Battery string and photovoltaic module

Abstract

The invention discloses a battery string and a photovoltaic module, and belongs to the field of photovoltaic technology, the battery string comprises a plurality of battery pieces arranged in sequence in a first direction, bus bars connecting adjacent battery pieces, and solder strips arranged on the surfaces of the battery pieces and connected with the bus bars; the welding strip comprises a front welding strip and a back welding strip which are respectively arranged on two side surfaces of the battery piece; the bus bars are arranged on the sides of the battery pieces along a second direction perpendicular to the first direction, and the welding strips extend out of the edges of the battery pieces along the second direction and are connected to the corresponding bus bars; and the front welding strip of one of the adjacent battery pieces and the back welding strip of the other battery piece are connected to the same bus bar, so that the adjacent battery pieces are electrically connected. The welding strips on the surfaces of the adjacent battery pieces are connected through the bus bars, and the adjacent battery pieces in the same battery string are connected in series, so that the problem of piece cracking caused by inter-piece stress can be effectively avoided.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a battery string and a photovoltaic module. Background Technology

[0002] With the development of solar cells and modules, cost reduction and efficiency improvement are the mainstream development directions in the industry. To improve the photoelectric conversion efficiency per unit light-receiving area, a commonly used interconnection method is to use shingled bonding technology to stack adjacent cells and connect them in series to form a cell string through solder ribbons. However, this interconnection method introduces stress between cells, which can easily lead to microcracks, cross-cracks, and other cell cracking problems during subsequent lamination. On the other hand, among the non-silicon costs of photovoltaic modules, the silver paste material used for cell printing accounts for the largest share of the cost. To further reduce the amount of silver paste used, OBB (Outer Busbar) module technology has emerged. Interconnection technology for OBB modules is currently a major research direction in the industry. Summary of the Invention

[0003] The purpose of this application is to provide a battery string and photovoltaic module to solve the problem of cell cracking caused by inter-cell stress.

[0004] To achieve the above objectives, this application provides a battery string, comprising: a plurality of battery cells arranged sequentially along a first direction, a busbar connecting adjacent battery cells, and solder strips disposed on the surface of the battery cells and connected to the busbars; the solder strips include front solder strips and back solder strips disposed on both sides of the battery cells.

[0005] The busbar is disposed on the side of the battery cell along a second direction perpendicular to the first direction, and the solder strip extends beyond the edge of the battery cell along the second direction and is connected to the corresponding busbar; the front solder strip of one of the adjacent battery cells and the back solder strip of the other battery cell are connected to the same busbar, so that the adjacent battery cells are electrically connected.

[0006] Optionally, the solar cell is a gridless solar cell; the solar cell includes fine grids extending along the first direction;

[0007] Optionally, the battery cell is rectangular, including a short side extending along the first direction and a long side extending along the second direction.

[0008] Optionally, the battery string further includes: a first carrier film and a second carrier film; the first carrier film is bonded to the front side of the battery cell and covers the front solder strip of the battery cell; the second carrier film is bonded to the back side of the battery cell and covers the back solder strip of the battery cell.

[0009] Optionally, the thickness of the first carrier membrane and / or the second carrier membrane is 50 μm to 200 μm, including the values ​​at both ends;

[0010] Alternatively, the thickness of the first carrier film and / or the second carrier film is 0.4 mm to 0.6 mm, including the values ​​at both ends; the first carrier film and / or the second carrier film are co-extruded films, and the pre-crosslinking degree of the co-extruded film on the side closer to the battery cell is higher than the pre-crosslinking degree of the co-extruded film on the side away from the battery cell.

[0011] Optionally, there may be a stacked region between adjacent battery cells;

[0012] The first carrier film and / or the second carrier film on the opposite side of the adjacent battery cells extend into the stacked region.

[0013] Optionally, the solder ribbon is a low-temperature solder ribbon, which includes tin-bismuth-silver system solder ribbon or tin-bismuth-lead system solder ribbon.

[0014] Optionally, the length of the solder strip extending beyond the edge of the battery cell is 1mm to 2mm, including the values ​​at both ends.

