Photovoltaic module

Abstract

The photovoltaic module comprises a battery string, the battery string comprises a plurality of battery pieces, each battery piece is provided with a first surface and a second surface which are opposite to each other, the battery pieces comprise a first battery piece and a second battery piece which are adjacent to each other, and the edges of the first battery piece and the second battery piece are mutually overlapped to form an overlapped area; the battery string further comprises a welding strip, and the welding strip comprises a first welding strip used for connecting the first surface of the first battery piece and the second surface of the second battery piece. The battery string further comprises a covering film, the covering film is laid on the surfaces of the battery pieces and at least covers part of the welding strip, and the covering film comprises a first covering film laid on the first surface of the first battery piece and a second covering film laid on the second surface of the second battery piece. The first covering film or the second covering film at least partially extends to the overlapping area in the second direction, and a gap is formed between the first covering film and the second covering film in the second direction. In the embodiment of the invention, the hidden crack risk of the battery piece can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and in particular to a photovoltaic module. Background Art

[0002] In the stacked assembly, the cells are arranged in an overlapping manner and connected into cell strings through a first welding ribbon, so that more cells can be arranged in a limited area, thereby improving the utilization of the space area and the power generation capacity of the assembly.

[0003] For a cell having electrodes on both the first and second surfaces, a first welding ribbon connects the first surface electrode of the preceding cell and the second surface electrode of the following cell, and the first welding ribbon passes through the overlapping area of ​​two adjacent cells.

[0004] However, during the hot pressing welding or lamination process, stress is concentrated in the overlapping area of ​​two adjacent battery cells, especially at the contact point between the first welding ribbon and the battery cell in the overlapping area, and the battery cell is prone to hidden cracks. Summary of the Invention

[0005] The present invention provides a photovoltaic module, aiming to at least solve the technical problem that in a stacked module, stress concentration occurs in the overlapping area of ​​two adjacent cells, especially at the contact point between the first welding strip and the cell in the overlapping area, which makes the cell prone to hidden cracks.

[0006] An embodiment of the present invention provides a photovoltaic module, comprising a plurality of cell strings arranged along a first direction, each of the cell strings comprising a plurality of cell slices arranged along a second direction, each cell slice having a first surface and a second surface disposed opposite to each other, the cell slices comprising a first cell slice and a second cell slice disposed adjacent to each other, edges of the first cell slice and the second cell slice overlapping to form an overlapping region; the first direction is perpendicular to the second direction; The battery string further includes a welding ribbon, wherein the welding ribbon includes a first welding ribbon for connecting the first surface of the first battery cell and the second surface of the second battery cell; The battery string also includes a covering film, which is laid on the surface of the battery cell and covers at least a portion of the welding ribbon. The covering film includes a first covering film laid on the first surface of the first battery cell and a second covering film laid on the second surface of the second battery cell; the first covering film or the second covering film extends at least partially to the overlapping area in the second direction, and the first covering film and the second covering film have a gap in the second direction.

[0007] Optionally, the gap is located outside the overlapping area.

[0008] Optionally, the first covering film of the first battery cell extends to the overlapping region, and an extending end of the second covering film of the second battery cell is located outside the overlapping region.

[0009] Optionally, in the second direction, a size of the first covering film is larger than a size of the second covering film.

[0010] Optionally, the thickness of the first coating is greater than the thickness of the second coating.

[0011] Optionally, an extended end of the first covering film of the first battery cell at least partially exceeds the overlapping area in the second direction.

[0012] Optionally, the first surface and the second surface of the battery cell are provided with a plurality of solder pads arranged at intervals along the second direction, the first solder strip is electrically connected to the solder pads, the solder pads include edge solder pads near the overlapping area, and the extended end of the second coating of the second battery cell is located between the edge solder pad of the second battery cell and the edge of the first battery cell.

[0013] Optionally, an end portion of the soldering ribbon connected to the second surface of the first battery cell is located outside the overlapping area, and an end portion of the soldering ribbon connected to the first surface of the second battery cell is located outside the overlapping area.

[0014] Optionally, an end of the first covering film of the first cell, which is away from the overlapping area of ​​the first cell and the second cell, is located between an edge pad of the first cell and an edge of the first cell; And / or, an extended end of the second cover film of the second cell facing away from the overlapping area of ​​the first cell and the second cell is located between the edge pad of the second cell and the edge of the second cell.

[0015] Optionally, both the first surface and the second surface of the cell have a plurality of fine grid electrodes; The fine gate electrode includes an edge fine gate electrode close to the edge of the cell, and the first covering film of the first cell covers the edge fine gate electrode on the first surface of the first cell.

[0016] Optionally, the material of the first coating is different from the material of the second coating.

[0017] Optionally, the first surface is the backlight surface of the battery cell, and the second surface is the light-receiving surface of the battery cell.

[0018] Optionally, the first welding strip includes a flat portion located at the overlapping area, such that along the second direction, the length of the flat portion is L, the width of the overlapping area is W, and L is greater than W.

[0019] Optionally, the flat portion includes a first sub-portion located on the first battery cell and a second sub-portion connected to the first sub-portion; The first covering film of the first battery cell at least covers a portion of the first sub-portion, and the second covering film of the second battery cell covers a portion of the second sub-portion.

[0020] Optionally, the first welding strip further includes a main body portion, and the cross-sectional shape of the main body portion is circular; The thickness of the first coating and the second coating is smaller than the diameter of the main body; And / or the thickness of the first coating and the second coating is greater than or equal to the thickness of the flat portion.

[0021] Optionally, the size of the battery cell in the first direction is 182 mm to 210 mm, and the size of the battery cell in the second direction is 53 mm to 210 mm; The diameter of the main body is 0.18mm-0.26mm.

