Photovoltaic module

Abstract

The application discloses a photovoltaic module, which comprises a cell string, the cell string comprises a plurality of cell pieces arranged in an overlapping manner and a string-interconnected structure connecting two adjacent cell pieces, two adjacent cell pieces in the cell string overlap to form an overlapping area, the string-interconnected structure comprises a string-interconnected piece, the string-interconnected piece comprises a flat part located at the overlapping area, the extension direction of the string-interconnected piece is a first direction, the length of the flat part is L along the first direction, the width of the overlapping area is W, L is greater than W, the Nth string-interconnected structure is connected to the front surface of the Nth cell piece and the back surface of the N+1th cell piece, the flat part of the string-interconnected piece of the Nth string-interconnected structure has a first end located at the back surface of the N+1th cell piece, the distance between the first end of the flat part and the Nth cell piece is D1 along the first direction, and 2W<=D1<=10W. In the application, the risk of hidden cracking of the cell piece can be effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and more particularly to a photovoltaic module. Background Technology

[0002] In laminated modules, solar cells are arranged in an overlapping manner and connected into a cell string by solder ribbons, so as to arrange more solar cells in a limited area, thereby improving the utilization rate of space area and the power generation of the module.

[0003] For solar cells with electrodes on both the front and back sides, the solder ribbon connects the front electrode of the previous solar cell to the back electrode of the next solar cell, and the solder ribbon will pass through the overlapping area of ​​the two adjacent solar cells.

[0004] However, during hot pressing or lamination, stress concentration occurs in the overlapping area of ​​two adjacent cells, especially at the contact point between the solder strip and the cell in the overlapping area, making the cell prone to microcracks. Summary of the Invention

[0005] This invention provides a photovoltaic module that aims to at least solve the technical problem of stress concentration and microcracks in the overlapping area of ​​two adjacent cells, especially at the contact point between the solder strip and the cell in the overlapping area, in laminated modules.

[0006] This invention provides a photovoltaic module, including a battery string, wherein the battery string includes multiple overlapping battery cells and an intra-string interconnection structure connecting two adjacent battery cells;

[0007] In the battery string, two adjacent battery cells overlap to form an overlapping area. The interconnection structure within the string includes an interconnection member. The interconnection member includes a flat portion located at the overlapping area. The extension direction of the interconnection member is taken as a first direction. Along the first direction, the length of the flat portion is L, and the width of the overlapping area is W. L is greater than W.

[0008] The Nth in-string interconnect structure is connected to the front side of the Nth battery cell and the back side of the (N+1)th battery cell. In the in-string interconnect of the Nth in-string interconnect structure, the flat portion has a first end located on the back side of the (N+1)th battery cell, such that along the first direction, the distance between the first end of the flat portion and the Nth battery cell is D1, where 2W≤D1≤10W.

[0009] Optionally, the (N+1)th battery cell has a first edge close to the Nth battery cell, and in the interconnect of the Nth interconnect structure, the distance between the first end of the flat portion and the first edge of the (N+1)th battery cell along the first direction is D2, where D2 ≥ 4W.

[0010] Optionally, in the Nth interconnection structure, the flat portion has a second end located on the front side of the Nth battery cell, such that along the first direction, the distance between the second end of the flat portion and the (N+1)th battery cell is D3, where W≤D3≤6W.

[0011] Optionally, both the front and back sides of the battery cell have edge connection portions near the edge of the battery cell, and the in-string interconnect is electrically connected to the edge connection portions;

[0012] The number of edge connections located in the overlapping region is 0.

[0013] Optionally, the edge connection portion in the Nth battery cell includes a first edge connection portion located on the front side and close to the N+1th battery cell, and the edge connection portion in the N+1th battery cell includes a second edge connection portion located on the back side and close to the Nth battery cell;

[0014] Along the first direction, the distance between the first edge connecting portion and the second edge connecting portion is D4, and L < D4.

[0015] Optionally, 0.3D4≤L≤0.9D4.

[0016] Optionally, the battery cell has several current collector electrodes on both its front and back sides;

[0017] The Nth solar cell overlaps with the (N+1)th solar cell to form the Nth overlapping region. The m1 front current collectors of the Nth solar cell are located in the Nth overlapping region, and the m2 back current collectors of the (N+1)th solar cell are located in the Nth overlapping region, where m1+m2≤2.

[0018] Optionally, m1 is 0 and m2 ≤ 1.

[0019] Optionally, the interconnecting element further includes a main body portion, wherein the ratio of the thickness of the flat segment in the flat portion to the thickness of the main body portion is 0.2-0.7 along the thickness direction of the battery cell.

[0020] Optionally, the solar cell includes an N-type monocrystalline silicon substrate; a P+ emitter, an anti-reflection layer, and a front electrode located on the front side of the N-type monocrystalline silicon substrate; and a tunneling oxide layer, a doped polycrystalline silicon layer, and a back electrode located on the back side of the N-type monocrystalline silicon substrate.

[0021] Optionally, both the front and back sides of the battery cell have edge connection portions near the edge of the battery cell, and the in-string interconnect is electrically connected to the edge connection portions;

[0022] The (N+1)th battery cell has a second edge away from the Nth battery cell, the Nth battery cell has a third edge away from the N+1th battery cell, the edge connection portion in the Nth battery cell includes a third edge connection portion located on the front side and close to the third edge, and the edge connection portion in the (N+1)th battery cell includes a fourth edge connection portion located on the back side and close to the second edge.

[0023] Along the first direction, the distance between the third edge connecting portion and the third edge is D5, and the distance between the fourth edge connecting portion and the second edge is D6, where W < D5 < D6.

[0024] Optionally, W is greater than or equal to 0.2 mm and less than or equal to 2 mm.

[0025] Optionally, both the front and back sides of the battery cell have edge connection portions near the edge of the battery cell, and the in-string interconnect is electrically connected to the edge connection portions;

[0026] Along the first direction, the distance between the edge connection portion on the front side of the same battery cell and the edge connection portion on the adjacent back side is greater than 0.

[0027] Optionally, the battery string further includes a coating, which is laid on the surface of the battery cells and at least covers a portion of the interconnects. The coating includes a first coating laid on the front side of the Nth battery cell and a second coating laid on the back side of the N+1th battery cell.

[0028] The first coating extends at least partially into the overlapping region in the first direction, and the first coating and the second coating have a gap in the first direction.

