Back contact photovoltaic module

Abstract

The invention relates to the photovoltaic field, and provides a back contact photovoltaic module, which comprises a plurality of battery strings, each battery string comprises a head end and a tail end which are oppositely arranged, and each battery string comprises a first battery piece arranged at the tail end and a second battery piece connected with the first battery piece; the first welding strip extends along the first direction and is electrically connected with the first battery piece and the second battery piece; the first isolating membrane is located on the second battery piece and located on the surface, deviating from the second battery piece, of the first welding strip; the first bus bar is located on the surface, deviating from the second battery piece, of the first isolating membrane; the second welding strip comprises a first part and a second part, the first part is located on the first battery piece and electrically connected with the first battery piece, and the second part is located on the surface, away from the second battery piece, of the first isolating membrane and electrically connected with the first bus bar. The power of the back contact photovoltaic module can be improved at least, and the reliability of the back contact photovoltaic module is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a back-contact photovoltaic module. Background Art

[0002] With the gradual depletion of fossil energy, solar energy, as a new energy alternative, is being used more and more widely. A solar cell is a device that converts the light energy of the sun into electrical energy. The solar cell utilizes the photovoltaic effect to generate carriers, and then uses electrodes to extract the carriers, thereby facilitating the effective utilization of electrical energy.

[0003] Current solar cells mainly include IBC (Interdigitated Back Contact) cells, TOPCON (Tunnel Oxide Passivated Contact) cells, PERC (Passivated Emitter and Real Cell), and heterojunction cells, etc.

[0004] For a back-contact cell photovoltaic module, a bus bar is usually provided at the edge of the module to electrically connect adjacent cell strings. However, setting the bus bar at the edge of the module will occupy the space of the module, resulting in a small area utilization rate of the back-contact photovoltaic module and affecting the power of the back-contact photovoltaic module. Summary of the Invention

[0005] Embodiments of the present disclosure provide a back-contact photovoltaic module, which at least helps to improve the power of the back-contact photovoltaic module and enhance the reliability of the back-contact photovoltaic module.

[0006] According to some embodiments of the present disclosure, embodiments of the present disclosure provide a back-contact photovoltaic module, including: a plurality of cell strings, each cell string including a head end and a tail end disposed opposite to each other, the cell string including a first cell sheet disposed at the tail end and a second cell sheet connected to the first cell sheet; a first solder ribbon, the first solder ribbon extending along a first direction and electrically connecting the first cell sheet and the second cell sheet; a first isolation film, the first isolation film being located on the second cell sheet and on the surface of the first solder ribbon facing away from the second cell sheet; a first bus bar, the first bus bar being located on the surface of the first isolation film facing away from the second cell sheet; a second solder ribbon, the second solder ribbon including a first part and a second part, the first part being located on the first cell sheet and electrically connected to the first cell sheet, the second part being located on the surface of the first isolation film facing away from the second cell sheet and electrically connected to the first bus bar.

[0007] In some embodiments, the second solder strip further includes a connecting portion located between the first portion and the second portion, and the extending direction of the connecting portion intersects the first direction; the second portion and the first solder strip on the second solar cell are spaced apart along the second direction.

[0008] In some embodiments, the distance between the second portion and the adjacent first solder strip along the second direction is 3 mm to 8 mm.

[0009] In some embodiments, the second solder strip is located between the first isolation film and the first bus bar. The first isolation film includes a first smooth portion and a first convex portion, and the first convex portion protrudes away from the second solar cell compared with the first smooth portion. The first solder strip is located between the first convex portion and the second solar cell. The surface of the first convex portion facing away from the second solar cell and the surface of the first smooth portion facing away from the second solar cell form a first concave portion, and the second solder strip is located in the first concave portion.

[0010] In some embodiments, the first bus bar is located between the first isolation film and the second solder strip. The first isolation film includes a first smooth portion and a first convex portion, and the first convex portion protrudes away from the second solar cell compared with the first smooth portion. The first solder strip is located between the first convex portion and the second solar cell; the first bus bar includes a second smooth portion and a second convex portion, the second smooth portion is located on the surface of the first smooth portion facing away from the second solar cell, the second convex portion protrudes away from the second solar cell compared with the second smooth portion, the second convex portion is located on the surface of the first convex portion facing away from the second solar cell, and the surface of the second convex portion facing away from the second solar cell and the surface of the second smooth portion facing away from the second solar cell form a second concave portion; the second solder strip is located in the second concave portion.

[0011] In some embodiments, the first isolation film includes a spacer portion and an isolation portion, the spacer portion is located between the first solar cell and the second solar cell, and the isolation portion is located on the surface of the second solar cell.

[0012] In some embodiments, the first isolation film is a transparent film layer.

[0013] In some embodiments, the width of the first isolation film along the first direction is greater than the width of the first bus bar along the first direction.

[0014] In some embodiments, the battery string further includes a third cell disposed at the first end and a fourth cell connected to the third cell, and the first solder ribbon is further configured to electrically connect the third cell and the fourth cell; the back-contact photovoltaic module further includes: a second bus bar that electrically connects the third cells of two of the battery strings arranged along the second direction, and the second bus bar is located on the fourth cell; a second isolation film that is located on the fourth cell and between the second bus bar and the fourth cell; a third solder ribbon that includes a first portion and a second portion, the first portion is located on the third cell and is electrically connected to the third cell, and the second portion is located on the surface of the second isolation film facing away from the fourth cell and is electrically connected to the second bus bar.

[0015] In some embodiments, the second solder ribbon further includes a connecting portion located between the first portion and the second portion, and the extending direction of the connecting portion intersects with the first direction; the second portion and the first solder ribbon on the fourth cell are spaced apart along the second direction.

