Back contact photovoltaic modules

Abstract

This disclosure relates to the photovoltaic field and provides a back-contact photovoltaic module. The back-contact photovoltaic module includes: multiple cell strings, each cell string having a head end and a tail end disposed opposite to each other; each cell string includes a first cell disposed at the tail end and a second cell connected to the first cell; a first solder strip extending along a first direction and electrically connecting the first cell and the second cell; a first separator film located on the second cell and on the surface of the first solder strip opposite to the second cell; a first busbar located on the surface of the first separator film opposite to the second cell; and a second solder strip including a first portion and a second portion, the first portion being located on the first cell and electrically connected to it, and the second portion being located on the surface of the first separator film opposite to the second cell and electrically connected to the first busbar. This disclosure can at least increase the power output of the back-contact photovoltaic module and improve its reliability.

Description

Technical Field

[0001] This disclosure relates to the photovoltaic field, and in particular to a back-contact photovoltaic module. Background Technology

[0002] As fossil fuels are gradually depleted, solar energy is becoming increasingly widely used as a new energy alternative. A solar cell is a device that converts sunlight into electrical energy. Solar cells utilize the photovoltaic principle to generate charge carriers, which are then extracted using electrodes, thus facilitating the efficient use 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) cells, and heterojunction cells.

[0004] For back-contact photovoltaic modules, busbars are usually installed at the edge of the module to electrically connect adjacent cell strings. However, placing the busbars at the edge of the module occupies module space, resulting in a lower area utilization rate of the back-contact photovoltaic module and affecting its power output. Summary of the Invention

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

[0006] According to some embodiments of this disclosure, an embodiment of this disclosure provides a back-contact photovoltaic module, comprising: a plurality of cell strings, each cell string including a head end and a tail end disposed opposite to each other, each cell string including a first cell disposed at the tail end and a second cell connected to the first cell; a first solder strip extending along a first direction and electrically connecting the first cell and the second cell; a first separator film located on the second cell and on the surface of the first solder strip opposite to the second cell; a first busbar located on the surface of the first separator film opposite to the second cell; and a second solder strip including a first portion and a second portion, the first portion being located on the first cell and electrically connected to the first cell, and the second portion being located on the surface of the first separator film opposite to the second cell and electrically connected to the first busbar.

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

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

[0009] In some embodiments, the second solder strip is located between the first separator and the first busbar. The first separator includes a first smooth portion and a first protrusion. The first protrusion protrudes in a direction away from the second battery cell relative to the first smooth portion. The first solder strip is located between the first protrusion and the second battery cell. The surface of the first protrusion away from the second battery cell and the surface of the first smooth portion away from the second battery cell form a first recess. The second solder strip is located within the first recess.

[0010] In some embodiments, the first busbar is located between the first separator and the second solder strip. The first separator includes a first smooth portion and a first protrusion. The first protrusion protrudes in a direction away from the second battery cell relative to the first smooth portion. The first solder strip is located between the first protrusion and the second battery cell. The first busbar includes a second smooth portion and a second protrusion. The second smooth portion is located on the surface of the first smooth portion away from the second battery cell. The second protrusion protrudes in a direction away from the second battery cell relative to the second smooth portion. The second protrusion is located on the surface of the first protrusion away from the second battery cell. The surface of the second protrusion away from the second battery cell and the surface of the second smooth portion away from the second battery cell form a second recess. The second solder strip is located within the second recess.

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

[0012] In some embodiments, the first separating membrane is a transparent membrane layer.

[0013] In some embodiments, the width of the first separator membrane along the first direction is greater than the width of the first busbar along the first direction.

[0014] In some embodiments, the battery string further includes a third battery cell disposed at the first end and a fourth battery cell connected to the third battery cell, and the first solder strip is also used to electrically connect the third battery cell and the fourth battery cell; the back contact photovoltaic module further includes: a second busbar, the second busbar electrically connecting the third battery cells of the two battery strings arranged along the second direction, the second busbar being located on the fourth battery cell; a second separator, the second separator being located on the fourth battery cell and between the second busbar and the fourth battery cell; a third solder strip, the third solder strip including a first portion and a second portion, the first portion being located on the third battery cell and electrically connected to the third battery cell, the second portion being located on the surface of the second separator facing away from the fourth battery cell and electrically connected to the second busbar.

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

[0016] The technical solution provided in this disclosure has at least the following advantages:

[0017] In the back-contact photovoltaic module provided in this disclosure, by placing the first busbar on the surface of the second cell, space is saved compared to placing the first busbar at the edge of the back-contact photovoltaic module. This allows for the placement of more cells or the use of larger cells without changing the overall size of the back-contact photovoltaic module, thus improving the area utilization rate and power output. Furthermore, a first insulating film is provided between the first busbar and the first solder strip on the second cell to prevent short circuits between the first solder strip electrically connected to the first busbar and the second solder strip on the second cell, which would affect the performance of the back-contact photovoltaic module and improve its reliability. Attached Figure Description

[0018] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a back-contact photovoltaic module provided in an embodiment of the present disclosure;

[0020] Figure 2 This is a schematic diagram of a structure of a first cell, a second cell, and an intermediate cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0021] Figure 3 A schematic cross-sectional structure of a second cell in a back-contact photovoltaic module provided in an embodiment of this disclosure;

[0022] Figure 4 This is a schematic diagram of another cross-sectional structure of the second cell in a back-contact photovoltaic module provided in an embodiment of this disclosure;

[0023] Figure 5 This is a cross-sectional structural diagram of a first solar cell, a second solar cell, and a first separator in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0024] Figure 6 This is a schematic diagram of a structure of a third, fourth, and intermediate solar cell in a back-contact photovoltaic module provided in an embodiment of the present disclosure.