[0022] Optionally, the flat portion has a first end located on the second surface of the second battery cell and a second end located on the first surface of the first battery cell, so that along the second direction, the distance between the first end of the flat portion and the first battery cell is D3, and the distance between the second end of the flat portion and the second battery cell is D4, and D4<D3.

[0023] Optionally, both the first surface and the second surface of the battery cell are provided with edge pads close to the overlapping region, and the number of the edge pads located in the overlapping region is 0.

[0024] Optionally, both the first surface and the second surface of the cell have a plurality of fine grid electrodes; Along the thickness direction of the battery cell, the orthographic projection of a single flat portion overlaps with the orthographic projections of y fine grid electrodes, where y is 3-6.

[0025] Optionally, both the first surface and the second surface of the cell have a plurality of fine grid electrodes; m1 fine gate electrodes on the first surface of the first cell are located in the overlapping region, and m2 fine gate electrodes on the second surface of the second cell are located in the overlapping region, where m1+m2≤2.

[0026] Optionally, m1 is 0 and m2≤1.

[0027] Optionally, the width of the overlapping area is greater than or equal to 0.2 mm and less than or equal to 2 mm.

[0028] In an embodiment of the present invention, the first coating or the second coating at least partially extends to the overlapping area in the second direction. The coating extending to the overlapping area acts as a buffer during lamination, which can reduce the stress of the first welding strip on the battery cell in the overlapping area, thereby reducing the risk of hidden cracks in the battery cell in the overlapping area.

[0029] In an embodiment of the present invention, the first coating or the second coating extends at least partially to the overlapping area in the second direction, and the first coating and the second coating have a gap in the second direction. The setting of the gap can prevent the first coating and the second coating from overlapping in the overlapping area, thereby preventing the height difference between the two battery cells in the overlapping area from increasing, thereby further reducing the risk of hidden cracks in the battery cells in the overlapping area.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a portion of the structure of a photovoltaic module provided by an embodiment of the present invention; Figure 2 Schematic diagram of a partial structure of a battery string in a photovoltaic module provided by an embodiment of the present invention Figure 1 ; Figure 3 Schematic diagram of a partial structure of a battery string in a photovoltaic module provided by an embodiment of the present invention Figure 2 ; Figure 4 A partial schematic diagram of the stacking of the first and second battery cells in a battery string according to an embodiment of the present invention Figure 1 ; Figure 5 A partial schematic diagram of the stacking of the first and second battery cells in a battery string according to an embodiment of the present invention Figure 2 ; Figure 6 A schematic top view of a portion of a battery string structure provided by an embodiment of the present invention; Figure 7 for Figure 6 A magnified schematic diagram of point A in the middle; Figure 8 A schematic top view of a first battery cell and a second battery cell in a battery string provided by an embodiment of the present invention; Figure 9 A schematic side view of the first welding strip provided in an embodiment of the present invention; Figure 10 A schematic top view of the first welding strip provided in an embodiment of the present invention; Figure 11 A partial schematic diagram of the stacking of the first cell and the second cell before heating the coating provided by an embodiment of the present invention.

[0032] Reference numerals: 10-battery cell, 11-edge pad, P1-first battery cell, P2-second battery cell; 20-first welding strip, 21-flat portion, 22-main portion, 221-first main portion, 222-second main portion, 23-transition portion; 30-first coating, 40-second coating. DETAILED DESCRIPTION

[0033] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0034] Reference Figures 1 to 7 The embodiment of the present invention provides a photovoltaic module, referring to the attached Figure 1 The photovoltaic module includes a plurality of battery strings arranged along a first direction, each battery string includes a plurality of battery cells 10 arranged along a second direction, Figure 2 , Attachment Figure 3 The battery cell 10 includes a first battery cell P1 and a second battery cell P2 arranged adjacent to each other, and the edges of the first battery cell P1 and the second battery cell P2 overlap with each other to form an overlapping area; the first direction is perpendicular to the second direction; each battery cell 10 has a first surface and a second surface arranged opposite to the first surface, and the battery string also includes a welding ribbon, which includes a first welding ribbon 20 for connecting the first surface of the first battery cell P1 and the second surface of the second battery cell P2; the battery string also includes a covering film, which is laid on the surface of the battery cell 10 and covers at least part of the welding ribbon, and the covering film includes a first covering film 30 laid on the first surface of the first battery cell P1 and a second covering film 40 laid on the second surface of the second battery cell P2; the first covering film 30 or the second covering film 40 extends at least partially to the overlapping area in the second direction, and the first covering film 30 and the second covering film 40 have a gap in the second direction.

[0035] The first direction can refer to Figure 1 and Figure 6 The direction indicated by the arrow F in the middle, the second direction can refer to Figure 1 、 Figure 4 、 Figure 5 、 Figure 6 and Figure 8 The direction is indicated by the arrow E in FIG. The battery string may include an odd number of battery cells 10 or an even number of battery cells 10. The length direction of the battery cell 10 may be consistent with the first direction.

[0036] Cell 10 is a bifacial cell, such as a TOPcon (Tunnel Oxide Passivating Contacts) cell and a heterojunction cell, with the positive and negative electrodes located on a first surface of cell 10 and a second surface opposite the first surface, respectively. Cell 10 can be a busbarless cell, meaning that cell 10 has a fine grid electrode and eliminates the busbars, saving on the slurry consumed by the busbars and thus reducing module costs. Cell 10 can also be a busbar-equipped cell. Cell 10 can be a full cell, a half cell, a third cell, or a quarter cell.

