This ensures that the epitaxial segment 202 and the second solder strip 300 are independent of each other in the extension direction. Even if the length of the epitaxial segment 202 is long, it can be ensured that the epitaxial segment 202 and the second solder strip 300 do not overlap in the thickness direction of the first busbar 400, and are distributed to avoid microcracks in the battery cell caused by local stress concentration in the module. Preferably, the spacing between the epitaxial segment 202 and the second solder strip 300 satisfies: 1mm≤L1≤1 / 2D, where L1 is the spacing between the epitaxial segment 202 and the second solder strip 300 in the second direction, and D is the distance between two adjacent second solder strips 300. The spacing between the epitaxial segment 202 and the second solder strip 300 within this range can fully ensure that the epitaxial segment 202 and the second solder strip 300 do not overlap or coincide in the length direction of the first busbar 400, achieving the effect of local stress dispersion in the battery module.

[0065] In some embodiments, the extension direction of the epitaxial segment 202 intersects the extension direction of the second solder strip 300. That is, the extension direction of the epitaxial segment 202 can be flexibly set, allowing for a large margin of error during the processing and installation of the first solder strip 200. The extension direction of the epitaxial segment 202 can be flexibly adjusted according to actual needs, thereby achieving the spacing between the epitaxial segment 202 and the second solder strip 300. Preferably, the minimum spacing between the epitaxial segment 202 and the second solder strip 300 satisfies: 1mm ≤ L2 ≤ 1 / 2D, where L2 is the minimum spacing between the epitaxial segment 202 and the second solder strip 300 in the second direction, and D is the distance between two adjacent second solder strips 300. Within this range, the minimum spacing between the epitaxial segment 202 and the second solder strip 300 ensures that the epitaxial segment 202 and the second solder strip 300 are completely non-overlapping or do not coincide along the length of the first busbar 400, achieving the effect of local stress dispersion in the battery module.

[0066] In some embodiments, the first battery cell 101 and the second battery cell 102 are disposed on the same plane, and the first battery cell 101 and the second battery cell 102 are spaced apart. This provides a buffer space between the battery cells, preventing them from contacting each other and being damaged when the battery assembly is subjected to external forces.

[0067] Specifically, the spacing between the first battery cell 101 and the second battery cell 102 is greater than or equal to 0 and less than or equal to 3 mm. In this embodiment, the spacing between the first battery cell 101 and the second battery cell 102 can be any value between 0 and 3 mm. For example, the spacing between the first battery cell 101 and the second battery cell 102 can be 0 mm, 1 mm, 2 mm, or 3 mm, and there is no specific limitation here. Within this range, while reducing the risk of battery cell merging, it also prevents the overall length of the battery string 100 from becoming too long, thus improving the stability of the connection between adjacent battery cells.

[0068] In some embodiments, in a first direction, the first battery cell 101 and the second battery cell 102 are partially overlapped. The contact areas between these overlaps are not electrically connected; that is, no conductive adhesive or other bonding agent is needed between the overlapping areas. The battery cells are simply overlapped. Thus, there is no gap between the first battery cell 101 and the second battery cell 102, allowing for better concealment of the series solder ribbons. There is no need to use a shielding insulating layer to hide the series solder ribbons in the gaps between the battery cells, thereby reducing the use of shielding insulating layers, lowering production costs, and simplifying rework. Furthermore, the overlapping arrangement of the battery cells allows for a smaller size of the battery string 100, resulting in a smaller footprint. In other words, with a fixed size for the battery string 100, more battery cells can be placed, increasing the power of the battery string 100 and reducing the cost per watt. Preferably, the partial overlap distance between the first battery cell 101 and the second battery cell 102 is greater than 0 and less than or equal to 1.5 mm. For example, the overlap width can be one of 0 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.5 mm, 1 mm, or 1.5 mm, and this disclosure does not limit it.