[0016] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages: In the back-contact photovoltaic module provided by the embodiments of the present disclosure, by disposing the first bus bar on the surface of the second cell, the space for placing the first bus bar at the edge of the back-contact photovoltaic module is saved, so that more cells can be placed or larger-sized cells can be used without changing the size of the back-contact photovoltaic module, which is beneficial to improving the area utilization rate of the back-contact solar cell module and further improving the power of the back-contact photovoltaic module. In addition, a first isolation film is provided between the first bus bar and the first solder ribbon on the second cell of the back-contact photovoltaic module, which can prevent a short circuit between the first solder ribbon electrically connected to the first bus bar and the second solder ribbon on the second cell, affecting the performance of the back-contact photovoltaic module, thereby improving the reliability of the back-contact photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a scale limitation; in order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1Schematic diagram of a structure of a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 2 Schematic diagram of a structure of a first cell, a second cell, and an intermediate cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 3 Schematic cross-sectional structure diagram of a second cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 4 Another schematic cross-sectional structure diagram of a second cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 5 Schematic cross-sectional structure diagram of a first cell, a second cell, and a first isolation film in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 6 Schematic diagram of a structure of a third cell, a fourth cell, and an intermediate cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 7 Schematic cross-sectional structure diagram of a fourth cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 8 Another schematic cross-sectional structure diagram of a fourth cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 9 Schematic cross-sectional structure diagram of a third cell, a fourth cell, and a second isolation film in a back-contact photovoltaic module provided by an embodiment of the present disclosure; Figure 10 Schematic cross-sectional structure diagram of a back-contact photovoltaic module provided by an embodiment of the present disclosure.

[0019] Explanation of reference numerals: 1. Battery string; 11. First end; 12. Second end; 13. First cell; 14. Second cell; 15. Intermediate cell; 16. Third cell; 17. Fourth cell; 2. First solder strip; 3. First isolation film; 31. First smooth part; 32. First convex part; 33. Spacing part; 34. Isolation part; 4. First bus bar; 41. Second smooth part; 42. Second convex part; 5. Second solder strip; 51. First part; 52. Second part; 53. Connection part; 6. Second isolation film; 61. First smooth part; 62. First convex part; 63. Spacing part; 64. Isolation part; 7. Second bus bar; 71. Second smooth part; 72. Second convex part; 8. Third solder strip; 81. First part; 82. Second part; 83. Connection part; 91. Encapsulation adhesive film; 92. Cover plate. Detailed implementation manners

[0020] As can be seen from the background art, the current area utilization rate of the back-contact photovoltaic module is small, resulting in the power of the back-contact photovoltaic module needing to be improved.

[0021] An embodiment of the present disclosure provides a back-contact photovoltaic module. By arranging the first bus bar on the surface of the second solar cell, the space for placing the first bus bar at the edge of the back-contact photovoltaic module is saved, so that more solar cells can be placed or larger-sized solar cells can be used under the condition that the size of the back-contact photovoltaic module remains unchanged, which is beneficial to improving the area utilization rate of the back-contact solar cell module and further improving the power of the back-contact photovoltaic module. In addition, a first isolation film is provided between the first bus bar and the first solder tape on the second solar cell, which can prevent short circuit between the first solder tape electrically connected to the first bus bar and the second solder tape on the second solar cell, affecting the performance of the back-contact photovoltaic module, thereby improving the reliability of the back-contact photovoltaic module.

[0022] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality of" is more than two, unless otherwise clearly and specifically defined.

[0023] Referring to "embodiment" herein means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0024] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally means that the associated objects before and after are in an "or" relationship.

[0025] In the description of the embodiments of the present disclosure, the term "a plurality of" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of sheets" refers to more than two sheets (including two sheets).

[0026] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the embodiments of the present disclosure.

[0027] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0028] In the drawings corresponding to the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0029] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / at" another component, it can be "directly on" the other component (that is, on the surface of the other component and there is no other component between the two), or there can be another component between them. In addition, when a layer, film, region, plate, etc. component is "directly located on" another component, or when a layer, film, region, plate, etc. component is located on the surface of another component, it means that there is no other component between them.

[0030] The following will elaborate on the embodiments of the present disclosure in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are presented to help readers better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0031] Figure 1 It is a schematic structural diagram of a back-contact photovoltaic module provided by an embodiment of the present disclosure. Figure 2 It is a schematic structural diagram of a first cell, a second cell, and an intermediate cell in a back-contact photovoltaic module provided by an embodiment of the present disclosure.

[0032] Referring to Figure 1 and Figure 2 The back-contact photovoltaic module includes a plurality of cell strings 1, a first solder tape 2, a first isolation film 3, a first bus bar 4, and a second solder tape 5. The cell string 1 includes a head end 11 and a tail end 12 arranged oppositely. The cell string 1 includes a first cell 13 disposed at the tail end 12 and a second cell 14 connected to the first cell 13. The first solder tape 2 extends along the first direction X and electrically connects the first cell 13 and the second cell 14. The first isolation film 3 is located on the second cell 14 and on the surface of the first solder tape 2 facing away from the second cell 14. The first bus bar 4 is located on the surface of the first isolation film 3 facing away from the second cell 14. The second solder tape 5 includes a first portion 51 and a second portion 52. The first portion 51 is located on the first cell 13 and is electrically connected to the first cell 13. The second portion 52 is located on the surface of the first isolation film 3 facing away from the second cell 14 and is electrically connected to the first bus bar 4.

[0033] The cell string 1 includes a plurality of serially connected cells.

[0034] In some embodiments, the cells in the cell string 1 can be IBC cells, HPBC (Hybrid Passivated Back Contact) cells, TBC cells that stack TOPCon technology and IBC technology, or HBC cells that stack heterojunction technology and IBC technology. It can also be other types of back-contact cells.

[0035] In some embodiments, the adjacent cells in the cell string 1 are arranged at intervals. In other embodiments, the adjacent cells in the cell string can be partially overlapped, such as in a shingled module.