[0037] The overlapping area is a long strip area extending along the length direction of the battery cell 10. An overlapping area can refer to Figure 7 The number of cells 10 in the battery string is x, and the number of overlapping areas in the battery string is x-1. From the beginning of the battery string to the end of the string, multiple cells 10 are arranged in an overlapping manner. The direction from the beginning of the battery string to the end of the string can be referred to as Figures 1 to 6 、 Figure 8 The arrow in C shows the direction.

[0038] Reference Figure 2 and Figure 4 , the first surface of the cell 10 can be the light-receiving surface, and the corresponding second surface can be the backlight surface. Figure 3 and Figure 5 The first surface of the cell 10 can also be the backlight surface, and the corresponding second surface can be the light-receiving surface. The direction of the light-receiving surface of the photovoltaic module pointing to the backlight surface can be referred to Figure 2 and Figure 4 The direction indicated by the arrow B. The first cell P1 may be the first cell, and the second cell P2 may be the second cell in the battery string. The first cell P1 may also be the last cell, and the second cell P2 may be the second-to-last cell in the battery string.

[0039] The first cover film 30 covers at least the portion of the first welding ribbon 20 connected to the first surface of the first cell P1, and the second cover film 40 covers at least the portion of the first welding ribbon 20 connected to the second surface of the second cell P2. The first and second covers 30, 40 can be made of EVA (ethylene-vinyl acetate copolymer) or POE (polyolefin elastomer). The material of the first cover film 30 can be different from that of the second cover film 40. The gap between the first and second covers 30, 40 in the second direction can be located outside the overlapping region, within the overlapping region, or partially within the overlapping region and partially outside the overlapping region.

[0040] During the battery string preparation process, after the first and second covering films 30, 40 are laid, they need to be cured to adhere to the battery cells 10 and pre-fix the first welding ribbon 20. The curing process can be achieved by heating.

[0041] During the production of photovoltaic modules, the front glass, front adhesive film, cell strings arranged on the front film, back adhesive film, and backsheet are typically laid out in sequence. This stack is then heated and pressured, a process known as lamination. During the lamination process, the temperature melts the tin layer on the surface of the solder ribbon, forming a metallized contact with the solder pads of the cell 10 and enabling soldering. This effectively avoids the increased soldering failure rate associated with traditional high-temperature soldering. The adhesive film can be made of EVA, POE, or EPE (expanded polyethylene). The front glass can be tempered, semi-tempered, or patterned glass. The backsheet can be white or glass.

[0042] In an embodiment of the present invention, the first coating 30 or the second coating 40 at least partially extends to the overlapping area in the second direction. The coating extending to the overlapping area acts as a buffer during lamination, which can reduce the stress of the first welding strip 20 on the battery cell 10 in the overlapping area, thereby reducing the risk of hidden cracks in the battery cell 10 in the overlapping area.

[0043] If the first cover film 30 and the second cover film 40 are stacked together in the overlapping region, the height difference between the two battery cells 10 in the overlapping region includes the height of the first cover film 30, the first welding ribbon 20, and the second cover film 40, which will result in a large height difference between the two battery cells 10 in the overlapping region. In this embodiment of the present invention, the first cover film 30 or the second cover film 40 extends at least partially into the overlapping region in the second direction, and a gap is formed between the first cover film 30 and the second cover film 40 in the second direction. The provision of this gap can prevent the height difference between the two battery cells 10 in the overlapping region from increasing due to the stacking of the first cover film 30 and the second cover film 40 in the overlapping region, thereby further reducing the risk of hidden cracks in the battery cells 10 in the overlapping region.

[0044] The battery string also includes second welding ribbons connected to the beginning and end of the string. The second welding ribbon connected to the beginning of the string is used to connect the first battery cell 10 in the battery string to the bus bar, and the second welding ribbon connected to the end of the string is used to connect the last battery cell 10 in the battery string to the bus bar.

[0045] During the preparation of the battery string, several second films 40 are first placed on the conveyor belt at intervals, and then the second welding ribbon is placed on the first second film 40, and then the first battery cell 10 is placed on the second welding ribbon, so that the second film 40 adheres the second welding ribbon to the second surface of the first battery cell 10; then, the first welding ribbon 20 is placed, and the first welding ribbon 20 is partially located on the first surface of the first battery cell and partially located on the second second film 40. After that, the first covering film 30 is placed on the first surface of the first battery cell 10, and then the second battery cell 10 is placed so that the edge of the second battery cell 10 overlaps the first battery cell 10. Then, the above steps of placing the first welding ribbon 20, the first covering film 30, and the battery cell 10 are repeated until the last battery cell 10 is placed, and then the second welding ribbon is placed on the first surface of the last battery cell 10, and the last first covering film 30 is placed on the first surface of the last battery cell 10.

[0046] It should be noted that during the battery string preparation process, the battery cells 10 are placed with the first surface of the battery cells 10 facing upward. After the first covering film 30 is placed, a pressing screen is placed on the first covering film 30. This allows the pressing screen to apply pressure to the covering film during subsequent curing, thereby better attaching the solder ribbon to the surface of the battery cell 10.

[0047] In some embodiments, reference Figure 4 and Figure 5 The gap is located outside the overlapping area. On the one hand, the back film or the front film can flow into the gap during lamination to avoid bubbles and improve water vapor sealing. On the other hand, it can prevent the coating that should not extend to the overlapping area from accidentally entering the overlapping area due to process errors.

[0048] In some embodiments, reference Figure 4 and Figure 5 The first covering film 30 of the first cell P1 extends into the overlapping region, while the extended end of the second covering film 40 of the second cell P2 is located outside the overlapping region. This means that the second covering film 40 does not extend into the overlapping region in the second direction. In the aforementioned battery string manufacturing process, several second covering films 40 are pre-placed on the conveyor belt, making it difficult to extend the second covering films 40 into the overlapping region. Therefore, positioning the extended end of the first covering film 30 of the first cell P1 within the overlapping region facilitates manufacturing.