[0015] To achieve the above objectives, this application also provides a photovoltaic module, comprising: a backsheet, a cell string layer, and a front sheet arranged sequentially along the thickness direction;

[0016] The battery string layer includes multiple battery strings as described above.

[0017] Optionally, the front panel has a raised structure on the side surface near the battery string layer; the position of the raised structure corresponds to the position of the busbar.

[0018] Optionally, the busbar includes an edge busbar and an inter-string busbar; the edge busbar is located on the side of the edge of the battery string that is away from the adjacent battery string; the inter-string busbar is located between the adjacent battery strings.

[0019] The inter-string busbar includes a low-temperature plating layer, a copper substrate, a support layer, and a reflective layer arranged sequentially along the thickness direction. The support layer is configured as an insulating layer. The inter-string busbar also includes an insulating material layer that penetrates the low-temperature plating layer and the copper substrate. The insulating material layer separates the low-temperature plating layer and the copper substrate to form two mutually insulated conductive parts. The two conductive parts are used to realize the electrical connection of adjacent cells in different battery strings.

[0020] Optionally, the width of the edge busbar is 2mm to 4mm, including the values ​​at both ends;

[0021] The width of the inter-string busbar is 6mm to 8mm, including the values ​​at both ends; the width of the inter-string busbar is greater than the spacing between adjacent battery strings.

[0022] Optionally, the support layer is a PET layer; the reflective layer has a triangular pyramidal prism structure formed on the surface opposite to the PET layer.

[0023] Obviously, the battery string provided in this application has busbars arranged on the sides of the battery cells along a direction perpendicular to the arrangement of the battery cells. The front solder strip of one adjacent battery cell is connected to the back solder strip of another adjacent battery cell via the busbars, thus connecting the solder strips on the surfaces of adjacent battery cells and achieving series connection of adjacent battery cells within the same battery string. This effectively avoids cell cracking caused by inter-cell stress. This application also provides a photovoltaic module with the above-mentioned beneficial effects. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of a gridless solar cell provided in an embodiment of this application;

[0026] Figure 2 This is a schematic diagram of a welding strip laying method provided in an embodiment of this application;

[0027] Figure 3 This is a schematic diagram of a carrier membrane in series provided in an embodiment of this application;

[0028] Figure 4 This is a schematic diagram of a component side structure provided in an embodiment of this application;

[0029] Figure 5 A schematic diagram of a battery bus provided in an embodiment of this application;

[0030] Figure 6 This is a schematic diagram of an inter-component interconnection structure provided in an embodiment of this application;

[0031] Figure 7 A schematic diagram of an inter-serial busbar structure provided in an embodiment of this application;

[0032] Figure 8 A schematic diagram of a component circuit is provided for an embodiment of this application;

[0033] Figure 9A flowchart illustrating a photovoltaic module fabrication method provided in this application embodiment;

[0034] Figure 10 A flowchart illustrating a battery string fabrication method provided in this application embodiment;

[0035] Figure 11 A schematic flowchart illustrating a photovoltaic module fabrication method provided in this application embodiment;

[0036] Figure 12 This is a schematic flowchart of another photovoltaic module manufacturing method provided in an embodiment of this application.

[0037] The annotations in the attached figures are explained as follows:

[0038] 1-Solar cell; 11-Silicon wafer; 12-Grid; 2-Solder ribbon; 21-Front solder ribbon; 22-Back solder ribbon; 3-Busbar; 31-Edge busbar; 32-Inter-string busbar; 321-Reflective layer; 322-Support layer / insulating layer / PET layer; 323-Copper substrate; 324-Insulating material layer; 325-Low temperature coating; 41-First carrier film; 42-Second carrier film; 5-Front panel; 6-Back panel; 7-Front adhesive film; 8-Back adhesive film. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Please refer to Figures 1 to 3 The present application provides a battery string, which may include: a plurality of battery cells 1 arranged sequentially along a first direction, a busbar 3 connecting adjacent battery cells 1, and a solder strip 2 disposed on the surface of the battery cells 1 and connected to the busbar 3; the solder strip 2 includes a front solder strip 21 and a back solder strip 22 disposed on the two sides of the battery cells respectively.