[0036] The cell includes a first cell 13, a second cell 14, and an intermediate cell 15. The first cell 13 is disposed at the end 12 of the cell string 1. The second cell 14 is located between the first cell 13 and the intermediate cell 15. The second cell 14 is electrically connected to the first cell 13 and is also electrically connected to the intermediate cell 15.

[0037] The cell can be a whole cell or a sliced cell. A sliced cell refers to a cell formed by cutting a complete whole cell through a cutting process. The sliced cell can be a two-part cell, a three-part cell, a four-part cell, etc.

[0038] The cell can be provided with chamfers (not marked), which can effectively reduce the stress concentration at the edge of the cell and reduce the risk of mechanical damage such as cell cracking and microcracks caused by stress concentration.

[0039] The first solder ribbon 2 is a series solder ribbon, which is used to electrically connect the first cell 13 and the second cell 14, and is also used to electrically connect the second cell 14 and the intermediate cell 15, and to electrically connect other adjacent intermediate cells 15.

[0040] In some embodiments, the first solder ribbon 2 can include a first series solder ribbon (not marked) and a second series solder ribbon (not marked). In the second direction Y, the first series solder ribbon and the second series solder ribbon are arranged in an interleaved manner. In a cell string 1, the Nth cell, the (N + 1)th cell, and the (N + 2)th cell (N is a positive integer greater than 1) are arranged in sequence along the first direction X. Among them, the positive electrode fine grid of the Nth cell is electrically connected to the negative electrode fine grid of the (N + 1)th cell through a plurality of first series solder ribbons, and the positive electrode fine grid of the (N + 1)th cell is electrically connected to the negative electrode fine grid of the (N + 2)th cell through a plurality of second series solder ribbons.

[0041] The second solder ribbon 5 is used to electrically connect the first cell 13 and the first bus bar 4. Among them, the first part 51 of the second solder ribbon 5 is located on the first cell 13 and is used to be electrically connected to the first cell 13, and the second part 52 is located on the second cell 14 and is used to be electrically connected to the first bus bar 4.

[0042] In some embodiments, the length of the first part 51 along the first direction X is 166 mm to 178 mm, such as 166 mm, 168 mm, 170 mm, 172 mm, 174 mm, or 178 mm. The length of the second part 52 along the first direction X is 8 mm to 15 mm, such as 8 mm, 10 mm, 12 mm, or 15 mm.

[0043] The first bus bar 4 is used for electrically connecting adjacent battery strings 1. Specifically, a part of the first bus bar 4 is electrically connected to the first solar cell 13 on a battery string 1 through a second solder tape 5, and another part of the first bus bar 4 is electrically connected to the first solar cell 13 on another battery string 1 through another second solder tape 5.

[0044] There is a gap between the first bus bar 4 and the first solar cell 13, that is, there is no first bus bar 4 on the first solar cell 13, which can avoid the situation of setting a part of the first bus bar 4 on the first solar cell 13 and reducing the contact area between the second solder tape 5 and the first solar cell 13, thereby affecting the current collection efficiency of the second solder tape 5. That is, there is a gap between the first bus bar 4 and the first solar cell 13, so that the contact area between the second solder tape 5 and the first solar cell 13 can be larger, which can improve the current collection efficiency of the second solder tape 5, thereby improving the performance of the back-contact photovoltaic module.

[0045] The first isolation film 3 is located between the first bus bar 4 and the second solar cell 14, which can prevent a short circuit between the first solder tape 2 and the second solder tape 5, avoid affecting the performance of the back-contact photovoltaic module, and thus improve the reliability of the back-contact photovoltaic module.

[0046] In some embodiments, after laying the first solder tape 2 on the solar cell, the first isolation film 3 can be laid, and then the first bus bar 4 and the second solder tape 5 are welded, and the welded first bus bar 4 and second solder tape 5 are laid on the solar cell. In other embodiments, after laying the first solder tape 2 on the solar cell, the first isolation film 3 and the second solder tape 5 are laid on the solar cell, and then the first bus bar 4 is welded on the second solder tape 5. In still other embodiments, after laying the first solder tape 2 on the solar cell; the first isolation film 3, the first bus bar 4 and the second solder tape 5 are first connected, and then the connected first isolation film 3, first bus bar 4 and second solder tape 5 are laid on the solar cell.

[0047] In some embodiments, the second solder tape 5 further includes a connecting portion 53. The connecting portion 53 is located between the first portion 51 and the second portion 52, and the extending direction of the connecting portion 53 intersects the first direction X; the second portion 52 and the first solder tape 2 on the second solar cell 14 are spaced apart along the second direction Y.

[0048] The extending direction of the connecting portion 53 intersects the first direction X, that is, the extending direction of the connecting portion 53 intersects the extending direction of the first portion 51 and intersects the extending direction of the second portion 52, so as to realize that the second portion 52 and the first solder tape 2 on the second solar cell 14 are spaced apart along the second direction Y, that is, they do not overlap.

[0049] The second part 52 is spaced from the first solder strip 2 on the second solar cell 14 along the second direction Y, which can prevent part of the first solder strip 2 on the second part 52 and the second solar cell 14 from being on the same straight line, thereby preventing this part of the first solder strip 2 from lifting the second part 52, making the second part 52 have a relatively higher height than the first part 51, pulling the first part 51, and causing the first part 51 to shift and affect the performance of the back-contact photovoltaic module. It can also prevent part of the first solder strip 2 from lifting the second part 52, resulting in the second part 52 having too high a height, and when the battery string 1 is subsequently laminated with the encapsulation adhesive film and the cover plate, stress concentration on the second part 52 with a higher height causes the solar cell to break.