[0049] In some embodiments, reference Figure 2 and Figure 3In the second direction, the first covering film 30 is larger than the second covering film 40. Based on the above-mentioned battery string manufacturing process, several second covering films 40 are pre-placed on the conveyor belt. The first covering film 30 of the previous battery cell 10 is laid first, and then the next battery cell 10 is stacked. The first covering film 30 is relatively larger in the second direction, while the second covering film 40 is relatively smaller in the second direction, which facilitates the manufacturing process.

[0050] In some embodiments, the thickness of the first coating 30 is greater than the thickness of the second coating 40. When designing the thickness of the first coating 30, it is necessary to consider both the pre-fixation of the soldering ribbon and the cushioning effect during lamination. When designing the thickness of the second coating 40, it is only necessary to consider the pre-fixation effect of the soldering ribbon, not the cushioning effect during lamination. Therefore, the thickness of the second coating 40 can be made thinner than that of the first coating 30 to reduce the cost of the second coating 40.

[0051] In some embodiments, reference Figure 4 and Figure 5 The extended end of the first covering film 30 of the first battery cell P1 at least partially exceeds the overlapping area in the second direction to prevent the edge of the second battery cell P2 from directly contacting the first welding ribbon 20 and easily causing lamination cracks.

[0052] Along the second direction, the distance between the extended end of the first covering film 30 of the first cell P1 and the edge of the second cell P2 close to the first cell P1 is D1, and the width of the overlapping area is W, where D1 is greater than W. The difference between D1 and W can be greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0053] Reference Figure 11 Along the second direction, the distance between the extended end of the first covering film 30 of the first cell P1 before heat shrinkage and the edge of the second cell P2 close to the first cell P1 is D2, D2 is greater than W, and the difference between D2 and W is 0.4 mm-2 mm. This prevents the extended end of the first covering film 30 from shrinking and warping after heat shrinkage, thereby preventing the extended end of the first covering film 30 of the first cell P1 from exceeding the overlapping area.

[0054] In some embodiments, reference Figure 4 、 Figure 5 and Figure 8 The first surface and the second surface of the battery cell 10 are both provided with a plurality of pads arranged at intervals along the second direction, the first welding ribbon 20 is electrically connected to the pads, and the pads include an edge pad 11 near the overlapping area, and the extended end of the second covering film 40 of the second battery cell P2 is located between the edge pad 11 of the second battery cell P2 and the edge of the first battery cell P1.

[0055] The first and second surfaces of the cell 10 each have a plurality of fine grid electrodes. When the cell 10 is a busbar-less cell, the edge pads 11 are pads disposed on the fine grid electrodes. Along the second direction, the first and second surfaces of the cell 10 further have an intermediate connecting portion located between the edge pads 11 on both sides. The intermediate connecting portion can be an intermediate pad disposed on the fine grid electrode or a portion of the fine grid electrode for electrical connection to the first soldering ribbon 20.

[0056] In this embodiment, the second covering film 40 of the second battery cell P2 covers the portion of the first welding strip 20 that is used to connect to the edge pad 11 on the second surface of the second battery cell P2 near the overlapping area, so as to achieve pre-fixation of this portion. This can avoid relative displacement between the first welding strip 20 and the edge pad 11 during the layout or stringing process, resulting in failure of the connection reliability after lamination, thereby ensuring the connection reliability between the edge pad 11 and the first welding strip 20.

[0057] In some embodiments, the end of the soldering ribbon connected to the second surface of the first cell P1 is located outside the overlapping region, and the end of the soldering ribbon connected to the first surface of the second cell P2 is located outside the overlapping region.

[0058] Among them, when the first battery cell P1 is not the first battery cell or the last battery cell, the welding ribbon connected to the second surface of the first battery cell P1 is the first welding ribbon 20. When the first battery cell P1 is the first battery cell or the last battery cell, the welding ribbon connected to the second surface of the first battery cell P1 is the second welding ribbon. The same applies to the second battery cell P2. The cross-sectional shape of the end of the welding ribbon connected to the second surface of the first battery cell P1 near the overlapping area and the end of the welding ribbon connected to the first surface of the second battery cell P2 near the overlapping area are circular. The contact between this end and the battery cell 10 is prone to stress concentration. In this embodiment, this end is located outside the overlapping area, which can further reduce the risk of hidden cracks in the battery cell 10 in the overlapping area.

[0059] In some embodiments, the first covering film 30 of the first cell P1 extends away from the overlapping area of ​​the first cell P1 and the second cell P2, and is located between the edge pad 11 of the first cell P1 and the edge of the first cell P1; the second covering film 40 of the second cell P2 extends away from the overlapping area of ​​the first cell P1 and the second cell P2, and is located between the edge pad 11 of the second cell P2 and the edge of the second cell P2.

[0060] In this embodiment, the extension end of the first covering film 30 of the first battery cell P1 away from the overlapping area of ​​the first battery cell P1 and the second battery cell P2 can exceed the end of the first welding ribbon 20 on the first battery cell P1, and the extension end of the second covering film 40 of the second battery cell P2 away from the overlapping area of ​​the first battery cell P1 and the second battery cell P2 can exceed the end of the first welding ribbon 20 on the second battery cell P2.