[0029] Optionally, the extended end of the second coating is located outside the overlapping area, and the gap is located outside the overlapping area.

[0030] Optionally, the extended end of the first coating extends at least partially beyond the overlapping area in the first direction.

[0031] In this embodiment of the invention, the flat portion of the interconnecting element is located in the overlapping area. The large contact area between the flat portion and the solar cell reduces stress concentration at the contact point between the interconnecting element and the solar cell in the overlapping area, thereby reducing the risk of microcracks in the solar cell. Since L is greater than W, it prevents other parts of the interconnecting element besides the flat portion from falling into the overlapping area, thus avoiding stress concentration at the contact point between other parts of the interconnecting element besides the flat portion and the solar cell in the overlapping area, which could lead to microcracks in the solar cell.

[0032] The first end of the flat portion protrudes towards the back of the (N+1)th solar cell, where stress concentration is likely to occur. In this embodiment of the invention, D1 ≥ 2W, ensuring sufficient spacing between the first end of the flat portion and the Nth solar cell. On one hand, keeping the first end of the flat portion away from the overlapping area prevents stress concentration at the first end from affecting the overlapping area, thus increasing the risk of microcracks in the solar cells at the overlapping area. On the other hand, it prevents the first end of the flat portion from falling into the overlapping area due to process errors, which would otherwise make the solar cells at the overlapping area prone to microcracks. D1 ≤ 10W avoids D1 being too large and affecting the light absorption rate on the back of the (N+1)th solar cell.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0034] Figure 1 This is a partial structural schematic diagram of a photovoltaic module provided in an embodiment of the present invention;

[0035] Figure 2 This is a partial structural diagram of a cell string in a photovoltaic module provided in an embodiment of the present invention;

[0036] Figure 3 This is a partial schematic diagram of the stacking of two adjacent battery cells in a battery string provided in an embodiment of the present invention;

[0037] Figure 4 This is a top view schematic diagram of the battery string section structure provided in an embodiment of the present invention;

[0038] Figure 5 for Figure 4 Enlarged view of point A in the middle;

[0039] Figure 6 This is a top view of two adjacent battery cells in a battery string provided in an embodiment of the present invention;

[0040] Figure 7 A side view of the interconnect component provided in an embodiment of the present invention;

[0041] Figure 8 This is a top view of the interconnect component provided in an embodiment of the present invention.

[0042] Figure label:

[0043] 10-Battery cell, 11-Edge connection part, 111-First edge connection part, 112-Second edge connection part, 113-Third edge connection part, 114-Fourth edge connection part;

[0044] 20-Interconnector, 21-Flat section, 211-Flat segment, 212-Transition segment, 22-Main body, 221-First main body, 222-Second main body;

[0045] 30 - First coating, 40 - Second coating. Detailed Implementation

[0046] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0047] Reference Figures 1 to 5 This invention provides a photovoltaic module, including a battery string, which includes multiple overlapping battery cells 10 and multiple interconnection structures. Each interconnection structure includes multiple interconnecting elements. The multiple interconnection structures include intra-string interconnection structures connecting two adjacent battery cells 10. Two adjacent battery cells 10 overlap in the battery string to form an overlapping region. The intra-string interconnection structure includes an intra-string interconnecting element 20. The intra-string interconnecting element 20 includes a flat portion 21 located at the overlapping region. Taking the extension direction of the intra-string interconnecting element 20 as a first direction, the length of the flat portion 21 along the first direction is L, and the width of the overlapping region is W, where L is greater than W. The Nth intra-string interconnection structure is connected to the front side of the Nth battery cell 10 and the back side of the (N+1)th battery cell 10. In the intra-string interconnecting element 20 of the Nth intra-string interconnection structure, the flat portion 21 has a first end located on the back side of the (N+1)th battery cell 10. Along the first direction, the distance between the first end of the flat portion 21 and the Nth battery cell 10 is D1, where 2W ≤ D1 ≤ 10W.

[0048] The battery string can include an odd number or an even number of solar cells 10. Solar cells 10 are bifacial cells, such as TOPcon (Tunnel Oxide Passivating Contacts) cells and heterojunction cells, with positive and negative electrodes located on the front and back sides of the cell 10, respectively. Solar cells 10 can be gridless cells, meaning they have current collector electrodes, eliminating some or all of the main grid lines, thus saving on paste consumption and reducing module costs. Solar cells 10 can also be grid-connected cells. Solar cells 10 can be full-size cells, half-size cells, third-size cells, or quarter-size cells.

[0049] The overlapping region is the area formed by the overlapping edges of two adjacent solar cells 10. The overlapping region is an elongated strip-shaped area extending along the length of the solar cell 10. Taking the length of the solar cell 10 as the second direction, the second direction can be referenced... Figure 1 and Figure 4 The direction indicated by the arrow F in the middle. An overlapping area can be referenced. Figure 5 G is shown in the figure.

[0050] The multiple interconnection structures also include a head-of-string interconnection structure and a tail-of-string interconnection structure. The head-of-string interconnection structure includes multiple head-of-string interconnection components, and the tail-of-string interconnection structure includes multiple tail-of-string interconnection components. The head-of-string interconnection components are used to connect the first battery cell 10 in the battery string to the busbar, and the tail-of-string interconnection components are used to connect the last battery cell 10 in the battery string to the busbar. The head-of-string interconnection components and the tail-of-string interconnection components may or may not have a flattened portion, or they may include a flattened portion that is different from the structure of the flattened portion 21.

[0051] The number of battery cells 10 in the battery string is x, the number of overlapping areas in the battery string is x-1, the total number of interconnection structures in the battery string is x+1, of which the number of intra-string interconnection structures is x-1, the number of head-of-string interconnection structures is 1, and the number of tail-of-string interconnection structures is 1.

[0052] N is a positive integer greater than or equal to 1 and less than or equal to x-1. Multiple battery cells 10 are arranged in an overlapping pattern, pointing from the beginning to the end of the battery string. The direction from the beginning to the end of the battery string can be referenced... Figures 1 to 4 , Figure 6 The direction indicated by arrow C. The Nth battery cell 10 is the Nth battery cell 10 in the direction from the beginning to the end of the battery string, and the (N+1)th battery cell 10 is the (N+1)th battery cell 10 in the direction from the beginning to the end of the battery string.