[0050] In some embodiments, the extending direction of the connecting portion 53 intersects with the first direction X, and the included angle between the extending direction of the connecting portion 53 and the first direction X is 20° to 90°, such as 20° to 45°, 45° to 70°, or 70° to 90°. Exemplarily, the included angle between the extending direction of the connecting portion 53 and the first direction X can be 20°, 32.5°, 45°, 55°, 57.5°, 70°, 80°, or 90°.

[0051] When the included angle between the extending direction of the connecting portion 53 and the first direction X is 90°, the extending direction of the connecting portion 53 can be parallel to the second direction Y.

[0052] In some embodiments, the length of the connecting portion 53 along its extending direction is 5 mm to 8 mm, such as 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, or 8 mm.

[0053] In some embodiments, the distance between the second part 52 and the adjacent first solder strip 2 along the second direction Y is 3 mm to 8 mm, such as 3 mm to 5 mm, 5 mm to 6 mm, or 6 mm to 8 mm. Optionally 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, or 8 mm. When the distance between the second part 52 and the adjacent first solder strip 2 along the second direction Y is within the above range, it can prevent the performance of the back-contact photovoltaic module from being affected by short circuit due to the too-close distance between the second part 52 and the adjacent first solder strip 2.

[0054] Figure 3 It is a schematic cross-sectional structure diagram of the second solar cell in the back-contact photovoltaic module provided by the embodiments of the present disclosure.

[0055] Reference Figures 1 to 3, in some embodiments, the second solder strip 5 is located between the first isolation film 3 and the first bus bar 4. The first isolation film 3 includes a first smooth portion 31 and a first convex portion 32. The first convex portion 32 protrudes away from the second solar cell 14 compared with the first smooth portion 31. The first solder strip 2 is located between the first convex portion 32 and the second solar cell 14. The surface of the first convex portion 32 facing away from the second solar cell 14 and the surface of the first smooth portion 31 facing away from the second solar cell 14 form a first recess, and the second solder strip 5 is located in the first recess.

[0056] The first isolation film 3 is configured to include a structure such as the first smooth portion 31 and the first convex portion 32, and the second solder strip 5 is arranged in the first recess, so that the height of the second part 52 of the second solder strip 5 relative to the second solar cell 14 can be relatively low, avoiding the situation that the first part 51 located on the first solar cell 13 is pulled and displaced due to the relatively high height of the second part 52 of the second solder strip 5 relative to the second solar cell 14, which may affect the performance of the back-contact photovoltaic module. It can also avoid the situation that when the battery string 1 is subsequently laminated with the encapsulation adhesive film and the cover plate, stress is concentrated on the second part 52 with a relatively high height, resulting in fragmentation of the solar cell.

[0057] The first smooth portion 31 is in direct contact with the second solar cell 14. The first convex portion 32 is lifted by the first solder strip 2 and protrudes away from the second solar cell 14 compared with the first smooth portion 31. The surfaces of two adjacent first convex portions 32 and the first smooth portion 31 located between the two first convex portions 32 facing away from the second solar cell 14 form a first recess.

[0058] In some embodiments, the thickness of the second solder strip 5 is less than or equal to the thickness of the first solder strip 2. That is, the thickness of the first solder strip 2 can be relatively large, so that the height by which the first solder strip 2 lifts the first convex portion 32 of the first isolation film 3 is relatively high, and the first recess formed by the surface of the first convex portion 32 facing away from the second solar cell 14 and the surface of the first smooth portion 31 facing away from the second solar cell 14 can completely accommodate the second part 52. Here, completely accommodating means that the height difference between the surface of the first convex portion 32 facing away from the second solar cell 14 and the surface of the first smooth portion 31 facing away from the second solar cell 14 can be greater than or equal to the thickness of the second part 52 of the second solder strip 5.

[0059] In some embodiments, the thickness of the first solder strip 2 is 0.1 mm to 0.28 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm or 0.28 mm.

[0060] The thickness of the second solder strip 5 is 0.1 mm to 0.28 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm or 0.28 mm.

[0061] In some embodiments, the thickness of the first isolation film 3 is 0.1 mm to 0.3 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm or 0.3 mm.

[0062] Figure 4 Another schematic cross-sectional structure diagram of the second cell in the back-contact photovoltaic module provided by the embodiments of the present disclosure.

[0063] Reference Figure 1 、 Figure 2 and Figure 4 In some embodiments, the first bus bar 4 is located between the first isolation film 3 and the second solder strip 5. The first isolation film 3 includes a first smooth portion 31 and a first convex portion 32. The first convex portion 32 protrudes away from the second cell 14 compared with the first smooth portion 31. The first solder strip 2 is located between the first convex portion 32 and the second cell 14. The first bus bar 4 includes a second smooth portion 41 and a second convex portion 42. The second smooth portion 41 is located on the surface of the first smooth portion 31 facing away from the second cell 14. The second convex portion 42 protrudes away from the second cell 14 compared with the second smooth portion 41. The second convex portion 42 is located on the surface of the first convex portion 32 facing away from the second cell 14. The surface of the second convex portion 42 facing away from the second cell 14 and the surface of the second smooth portion 41 facing away from the second cell 14 form a second recess. The second solder strip 5 is located in the second recess.

[0064] The surface of the second convex portion 42 facing away from the second cell 14 and the surface of the second smooth portion 41 facing away from the second cell 14 form a second recess. Specifically, two adjacent second convex portions 42 and the second smooth portion 41 located between the two second convex portions 42 form a second recess.

[0065] The first isolation film 3 is configured to include a first smooth portion 31 and a first raised portion 32, and the first bus bar 4 is configured to include a second smooth portion 41 and a second raised portion 42, so that the first bus bar 4 is in close contact with the first isolation film 3, thereby improving the structural stability of the back contact photovoltaic module. In addition, the second welding strip 5 is configured in the second recessed portion formed by the second smooth portion 41 and the second raised portion 42, so that the second portion 52 of the second welding strip 5 can be relatively low in height relative to the second battery cell 14, thereby avoiding the second portion 52 of the second welding strip 5 being relatively high in height relative to the second battery cell 14, thereby avoiding the first portion 51 located on the first battery cell 13 being pulled, thereby causing the first portion 51 to shift and affect the performance of the back contact photovoltaic module, and also avoiding the stress concentration on the second portion 52 of the second welding strip 5 being relatively high in height relative to the second battery cell 14, thereby causing the battery cell to be broken when the battery string 1 is subsequently laminated with the packaging film and the cover plate.