[0061] The first covering film 30 of the first battery cell P1 covers the portion of the first welding strip 20 that is used to connect to the edge pad 11 on the first surface of the first battery cell P1 away from the overlapping area, so as to achieve pre-fixation of this portion. This can avoid relative displacement between the first welding strip 20 and the edge pad 11 during the layout or stringing process, resulting in failure of the connection reliability after lamination, so as to ensure the connection reliability between the edge pad 11 and the first welding strip 20.

[0062] The second covering film 40 of the second battery cell P2 covers the portion of the first welding strip 20 that is used to connect to the edge pad 11 on the second surface of the second battery cell P2 away from the overlapping area, so as to achieve pre-fixation of this portion. This can avoid relative displacement between the first welding strip 20 and the edge pad 11 during the layout or stringing process, resulting in failure of the connection reliability after lamination, so as to ensure the connection reliability between the edge pad 11 and the first welding strip 20.

[0063] In some embodiments, both the first surface and the second surface of the battery cell 10 have a plurality of fine gate electrodes; the fine gate electrodes include edge fine gate electrodes close to the edge of the battery cell 10, and the first covering film 30 of the first battery cell P1 covers the edge fine gate electrodes on the first surface of the first battery cell P1 to protect the edge fine gate electrodes on the first surface of the first battery cell P1 and prevent damage to the edge fine gate electrodes.

[0064] In some embodiments, the material of the first coating 30 is different from the material of the second coating 40. The coating applied to the light-receiving side of the cell 10 needs to have functions such as anti-PID (Potential Induced Degradation). Therefore, the material of the coating applied to the light-receiving side of the cell 10 is superior to the material of the coating applied to the backlight side of the cell 10. The material cost of the coating applied to the light-receiving side of the cell 10 is higher than the material cost of the coating applied to the backlight side of the cell 10.

[0065] In some embodiments, reference Figure 3 and Figure 5 The first surface is the backlight surface of the battery cell 10 , and the second surface is the light-receiving surface of the battery cell 10 .

[0066] The extended end of the first coating 30 on the backlight side of the first cell P1 is located within the overlapping region, while the extended end of the second coating 40 on the light-receiving side of the second cell P2 is located outside the overlapping region. In the second direction, the dimensions of the first coating 30 on the backlight side are larger than those of the second coating 40 on the light-receiving side. The thickness of the first coating 30 on the backlight side is greater than that of the second coating 40 on the light-receiving side. The material cost of the second coating 40 on the light-receiving side is higher than that of the first coating 30 on the backlight side. Compared to the first coating 30 on the backlight side, the second coating 40 on the light-receiving side is smaller in thickness and dimension in the second direction, thereby reducing the overall coating cost.

[0067] In some embodiments, reference Figure 2 and Figure 4 The first surface is the light-receiving surface of the battery cell 10 , and the second surface is the backlight surface of the battery cell 10 .

[0068] In some embodiments, reference Figure 4 、 Figure 5 and Figure 7 The first welding strip 20 includes a flat portion 21 located at the overlapping area, with a length of L and a width of W in the overlapping area along the second direction, where L is greater than W.

[0069] The flat portion 21 can have a rectangular cross-section, while the cross-section of the first welding ribbon 20 other than the flat portion 21 can be circular. The flat portion 21 can be formed by partially flattening a round welding ribbon. The wall thickness of the flat portion 21 is substantially uniform along the second direction.

[0070] Reference Figure 4 、 Figure 5 、 Figure 6 、 Figure 9 and Figure 10 The first welding ribbon 20 also includes a main body 22, which includes a first main body 221 and a second main body 222 respectively connected to the two ends of the flat portion 21. The first main body 221 and the second main body 222 can be connected to the flat portion 21 through a transition portion 23. The surface of the transition portion 23 can be an inclined surface or an arc surface. The first main body 221 is connected to the first surface of the first battery cell P1, and the second main body 222 is connected to the second surface of the second battery cell P2. It should be noted that Figure 9 and Figure 10 1 shows the structure of the first welding strip 20 before lamination, wherein the flat portion 21 is flat before lamination. After lamination, the shape of the flat portion 21 may be slightly deformed, but its wall thickness remains substantially uniform.

[0071] When measuring the length L of the flat portion 21, the two ends of the flat portion 21, i.e., the connection between the flat portion 21 and the two transition portions 23, are preferably greater than or equal to 3W and less than or equal to 15W. For example, if W is 0.5 mm, L is 5.1 mm or 5.5 mm.

[0072] In the embodiment of the present invention, the flat portion 21 of the first welding ribbon 20 is located in the overlapping region. The contact area between the flat portion 21 and the cell 10 is large, which can reduce stress concentration at the contact point between the first welding ribbon 20 and the cell 10 in the overlapping region, thereby reducing the risk of hidden cracks in the cell 10. L is greater than W, which can prevent the remaining portion of the first welding ribbon 20 other than the flat portion 21 from falling into the overlapping region due to process errors, thereby avoiding stress concentration at the contact point between the remaining portion of the first welding ribbon 20 and the cell 10 in the overlapping region, which can lead to hidden cracks in the cell.

[0073] In some embodiments, the second welding strip may not have a flattened portion, or may include a flattened portion having a structure different from the flat portion 21 .

[0074] In some embodiments, reference Figure 4 The flat portion 21 has a first end located on the second surface of the second battery cell P2 and a second end located on the first surface of the first battery cell P1, so that along the second direction, the distance between the first end of the flat portion 21 and the first battery cell P1 is D3, and the distance between the second end of the flat portion 21 and the second battery cell P2 is D4, and D4 is less than D3.