[0025] Figure 7 This is a schematic cross-sectional view of a fourth cell in a back-contact photovoltaic module provided in an embodiment of the present disclosure;

[0026] Figure 8 This is a schematic diagram of another cross-sectional structure of the fourth cell in a back-contact photovoltaic module provided in an embodiment of this disclosure;

[0027] Figure 9 This is a cross-sectional structural diagram of a third solar cell, a fourth solar cell, and a second separator in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0028] Figure 10 This is a cross-sectional structural diagram of a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Battery string; 11. First end; 12. Last end; 13. First battery cell; 14. Second battery cell; 15. Middle battery cell; 16. Third battery cell; 17. Fourth battery cell; 2. First solder strip; 3. First separator; 31. First smooth portion; 32. First protrusion; 33. Spacer portion; 34. Isolation portion; 4. First busbar; 41. Second smooth portion; 42. Second protrusion; 5. Second solder strip; 51. First part; 52. Second part; 53. Connecting part; 6. Second separator; 61. First smooth portion; 62. First protrusion portion; 63. Spacer portion; 64. Isolation portion; 7. Second busbar; 71. Second smooth portion; 72. Second protrusion portion; 8. Third solder strip; 81. First part; 82. Second part; 83. Connecting part; 91. Encapsulating film; 92. Cover plate. Detailed Implementation

[0031] As can be seen from the background technology, the current back-contact photovoltaic modules have a low area utilization rate, which means that the power of back-contact photovoltaic modules needs to be improved.

[0032] This disclosure provides a back-contact photovoltaic (PV) module. By placing the first busbar on the surface of the second solar cell, the space previously occupied by placing the first busbar at the edge of the back-contact PV module is saved. This allows for the placement of more solar cells or the use of larger-sized solar cells without changing the overall size of the back-contact PV module, thus improving the area utilization rate and power output. Furthermore, a first insulating film is provided between the first busbar and the first solder strip on the second solar cell. This prevents short circuits between the first solder strip electrically connected to the first busbar and the second solder strip on the second solar cell, which could affect the performance of the back-contact PV module and improve its reliability.

[0033] In the description of the embodiments of this disclosure, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of embodiments of this disclosure, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this disclosure, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0038] In the description of the embodiments of this disclosure, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0039] In the accompanying drawings corresponding to the embodiments of this disclosure, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0040] In the description of embodiments of this disclosure, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Additionally, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0041] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0042] Figure 1 This is a schematic diagram of a back-contact photovoltaic module provided in an embodiment of this disclosure. Figure 2 This is a schematic diagram of a structure of a first cell, a second cell, and an intermediate cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0043] refer to Figure 1 and Figure 2 The back-contact photovoltaic module includes multiple cell strings 1, a first solder ribbon 2, a first separator 3, a first busbar 4, and a second solder ribbon 5. Each cell string 1 includes a head end 11 and a tail end 12 disposed opposite to each other. Each 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 ribbon 2 extends along a first direction X and electrically connects the first cell 13 and the second cell 14. The first separator 3 is located on the second cell 14 and on the surface of the first solder ribbon 2 facing away from the second cell 14. The first busbar 4 is located on the surface of the first separator 3 facing away from the second cell 14. The second solder ribbon 5 includes a first part 51 and a second part 52. The first part 51 is located on the first cell 13 and electrically connected to it, while the second part 52 is located on the surface of the first separator 3 facing away from the second cell 14 and electrically connected to the first busbar 4.

[0044] Battery string 1 consists of multiple battery cells connected in series.

[0045] In some embodiments, the battery cells in the battery string 1 can be IBC batteries, HPBC (Hybrid Passivated Back Contact) batteries, TBC batteries with TOPCON and IBC technologies, or HBC batteries with heterojunction and IBC technologies, or other types of back contact batteries.

[0046] In some embodiments, adjacent cells in the battery string 1 are spaced apart. In other embodiments, adjacent cells in the battery string may be partially overlapped, such as in a shingled assembly.

[0047] The battery cell includes a first battery cell 13, a second battery cell 14, and an intermediate battery cell 15. The first battery cell 13 is disposed at the tail end 12 of the battery string 1, and the second battery cell 14 is located between the first battery cell 13 and the intermediate battery cell 15. The second battery cell 14 is electrically connected to the first battery cell 13 and to the intermediate battery cell 15.

[0048] Solar cells can be either whole cells or sliced ​​cells. Sliced ​​cells refer to cells formed from a single, whole cell through a cutting process. Sliced ​​cells can be divided into two-piece, three-piece, or four-piece cells, etc.