[0066] Figure 5 A schematic cross-sectional structure diagram of a first cell, a second cell and a first isolation film in a back-contact photovoltaic module provided in an embodiment of the present disclosure.

[0067] refer to Figure 1 , Figure 2 and Figure 5 In some embodiments, the first isolation film 3 includes a spacer 33 and a spacer 34, wherein the spacer 33 is located between the first cell 13 and the second cell 14, and the spacer 34 is located on the surface of the second cell 14. The spacer 33 is located between the first cell 13 and the second cell 14, and the spacer 33 can serve as a buffer layer between the first cell 13 and the second cell 14 to prevent the first cell 13 and the second cell 14 from being too close to each other and causing collisions. At the same time, the first cell 13 and the second cell 14 can also be insulated from each other, which can be beneficial to further shorten the distance between the first cell 13 and the second cell 14, and improve the area utilization of the back contact photovoltaic module.

[0068] The isolation portion 34 is located on the surface of the second battery cell 14 and is used to isolate the first bus bar 4 from the first welding ribbon 2 .

[0069] In some embodiments, the first isolation film 3 is a transparent film layer, so that more sunlight can be absorbed by the solar cell through the first isolation film 3, which is beneficial to improving the performance of the back contact photovoltaic module.

[0070] Continue to refer Figure 1 and Figure 2 In some embodiments, the width of the first isolation film 3 along the first direction X is greater than the width of the first bus bar 4 along the first direction X. In this way, the first isolation film 3 has a larger width, which can effectively achieve electrical isolation between the first bus bar 4 and the first welding ribbon 2 .

[0071] In some embodiments, the width of the first isolation film 3 in the first direction X is 10 mm to 20 mm, such as 10 mm, 12 mm, 14 mm, 16 mm, 18 mm or 20 mm. When the width of the first isolation film 3 is within the above range, it can effectively isolate the first bus bar 4 from the first solder strip 2 on the second solar cell 14, and can also avoid the problems that the width of the first isolation film 3 is too wide, which affects the second solar cell 14's absorption of sunlight and the cost increase due to the too wide width.

[0072] The width of the first bus bar 4 in the first direction X is 8 mm to 15 mm, such as 8 mm, 10 mm, 12 mm, 14 mm or 15 mm.

[0073] Figure 6 It is a schematic structural diagram of the third solar cell, the fourth solar cell and the intermediate solar cell in the back-contact photovoltaic module provided by the embodiments of the present disclosure.

[0074] Refer to Figure 1 and Figure 6 In some embodiments, the battery string 1 further includes a third solar cell 16 disposed at the first end 11 and a fourth solar cell 17 connected to the third solar cell 16, and the first solder strip 2 is also electrically connected to the third solar cell 16 and the fourth solar cell 17; the back-contact photovoltaic module further includes a second bus bar 7, a second isolation film 6 and a third solder strip 8. The second bus bar 7 is electrically connected to the third solar cells 16 of two battery strings 1 arranged along the second direction Y, and the second bus bar 7 is located on the fourth solar cell 17; the second isolation film 6 is located on the fourth solar cell 17 and is between the second bus bar 7 and the fourth solar cell 17; the third solder strip 8 includes a first part 81 and a second part 82. The first part 81 is located on the third solar cell 16 and is electrically connected to the third solar cell 16, and the second part 82 is located on the surface of the second isolation film 6 facing away from the fourth solar cell 17 and is electrically connected to the second bus bar 7.

[0075] By disposing the second bus bar 7 on the surface of the fourth solar cell 17, the space for placing the second bus bar 7 in the middle of the back-contact photovoltaic module is saved, so that more solar cells can be placed or larger-sized solar cells can be used without changing the size of the back-contact photovoltaic module, which is beneficial to improving the area utilization rate of the back-contact solar cell module and thus improving the power of the back-contact photovoltaic module. In addition, the back-contact photovoltaic module also has a second isolation film 6 between the second bus bar 7 and the first solder strip 2 on the fourth solar cell 17, which can prevent a short circuit between the third solder strip 8 electrically connected to the second bus bar 7 and the first solder strip 2 on the fourth solar cell 17, affecting the performance of the back-contact photovoltaic module, and thus can improve the reliability of the back-contact photovoltaic module.

[0076] The third cell 16 is disposed at the first end 11 of the cell string 1. The fourth cell 17 is located between the third cell 16 and the middle cell 15. The fourth cell 17 is electrically connected to the third cell 16 and is also electrically connected to the middle cell 15.

[0077] The first solder strip 2 is also used to electrically connect the third cell 16 and the fourth cell 17, and to electrically connect the fourth cell 17 and the middle cell 15.

[0078] The third solder strip 8 is used to electrically connect the third cell 16 and the second bus bar 7. Among them, the first part 81 of the third solder strip 8 is located on the third cell 16 and is used to be electrically connected to the third cell 16. And the first part 81 is electrically connected to the third cells 16 of the two cell strings 1 arranged along the second direction Y. The second part 82 is located on the fourth cell 17 and is used to be electrically connected to the second bus bar 7.

[0079] The second bus bar 7 is electrically connected to the third cells 16 at the first ends 11 of the 2 cell strings 1 arranged along the second direction Y to parallel adjacent cell strings 1.