[0041] Busbar 3 is disposed on the side of cell 1 along a second direction perpendicular to the first direction, and solder strip 2 extends beyond the edge of cell 1 along the second direction and is connected to the corresponding busbar 3; the front solder strip 21 of one cell 1 and the back solder strip 22 of another cell 1 are connected to the same busbar 3, so that the adjacent cells 1 are electrically connected.

[0042] This embodiment does not limit the specific type of the battery cell 1, and may include, but is not limited to, a gridless battery cell 1; the battery cell 1 includes fine grids 12 extending along a first direction. This embodiment does not limit the specific shape of the battery cell 1, and may include, but is not limited to, a rectangular shape, including a short side extending along the first direction and a long side extending along a second direction.

[0043] This embodiment uses a gridless solar cell 1, as shown in... Figure 1 As shown in the figure, the silicon wafer 11 is mainly responsible for absorbing solar photons and outputting current and voltage. Fine grids 12 are provided on both the front and back sides of the silicon wafer 11. The fine grids 12 are parallel to the short side of the solar cell 1 (i.e., perpendicular to the cut edge of the solar cell 1), which differs from the conventional arrangement direction of fine grids in solar cells. This embodiment does not limit the specific size of the fine grids 12. For example, the height of the fine grids 12 can be 5μm to 10μm, including the values ​​at both ends; the width of the fine grids 12 can be 5μm to 10μm, including the values ​​at both ends.

[0044] The specific arrangement of the solder strips 2 in this embodiment is as follows: Figure 2 As shown in the figure, the front and back sides of the solar cell 1 are respectively provided with a front solder strip 21 and a back solder strip 22. Both the front solder strip 21 and the back solder strip 22 are parallel to the long side of the solar cell 1 (i.e., parallel to the cut edge of the solar cell 1). This embodiment does not limit the specific type of solder strip 2. Solder strip 2 can be, but is not limited to, a low-temperature solder strip. Low-temperature solder strips can include tin-bismuth-silver system solder strips or tin-bismuth-lead system solder strips. Among them, the silver content in the tin-bismuth-silver system solder strip can be 1%~2%, including the values ​​at both ends; the bismuth content in the tin-bismuth-lead system solder strip can be 14%~26%, including the values ​​at both ends. This embodiment does not limit the specific diameter of solder strip 2. It can be determined according to the power requirements and actual conditions. For example, the diameter of solder strip 2 can be 0.18mm~0.22mm, including the values ​​at both ends. This embodiment does not limit the specific length of solder strip 2. In order to reduce the edge stress of the solar cell 1 during the lamination process of solder strip 2, the length of solder strip 2 extending beyond the edge of the solar cell 1 can be 1mm~2mm, including the values ​​at both ends.

[0045] Furthermore, in this embodiment, the battery string may further include: a first carrier film and a second carrier film; the first carrier film is bonded to the front side of the battery cell 1 and covers the front solder ribbon 21 of the battery cell 1; the second carrier film is bonded to the back side of the battery cell 1 and covers the back solder ribbon 22 of the battery cell 1. In this embodiment, the first carrier film 41 and / or the second carrier film 42 on the opposite side of adjacent battery cells 1 extend to the stacked area. It should be noted that in this embodiment, the first carrier film and the second carrier film are adhesive, which can fix the solder ribbon 2 to the surface of the battery cell 1 on the one hand, and can also bond adjacent battery cells 1 together through the first carrier film 41 and / or the second carrier film 42 on the opposite side of adjacent battery cells 1 on the other hand. This embodiment does not limit the spacing between adjacent battery cells 1, and can be a small spacing or a negative spacing (stacked cells).

[0046] A preferred approach is stacking, which can be combined with large-size cells to adapt to different module size schemes. This approach can shorten the module length and facilitate high-density packaging. In this embodiment, there is a stacked region between adjacent cells 1; the first carrier film 41 and / or the second carrier film 42 on the opposite side of the adjacent cells 1 extend into the stacked region.