[0049] The solar cells can be chamfered (not marked), which can effectively reduce stress concentration at the edges of the solar cells and reduce the risk of mechanical damage such as cell breakage and microcracks caused by stress concentration.

[0050] The first solder strip 2 is a series solder strip used to electrically connect the first battery cell 13 and the second battery cell 14, and also to electrically connect the second battery cell 14 and the intermediate battery cell 15, as well as to electrically connect other adjacent intermediate battery cells 15.

[0051] In some embodiments, the first solder strip 2 may include a first series solder strip (not labeled) and a second series solder strip (not labeled), which are staggered in the second direction Y. In a battery string 1, the Nth battery cell, the (N+1)th battery cell, and the (N+2)th battery cell (N is a positive integer greater than 1) are arranged sequentially along the first direction X. The positive electrode grid of the Nth battery cell is electrically connected to the negative electrode grid of the (N+1)th battery cell through multiple first series solder strips, and the positive electrode grid of the (N+1)th battery cell is electrically connected to the negative electrode grid of the (N+2)th battery cell through multiple second series solder strips.

[0052] The second solder strip 5 is used to electrically connect the first battery cell 13 and the first busbar 4. Specifically, the first part 51 of the second solder strip 5 is located on the first battery cell 13 and is used to electrically connect with the first battery cell 13, and the second part 52 is located on the second battery cell 14 and is used to electrically connect with the first busbar 4.

[0053] In some embodiments, the length of the first part 51 along the first direction X is 166mm to 178mm, for example 166mm, 168mm, 170mm, 172mm, 174mm or 178mm. The length of the second part 52 along the first direction X is 8mm to 15mm, for example 8mm, 10mm, 12mm or 15mm.

[0054] The first busbar 4 is used to electrically connect adjacent battery strings 1. Specifically, part of the first busbar 4 is electrically connected to the first battery cell 13 on a battery string 1 via a second solder strip 5, and another part of the first busbar 4 is electrically connected to the first battery cell 13 on another battery string 1 via another second solder strip 5.

[0055] There is a gap between the first busbar 4 and the first solar cell 13, meaning that the first solar cell 13 does not have the first busbar 4. This avoids the situation where part of the first busbar 4 is placed on the first solar cell 13, reducing the contact area between the second solder ribbon 5 and the first solar cell 13, thus affecting the current collection efficiency of the second solder ribbon 5. In other words, the gap between the first busbar 4 and the first solar cell 13 allows for a larger contact area between the second solder ribbon 5 and the first solar cell 13, improving the current collection efficiency of the second solder ribbon 5 and thus enhancing the performance of the back-contact photovoltaic module.

[0056] The first separator 3 is located between the first busbar 4 and the second cell 14, which can prevent short circuits between the first solder strip 2 and the second solder strip 5, thus avoiding affecting the performance of the back contact photovoltaic module and improving the reliability of the back contact photovoltaic module.

[0057] In some embodiments, after laying the first solder ribbon 2 on the battery cell, the first separator 3 can be laid, and then the first busbar 4 can be welded to the second solder ribbon 5. The welded first busbar 4 and second solder ribbon 5 can then be laid on the battery cell. In other embodiments, after laying the first solder ribbon 2 on the battery cell, the first separator 3 and the second solder ribbon 5 can be laid on the battery cell, and then the first busbar 4 can be welded to the second solder ribbon 5. In still other embodiments, after laying the first solder ribbon 2 on the battery cell, the first separator 3, the first busbar 4, and the second solder ribbon 5 can be connected first, and then the connected first separator 3, the first busbar 4, and the second solder ribbon 5 can be laid on the battery cell.

[0058] In some embodiments, the second solder strip 5 further includes a connecting portion 53, which is located between the first portion 51 and the second portion 52, and the extending direction of the connecting portion 53 intersects with the first direction X; the second portion 52 and the first solder strip 2 on the second battery cell 14 are spaced apart along the second direction Y.

[0059] The extension direction of the connecting part 53 intersects the first direction X, that is, the extension direction of the connecting part 53 intersects the extension direction of the first part 51 and the extension direction of the second part 52, so as to realize that the second part 52 and the first solder strip 2 on the second battery cell 14 are spaced apart along the second direction Y, that is, they do not overlap.

[0060] The second part 52 and the first solder strip 2 on the second cell 14 are distributed at intervals along the second direction Y. This can prevent the second part 52 and part of the first solder strip 2 on the second cell 14 from being on the same straight line, thereby preventing these parts of the first solder strip 2 from lifting the second part 52, making the second part 52 relatively higher than the first part 51, pulling the first part 51, 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. If the second part 52 is too high, stress will be concentrated on the higher second part 52 when the cell string 1 is subsequently laminated with the encapsulating film and cover plate, which may cause the cell to break.

[0061] In some embodiments, the extending direction of the connecting portion 53 intersects the first direction X, and the angle between the extending direction of the connecting portion 53 and the first direction X is 20° to 90°, for example, 20° to 45°, 45° to 70°, or 70° to 90°. For example, the 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°.

[0062] When the angle between the extension direction of the connecting part 53 and the first direction X is 90°, the extension direction of the connecting part 53 can be parallel to the second direction Y.