[0053] The interconnect structure includes multiple interconnect components 20 spaced apart along a second direction. The interconnect components 20 can be ordinary solder strips or coated solder strips. The cross-sectional shape of the flat portion 21 can be rectangular, and the cross-sectional shape of the other parts of the interconnect components 20, excluding the flat portion 21, can be circular. The flat portion 21 can be formed by partially flattening a round wire solder strip. The flat portion 21 can include a flat segment 211 and a very short transition segment 212 located at both ends of the flat portion 21. Along the first direction, the wall thickness of the flat segment 211 in the flat portion 21 is substantially uniform.

[0054] The first direction can be referenced. Figure 3 , Figure 4 and Figure 6 The direction indicated by the arrow E in the middle. (Refer to...) Figure 3 , Figure 4 , Figure 7 and Figure 8The interconnect component 20 also includes a main body 22, which comprises a first main body 221 and a second main body 222 respectively connected to the two ends of the flat section 21. Both the first main body 221 and the second main body 222 can be connected to the flat section 211 via a transition section 212. The surface of the transition section 212 can be either a sloped surface or a curved surface. In the Nth interconnect component 20 of the interconnect structure, the first main body 221 is connected to the front side of the Nth battery cell 10, and the second main body 222 is connected to the back side of the (N+1)th battery cell 10. It should be noted that... Figure 7 and Figure 8 The diagram shows the structure of the interconnect 20 before lamination. Before lamination, the flat section 211 in the flat part 21 is straight. After lamination, the shape of the flat section 211 may be slightly deformed, but its wall thickness is still basically uniform.

[0055] The direction in which the front of a photovoltaic module faces the back can be referenced. Figure 2 and Figure 3 The direction indicated by arrow B. In the Nth interconnection structure, along the thickness direction of the battery cell 10, the distance between the front side of the flat portion 21 and the back side of the (N+1)th battery cell 10 is greater than the distance between the back side of the flat portion 21 and the front side of the Nth battery cell 10. That is, the thickness difference between the front side of the flat portion 21 and the main body portion 22 is greater than the thickness difference between the back side of the flat portion 21 and the main body portion 22.

[0056] When the flat portion 21 includes transition sections 212, the length L of the flat portion 21 is measured at both ends of the flat portion 21, which are also the connection points between the two transition sections 212 and the main body portion 22. L is preferably greater than or equal to 3W and less than or equal to 15W. For example, W is 0.5mm, and L is 5.1mm or 5.5mm. D1 can be 2W, 4W, 5W, 6W, 7W, 10W, etc. For example, when D1 is 6W and W is 0.5mm, D1 is 3mm.

[0057] In the manufacturing process of photovoltaic modules, the following steps are typically performed sequentially: front glass, front encapsulating film, cell strings arranged on the front encapsulating film, back encapsulating film, and backsheet. This laminated assembly is then heated and pressure is applied. The encapsulating film can be made of EVA (ethylene-vinyl acetate copolymer), POE (polyolefin elastomer), or EPE (expanded polyethylene), among others. The front glass can be tempered glass, semi-tempered glass, or patterned glass. The backsheet can be white or made of glass.

[0058] In this embodiment of the invention, the flat portion 21 of the interconnect 20 is located in the overlapping region. The flat portion 21 has a large contact area with the battery cell 10, which can reduce stress concentration at the contact point between the interconnect 20 and the battery cell 10 in the overlapping region, thereby reducing the risk of microcracks in the battery cell 10. Since L is greater than W, it can prevent other parts of the interconnect 20 besides the flat portion 21 from falling into the overlapping region, thus avoiding microcracks in the battery cell due to stress concentration at the contact point between other parts of the interconnect 20 and the battery cell 10 in the overlapping region.

[0059] The first end of the flat portion 21 protrudes towards the back of the (N+1)th solar cell 10, where stress concentration is likely to occur. In this embodiment of the invention, D1 ≥ 2W, ensuring sufficient spacing between the first end of the flat portion 21 and the Nth solar cell 10. On one hand, keeping the first end of the flat portion 21 away from the overlapping area prevents stress concentration at the first end from affecting the overlapping area, thereby increasing the risk of microcracks in the solar cell 10 at the overlapping area. On the other hand, it prevents the first end of the flat portion 21 from falling into the overlapping area due to process errors, thus preventing microcracks in the solar cell 10 at the overlapping area. D1 ≤ 10W avoids excessively large D1 affecting the light absorption rate on the back of the (N+1)th solar cell 10.

[0060] In some embodiments, refer to Figure 3 The (N+1)th battery cell 10 has a first edge close to the Nth battery cell 10. In the interconnect member 20 of the Nth interconnect structure, the distance between the first end of the flat portion 21 and the first edge of the (N+1)th battery cell 10 along the first direction is D2, where D2 ≥ 4W.

[0061] D2 can be 4W, 5W, 6W, 7W, 8W, 9W, etc. For example, when D2 is 7W and W is 0.5mm, D2 is 3.5mm. D2 is equal to the sum of D1 and W.

[0062] During the fabrication of the battery string, the first interconnecting element is usually placed first, then the first battery cell 10 is placed on the first interconnecting element, then the internal interconnecting element 20 is placed on the front of the first battery cell 10, then the second battery cell 10 is placed, then the internal interconnecting element 20 is placed on the front of the second battery cell 10, and so on, until the last battery cell 10 is placed, and then the end interconnecting element is placed on the last battery cell 10.

[0063] In this embodiment, D2≥4W, which ensures that the flat portion 21 and the N+1th battery cell 10 have sufficient overlapping area, and can prevent the interconnecting member 20 in the string from rotating during the battery string preparation process, thereby preventing the flat portion 21 from scratching the N+1th battery cell 10 by standing up.

[0064] In some embodiments, refer to Figure 3 In the Nth intra-string interconnection structure, the flat portion 21 has a second end located on the front side of the Nth battery cell 10, such that along the first direction, the distance between the second end of the flat portion 21 and the (N+1)th battery cell 10 is D3, where W≤D3≤6W.

[0065] D3 can be W, 2W, 3W, 4W, 5W, 6W, etc. For example, when D3 is 4W and W is 0.5mm, D3 is 2mm. On the one hand, D3 ≥ W can prevent the second end of the flat portion 21 from falling into the overlapping area due to process errors, which would make the cell 10 in the overlapping area prone to microcracks. On the other hand, D3 ≤ 6W can avoid excessive light blocking by the flat portion 21 due to an excessively large D3, which would affect the light absorption rate of the front side of the Nth cell 10 and thus affect the efficiency of the Nth cell 10.