[0075] The difference between D3 and D4 can be greater than or equal to W and less than or equal to 3W. D4 is greater than W. When the first surface is the light-receiving surface and the second surface is the backlight surface, the first surface of the cell 10 is the primary light-receiving surface, and shading of the first surface has a greater impact on photoelectric conversion than shading of the second surface. In this embodiment, the distance between the second end of the flat portion 21 and the second cell P2 is less than the distance between the first end of the flat portion 21 and the first cell P1. This can reduce shading of the first surface while preventing the end of the flat portion 21 from falling into the overlapping area due to process errors.

[0076] In some embodiments, reference Figure 4 and Figure 5 The flat portion 21 includes a first sub-portion located on the first battery cell P1 and a second sub-portion connected to the first sub-portion; the first covering film 30 of the first battery cell P1 at least covers a portion of the first sub-portion, and the second covering film 40 of the second battery cell P2 covers a portion of the second sub-portion.

[0077] In the second direction, the length of the first sub-portion is equal to the sum of D4 and W, and the length of the second sub-portion is equal to D3. When the extended end of the first covering film 30 of the first battery cell P1 at least partially exceeds the overlapping area in the second direction, the first covering film 30 of the first battery cell P1 completely covers the first sub-portion. Along the second direction, the length of the portion of the second sub-portion covered by the second covering film 40 of the second battery cell P2 can be greater than or equal to 0.5 mm. In this embodiment, before lamination, the flat portion 21 can be pre-fixed by the first covering film 30 and the second covering film 40, thereby preventing the flat portion 21 from standing upright and scratching the battery cell 10, and preventing the battery cell 10 from being easily broken during lamination after the flat portion 21 is upright.

[0078] In some embodiments, reference Figure 4 、 Figure 5 、 Figure 6 、 Figure 9 and Figure 10 The cross-sectional shape of the main body 22 is circular; the thickness of the first coating 30 and the second coating 40 is smaller than the diameter of the main body 22 ; the thickness of the first coating 30 and the second coating 40 is greater than or equal to the thickness of the flat portion 21 .

[0079] Among them, the diameter of the main body 22 can be 0.18mm-0.26mm, for example, 0.22mm. The thickness of the flat portion 21 can be 0.05mm-0.13mm, for example, 0.08mm-0.09mm. The thickness of the first coating 30 and the second coating 40 is preferably greater than the thickness of the flat portion 21, for example, greater than or equal to 0.1mm. In this embodiment, the thickness of the coating is greater than or equal to the thickness of the flat portion 21 and less than the diameter of the main body 22, which can avoid the poor buffering effect caused by the coating thickness being too thin, and can avoid the increase in the height difference between the two battery cells 10 in the overlapping area due to the coating thickness being too thick.

[0080] In some embodiments, the size of the battery cell 10 in the first direction is 182 mm to 210 mm, and the size of the battery cell 10 in the second direction is 53 mm to 210 mm; the diameter of the main body 22 is 0.18 mm to 0.26 mm.

[0081] The dimensions of the battery cell 10 in the first direction and the second direction may be different or equal. The dimension of the battery cell 10 in the second direction may be less than or equal to half of the dimension of the battery cell 10 in the first direction. For example, the dimension of the battery cell 10 in the first direction is 182 mm, and the dimension of the battery cell 10 in the second direction is 53 mm. The diameter of the main body 22 may be 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, etc. The smaller the dimensions of the battery cell 10 in the first direction and the second direction, the smaller the diameter of the main body 22 may be, which is conducive to reducing welding stress and can reduce the shading area.

[0082] In some embodiments, reference Figure 4 and Figure 5 , both the first surface and the second surface of the battery cell 10 are provided with edge pads 11 close to the overlapping area, and the number of edge pads 11 located in the overlapping area is 0.

[0083] If the edge pads 11 are located in the overlapping area, the height difference between the two cells 10 in the overlapping area includes the height of the edge pads 11 and the first soldering ribbon 20. This will result in a large height difference between the two cells 10 in the overlapping area, which can easily cause hidden cracks in the cells 10. In this embodiment, the number of edge pads 11 located in the overlapping area is zero, that is, the edge pads 11 are outside the overlapping area, which can avoid the hidden cracks in the cells 10 caused by the large height difference between the two cells 10 in the overlapping area.

[0084] In some embodiments, along the thickness direction of the cell 10 , the orthographic projection of a single flat portion 21 overlaps with the orthographic projections of y fine gate electrodes, where y is 3-6.

[0085] Wherein, y can be 3, 4, 5, 6, etc. Along the second direction, the spacing between two adjacent fine grid electrodes on the battery cell 10 can be 0.9 mm to 1 mm. The spacing between two adjacent fine grid electrodes on the first surface of the battery cell 10 can be different from the spacing between two adjacent fine grid electrodes on the second surface. Along the second direction, the distance between the edge fine grid electrode and the edge of the battery cell 10 can be 0.4 mm to 0.8 mm. The distance between the edge fine grid electrode on the first surface of the battery cell 10 and the edge of the battery cell 10 can be different from the distance between the edge fine grid electrode on the second surface and the edge of the battery cell 10.

[0086] In this embodiment, along the second direction, the flat portion 21 spans at least three fine gate electrodes. The flat portion 21 has a certain length, which can avoid the increased risk of hidden cracks on the edge of the battery cell 10 caused by the flat portion 21 being too short. In addition, the flat portion 21 spans at most six fine gate electrodes, which can avoid the increase in the shading area caused by the flat portion 21 being too long.

[0087] In some embodiments, m1 first-surface fine gate electrodes in the first cell P1 are located in the overlapping region, and m2 second-surface fine gate electrodes in the second cell P2 are located in the overlapping region, and m1+m2≤2.