[0063] In some embodiments, the length of the connecting portion 53 along its own extending direction is 5mm to 8mm, for example 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm or 8mm.

[0064] In some embodiments, the distance between the second part 52 and the adjacent first solder strip 2 along the second direction Y is 3mm to 8mm, for example, 3mm to 5mm, 5mm to 6mm, or 6mm to 8mm. Optional distances include 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm. 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 short circuits from occurring due to the second part 52 being too close to the adjacent first solder strip 2, thus avoiding impact on the performance of the back-contact photovoltaic module.

[0065] Figure 3 This is a schematic cross-sectional view of the second cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0066] refer to Figures 1 to 3 In some embodiments, the second solder ribbon 5 is located between the first separator 3 and the first busbar 4. The first separator 3 includes a first smooth portion 31 and a first protrusion 32. The first protrusion 32 protrudes in a direction away from the second battery cell 14 relative to the first smooth portion 31. The first solder ribbon 2 is located between the first protrusion 32 and the second battery cell 14. The surface of the first protrusion 32 away from the second battery cell 14 and the surface of the first smooth portion 31 away from the second battery cell 14 form a first recess. The second solder ribbon 5 is located in the first recess.

[0067] The first separator 3 is configured to include a first smooth portion 31 and a first protrusion 32, and the second solder ribbon 5 is disposed in the first recess. This allows the second portion 52 of the second solder ribbon 5 to be lower in height relative to the second cell 14. This avoids the first portion 51 on the first cell 13 being pulled due to the higher height of the second portion 52 of the second solder ribbon 5 relative to the second cell 14, which could cause the first portion 51 to shift and affect the performance of the back contact photovoltaic module. It also avoids the situation where the stress is concentrated on the higher second portion 52 when the cell string 1 is subsequently laminated with the encapsulating film and cover plate due to the higher height of the second portion 52 of the second solder ribbon 5 relative to the second cell 14, which could cause cell fragmentation.

[0068] The first smooth portion 31 is in direct contact with the second battery cell 14, and the first protrusion 32 is pushed up by the first solder strip 2, protruding in a direction away from the second battery cell 14 relative to the first smooth portion 31. The surfaces of two adjacent first protrusions 32 and the first smooth portion 31 located between the two first protrusions 32 that are away from the second battery cell 14 form a first recess.

[0069] In some embodiments, the thickness of the second solder ribbon 5 is less than or equal to the thickness of the first solder ribbon 2. That is, the thickness of the first solder ribbon 2 can be relatively large so that the first solder ribbon 2 can lift the first protrusion 32 of the first separator 3 to a higher height, so that the first recess formed by the surface of the first protrusion 32 facing away from the second battery cell 14 and the surface of the first smooth portion 31 facing away from the second battery cell 14 can completely accommodate the second portion 52. Here, "completely accommodate" means that the height difference between the surface of the first protrusion 32 facing away from the second battery cell 14 and the surface of the first smooth portion 31 facing away from the second battery cell 14 can be greater than or equal to the thickness of the second portion 52 of the second solder ribbon 5.

[0070] In some embodiments, the thickness of the first solder strip 2 is 0.1mm to 0.28mm, for example 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.24mm or 0.28mm.

[0071] The thickness of the second welding strip 5 is 0.1mm to 0.28mm, for example, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.24mm or 0.28mm.

[0072] In some embodiments, the thickness of the first separator 3 is 0.1 mm to 0.3 mm, for example 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm or 0.3 mm.

[0073] Figure 4 This is a schematic diagram of another cross-sectional structure of the second cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0074] refer to Figure 1 , Figure 2 and Figure 4 In some embodiments, the first busbar 4 is located between the first separator 3 and the second solder ribbon 5. The first separator 3 includes a first smooth portion 31 and a first protrusion 32. The first protrusion 32 protrudes in a direction away from the second battery cell 14 relative to the first smooth portion 31. The first solder ribbon 2 is located between the first protrusion 32 and the second battery cell 14. The first busbar 4 includes a second smooth portion 41 and a second protrusion 42. The second smooth portion 41 is located on the surface of the first smooth portion 31 away from the second battery cell 14. The second protrusion 42 protrudes in a direction away from the second battery cell 14 relative to the second smooth portion 41. The surface of the second protrusion 42 away from the second battery cell 14 and the surface of the second smooth portion 41 away from the second battery cell 14 form a second recess. The second solder ribbon 5 is located within the second recess.

[0075] The second protrusion 42 and the second smooth portion 41, which are opposite to the surface of the second battery cell 14, form a second recess. Specifically, two adjacent second protrusions 42 and the second smooth portion 41 located between the two second protrusions 42 form a second recess.

[0076] The first separator 3 is configured to include a first smooth portion 31 and a first protrusion 32, while the first busbar 4 is configured to include a second smooth portion 41 and a second protrusion 42. This ensures that the first busbar 4 is in close contact with the first separator 3, improving the structural stability of the back-contact photovoltaic module. Furthermore, the second solder ribbon 5 is positioned within the second recess formed by the second smooth portion 41 and the second protrusion 42. This allows the second portion 52 of the second solder ribbon 5 to be lower relative to the second cell 14, preventing the second portion 51 on the first cell 13 from being pulled and displaced, thus affecting the performance of the back-contact photovoltaic module. It also prevents stress concentration on the higher second portion 52 during subsequent lamination of the cell string 1 with the encapsulating film and cover plate, thus avoiding cell fragmentation.