[0066] D3 is less than D1. The difference between D1 and D3 can be greater than or equal to W and less than or equal to 3W. The front side of the solar cell 10 is the main light-receiving surface, and shading on the front side has a greater impact on photoelectric conversion than shading on the back side. In this embodiment, D3 is less than D1, which can reduce front shading.

[0067] In some embodiments, refer to Figure 3 and Figure 6 Both the front and back sides of the battery cell 10 have edge connection portions 11 near the edge of the battery cell 10, and the in-string interconnect 20 is electrically connected to the edge connection portions 11; the number of edge connection portions 11 located in the overlapping area is 0.

[0068] The front and back sides of the solar cell 10 have several current collector electrodes. When the solar cell 10 is a gridless solar cell, the edge connection portion 11 is a pad provided on the current collector electrode. Along the first direction, the front and back sides of the solar cell 10 also have an intermediate connection portion located between the two edge connection portions 11. The intermediate connection portion can be a pad provided on the current collector electrode, or it can be a part on the current collector electrode used for electrical connection with the string interconnect 20.

[0069] If the edge connection portion 11 is located in the overlapping area, the height difference between the two battery cells 10 in the overlapping area includes the height of the edge connection portion 11 and the height of the interconnect 20 within the string. This can result in a large height difference between the two battery cells 10 in the overlapping area, which can easily cause microcracks in the battery cells 10. In this embodiment, the number of edge connection portions 11 located in the overlapping area is 0, that is, the edge connection portions 11 are outside the overlapping area, which can avoid the large height difference between the two battery cells 10 in the overlapping area from causing microcracks in the battery cells 10.

[0070] In some embodiments, refer to Figure 3 and Figure 6The edge connection portion 11 in the Nth battery cell 10 includes a first edge connection portion 111 located on the front and close to the N+1th battery cell 10, and the edge connection portion 11 in the N+1th battery cell 10 includes a second edge connection portion 112 located on the back and close to the Nth battery cell 10; the distance between the first edge connection portion 111 and the second edge connection portion 112 along the first direction is D4, and L < D4.

[0071] The difference between D4 and L can be greater than or equal to 1.5 mm. Along the first direction, the distance between the first edge connecting portion 111 and the second end of the flat portion 21 can be greater than or equal to 0.5 mm, and the distance between the second edge connecting portion 112 and the first end of the flat portion 21 can be greater than or equal to 0.5 mm. In this embodiment, L < D4, meaning the edge connecting portion 11 is outside the flat portion 21, ensuring effective welding of the edge connecting portion 11 to other parts of the interconnecting member 20.

[0072] In some embodiments, 0.3D4 ≤ L ≤ 0.9D4.

[0073] In two adjacent battery cells 10, the positions of the first edge connecting portion 111 and the second edge connecting portion 112 are fixed, that is, the value of D4 is fixed. Preferably, 0.4L4≤L≤0.8D4. For example, D4 ​​is 12.14mm or 7.38mm, and L is 5.1mm or 5.5mm.

[0074] Due to welding reliability requirements, the pull-out force at the weld joints between the intra-string interconnect 20 and the first edge connection portion 111 and the second edge connection portion 112 is relatively large. When the intra-string interconnect 20 has a high degree of freedom, if there is a slight misalignment of the two battery cells 10 at the overlapping point along the second direction, the intra-string interconnect 20 is prone to twisting, and the stress at the weld joints between the intra-string interconnect 20 and the first edge connection portion 111 and the second edge connection portion 112 is relatively large, which can easily lead to poor welding.

[0075] In this embodiment, L ≥ 0.3D4 avoids the first end of the flat portion 21 being too short, which would cause it to be close to the edge of the battery cell 10, thus increasing the risk of microcracks at the edge of the battery cell 10. The longer the length L of the flat portion 21, the lower the degree of freedom of the interconnecting element 20, and the less likely the interconnecting element 20 is to twist. In this embodiment, the flat portion 21 has a certain length, which can limit the degree of freedom of the interconnecting element 20 and reduce the degree of twisting of the interconnecting element 20 when the two battery cells 10 at the overlapping point are slightly misaligned. This avoids poor welding at the welding points between the interconnecting element 20 and the first edge connection portion 111 and the second edge connection portion 112, ensuring welding reliability. L ≤ 0.9D4 avoids an increase in the light-shielding area caused by an excessively long flat portion 21. In summary, when the length of the flat portion 21 is within the above range, it can balance the degree of freedom of the interconnecting element 20, welding reliability, light-shielding degree, and the risk of microcracks in the battery cell 10.

[0076] In some embodiments, the front and back sides of the battery cell 10 have a plurality of current collector electrodes; the Nth battery cell 10 overlaps with the (N+1)th battery cell 10 to form the Nth overlapping region, m1 of the front current collector electrodes of the Nth battery cell 10 are located in the Nth overlapping region, and m2 of the back current collector electrodes of the (N+1)th battery cell 10 are located in the Nth overlapping region, where m1+m2≤2.

[0077] 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 current collector electrodes protrude from the cell body. If there are many current collector electrodes in the overlapping area, it will lead to localized stress concentration at the overlapping area (where there are current collector electrodes). In this embodiment, the number of current collector electrodes in the overlapping area is small, which can reduce stress concentration in the overlapping area and reduce the risk of microcracks in the cell 10 at the overlapping area.

[0078] Within the overlapping area, the part of the front of the Nth solar cell 10 that is blocked by the N+1th solar cell 10 cannot generate electricity because it is not illuminated. A current collector electrode can be designed here to collect the charge carriers excited by light refraction and scattering at the edge of the overlapping area. Designing more than two current collector electrodes here is uneconomical. At the same time, a large number of current collector electrodes can easily cause stress concentration and microcracks at the stacking point.

[0079] Within the overlapping area, the part of the back of the N+1th solar cell 10 that is blocked by the Nth solar cell 10 cannot generate electricity because it is not illuminated. A current collector electrode can be designed here to collect the charge carriers excited by light refraction and scattering at the edge of the overlapping area. Designing more than two current collector electrodes here is uneconomical. At the same time, a large number of current collector electrodes can easily cause stress concentration and microcracks at the stacking point.