[0047] This embodiment provides a stacking scheme as follows: Figure 3 As shown, adjacent solar cells 1 have a stacked region; the second carrier film covers the entire stacked region. The second carrier film in the figure acts as a plug (providing stress to the stacked solar cells 1 during the stacking process and connecting the previous and next cells). It should be noted that traditionally, connecting the same string of solar cells requires solder ribbons, while shingled modules require conductive adhesive. In this embodiment, the connection of adjacent solar cells 1 in the string is achieved through both solder ribbons 2 and busbars 3, so the stacked region does not need to consider electrical connection requirements.

[0048] This embodiment does not limit the specific width of the first carrier film and the second carrier film. The width can be set according to the width of the battery cell 1. A preferred option is that the width of the first carrier film and / or the second carrier film can be equal to the width of the battery cell 1, or 2 mm smaller than the width of the battery cell 1.

[0049] This embodiment does not limit the specific lengths of the first and second carrier films; the lengths of the first and second carrier films can be set and adjusted separately. For example, the length of the second carrier film can be adjusted according to the width of the laminated region. Because, as... Figure 3In the structure shown, if there is no second carrier film as a buffer between two adjacent solar cells 1 in the stacked area, it will cause hard contact between the two solar cells 1, resulting in defects such as cell cracking. Therefore, it is necessary to ensure that the second carrier film can completely cover the entire stacked area. Thus, the length of the second carrier film can be adjusted according to the width of the stacked area. Generally, the width of the stacked area can be 0.5mm-1mm, including both ends; a preferred solution is that the width of the stacked area can be 0.6mm-0.9mm, including both ends. Taking a stacked area length of 0.6mm as an example, the length of the second carrier film and the edge of the solar cell 1 it covers should be less than 0.6mm to ensure that there is a buffer between the two solar cells 1 in the stacked area; of course, the second carrier film can also be set to completely cover the entire stacked area.

[0050] This embodiment does not limit the specific types of the first and second carrier films. The first and / or second carrier films can be cross-linked or non-cross-linked films, such as EVA films, co-extruded EPE films, co-extruded EE films, co-extruded EP films, POE films, PVB films, TPO films, etc. EVA (Ethylene Vinyl Acetate Copolymer) is an ethylene-vinyl acetate copolymer; POE (Polyolefin elastomer) is a polyolefin elastomer; PVB (Poly Vinyl Butyral) is polyvinyl butyral; TPO (Thermoplastic polyolefin) is a thermoplastic polyolefin; co-extruded EPE films, co-extruded EE films, and co-extruded EP films are films manufactured from EVA films and POE films through a co-extrusion process.

[0051] This embodiment does not limit the specific thickness of the first and second carrier films. For example, the thickness of the first and / or second carrier films can be 50μm to 200μm, including the values ​​at both ends; or, the thickness of the first and / or second carrier films can be 0.4mm to 0.6mm, including the values ​​at both ends. A preferred embodiment is that the first and / or second carrier films can be co-extruded films, with the pre-crosslinking degree of the co-extruded film on the side closer to the battery cell 1 being higher than the pre-crosslinking degree of the co-extruded film on the side away from the battery cell 1. The thickness on one side can be selected according to actual production capacity. It should be noted that the former uses the first and second carrier films, which can reduce the basis weight of the front adhesive film 7 and the back adhesive film 8, thereby achieving cost reduction; the latter uses the first and second carrier films, which can completely replace the front adhesive film 7 and the back adhesive film 8, further reducing costs.

[0052] Based on the above embodiments, this application provides a busbar on the side of the battery cell along the arrangement direction perpendicular to the battery cell, and connects the front solder strip of one battery cell and the back solder strip of another battery cell to the same busbar, so as to connect the solder strips on the surface of adjacent battery cells through the busbar, thereby realizing the series connection of adjacent battery cells in the same battery string, which can effectively avoid the problem of cell cracking caused by inter-cell stress.

[0053] Please refer to Figures 4 to 8 This application embodiment also provides a photovoltaic module, which may include: a back sheet 6, a battery string layer and a front sheet 5 arranged sequentially along the thickness direction;

[0054] The battery string layer comprises multiple battery strings as described above.