[0080] There is a gap between the second bus bar 7 and the third cell 16, that is, there is no second bus bar 7 on the third cell 16, which can avoid setting part of the second bus bar 7 on the third cell 16 and reduce the contact area between the third solder strip 8 and the third cell 16, thereby affecting the current collection efficiency of the third solder strip 8. That is, there is a gap between the second bus bars 7 among the third cells 16, so that the contact area between the third solder strip 8 and the third cell 16 can be larger, which can improve the current collection efficiency of the third solder strip 8, thereby improving the performance of the back-contact photovoltaic module.

[0081] The second isolation film 6 is located between the second bus bar 7 and the fourth cell 17, which can avoid short circuit between the first solder strip 2 and the third solder strip 8, avoid affecting the performance of the back-contact photovoltaic module, and thus can improve the reliability of the back-contact photovoltaic module.

[0082] In some embodiments, the third solder strip 8 further includes a connecting portion 83. The connecting portion 83 is located between the first part 81 and the second part 82. The extending direction of the connecting portion 83 intersects with the first direction X; the second part 82 and the first solder strip 2 on the fourth cell 17 are spaced apart along the second direction Y.

[0083] The extending direction of the connecting portion 83 intersects with the first direction X, that is, the extending direction of the connecting portion 83 intersects with the extending direction of the first part 81 and intersects with the extending direction of the second part 82, so as to realize that the second part 82 and the first solder strip 2 on the fourth cell 17 are spaced apart along the second direction Y.

[0084] The second part 82 and the first solder tape 2 on the fourth cell 17 are arranged at intervals along the second direction Y, which can prevent the second part 82 and some of the first solder tapes 2 on the fourth cell 17 from being on the same straight line, thereby avoiding these first solder tapes 2 from lifting the second part 82, resulting in a relatively high height of the second part 82 relative to the first part 81, pulling the first part 81, causing the first part 81 to shift and affecting the performance of the back-contact photovoltaic module. It can also prevent some of the first solder tapes 2 from lifting the second part 82, resulting in an excessive height of the second part 82. When the battery string 1 is subsequently laminated with the encapsulation adhesive film and the cover plate, stress is concentrated on the second part 82 with a relatively high height, resulting in the situation of cell fragmentation.

[0085] In some embodiments, the extending direction of the connecting part 83 intersects with the first direction X, and the included angle between the extending direction of the connecting part 83 and the first direction X is 20° to 90°, such as 20° to 45°, 45° to 70°, or 70° to 90°. Exemplarily, the included angle between the extending direction of the connecting part 83 and the first direction X can be 20°, 32.5°, 45°, 55°, 57.5°, 70°, 80°, or 90°.

[0086] When the included angle between the extending direction of the connecting part 83 and the first direction X is 90°, the extending direction of the connecting part 83 can be parallel to the second direction Y.

[0087] In some embodiments, the distance between the second part 82 and the adjacent first solder tape 2 along the second direction Y is 3 mm to 8 mm, such as 3 mm to 5 mm, 5 mm to 6 mm, or 6 mm to 8 mm. Optionally, it can be 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, or 8 mm. When the distance between the second part 82 and the adjacent first solder tape 2 along the second direction Y is within the above range, it can prevent the performance of the back-contact photovoltaic module from being affected by short circuit due to the too-close distance between the second part 82 and the adjacent first solder tape 2.

[0088] Figure 7 This is a schematic cross-sectional structure diagram of the fourth cell in the back-contact photovoltaic module provided by the embodiments of the present disclosure.

[0089] Reference Figure 1 、 Figure 6 and Figure 7, in some embodiments, the third solder strip 8 is located between the second isolation film 6 and the second bus bar 7. The second isolation film 6 includes a first smooth portion 61 and a first convex portion 62. The first convex portion 62 protrudes in a direction away from the fourth solar cell 17 compared to the first smooth portion 61. The first solder strip 2 is located between the first convex portion 62 and the fourth solar cell 17. The surface of the first convex portion 62 facing away from the fourth solar cell 17 and the surface of the first smooth portion 61 facing away from the fourth solar cell 17 form a first concave portion, and the third solder strip 8 is located within the first concave portion. The second isolation film 6 is configured to include the structure of the first smooth portion 61 and the first convex portion 62, and the third solder strip 8 is disposed within the first concave portion formed by the first smooth portion 61 and the first convex portion 62, so that the height of the second portion 82 of the third solder strip 8 relative to the fourth solar cell 17 can be relatively low, avoiding the situation that the first portion 81 located on the third solar cell 16 is pulled and displaced due to the relatively high height of the second portion 82 of the third solder strip 8 relative to the fourth solar cell 17, which affects the performance of the back-contact photovoltaic module. It can also avoid the situation that when the battery string 1 is subsequently laminated with the encapsulation adhesive film and the cover plate, stress is concentrated on the relatively high second portion 82, resulting in fragmentation of the solar cell.

[0090] The first smooth portion 61 is in direct contact with the fourth solar cell 17. The first convex portion 62 is lifted by the first solder strip 2 and protrudes in a direction away from the fourth solar cell 17 compared to the first smooth portion 61. The surfaces of two adjacent first convex portions 62 and the first smooth portion 61 located between the two first convex portions 62 facing away from the fourth solar cell 17 form a first concave portion.

[0091] In some embodiments, the thickness of the third solder strip 8 is less than or equal to the thickness of the first solder strip 2. That is, the thickness of the first solder strip 2 can be relatively large so that the first solder strip 2 can lift the first convex portion 62 of the second isolation film 6 to a relatively high height, and the first concave portion formed by the surface of the first convex portion 62 facing away from the fourth solar cell 17 and the surface of the first smooth portion 61 facing away from the fourth solar cell 17 can completely accommodate the second portion 82. Here, completely accommodating means that the height difference between the surface of the first convex portion 62 facing away from the fourth solar cell 17 and the surface of the first smooth portion 61 facing away from the fourth solar cell 17 can be greater than or equal to the thickness of the second portion 82 of the third solder strip 8.