[0080] In some embodiments, m1 is 0 and m2 ≤ 1.

[0081] m2 can be either 0 or 1. In this embodiment, the number of current collectors located in the overlapping region is further reduced, which can further reduce the risk of microcracks in the solar cell 10 at the overlapping region. The front side of the solar cell 10 is the main light-receiving surface, and the shading on the front side has a greater impact on photoelectric conversion than the shading on the back side. The distance between the current collector at the edge of the front side of the solar cell 10 and the edge of the solar cell 10 is small, for example, it can be 0.72 mm. If the overlapping region extends to the current collector at the edge of the front side of the previous solar cell, there will be more shading on the front side of the previous solar cell. In this embodiment, the current collector at the edge of the front side of the Nth solar cell 10 is located outside the overlapping region, and the width of the overlapping region is small, which can minimize unnecessary shading loss.

[0082] The preceding cell refers to the cell 10 closer to the beginning of the string among two adjacent cells 10, and the following cell refers to the cell 10 closer to the end of the string among two adjacent cells 10. For example, for the Nth cell 10 and the (N+1)th cell 10, the Nth cell 10 is the preceding cell, and the (N+1)th cell 10 is the following cell. Process errors are permissible throughout the photovoltaic module. For example, if most overlapping areas in the photovoltaic module do not have a current collector electrode located on the front of the preceding cell, and if the current collector electrode on the front of a few preceding cells is located within the overlapping area, this is considered a process error.

[0083] In some embodiments, refer to Figure 4 , Figure 7 and Figure 8 Along the thickness direction of the battery cell 10, the ratio of the thickness of the flat section 211 in the flat portion 21 to the thickness of the main body portion 22 is 0.2-0.7.

[0084] The ratio of the thickness of the flat segment 211 to the thickness of the main body 22 can be 0.2, 0.35, 0.36, 0.4, 0.45, 0.5, 0.7, etc. The cross-sectional shape of the main body 22 can be circular, in which case the thickness of the main body 22 is also its diameter. The diameter of the main body 22 can be 0.18mm-0.26mm, for example, 0.22mm. The thickness of the flat segment 211 can be 0.05mm-0.13mm, for example, 0.08mm-0.09mm. In this embodiment, when the ratio of the thickness of the flat segment 21 to the thickness of the main body 22 is within the above range, the risk of welding reliability failure caused by excessive flattening of the interconnect 20 can be effectively avoided, and the risk of lamination microcracks caused by insufficient flattening thickness can also be effectively avoided.

[0085] In some embodiments, the size of the battery cell 10 in the second direction is 182mm-210mm, and the size of the battery cell 10 in the first direction is 53mm-210mm; the diameter of the main body 22 is 0.18mm-0.26mm.

[0086] The dimensions of the solar cell 10 in the first and second directions can be unequal or equal. The dimension of the solar cell 10 in the first direction can be less than or equal to half of the dimension of the solar cell 10 in the second direction; for example, the dimension of the solar cell 10 in the second direction is 182 mm, and the dimension of the solar cell 10 in the first direction is 53 mm. The diameter of the main body 22 can be 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, etc. The smaller the dimensions of the solar cell 10 in the first and second directions, the smaller the diameter of the main body 22 can be, which helps to reduce welding stress and reduce the light-shielding area.

[0087] In some embodiments, the solar cell 10 includes an N-type monocrystalline silicon substrate; a P+ emitter, an anti-reflection layer, and a front electrode located on the front side of the N-type monocrystalline silicon substrate; and a tunneling oxide layer, a doped polycrystalline silicon layer, and a back electrode located on the back side of the N-type monocrystalline silicon substrate. The solar cell 10 uses an N-type monocrystalline silicon substrate as its base, forming layer structures and electrodes on both its front and back sides to constitute a high-efficiency solar cell. The anti-reflection layer on the front side reduces light reflection loss at the silicon wafer surface.

[0088] In some embodiments, refer to Figure 6 The (N+1)th battery cell 10 has a second edge away from the Nth battery cell 10, the Nth battery cell 10 has a third edge away from the N+1th battery cell 10, the edge connection portion 11 in the Nth battery cell 10 includes a third edge connection portion 113 located on the front side and close to the third edge, the edge connection portion 11 in the N+1th battery cell 10 includes a fourth edge connection portion 114 located on the back side and close to the second edge; along the first direction, the distance between the third edge connection portion 113 and the third edge is D5, the distance between the fourth edge connection portion 114 and the second edge is D6, W < D5 < D6.

[0089] The Nth battery cell 10 also has a fourth edge close to the (N+1)th battery cell 10. Along the first direction, in the Nth battery cell 10, the distance between the first edge connecting portion 111 and the fourth edge is equal to the distance between the third edge connecting portion 113 and the third edge. In the (N+1)th battery cell 10, the distance between the second edge connecting portion 112 and the first edge is equal to the distance between the fourth edge connecting portion 114 and the second edge. D5 can be 3mm-6mm, for example, 3.72mm or 5.72mm. D6 can be 4mm-7mm, for example, 4.16mm or 6.92mm.

[0090] If the edge connection portion 11 is located in the overlapping area, the height difference between the two battery cells 10 in the overlapping area includes the height of the edge connection portion 11 and the in-string interconnect 20. This will result in a large height difference between the two battery cells 10 in the overlapping area, which can easily cause microcracks in the battery cells 10. In this embodiment, D5 and D6 are both greater than W, that is, the edge connection portion 11 is outside the overlapping area, which can avoid the large height difference between the two battery cells 10 in the overlapping area from causing microcracks in the battery cells 10.

[0091] In this embodiment, compared to the fourth edge connection portion 114 located on the back side, the third edge connection portion 113 located on the front side is closer to the edge of the battery cell 10, which facilitates the collection of current at the front edge of the battery cell 10. Furthermore, increasing D6 helps to shorten the length of the in-string interconnect 20, reducing material costs.

[0092] The emitter of the N-type TOPcon solar cell is on the front side of the solar cell 10, which is the light-receiving surface. The front electrode is used to collect and transport holes, while the back electrode is used to collect and transport electrons. Holes have a shorter lifetime than electrons and are more likely to recombine, reducing D5. This allows the third edge connection 113 on the front side to be closer to the edge of the solar cell 10, facilitating the collection and transport of holes at the edge of the solar cell 10.

[0093] In some embodiments, W is greater than or equal to 0.2 mm and less than or equal to 2 mm.