[0069] As shown in Figure 5, the back-contact battery assembly also includes a third solder strip 600. Along a first direction, the third solder strip 600 extends from the first battery cell 101 to the second battery cell 102, connecting the first battery cell 101 and the second battery cell 102. Specifically, a portion of the third solder strip 600 is disposed on the first battery cell 101, and another portion of the third solder strip 600 is disposed on the second battery cell 102. Exemplarily, the third solder strip 600 can be used to achieve a series connection between the first battery cell 101 and the second battery cell 102. Understandably, the extension segment 202 and the other portion of the third solder strip 600 disposed on the second battery cell 102 do not overlap. Along the length direction of the first busbar 400, the extension segment 202 of the first solder strip 200 and the other portion of the third solder strip 600 disposed on the second battery cell 102 are arranged at intervals to achieve the effect of local stress dispersion in the battery assembly. Furthermore, the portion of the third solder strip 600 located on the second solar cell 102 is isolated by the first insulating strip 500 and the first busbar 400. In this embodiment of the present disclosure, there are multiple third solder strips 600, and at least one first solder strip 200 and one second solder strip 300 are provided between two adjacent third solder strips 600 to achieve a uniform distribution of current on the solar cell.

[0070] In some embodiments, a first solder joint 700 is provided at one end of the first battery cell 101 near the second battery cell 102, and the first solder joint 700 is connected to the first solder strip 200. It can be understood that the first solder joint 700 is located at the effective welding position of the first battery cell 101 closest to the edge of the second battery cell 102 (that is, the connection point of the first solder strip 200 on the outermost edge of the first battery cell 101). The first solder joint 700 can be a grid line or a solder pad, which realizes sufficient collection of charge carriers on the first battery cell, and at the same time improves the stability of the connection between the first solder strip 200 and the first battery cell 101.

[0071] As shown in Figure 6, in some embodiments, the back-contact battery assembly includes at least two sets of battery strings 100 arranged along a second direction. Along this second direction, a first insulating strip 500 extends from one of the two sets of battery strings to the other. This allows the first insulating strip 500 to be installed in one continuous operation between at least two adjacent sets of battery strings, simplifying the assembly steps and improving the production efficiency of the battery assembly. It is understood that the back-contact battery assembly includes multiple sets of battery strings, and the first insulating strip can be installed along multiple sets of battery strings in one continuous operation. For example, if the back-contact battery assembly includes three sets of battery strings, the first insulating strip can extend from the first set of battery strings to the third set of battery strings.

[0072] A photovoltaic (PV) system includes the back-contact battery module as described above. It is understood that the PV power generation system includes at least one back-contact battery module as described above, and that the back-contact battery modules can be electrically connected in parallel or in series, depending on actual needs. In this embodiment, the PV system can be applied in PV power plants, such as ground-mounted power plants, rooftop power plants, and floating power plants, and can also be applied to equipment or devices that utilize solar energy for power generation, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it is understood that the application scenarios of the PV system are not limited to these; that is, the PV system can be applied in all fields that require solar energy for power generation. Taking a PV power generation system grid as an example, the PV system may include a PV array, a combiner box, and an inverter. The PV array may be an array combination of multiple battery modules; for example, multiple battery modules can form multiple PV arrays. The PV array is connected to the combiner box, which can collect the current generated by the PV array. The collected current flows through the inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0073] In the description of this specification, references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A back-contact battery assembly, comprising: A battery string, comprising at least a first battery cell and a second battery cell arranged sequentially along a first direction, the first battery cell being disposed at the end of the battery string; a first solder strip disposed on the backlight surface of the first battery cell; a second solder strip disposed on the backlight surface of the second battery cell; a first busbar disposed on the backlight surface of the second battery cell; and a first insulating strip disposed between the first busbar and the second battery cell, the first insulating strip being used to isolate the second solder strip and the first busbar. Both the first insulating strip and the first busbar extend along a second direction, the first direction intersecting the second direction. The first solder strip comprises a main body segment electrically connected to the first battery cell and an extension segment electrically connected to the first busbar. In the second direction, the extension segment and the second solder strip are spaced apart. In the first direction, the main body segment and the second solder strip are collinear.