[0077] Figure 5 This is a cross-sectional structural diagram of a first solar cell, a second solar cell, and a first separator in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0078] refer to Figure 1 , Figure 2 and Figure 5 In some embodiments, the first separator 3 includes a spacer portion 33 and a spacer portion 34. The spacer portion 33 is located between the first solar cell 13 and the second solar cell 14, and the spacer portion 34 is located on the surface of the second solar cell 14. The spacer portion 33, located between the first solar cell 13 and the second solar cell 14, can serve as a buffer layer between the first solar cell 13 and the second solar cell 14, preventing them from colliding due to excessively close spacing. It also provides mutual insulation between the first solar cell 13 and the second solar cell 14, which can further shorten the spacing between them and improve the area utilization rate of the back-contact photovoltaic module.

[0079] The isolation section 34 is located on the surface of the second battery cell 14 and is used to isolate the first busbar 4 from the first solder strip 2.

[0080] In some embodiments, the first separator 3 is a transparent film layer. This allows more sunlight to pass through the first separator 3 and be absorbed by the solar cells, which is beneficial for improving the performance of the back-contact photovoltaic module.

[0081] Continue to refer to Figure 1 and Figure 2 In some embodiments, the width of the first isolation membrane 3 along the first direction X is greater than the width of the first busbar 4 along the first direction X. Thus, the larger width of the first isolation membrane 3 effectively achieves electrical isolation between the first busbar 4 and the first solder strip 2.

[0082] In some embodiments, the width of the first separator 3 along the first direction X is 10mm to 20mm, for example, 10mm, 12mm, 14mm, 16mm, 18mm, or 20mm. The width of the first separator 3 within the above range can effectively isolate the first busbar 4 from the first solder strip 2 on the second battery cell 14, and also avoids the problems of the first separator 3 being too wide, affecting the absorption of sunlight by the second battery cell 14, and increasing costs due to excessive width.

[0083] The width of the first busbar 4 along the first direction X is 8mm to 15mm, for example, 8mm, 10mm, 12mm, 14mm or 15mm.

[0084] Figure 6 This is a schematic diagram of a structure of a third, fourth, and intermediate solar cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0085] refer to Figure 1 and Figure 6 In some embodiments, the battery string 1 further includes a third battery cell 16 disposed at the first end 11 and a fourth battery cell 17 connected to the third battery cell 16, and the first solder strip 2 is also electrically connected to the third battery cell 16 and the fourth battery cell 17; the back contact photovoltaic module further includes a second busbar 7, a second separator 6 and a third solder strip 8, the second busbar 7 is electrically connected to the third battery cell 16 of the two battery strings 1 arranged along the second direction Y, and the second busbar 7 is located on the fourth battery cell 17; the second separator 6 is located on the fourth battery cell 17 and is located between the second busbar 7 and the fourth battery 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 battery cell 16 and is electrically connected to the third battery cell 16, and the second part 82 is located on the surface of the second separator 6 away from the fourth battery cell 17 and is electrically connected to the second busbar 7.

[0086] By placing the second busbar 7 on the surface of the fourth cell 17, space is saved by eliminating the need to place the second busbar 7 in the middle of the back-contact photovoltaic module. This allows for the placement of more cells or the use of larger cells without changing the overall size of the back-contact photovoltaic module, thus improving the area utilization rate and power output. Furthermore, the back-contact photovoltaic module also features a second separator 6 between the second busbar 7 and the first solder strip 2 on the fourth cell 17. This separator prevents short circuits between the third solder strip 8 (electrically connected to the second busbar 7) and the first solder strip 2 on the fourth cell 17, which could affect the performance of the back-contact photovoltaic module and improve its reliability.

[0087] The third battery cell 16 is located at the first end 11 of the battery string 1, and the fourth battery cell 17 is located between the third battery cell 16 and the intermediate battery cell 15. The fourth battery cell 17 is electrically connected to the third battery cell 16 and to the intermediate battery cell 15.

[0088] The first welding strip 2 is also used to electrically connect the third battery cell 16 and the fourth battery cell 17, and to electrically connect the fourth battery cell 17 and the intermediate battery cell 15.

[0089] The third solder strip 8 is used to electrically connect the third battery cell 16 and the second busbar 7. Specifically, the first portion 81 of the third solder strip 8 is located on the third battery cell 16 and is used for electrical connection to the third battery cell 16. The first portion 81 is also electrically connected to the third battery cell 16 of the two battery strings 1 arranged along the second direction Y. The second portion 82 is located on the fourth battery cell 17 and is used for electrical connection to the second busbar 7.

[0090] The second busbar 7 is electrically connected to the third battery cell 16 located at the first end 11 of the two battery strings 1 arranged along the second direction Y, so as to connect the adjacent battery strings 1 in parallel.