[0094] The width W of the overlapping region can be 0.2mm, 0.3mm, 0.5mm, 0.7mm, 1mm, 1.2mm, etc. The preferred width of the overlapping region is 0.3mm-0.7mm, for example, 0.5mm. If the width of the overlapping region is too small, stress concentration occurs at the stacking point of adjacent solar cells 10, making the solar cells 10 prone to microcracks. If the width of the overlapping region is too large, it will block too many electrodes and excessively obscure the front surface of the preceding solar cell at the overlapping point, resulting in wasted silicon wafer resources. In this embodiment, when the overlapping region is within the above-mentioned range, the risk of microcracks in the solar cells 10 at the overlapping region can be effectively reduced. Simultaneously, the number of blocked electrodes can be reduced, and the area of ​​the front surface of the preceding solar cell at the overlapping point can be reduced, ensuring that the preceding solar cell has sufficient light-receiving area.

[0095] In some embodiments, refer to Figure 3 Along the first direction, the distance between the edge connection portion 11 on the front side of the same battery cell 10 and the adjacent edge connection portion 11 on the back side is greater than 0.

[0096] In this embodiment, along the first direction, the distance between the edge connection portion 11 on the front side of the same solar cell 10 and the adjacent edge connection portion 11 on the back side can be 0.1mm-0.3mm. As the solar cell 10 becomes thinner, if the edge connection portion 11 on the front side of the same solar cell 10 corresponds to the edge connection portion 11 on the adjacent back side, i.e., the distance between them is 0, stress concentration is likely to occur. In this embodiment, the edge connection portion 11 on the front side of the same solar cell 10 and the adjacent edge connection portion 11 on the back side are staggered along the first direction, which can avoid microcracks and fragmentation of the solar cell caused by stress concentration at the solder joints on the front and back sides. In addition, by setting the edge connection portion 11 on the front side of the same solar cell 10 and the adjacent edge connection portion 11 on the back side to be staggered along the first direction, the thickness of the silicon wafer can be further reduced, thereby reducing material costs.

[0097] In some embodiments, along the thickness direction of the battery cell 10, the orthographic projection of a single flat portion 21 overlaps with the orthographic projection of y current collector electrodes, where y is 3-6.

[0098] Where y can be 3, 4, 5, 6, etc. Along the first direction, the spacing between two adjacent current collector electrodes on the solar cell 10 can be 0.9mm-1mm. The spacing between two adjacent current collector electrodes on the front side of the solar cell 10 can be different from the spacing between two adjacent current collector electrodes on the back side. The current collector electrodes include edge current collector electrodes near the edge of the solar cell 10. Along the second direction, the distance between the edge current collector electrodes and the edge of the solar cell 10 can be 0.4mm-0.8mm. The distance between the edge current collector electrodes on the front side of the solar cell 10 and the edge of the solar cell 10 can be different from the distance between the edge current collector electrodes on the back side of the solar cell 10.

[0099] In this embodiment, along the first direction, the flat portion 21 spans at least 3 current collectors. The flat portion 21 has a certain length, which can avoid the risk of microcracks at 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 6 current collectors, which can avoid the increase in the light-shielding area caused by the flat portion 21 being too long.

[0100] In some embodiments, refer to Figure 3 The battery string also includes a coating, which is laid on the surface of the battery cell 10 and at least covers a portion of the interconnects. The coating includes a first coating 30 laid on the front side of the Nth battery cell 10 and a second coating 40 laid on the back side of the N+1th battery cell 10. The first coating 30 extends at least partially to the overlapping area in a first direction, and the first coating 30 and the second coating 40 have a gap in the first direction.

[0101] For two adjacent solar cells 10, the first coating 30 covers at least a portion of the in-string interconnect 20 connected to the front side of the Nth solar cell 10, and the second coating 40 covers at least a portion of the in-string interconnect 20 connected to the back side of the (N+1)th solar cell 10. The materials of the first coating 30 and the second coating 40 can be EVA (ethylene-vinyl acetate copolymer) or POE (polyolefin elastomer). The material of the first coating 30 can be different from that of the second coating 40. The gap between the first coating 30 and the second coating 40 in the first direction can be located outside the overlapping area, within the overlapping area, or partially within and partially outside the overlapping area.

[0102] During the battery string fabrication process, after the first coating 30 and the second coating 40 are laid, they need to be cured to bond them to the battery cell 10, thus pre-fixing the interconnect components 20 within the string. Curing can be achieved by heating. During lamination, the temperature melts the tin layer on the surface of the interconnect components 20, forming a metallized contact with the pads of the battery cell 10, thus achieving welding. This effectively avoids the increased welding defect rate caused by traditional high-temperature welding.

[0103] In this embodiment of the invention, the first coating 30 extends at least partially into the overlapping region in a first direction. The first coating 30 extending into the overlapping region acts as a buffer during lamination, reducing the stress on the battery cell 10 from the interconnecting elements 20 in the overlapping region, thereby reducing the risk of microcracks in the battery cell 10 at the overlapping region. Furthermore, before lamination, the first coating 30 can pre-fix the flat portion 21, thereby preventing the vertical surface of the flat portion 21 from scratching the battery cell 10.

[0104] If the first coating 30 and the second coating 40 overlap at the overlapping area, the height difference between the two battery cells 10 at the overlapping area includes the heights of the first coating 30, the in-string interconnect 20, and the second coating 40. This results in a significant height difference between the two battery cells 10 at the overlapping area. In this embodiment of the invention, the first coating 30 extends at least partially into the overlapping area in a first direction, and the first coating 30 and the second coating 40 have a gap in the first direction. By providing this gap, the height difference between the two battery cells 10 at the overlapping area caused by the first coating 30 and the second coating 40 overlapping at the overlapping area can be prevented from increasing, thereby further reducing the risk of microcracks in the battery cells 10 at the overlapping area.

[0105] In some embodiments, the extended end of the second coating 40 is located outside the overlapping area, and the gap is located outside the overlapping area. The gap between the first coating 30 and the second coating 40 in the first direction is located outside the overlapping area. On the one hand, the back adhesive film can flow and fill the gap during lamination to avoid air bubbles and improve moisture sealing. On the other hand, it can prevent coatings that should not extend into the overlapping area due to process errors from accidentally entering the overlapping area.