[0088] The sum of m1 and m2 can be 0, 1, 2, etc. m1 can be less than or equal to 1, and m2 can be less than or equal to 1. The fine gate electrodes protrude from the cell body. If a large number of fine gate electrodes are located in the overlapping region, stress concentration can occur locally in the overlapping region (where the fine gate electrodes are located). In this embodiment, a small number of fine gate electrodes are located in the overlapping region, which can reduce stress concentration in the overlapping region and mitigate the risk of hidden cracks in the cell 10 in the overlapping region.

[0089] In the overlapping area, the part of the first surface of the first cell P1 that is blocked by the second cell P2 cannot generate electricity because there is no light. A fine gate electrode can be designed here to collect carriers excited by light refraction, scattering, etc. at the edge of the overlapping area. It is not economical to design more than two fine gate electrodes here. At the same time, too many fine gate electrodes are prone to stress concentration at the stacking point, causing hidden cracks.

[0090] In the overlapping area, the part of the second surface of the second cell P2 that is blocked by the Nth cell 10 cannot generate electricity because there is no light. A fine gate electrode can be designed here to collect carriers excited by light refraction, scattering, etc. at the edge of the overlapping area. It is not economical to design more than two fine gate electrodes here. At the same time, too many fine gate electrodes are prone to stress concentration at the stacking point, causing hidden cracks.

[0091] In some embodiments, m1 is 0, and m2≤1.

[0092] m2 can be 0 or 1. In this embodiment, the number of fine gate electrodes located in the overlapping area is further reduced, which can further reduce the risk of hidden cracks in the battery cell 10 in the overlapping area. When the first surface is the light-receiving surface and the second surface is the backlight surface, the first surface of the battery cell 10 is the main light-receiving surface, and the shading of the first surface has a greater impact on photoelectric conversion than the shading of the second surface. The distance between the fine gate electrode at the edge of the first surface of the battery cell 10 and the edge of the battery cell 10 is relatively small, for example, it can be 0.72mm. If the overlapping area extends to the fine gate electrode at the edge of the first surface of the first battery cell P1, the first surface of the first battery cell P1 will be more shaded. In this embodiment, the fine gate electrode at the edge of the first surface of the first battery cell P1 is located outside the overlapping area, and the width of the overlapping area is relatively small, which can minimize unnecessary shading losses.

[0093] In some embodiments, the width of the overlapping region is greater than or equal to 0.2 mm and less than or equal to 2 mm.

[0094] Among them, the width W of the overlapping area can be 0.2mm, 0.3mm, 0.5mm, 0.7mm, 1mm, 1.2mm, etc. The width of the overlapping area is preferably 0.3mm-0.7mm, for example, 0.5mm. When the width of the overlapping area is too small, stress is concentrated at the stacking of two adjacent battery cells 10, and the battery cell 10 is prone to hidden cracks. When the width of the overlapping area is too large, too many electrodes will be covered, and the light-receiving surface of the previous battery cell at the overlap will be covered too much, resulting in a waste of silicon wafer resources. In this embodiment, when the overlapping area is within the above range, it can effectively reduce the risk of hidden cracks in the battery cell 10 at the overlapping area. At the same time, it can reduce the number of covered electrodes and the area of ​​the light-receiving surface of the first battery cell P1 or the light-receiving surface of the second battery cell P2 at the overlap, so that the light-receiving surface of the first battery cell P1 or the light-receiving surface of the second battery cell P2 has sufficient light-receiving area.

[0095] In some embodiments, reference Figure 4 、 Figure 5 and Figure 8 Along the second direction, the distance between the edge pad 11 located on the first surface of the first cell P1 and close to the second cell P2 and the edge pad 11 located on the second surface of the second cell P2 and close to the first cell P1 is D5, and L < D5. The difference between D5 and L can be greater than or equal to 1.5 mm. In this embodiment, L < D5, which means that the edge pad 11 is outside the flat portion 21, can ensure effective welding between the edge pad 11 and other parts of the first welding ribbon 20.

[0096] In some embodiments, reference Figure 4 and Figure 5 , along the first direction, the distance between the edge pad 11 on the first surface of the same battery cell 10 and the edge pad 11 on the adjacent second surface is greater than 0.

[0097] Among them, along the first direction, the distance between the edge pad 11 on the first surface of the same battery cell 10 and the edge pad 11 on the adjacent second surface can be 0.1mm-0.3mm. As the battery cell 10 becomes thinner and thinner, if the edge pad 11 on the first surface of the same battery cell 10 corresponds to the edge pad 11 on the adjacent second surface, that is, the distance between them is 0, stress concentration is likely to occur. In this embodiment, the edge pad 11 on the first surface of the same battery cell 10 and the edge pad 11 on the adjacent second surface are staggered along the first direction, which can avoid hidden cracks and fragments of the battery cell caused by stress concentration on the solder joints of the first and second surfaces. In addition, by staggering the edge pad 11 on the first surface of the same battery cell 10 and the edge pad 11 on the adjacent second surface along the first direction, the thickness of the silicon wafer can be further reduced and the material cost can be reduced.

[0098] In some embodiments, the cell 10 includes an N-type monocrystalline silicon substrate; a P+ emitter, an antireflection layer, and a front electrode located on the front surface of the N-type monocrystalline silicon substrate; and a tunneling oxide layer, a doped polysilicon layer, and a back electrode located on the back surface of the N-type monocrystalline silicon substrate. The cell 10 utilizes the N-type monocrystalline silicon substrate as a base, with layer structures and electrodes formed on its front and back surfaces, respectively, to form a high-efficiency solar cell. The antireflection layer located on the front surface reduces light reflection losses on the silicon wafer surface.

[0099] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0100] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the purpose and scope of protection of the present invention, which are all protected by the present invention.