[0055] It should be noted that traditional photovoltaic modules have low inter-string utilization and require methods such as glazing and meshing to improve power. However, this embodiment makes full use of the space between cell strings by setting busbars 3 between cell strings and extending the solder strips 2 laterally to the busbars 3 to achieve series connection of the cells 1 in the same cell string.

[0056] This embodiment does not limit the specific types of the front panel 5 and the back panel 6. The specific types of the front panel 5 and the back panel 6 can be determined according to actual needs. For example, the front panel 5 and / or the back panel 6 can be glass. This embodiment does not limit the specific structure of the battery string. For details, please refer to the above embodiments regarding battery strings, which will not be repeated here.

[0057] It should be noted that when the battery string adopts the above-mentioned carrier film stringing technology, photovoltaic modules can have different structures by using first and second carrier films of different thicknesses. For example, they can include the following two structures:

[0058] (1) When the thickness of the first carrier membrane and / or the second carrier membrane is 50 μm to 200 μm, including the values ​​at both ends, such as Figure 4 The photovoltaic module shown may include a backsheet 6, a back film 8, a cell string layer, a front film 7, and a front panel 5 arranged sequentially along the thickness direction. This photovoltaic module is a conventional structure combining a film and a carrier film.

[0059] (2) When the thickness of the first carrier film and / or the second carrier film is 0.4 mm to 0.6 mm, including both ends; and the first carrier film and / or the second carrier film are co-extruded films, and the pre-crosslinking degree of the co-extruded film on the side closer to the solar cell 1 is higher than the pre-crosslinking degree of the co-extruded film on the side away from the solar cell 1, the photovoltaic module may include a back sheet 6, a cell string layer, and a front sheet 5 arranged sequentially along the thickness direction. This photovoltaic module completely replaces the front film 7 and the back film 8 with the first carrier film and the second carrier film, which is a non-conventional film structure. It should be noted that the different pre-crosslinking degrees on the two sides of the first carrier film and the second carrier film are because this photovoltaic module does not have conventional film filling, and a high-flow type is required on one side for gap filling.

[0060] Furthermore, in this embodiment, the surface of the front plate 5 near the battery string layer can be provided with a raised structure; the position of the raised structure corresponds to the position of the busbar 3. It should be noted that the raised structure design for the inter-string layer, with its special shape, can enhance the clamping force between the busbar 3 and the solder strip 2.

[0061] Furthermore, such as Figure 5 As shown, in this embodiment, the busbar 3 of the battery string layer may include an edge busbar 31 and an inter-string busbar 32; the edge busbar 31 is located on the side of the edge battery string away from the adjacent battery string; the inter-string busbar 32 is located between adjacent battery strings. Figure 5 and Figure 6 As shown, the solar cell 1 is mainly responsible for collecting solar energy and is connected in series by the substrate film. The welding strip 2 laid horizontally on the surface of the solar cell 1 is mainly responsible for collecting the current generated in the solar cell 1 and then converging the current into the edge bus bar 31 or the inter-string bus bar 32. The edge bus bar 31 is mainly used to connect the positive and negative terminals of adjacent solar cells 1 in the side solar cell string. The inter-string bus bar 32 is mainly used to connect adjacent solar cells 1 in the side solar cell string at the same time.

[0062] This embodiment does not limit the specific structure of the edge busbar 31. For example, the edge busbar 31 may include a tin-bismuth-silver system plating or a tin-bismuth-lead system plating. The silver content in the tin-bismuth-silver system plating can be 1% to 2%, including the values ​​at both ends; the bismuth content in the tin-bismuth-lead system plating can be 14% to 26%, including the values ​​at both ends. This embodiment does not limit the specific thickness of the plating. For example, the plating thickness can be 0.25mm to 0.35mm, including the values ​​at both ends. This embodiment does not limit the specific width of the edge busbar 31. For example, the width of the edge busbar 31 can be 2mm to 4mm, including the values ​​at both ends. A preferred embodiment is that the width of the edge busbar 31 is 3mm, with 1mm overlapping below the battery cell 1 and 2mm protruding to maintain consistency with the string spacing, ensuring a better appearance.