[0106] In the battery string manufacturing process, several second coatings 40 are first placed at intervals on a conveyor belt. Then, the string head interconnect is placed on the first second coating 40, and the first battery cell 10 is placed on the string head interconnect, so that the second coating 40 adheres the string head interconnect to the back of the first battery cell 10. Next, the string internal interconnect is placed, with part of the string internal interconnect located on the front of the first battery cell 10 and part on the second second coating 40. Then, the first coating 30 is placed on the front of the first battery cell 10. Then, the second battery cell 10 is placed, with the edge of the second battery cell 10 overlapping the front of the first battery cell 10. The above steps of placing the string internal interconnect 20, the first coating 30, and the battery cell 10 are repeated until the last battery cell 10 is placed. Then, the string tail interconnect is placed on the front of the last battery cell 10, and the last first coating 30 is placed on the front of the last battery cell 10.

[0107] It should be noted that during the battery string preparation process, when placing the battery cell 10, the front side of the battery cell 10 faces upwards. After placing the first coating 30, a pressure mesh is also placed on the first coating 30 so that during the subsequent coating curing, the pressure mesh applies a certain pressure to the coating, which can better adhere the interconnects to the surface of the battery cell 10.

[0108] The extended end of the second coating 40 is located outside the overlapping area, that is, the second coating 40 does not extend into the overlapping area in the first direction. Based on the above-mentioned battery string manufacturing process, several second coatings 40 are pre-placed on the conveyor belt, making it difficult for the second coatings 40 to extend into the overlapping area. Therefore, the extended end of the second coating 40 is located outside the overlapping area, which is beneficial to the manufacturing process.

[0109] In some embodiments, in the first direction, the size of the first coating 30 is larger than the size of the second coating 40. Based on the above-described battery string manufacturing process, several second coatings 40 are pre-placed on the conveyor belt. The first coating 30 of the previous battery cell 10 is laid first, and then the next battery cell 10 is stacked. The size of the first coating 30 in the first direction is relatively large, and the size of the second coating 40 in the first direction is relatively small, which is beneficial to the manufacturing process.

[0110] In some embodiments, the thickness of the first coating 30 is greater than the thickness of the second coating 40. The thickness of the first coating 30 is designed to consider both the pre-fixation effect of the interconnects and the buffering effect during lamination. The thickness of the second coating 40 is designed to only consider the pre-fixation effect of the interconnects and does not need to consider the buffering effect during lamination. Therefore, the thickness of the second coating 40 can be less than the thickness of the first coating 30, thereby reducing the cost of the second coating 40.

[0111] In some embodiments, the extended end of the first coating 30 extends at least partially beyond the overlapping area in a first direction to avoid the edge of the N+1th cell 10 directly contacting the in-string interconnect 20, which could easily lead to lamination microcracks.

[0112] Along the first direction, the distance between the extended end of the first coating 30 of the Nth solar cell 10 and the edge of the (N+1)th solar cell 10 near the Nth solar cell 10 is defined as D7, where D7 is greater than W. The difference between D7 and W can be greater than or equal to 0.1 mm and less than or equal to 0.5 mm.

[0113] Along the first direction, the distance between the extended end of the first coating 30 of the Nth battery cell 10 before heat shrinkage and the edge of the (N+1)th battery cell 10 near the Nth battery cell 10 is defined as D8, where D8 is greater than W and the difference between D8 and W is 0.4mm-2mm, in order to prevent the extended end of the first coating 30 from shrinking and warping after heat shrinkage, thereby preventing the extended end of the first coating 30 from exceeding the overlapping area.

[0114] In some embodiments, the front and back sides of the battery cell 10 each have an edge connection portion 11 near the edge of the battery cell 10. The edge connection portion 11 in the N+1th battery cell 10 includes a second edge connection portion 112 located on the back side and near the Nth battery cell 10. The extended end of the second coating 40 of the N+1th battery cell 10 is located between the second edge connection portion 112 and the edge of the Nth battery cell 10.

[0115] In this embodiment, the second coating 40 of the N+1th battery cell 10 covers the part of the in-string interconnect 20 that is connected to the second edge connection part 112, so as to achieve pre-fixation of this part. This can prevent relative displacement between the in-string interconnect 20 and the edge connection part 11 during the layout or stringing process, which would lead to failure of connection reliability after lamination, and thus ensure the connection reliability between the edge connection part 11 and the in-string interconnect 20.

[0116] In some embodiments, the end of the interconnect connected to the back side of the Nth battery cell 10 is located outside the overlapping area, and the end of the interconnect connected to the front side of the N+1th battery cell 10 is located outside the overlapping area.

[0117] When the Nth cell 10 is not the first cell, the interconnect connected to the back of the Nth cell 10 is an intra-series interconnect 20. When the Nth cell 10 is the first cell, the interconnect connected to the back of the Nth cell 10 is a first-series interconnect. The same applies to the (N+1)th cell 10. The ends of the interconnects connected to the back of the Nth cell 10 near the Nth overlapping region and the ends of the interconnects connected to the front of the (N+1)th cell 10 near the Nth overlapping region have circular cross-sectional shapes. Stress concentration is easily formed at the contact point between these ends and the cell 10. In this embodiment, these ends are located outside the overlapping region, which can further reduce the risk of microcracks in the cell 10 at the overlapping region.

[0118] In some embodiments, the first coating 30 of the Nth cell 10 covers the edge current collector electrode on the front side of the Nth cell 10 to protect the edge current collector electrode on the front side of the Nth cell 10 and prevent damage to the edge current collector electrode.

[0119] In some embodiments, the material of the first coating 30 is different from the material of the second coating 40. For the coating laid on the front side of the solar cell 10, it needs to have functions such as resistance to PID (Potential Induced Degradation). Therefore, the material of the coating laid on the front side of the solar cell 10 can be superior to the material of the coating laid on the back side of the solar cell 10.

[0120] In some embodiments, the flat portion 21 includes a first sub-portion located on the Nth battery cell 10 and a second sub-portion connected to the first sub-portion; the first coating 30 of the Nth battery cell 10 at least covers a portion of the first sub-portion, and the second coating 40 of the N+1th battery cell 10 covers a portion of the second sub-portion.