[0091] There is a gap between the second busbar 7 and the third solar cell 16, meaning that the third solar cell 16 does not have the second busbar 7. This avoids the situation where part of the second busbar 7 is placed on the third solar cell 16, reducing the contact area between the third solder ribbon 8 and the third solar cell 16, thus affecting the current collection efficiency of the third solder ribbon 8. In other words, the gap between the second busbar 7 and the third solar cells 16 allows for a larger contact area between the third solder ribbon 8 and the third solar cell 16, improving the current collection efficiency of the third solder ribbon 8 and thus enhancing the performance of the back-contact photovoltaic module.

[0092] The second separator 6 is located between the second busbar 7 and the fourth cell 17. It can prevent short circuits between the first solder strip 2 and the third solder strip 8, thus avoiding affecting the performance of the back contact photovoltaic module and improving the reliability of the back contact photovoltaic module.

[0093] In some embodiments, the third solder strip 8 further includes a connecting portion 83 located between the first portion 81 and the second portion 82, and the extending direction of the connecting portion 83 intersects the first direction X; the second portion 82 and the first solder strip 2 on the fourth battery cell 17 are spaced apart along the second direction Y.

[0094] The extension direction of the connecting portion 83 intersects the first direction X, that is, the extension direction of the connecting portion 83 intersects the extension direction of the first portion 81 and the extension direction of the second portion 82, so as to realize that the second portion 82 and the first solder strip 2 on the fourth battery cell 17 are spaced apart along the second direction Y.

[0095] The second part 82 and the first solder strip 2 on the fourth cell 17 are arranged at intervals along the second direction Y. This can prevent the second part 82 and part of the first solder strip 2 on the fourth cell 17 from being on the same straight line, thereby preventing the first solder strip 2 from lifting the second part 82, making the second part 82 relatively higher than the first part 81, pulling the first part 81, causing the first part 81 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 82. If the second part 82 is too high, stress will be concentrated on the higher second part 82 when the cell string 1 is subsequently laminated with the encapsulation film and cover plate, which may cause the cell to break.

[0096] In some embodiments, the extending direction of the connecting portion 83 intersects the first direction X, and the angle between the extending direction of the connecting portion 83 and the first direction X is 20° to 90°, for example, 20° to 45°, 45° to 70°, or 70° to 90°. For example, the angle between the extending direction of the connecting portion 83 and the first direction X can be 20°, 32.5°, 45°, 55°, 57.5°, 70°, 80°, or 90°.

[0097] When the angle between the extension direction of the connecting portion 83 and the first direction X is 90°, the extension direction of the connecting portion 83 can be parallel to the second direction Y.

[0098] In some embodiments, the distance between the second portion 82 and the adjacent first solder strip 2 along the second direction Y is 3mm to 8mm, for example, 3mm to 5mm, 5mm to 6mm, or 6mm to 8mm. Optional distances include 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, or 8mm. When the distance between the second portion 82 and the adjacent first solder strip 2 along the second direction Y is within the above range, it can prevent short circuits from occurring due to the second portion 82 being too close to the adjacent first solder strip 2, thus avoiding impact on the performance of the back-contact photovoltaic module.

[0099] Figure 7 This is a schematic cross-sectional view of the fourth cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0100] refer to Figure 1 , Figure 6 and Figure 7In some embodiments, the third solder strip 8 is located between the second separator 6 and the second busbar 7. The second separator 6 includes a first smooth portion 61 and a first protruding portion 62. The first protruding portion 62 protrudes in a direction away from the fourth battery cell 17 relative to the first smooth portion 61. The first solder strip 2 is located between the first protruding portion 62 and the fourth battery cell 17. The surface of the first protruding portion 62 away from the fourth battery cell 17 and the surface of the first smooth portion 61 away from the fourth battery cell 17 form a first recessed portion. The third solder strip 8 is located in the first recessed portion. The second separator 6 is configured to include a first smooth portion 61 and a first raised portion 62, and the third solder ribbon 8 is disposed within the first recess formed by the first smooth portion 61 and the first raised portion 62. This allows the second portion 82 of the third solder ribbon 8 to be lower in height relative to the fourth solar cell 17, preventing the first portion 81 on the third solar cell 16 from being pulled due to the higher height of the second portion 82 of the third solder ribbon 8 relative to the fourth solar cell 17, which could cause the first portion 81 to shift and affect the performance of the back contact photovoltaic module. It also prevents stress concentration on the higher second portion 82 during subsequent lamination of the cell string 1 with the encapsulating film and cover plate, which could lead to cell fragmentation.

[0101] The first smooth portion 61 is in direct contact with the fourth battery cell 17, and the first protruding portion 62 is lifted by the first solder strip 2, protruding in a direction away from the fourth battery cell 17 relative to the first smooth portion 61. The two adjacent first protruding portions 62 and the first smooth portion 61 located between the two first protruding portions 62 form a first recessed portion on the surface away from the fourth battery cell 17.

[0102] 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 lifts the first protruding portion 62 of the second separator 6 to a higher height, so that the first recessed portion formed by the first protruding portion 62 facing away from the surface of the fourth battery cell 17 and the first smooth portion 61 facing away from the surface of the fourth battery cell 17 can completely accommodate the second portion 82. Here, "completely accommodate" means that the height difference between the surface of the first protruding portion 62 facing away from the fourth battery cell 17 and the surface of the first smooth portion 61 facing away from the surface of the fourth battery cell 17 can be greater than or equal to the thickness of the second portion 82 of the third solder strip 8.