[0092] In some embodiments, the thickness of the first solder strip 2 is 0.1 mm to 0.28 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm, or 0.28 mm.

[0093] In some embodiments, the thickness of the third solder strip 8 is 0.1 mm to 0.28 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm or 0.28 mm.

[0094] In some embodiments, the thickness of the second isolation film 6 is 0.1 mm to 0.3 mm, such as 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm or 0.3 mm.

[0095] Figure 8 It is another schematic cross-sectional structure diagram of the fourth cell in the back-contact photovoltaic module provided by the embodiments of the present disclosure.

[0096] Reference Figure 1 、 Figure 6 and Figure 8 In some embodiments, the second bus bar 7 is located between the second isolation film 6 and the third solder strip 8. The second isolation film 6 includes a first smooth portion 61 and a first convex portion 62. The first convex portion 62 protrudes in a direction away from the fourth cell 17 compared with the first smooth portion 61. The first solder strip 2 is located between the first convex portion 62 and the fourth cell 17. The second bus bar 7 includes a second smooth portion 71 and a second convex portion 72. The second smooth portion 71 is located on the surface of the first smooth portion 61 away from the fourth cell 17. The second convex portion 72 protrudes in a direction away from the fourth cell 17 compared with the second smooth portion 71. The second convex portion 72 is located on the surface of the first convex portion 62 away from the fourth cell 17. A second concave portion (not labeled) is formed between the surface of the second convex portion 72 away from the fourth cell 17 and the surface of the second smooth portion 71 away from the fourth cell 17. The third solder strip 8 is located in the second concave portion.

[0097] The surface of the second convex portion 72 away from the fourth cell 17 and the surface of the second smooth portion 71 away from the fourth cell 17 form a second concave portion. Specifically, two adjacent second convex portions 72 and the second smooth portion 71 located between the two second convex portions 72 form a second concave portion.

[0098] The second isolation film 6 is configured to have a structure including a first smooth portion 61 and a first protruding portion 62, while the second bus bar 7 is configured to have a structure including a second smooth portion 71 and a second protruding portion 72, so that the second bus bar 7 is in close contact with the second isolation film 6, improving the structural stability of the back-contact photovoltaic module. Additionally, the third solder tape 8 is disposed within a second recessed portion formed by the second smooth portion 71 and the second protruding portion 72, such that the height of the second portion 82 of the third solder tape 8 relative to the fourth cell 17 can be relatively low, avoiding the situation where the first portion 81 located on the third cell 16 is pulled and displaced due to the relatively high height of the second portion 82 of the third solder tape 8 relative to the fourth cell 17, which would affect the performance of the back-contact photovoltaic module. It can also avoid the occurrence of cell fragmentation due to stress concentration on the relatively high second portion 82 during subsequent lamination of the cell string 1 with the encapsulant film and the cover plate when the height of the second portion 82 of the third solder tape 8 relative to the fourth cell 17 is relatively high.

[0099] Figure 9 FIG. is a schematic cross-sectional structure diagram of a third cell, a fourth cell, and a second isolation film in the back-contact photovoltaic module provided by an embodiment of the present disclosure.

[0100] Reference Figure 1 、 Figure 6 and Figure 9 In some embodiments, the second isolation film 6 includes a spacer portion 63 and an isolation portion 64. The spacer portion 63 is located between the third cell 16 and the fourth cell 17, and the isolation portion 64 is located on the surface of the fourth cell 17. The spacer portion 63 being located between the third cell 16 and the fourth cell 17 can serve as a buffer layer between the third cell 16 and the fourth cell 17, preventing the third cell 16 and the fourth cell 17 from coming too close and colliding, and at the same time can also achieve electrical insulation between the third cell 16 and the fourth cell 17. In this way, it is beneficial to further shorten the distance between the third cell 16 and the fourth cell 17, improving the area utilization rate of the back-contact photovoltaic module.

[0101] The isolation portion 64 is located on the surface of the fourth cell 17 and is used to isolate the second bus bar 7 from the first solder tape 2.

[0102] In some embodiments, the second isolation film 6 is a transparent film layer. In this way, more light can pass through the second isolation film 6 and be absorbed by the fourth cell 17, which is beneficial to improving the performance of the back-contact photovoltaic module.

[0103] Continue to refer to Figure 1 and Figure 6, in some embodiments, the width of the second isolation film 6 in the first direction X is greater than the width of the second bus bar 7 in the first direction X. In this way, the relatively large width of the second isolation film 6 can effectively achieve electrical isolation between the second bus bar 7 and the first solder strip 2.

[0104] In some embodiments, the width of the second isolation film 6 in the first direction X is 10 mm to 20 mm, such as 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, or 20 mm. When the width of the second isolation film 6 is within the above range, it can effectively isolate the second bus bar 7 from the first solder strip 2 on the fourth solar cell 17, and can also avoid the problems that an overly wide second isolation film 6 affects the fourth solar cell 17's absorption of sunlight and increases costs due to its overly wide width.

[0105] The width of the second bus bar 7 in the first direction X is 8 mm to 15 mm, such as 8 mm, 10 mm, 12 mm, 14 mm, or 15 mm.

[0106] Figure 10 FIG. is a schematic cross-sectional structure diagram of a back-contact photovoltaic module provided by an embodiment of the present disclosure.

[0107] Referring to Figure 1 and Figure 10 , in some embodiments, the back-contact photovoltaic module further includes a packaging adhesive film 91 and a cover plate 92. The packaging adhesive film 91 is used to cover the surface of the battery string 1; the cover plate 92 is used to cover the surface of the packaging adhesive film 91 facing away from the battery string 1.