Claims

1. A photovoltaic module, characterized in that: The invention comprises a plurality of battery strings arranged along a first direction, each of the battery strings comprising a plurality of battery cells arranged along a second direction, each battery cell having a first surface and a second surface opposite to each other, the battery cells comprising a first battery cell and a second battery cell adjacent to each other, edges of the first battery cell and the second battery cell overlapping to form an overlapping region; the first direction is perpendicular to the second direction; The battery string further includes a welding ribbon, wherein the welding ribbon includes a first welding ribbon for connecting the first surface of the first battery cell and the second surface of the second battery cell; The battery string also includes a covering film, which is laid on the surface of the battery cell and covers at least a portion of the welding ribbon. The covering film includes a first covering film laid on the first surface of the first battery cell and a second covering film laid on the second surface of the second battery cell; the first covering film or the second covering film extends at least partially to the overlapping area in the second direction, and the first covering film and the second covering film have a gap in the second direction.

2. The photovoltaic module according to claim 1, characterized in that The gap is located outside the overlapping area.

3. The photovoltaic module according to claim 1, characterized in that The first covering film of the first battery cell extends to the overlapping area, and the extending end of the second covering film of the second battery cell is located outside the overlapping area.

4. The photovoltaic module according to claim 3, characterized in that In the second direction, the size of the first covering film is larger than that of the second covering film.

5. The photovoltaic module according to claim 3, characterized in that: The thickness of the first coating is greater than the thickness of the second coating.

6. The photovoltaic module according to claim 3, characterized in that An extended end of the first covering film of the first battery cell at least partially extends beyond the overlapping area in the second direction.

7. The photovoltaic module according to claim 3, characterized in that: The first surface and the second surface of the battery cell are both provided with a plurality of solder pads arranged at intervals along the second direction, the first solder strip is electrically connected to the solder pads, the solder pads include edge solder pads near the overlapping area, and the extended end of the second coating of the second battery cell is located between the edge solder pad of the second battery cell and the edge of the first battery cell.

8. The photovoltaic module according to any one of claims 1 to 7, characterized in that: An end portion of the soldering ribbon connected to the second surface of the first battery cell is located outside the overlapping area, and an end portion of the soldering ribbon connected to the first surface of the second battery cell is located outside the overlapping area.

9. The photovoltaic module according to any one of claims 1 to 7, characterized in that: An end of the first covering film of the first cell, which extends away from the overlapping area of ​​the first cell and the second cell, is located between the edge pad of the first cell and the edge of the first cell; And / or, an extended end of the second cover film of the second cell facing away from the overlapping area of ​​the first cell and the second cell is located between the edge pad of the second cell and the edge of the second cell.

10. The photovoltaic module according to any one of claims 3 to 7, characterized in that: The first surface and the second surface of the cell both have a plurality of fine grid electrodes; The fine gate electrode includes an edge fine gate electrode close to the edge of the cell, and the first covering film of the first cell covers the edge fine gate electrode on the first surface of the first cell.

11. The photovoltaic module according to any one of claims 1 to 7, characterized in that: The material of the first coating is different from the material of the second coating.

12. The photovoltaic module according to any one of claims 1 to 7, characterized in that: The first surface is the backlight surface of the battery cell, and the second surface is the light-receiving surface of the battery cell.

13. The photovoltaic module according to any one of claims 3 to 7, characterized in that: The first welding strip includes a flat portion located at the overlapping area, such that along the second direction, the length of the flat portion is L, the width of the overlapping area is W, and L is greater than W.

14. The photovoltaic module according to claim 13, characterized in that: The flat portion includes a first sub-portion located on the first battery cell and a second sub-portion connected to the first sub-portion; The first covering film of the first battery cell at least covers a portion of the first sub-portion, and the second covering film of the second battery cell covers a portion of the second sub-portion.

15. The photovoltaic module according to claim 13, characterized in that: The first welding strip further includes a main body portion, and the cross-sectional shape of the main body portion is circular; The thickness of the first coating and the second coating is smaller than the diameter of the main body; And / or the thickness of the first coating and the second coating is greater than or equal to the thickness of the flat portion.

16. The photovoltaic module according to claim 15, characterized in that: The size of the battery cell in the first direction is 182 mm to 210 mm, and the size of the battery cell in the second direction is 53 mm to 210 mm; The diameter of the main body is 0.18mm-0.26mm.

17. The photovoltaic module according to claim 13, characterized in that: The flat portion has a first end located on the second surface of the second battery cell and a second end located on the first surface of the first battery cell, such that along the second direction, a distance D3 is provided between the first end of the flat portion and the first battery cell, and a distance D4 is provided between the second end of the flat portion and the second battery cell, where D4 is less than D3.

18. The photovoltaic module according to claim 13, characterized in that: The first surface and the second surface of the battery cell are both provided with edge pads close to the overlapping area, and the number of the edge pads located in the overlapping area is 0.

19. The photovoltaic module according to claim 13, characterized in that: The first surface and the second surface of the cell both have a plurality of fine grid electrodes; Along the thickness direction of the battery cell, the orthographic projection of a single flat portion overlaps with the orthographic projections of y fine grid electrodes, where y is 3-6.

20. The photovoltaic module according to any one of claims 1 to 7, characterized in that The first surface and the second surface of the cell both have a plurality of fine grid electrodes; m1 fine gate electrodes on the first surface of the first cell are located in the overlapping region, and m2 fine gate electrodes on the second surface of the second cell are located in the overlapping region, where m1+m2≤2.

21. The photovoltaic module according to claim 20, characterized in that: m1 is 0, m2≤1.

22. The photovoltaic module according to any one of claims 1 to 7, characterized in that The width of the overlapping area is greater than or equal to 0.2 mm and less than or equal to 2 mm.

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