[0103] In some embodiments, the thickness of the first solder strip 2 is 0.1mm to 0.28mm, for example 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.24mm or 0.28mm.

[0104] In some embodiments, the thickness of the third solder strip 8 is 0.1 mm to 0.28 mm, for example 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.24 mm or 0.28 mm.

[0105] In some embodiments, the thickness of the second separator 6 is 0.1 mm to 0.3 mm, for example 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm or 0.3 mm.

[0106] Figure 8 This is a schematic diagram of another cross-sectional structure of the fourth cell in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0107] refer to Figure 1 , Figure 6 and Figure 8 In some embodiments, the second busbar 7 is located between the second separator 6 and the third solder strip 8. The second separator 6 includes a first smooth portion 61 and a first protruding portion 62. The first protruding portion 62 protrudes in a direction away from the fourth battery cell 17 relative to the first smooth portion 61. The first solder strip 2 is located between the first protruding portion 62 and the fourth battery cell 17. The second busbar 7 includes a second smooth portion 71 and a second protruding portion 72. The second smooth portion 71 is located on the surface of the first smooth portion 61 away from the fourth battery cell 17. The second protruding portion 72 protrudes in a direction away from the fourth battery cell 17 relative to the second smooth portion 71. The second protruding portion 72 is located on the surface of the first protruding portion 62 away from the fourth battery cell 17. The surface of the second protruding portion 72 away from the fourth battery cell 17 and the surface of the second smooth portion 71 away from the fourth battery cell 17 form a second recessed portion (not identified). The third solder strip 8 is located within the second recessed portion.

[0108] The second protruding portion 72, facing away from the surface of the fourth battery cell 17, and the second smooth portion 71, facing away from the surface of the fourth battery cell 17, form a second recess. Specifically, two adjacent second protruding portions 72 and the second smooth portion 71 located between the two second protruding portions 72 form a second recess.

[0109] The second separator 6 is configured to include a first smooth portion 61 and a first raised portion 62, while the second busbar 7 is configured to include a second smooth portion 71 and a second raised portion 72. This ensures close contact between the second busbar 7 and the second separator 6, improving the structural stability of the back-contact photovoltaic module. Furthermore, the third solder ribbon 8 is positioned within the second recess formed by the second smooth portion 71 and the second raised portion 72. This allows the second portion 82 of the third solder ribbon 8 to be lower relative to the fourth cell 17, preventing the first portion 81 on the third cell 16 from being pulled and displaced due to its higher relative height. This also avoids stress concentration on the higher second portion 82 during subsequent lamination of the cell string 1 with the encapsulating film and cover plate, which could lead to cell fragmentation.

[0110] Figure 9 This is a cross-sectional structural diagram of the third and fourth solar cells and the second separator in a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0111] refer to Figure 1 , Figure 6 and Figure 9 In some embodiments, the second separator 6 includes a spacer portion 63 and a spacer portion 64. The spacer portion 63 is located between the third solar cell 16 and the fourth solar cell 17, and the spacer portion 64 is located on the surface of the fourth solar cell 17. The spacer portion 63, located between the third solar cell 16 and the fourth solar cell 17, can serve as a buffer layer between the third solar cell 16 and the fourth solar cell 17, preventing them from colliding due to excessively close spacing. It also provides mutual insulation between the third solar cell 16 and the fourth solar cell 17, thus facilitating a further reduction in the spacing between them and improving the area utilization rate of the back-contact photovoltaic module.

[0112] The isolation portion 64 is located on the surface of the fourth battery cell 17 and is used to isolate the second busbar 7 from the first solder strip 2.

[0113] In some embodiments, the second separator 6 is a transparent film layer. This allows more light to pass through the second separator 6 and be absorbed by the fourth solar cell 17, which is beneficial for improving the performance of the back-contact photovoltaic module.

[0114] Continue to refer to Figure 1 and Figure 6In some embodiments, the width of the second isolation membrane 6 along the first direction X is greater than the width of the second busbar 7 along the first direction X. Thus, the larger width of the second isolation membrane 6 effectively achieves electrical isolation between the second busbar 7 and the first solder strip 2.

[0115] In some embodiments, the width of the second separator 6 along the first direction X is 10mm to 20mm, for example, 10mm, 12mm, 14mm, 16mm, 18mm, or 20mm. The width of the second separator 6 within the above range can effectively isolate the second busbar 7 from the first solder strip 2 on the fourth solar cell 17, and also avoids the problems of the second separator 6 being too wide, affecting the absorption of sunlight by the fourth solar cell 17, and increasing costs due to excessive width.

[0116] The width of the second busbar 7 along the first direction X is 8mm to 15mm, for example, 8mm, 10mm, 12mm, 14mm or 15mm.

[0117] Figure 10 This is a cross-sectional structural diagram of a back-contact photovoltaic module provided in an embodiment of this disclosure.