[0108] In some embodiments, the packaging adhesive film 91 includes a first packaging layer and a second packaging layer. The first packaging layer covers one of the front or back surfaces of the battery string 1, and the second packaging layer covers the other of the front or back surfaces of the battery string 1. Specifically, at least one of the first packaging layer and the second packaging layer can be an organic packaging adhesive film such as a polyvinyl butyral (PVB) adhesive film, an ethylene-vinyl acetate copolymer (EVA) adhesive film, a polyethylene octene co-elastic body (POE) adhesive film, or a polyethylene terephthalate (PET) adhesive film, or at least one of the first packaging layer and the second packaging layer can also be an adhesive film such as an EP adhesive film, an EPE adhesive film, or a PVP adhesive film.

[0109] Among them, the EP film refers to a co-extruded film composed of an EVA film and a POE film stacked on top of each other. The EPE film refers to a co-extruded film formed by sequentially stacking an EVA film + a POE film + an EVA film. The PVP film refers to a co-extruded film formed by stacking a POE film + an EVA film + a POE film. The co-extruded film can be manufactured by extruding one or more raw materials onto another already manufactured film in sequence during the film processing, or by bonding different types of already manufactured films together.

[0110] In some cases, there is also a demarcation line between the first encapsulation layer and the second encapsulation layer before lamination. After the lamination process, there will no longer be the concept of the first encapsulation layer and the second encapsulation layer in the formed photovoltaic module, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film.

[0111] In some embodiments, the cover plate 92 can be a cover plate with a light-transmitting function such as a glass cover plate or a plastic cover plate. Specifically, the surface of the cover plate facing the encapsulation film can be a concave-convex surface or a suede surface containing multiple protruding structures, so as to increase the utilization rate of incident light. The cover plate 92 includes a first cover plate and a second cover plate. The first cover plate is opposite to the first encapsulation layer, and the second cover plate is opposite to the second encapsulation layer.

[0112] Those of ordinary skill in the art can understand that the above embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made to it in form and details without departing from the spirit and scope of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A back contact photovoltaic module, characterized in that: include: A plurality of battery strings, each battery string comprising a head end and a tail end arranged opposite to each other, each battery string comprising a first battery cell arranged at the tail end and a second battery cell connected to the first battery cell; A first welding strip extending along a first direction and electrically connecting the first battery cell and the second battery cell; a first isolation film, wherein the first isolation film is located on the second battery cell and is located on a surface of the first welding strip facing away from the second battery cell; a first bus bar, the first bus bar being located on a surface of the first isolation film facing away from the second battery sheet; The second welding strip includes a first portion and a second portion, the first portion is located on the first battery cell and electrically connected to the first battery cell, and the second portion is located on a surface of the first isolation film away from the second battery cell and electrically connected to the first bus bar.

2. The back contact photovoltaic module according to claim 1, characterized in that: The second welding strip further includes a connecting portion, the connecting portion is located between the first portion and the second portion, and an extending direction of the connecting portion intersects with the first direction; the second portion and the first welding strip on the second battery cell are spaced apart along the second direction.

3. The back contact photovoltaic module according to claim 2, characterized in that: A distance between the second portion and the adjacent first welding strip along the second direction is 3 mm to 8 mm.

4. The back contact photovoltaic module according to claim 2, characterized in that: The second welding strip is located between the first isolation film and the first bus bar, the first isolation film includes a first smooth portion and a first protruding portion, the first protruding portion protrudes in a direction away from the second battery cell compared to the first smooth portion, the first welding strip is located between the first protruding portion and the second battery cell, the surface of the first protruding portion away from the second battery cell and the surface of the first smooth portion away from the second battery cell form a first recessed portion, and the second welding strip is located in the first recessed portion.

5. The back contact photovoltaic module according to claim 2, characterized in that: The first bus bar is located between the first isolation film and the second welding strip, the first isolation film includes a first smooth portion and a first convex portion, the first convex portion is convex in a direction away from the second battery cell compared to the first smooth portion, and the first welding strip is located between the first convex portion and the second battery cell; The first bus bar includes a second smooth portion and a second raised portion, the second smooth portion is located on a surface of the first smooth portion facing away from the second battery cell, the second raised portion is raised in a direction away from the second battery cell compared to the second smooth portion, the second raised portion is located on a surface of the first raised portion facing away from the second battery cell, the surface of the second raised portion facing away from the second battery cell and the surface of the second smooth portion facing away from the second battery cell form a second recessed portion; the second welding strip is located in the second recessed portion.

6. The back contact photovoltaic module according to claim 2, characterized in that: The first isolation film includes a spacer and an isolation portion, the spacer is located between the first battery cell and the second battery cell, and the isolation portion is located on a surface of the second battery cell.

7. The back contact photovoltaic module according to claim 1, characterized in that: The first isolation film is a transparent film layer.

8. The back contact photovoltaic module according to claim 1, characterized in that: A width of the first isolation film along the first direction is greater than a width of the first bus bar along the first direction.

9. The back contact photovoltaic module according to claim 1, characterized in that: The battery string further includes a third battery cell disposed at the head end and a fourth battery cell connected to the third battery cell, and the first welding strip is further used to electrically connect the third battery cell and the fourth battery cell; The back contact photovoltaic module further comprises: a second bus bar, the second bus bar electrically connecting the third battery cells of the two battery strings arranged along the second direction, the second bus bar being located on the fourth battery cell; a second isolation film, the second isolation film being located on the fourth battery cell and between the second bus bar and the fourth battery cell; The third welding strip includes a first portion and a second portion, the first portion is located on the third battery cell and electrically connected to the third battery cell, and the second portion is located on a surface of the second isolation film away from the fourth battery cell and electrically connected to the second bus bar.

10. The back contact photovoltaic module according to claim 9, characterized in that: The second welding strip further includes a connecting portion, which is located between the first portion and the second portion, and an extending direction of the connecting portion intersects with the first direction; the second portion and the first welding strip on the fourth battery cell are spaced apart along the second direction.

Images