2. The back contact battery assembly as claimed in claim 1, wherein, The first solder strip further includes a connecting segment, which connects the main body segment and the extension segment.

3. The back contact battery assembly as described in claim 2, wherein, The back contact battery assembly satisfies at least one of the following: the main body segment and the connecting segment are smoothly connected; the extension segment and the connecting segment are smoothly connected.

4. The back contact battery assembly as described in claim 2, wherein, In the second direction, the connecting segment is bent relative to the main body segment.

5. The back contact battery assembly as claimed in claim 4, wherein, The back contact battery assembly satisfies one of the following: the first solder strip is multiple strips, and in the second direction, the connecting segments of the multiple first solder strips are all bent toward the first side of the main body segment; the connecting segments of the multiple first solder strips are all bent toward the second side of the main body segment; a portion of the connecting segments of the multiple first solder strips is bent toward the first side of the main body segment, and another portion of the connecting segments of the multiple first solder strips is bent toward the second side of the main body segment, with the first side and the second side opposite to each other.

6. The back contact battery assembly as claimed in claim 4, wherein, The bending angle of the connecting segment relative to the main body segment is greater than or equal to 10° and less than or equal to 70°.

7. The back contact battery assembly as claimed in claim 4, wherein, The bending angle of the connecting segment relative to the main body segment is greater than or equal to 30° and less than or equal to 60°.

8. The back contact battery assembly as claimed in claim 1, wherein, The extension segment and the second welding strip are arranged in parallel.

9. The back contact battery assembly as claimed in claim 8, wherein, The distance between the extension segment and the second solder strip satisfies: 1mm≤L1≤1 / 2D, where L1 is the distance between the extension segment and the second solder strip in the second direction, and D is the spacing between two adjacent second solder strips.

10. The back contact battery assembly as claimed in claim 1, wherein, The extension direction of the outer segment intersects with the extension direction of the second welding strip.

11. The back contact battery assembly of claim 10, wherein, The minimum spacing between the extension segment and the second solder strip satisfies: 1mm≤L2≤1 / 2D, where L2 is the minimum spacing between the extension segment and the second solder strip in the second direction, and D is the spacing between two adjacent second solder strips.

12. The back contact battery assembly as claimed in claim 1, wherein, The first battery cell and the second battery cell are disposed on the same plane and are spaced apart.

13. The back contact battery assembly as claimed in claim 12, wherein, The distance between the first battery cell and the second battery cell is greater than or equal to 0 and less than or equal to 3 mm.

14. The back contact battery assembly as claimed in claim 1, wherein, In the first direction, the first battery cell and the second battery cell are partially overlapped.

15. The back contact battery assembly as claimed in claim 14, wherein, The local overlap distance between the first and second battery cells is greater than 0 and less than or equal to 1.5 mm.

16. The back contact battery assembly as claimed in claim 1, wherein, The back contact battery assembly also includes a third solder strip that extends from the first battery cell to the second battery cell along the first direction, and the third solder strip connects the first battery cell and the second battery cell.

17. The back contact battery assembly of claim 16, wherein, The third welding strip consists of multiple strips, with at least one first welding strip and one second welding strip placed between two adjacent third welding strips.

18. The back contact battery assembly as claimed in claim 1, wherein, A first solder joint is provided at one end of the first battery cell near the second battery cell, and the first solder joint is connected to the first solder strip.

19. The back contact battery assembly as claimed in claim 1, wherein, The first busbar is located at the end of the second battery cell near the first battery cell.

20. The back contact battery assembly as claimed in claim 1, wherein, The back contact battery assembly includes at least two sets of battery strings arranged along the second direction, wherein the first insulating strip extends from one of the two sets of battery strings to the other of the two sets of battery strings along the second direction.

21. A photovoltaic system comprising a back-contact battery module as described in any one of claims 1-20.

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