[0121] In this embodiment, along the second direction, the length of the first sub-part is equal to the sum of D3 and W, and the length of the second sub-part is equal to D1. When the extended end of the first coating 30 of the Nth battery cell 10 at least partially extends beyond the overlapping area in the first direction, the first coating 30 of the Nth battery cell 10 completely covers the first sub-part. Along the second direction, the length of the portion of the second sub-part covered by the second coating 40 of the (N+1)th battery cell 10 can be greater than or equal to 0.5 mm. In this embodiment, before lamination, the first coating 30 and the second coating 40 together serve to pre-fix the flat portion 21, preventing the vertical surface of the flat portion 21 from scratching the battery cell 10, and preventing the battery cell 10 from easily breaking during lamination after the vertical surface of the flat portion 21 is erected.

[0122] In some embodiments, refer to Figure 3 , Figure 4 , Figure 7 and Figure 8The cross-sectional shape of the main body 22 is circular; the thickness of the first coating 30 and the second coating 40 is less than the diameter of the main body 22; and / or, 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.

[0123] Preferably, the thickness of the first coating 30 and the second coating 40 is greater than the thickness of the flat portion 21, for example, greater than or equal to 0.1 mm. 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 portion 22. This avoids poor buffering effect caused by excessively thin coatings and also avoids an increase in the height difference between the two battery cells 10 at the overlapping area caused by excessively thick coatings.

[0124] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0125] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the present invention, and all of these modifications are within the protection scope of the present invention.

Claims

1. A photovoltaic module, characterized by, The battery string comprises a plurality of battery pieces arranged in an overlapping manner and a string interconnection structure connecting adjacent two battery pieces; The adjacent two battery pieces in the battery string overlap to form an overlapping area, and the string interconnection structure comprises a string interconnection member, the string interconnection member comprises a flat part located at the overlapping area, the extension direction of the string interconnection member is a first direction, the length of the flat part is L along the first direction, the width of the overlapping area is W, and L is greater than W; The Nth string interconnection structure is connected to the front surface of the Nth battery piece and the back surface of the N+1th battery piece, and in the string interconnection member of the Nth string interconnection structure, the flat part has a first end located at the back surface of the N+1th battery piece, the first end of the flat part protrudes towards the back surface of the N+1th battery piece, the distance between the first end of the flat part and the Nth battery piece is D1 along the first direction, and 2W≤D1≤10W; In the string interconnection member of the Nth string interconnection structure, the flat part has a second end located at the front surface of the Nth battery piece, the distance between the second end of the flat part and the N+1th battery piece is D3 along the first direction, D3 is greater than or equal to W, D3 is less than D1, the difference between D1 and D3 is greater than or equal to W, and less than or equal to 3W.

2. The photovoltaic module of claim 1, wherein, The N+1th battery piece has a first edge close to the Nth battery piece, and in the string interconnection member of the Nth string interconnection structure, the distance between the first end of the flat part and the first edge of the N+1th battery piece is D2 along the first direction, and D2≥4W.

3. The photovoltaic module of claim 1, wherein, D3≤6W.

4. The photovoltaic module of claim 1, wherein, The front surface and the back surface of the battery piece each have an edge connecting part close to the edge of the battery piece, and the string interconnection member is electrically connected to the edge connecting part; The number of the edge connecting parts located at the overlapping area is 0.

5. The photovoltaic module of claim 4, wherein, The edge connecting part in the Nth battery piece comprises a first edge connecting part located at the front surface and close to the N+1th battery piece, and the edge connecting part in the N+1th battery piece comprises a second edge connecting part located at the back surface and close to the Nth battery piece; The distance between the first edge connecting part and the second edge connecting part is D4 along the first direction, and L<D4.

6. The photovoltaic module of claim 5, wherein, 0.3D4≤L≤0.9D4.

7. The photovoltaic module of claim 1, wherein, The front surface and the back surface of the battery piece each have a plurality of current collecting electrodes; The Nth battery piece and the N+1th battery piece overlap to form the Nth overlapping area, m1 current collecting electrodes of the front surface of the Nth battery piece are located in the Nth overlapping area, and m2 current collecting electrodes of the back surface of the N+1th battery piece are located in the Nth overlapping area, and m1+m2≤2.

8. The photovoltaic module of claim 7, wherein, m1 is 0, and m2≤1.

9. The photovoltaic module of claim 1, wherein, The string interconnection member further comprises a main body part, and the ratio of the thickness of the flat section in the flat part to the thickness of the main body part is 0.2-0.7 along the thickness direction of the battery piece.

10. The photovoltaic module of claim 1, wherein, The battery piece comprises an N-type monocrystalline silicon substrate; a P+ emitter, an anti-reflection layer and a front electrode on the front of the N-type monocrystalline silicon substrate; a tunneling oxide layer, a doped polysilicon layer and a back electrode on the back of the N-type monocrystalline silicon substrate.

11. The photovoltaic module of claim 10, wherein, The front and back of the battery piece each have an edge connection portion near the edge of the battery piece, and the intra-string interconnect is electrically connected to the edge connection portion; The N+1th battery piece has a second edge away from the Nth battery piece, the Nth battery piece has a third edge away from the N+1th battery piece, the edge connection portion in the Nth battery piece comprises a third edge connection portion on the front and near the third edge, and the edge connection portion in the N+1th battery piece comprises a fourth edge connection portion on the back and near the second edge; In the first direction, the distance between the third edge connection portion and the third edge is D5, the distance between the fourth edge connection portion and the second edge is D6, and W < D5 < D6.

12. The photovoltaic module of claim 1, wherein, W is greater than or equal to 0.2 mm and less than or equal to 2 mm.

13. The photovoltaic module of claim 1, wherein, The front and back of the battery piece each have an edge connection portion near the edge of the battery piece, and the intra-string interconnect is electrically connected to the edge connection portion; In the first direction, the distance between the edge connection portion on the front of the same battery piece and the edge connection portion on the adjacent back is greater than 0.

14. The photovoltaic module according to any of claims 1 to 13, characterized in that, The battery string further comprises a film, the film is laid on the surface of the battery piece and covers at least part of the interconnect, the film comprises a first film laid on the front of the Nth battery piece and a second film laid on the back of the N+1th battery piece; The first film extends at least partially to the overlap area in the first direction, and the first film and the second film have a gap in the first direction.

15. The photovoltaic module of claim 14, wherein, The extension end of the second film is located outside the overlap area, and the gap is located outside the overlap area.

16. The photovoltaic module of claim 15, wherein, The extension end of the first film at least partially exceeds the overlap area in the first direction.

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