[0118] refer to Figure 1 and Figure 10 In some embodiments, the back-contact photovoltaic module further includes an encapsulating film 91 and a cover plate 92, wherein the encapsulating film 91 is used to cover the surface of the battery string 1; and the cover plate 92 is used to cover the surface of the encapsulating film 91 that is away from the battery string 1.

[0119] In some embodiments, the encapsulating film 91 includes a first encapsulating layer and a second encapsulating layer. The first encapsulating layer covers one of the front or back sides of the battery string 1, and the second encapsulating layer covers the other of the front or back sides of the battery string 1. Specifically, at least one of the first encapsulating layer and the second encapsulating layer can be an organic encapsulating film such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyvinyl octene coelastomer (POE) film, or polyethylene terephthalate (PET) film. Alternatively, at least one of the first encapsulating layer and the second encapsulating layer can also be an EP film, EPE film, or PVP film.

[0120] Among them, EP film refers to a co-extruded film composed of stacked EVA film and POE film; EPE film refers to a co-extruded film formed by sequentially stacking EVA film, POE film, and EVA film; and PVP film refers to a co-extruded film formed by stacking POE film, EVA film, and POE film. Co-extruded films can be manufactured by sequentially extruding one or more raw materials onto another pre-made film during the film processing, or by bonding different types of pre-made films together.

[0121] In some cases, the first encapsulation layer and the second encapsulation layer still have a boundary line before lamination. After lamination, the photovoltaic module no longer has the concept of a first encapsulation layer and a second encapsulation layer, that is, the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film.

[0122] In some embodiments, the cover plate 92 can be a glass cover plate, a plastic cover plate, or other cover plate with light-transmitting function. Specifically, the surface of the cover plate facing the encapsulating film can be an uneven surface or a textured surface containing multiple raised structures, thereby increasing the utilization rate of incident light. The cover plate 92 includes a first cover plate and a second cover plate, the first cover plate being opposite to the first encapsulation layer, and the second cover plate being opposite to the second encapsulation layer.

[0123] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this disclosure. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A back-contact photovoltaic module, characterized in that, include: Multiple battery strings, each battery string having a front end and a rear end disposed opposite to each other, each battery string having a first battery cell disposed at the rear end and a second battery cell connected to the first battery cell; The first solder strip extends along a first direction and electrically connects the first battery cell and the second battery cell. There are multiple first solder strips, and the multiple first solder strips are arranged along a second direction. A first separator is located on the second battery cell and on the surface of the first solder strip facing away from the second battery cell. The first busbar is located on the side of the first separator membrane opposite to the second battery cell; The second solder strip includes a first part and a second part. The first part is located on the first battery cell and is electrically connected to the first battery cell. The second part is located on the surface of the first separator membrane facing away from the second battery cell and is electrically connected to the first busbar. The distance between the second part and the adjacent first solder strip along the second direction is 3mm to 8mm. The second solder strip further includes a connecting portion located between the first portion and the second portion, the extending direction of the connecting portion intersecting the first direction; the second portion and the first solder strip on the second battery cell are spaced apart along the second direction; The second solder strip is located between the first separator and the first busbar. The first separator includes a first smooth portion and a first protrusion. The first protrusion protrudes in a direction away from the second battery cell relative to the first smooth portion. The first solder strip is located between the first protrusion and the second battery cell. The surface of the first protrusion away from the second battery cell and the surface of the first smooth portion away from the second battery cell form a first recess. The second solder strip is located in the first recess. The first protrusion is also in contact with the first busbar. The thickness of the second solder strip is less than the thickness of the first solder strip, the thickness of the first solder strip is 0.1mm~0.28mm, and the thickness of the second solder strip is 0.1mm~0.24mm.

2. The back-contact photovoltaic module according to claim 1, characterized in that, The first separator includes a spacer portion and an isolation portion, the spacer portion being located between the first battery cell and the second battery cell, and the isolation portion being located on the surface of the second battery cell.

3. The back-contact photovoltaic module according to claim 1, characterized in that, The first isolation membrane is a transparent membrane layer.

4. The back-contact photovoltaic module according to claim 1, characterized in that, The width of the first separator membrane along the first direction is greater than the width of the first busbar along the first direction.

5. The back-contact photovoltaic module according to claim 1, characterized in that, The battery string also includes a third battery cell disposed at the first end and a fourth battery cell connected to the third battery cell, and the first solder strip is also used to electrically connect the third battery cell and the fourth battery cell; The back-contact photovoltaic module also includes: The second busbar is electrically connected to the third battery cell of the two battery strings arranged along the second direction, and the second busbar is located on the fourth battery cell; The second separator is located on the fourth battery cell and between the second busbar and the fourth battery cell; The third solder strip includes a first part and a second part. The first part is located on the third battery cell and is electrically connected to the third battery cell. The second part is located on the surface of the second separator membrane opposite to the fourth battery cell and is electrically connected to the second busbar.

6. The back-contact photovoltaic module according to claim 5, characterized in that, The second solder strip further includes a connecting portion located between the first portion and the second portion, the extending direction of the connecting portion intersecting the first direction; the second portion and the first solder strip on the fourth battery cell are spaced apart along the second direction.

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