[0063] This embodiment does not limit the specific width of the inter-string busbar 32. For example, the width of the inter-string busbar 32 can be 6mm to 8mm, including the values ​​at both ends. A preferred embodiment is that the width of the inter-string busbar 32 can be 8mm. The width of the inter-string busbar 32 is greater than the spacing between adjacent battery strings. This embodiment does not limit the specific spacing between adjacent battery strings. For example, the spacing between adjacent battery strings can be 4mm to 6mm, including the values ​​at both ends. A preferred embodiment is that the spacing between adjacent battery strings is 6mm, in which case the excess portion of the inter-string busbar 32 overlaps below the batteries.

[0064] This embodiment does not limit the specific structure of the inter-string bus 32, for example, Figure 7 The inter-string busbar 32 shown may include, but is not limited to, a low-temperature plating layer 325, a copper substrate 323, a support layer 322, and a reflective layer 321 arranged sequentially along the thickness direction. The support layer 322 is configured as an insulating layer. The inter-string busbar 32 also includes an insulating material layer 324 penetrating the low-temperature plating layer 325 and the copper substrate 323. The insulating material layer 324 separates the low-temperature plating layer 325 and the copper substrate 323 into two mutually insulated conductive parts. The two conductive parts are used to realize the electrical connection between adjacent battery cells 1 in different battery strings. In this embodiment, the support layer 322 may include, but is not limited to, a PET (Polyethylene terephthalate) layer 322; the reflective layer 321 may include, but is not limited to, a triangular pyramidal prism structure formed on the surface facing away from the PET layer 322. Furthermore, the interfaces between the layers of the inter-string busbar 32 can be bonded together using an interface adhesive. It should be noted that the material of the reflective layer 321 in this embodiment may include, but is not limited to, resin. Its shape is prepared by a special roller press and then shaped at high temperature to form a triangular pyramidal prism structure on its surface. This structure can form diffuse reflection, and its main function is to reflect light between strings and light transmitted through the silicon substrate. The PET layer 322 mainly plays a buffering and supporting role. The insulating material layer 324 that penetrates the low-temperature plating layer 325 and the copper substrate 323 mainly functions to insulate the current on the left and right sides. Its material may be, but is not limited to, ceramic-based thermally conductive insulating material. The interconnected interfaces are bonded together by an interface adhesive.

[0065] In this embodiment, the battery string layer includes multiple battery strings. This embodiment does not limit the interconnection method between battery strings; they can be connected in series, in parallel, or a combination of series and parallel connections. For example... Figure 8 In the structure shown, the battery strings are connected in pairs to form a string group. The battery string layer includes upper and lower parts, and each upper and lower part includes three string groups; the corresponding upper and lower string groups are connected in parallel. It should be noted that the ends of the two battery strings in the string group can be connected in series using ordinary busbars or directly using solder strips.

[0066] Based on the above embodiments, in the photovoltaic module of this application, a busbar is provided on the side of the cell along the arrangement direction perpendicular to the cell. The front solder strip of one cell and the back solder strip of another cell are connected to the same busbar. The solder strips on the surface of adjacent cells are connected by the busbar, thereby realizing the series connection of adjacent cells in the same cell string. This can effectively avoid the problem of cell cracking caused by inter-cell stress.

[0067] Please refer to Figure 9 This application also provides a method for manufacturing photovoltaic modules, which may include:

[0068] S101: Prepare a battery string layer on the front panel surface; the battery string layer includes multiple battery strings as described above.

[0069] This embodiment does not limit the specific structure of the front panel, back panel, and cell string layer. For details, please refer to the above embodiment on photovoltaic modules, which will not be repeated here.

[0070] This embodiment does not limit the specific method of preparing the battery string layer, and may include, but is not limited to, the following: Figure 10 The method shown is based on carrier membrane stringing technology:

[0071] S201: The front solder strip is laid on the front side of the battery cell along the direction parallel to the long side of the battery cell, and then the first carrier film is laid on the front side of the battery cell, covering the front solder strip; the back solder strip is laid on the back side of the battery cell along the direction parallel to the long side of the battery cell, and then one side of the second carrier film is laid on the back side of the battery cell, covering the back solder strip.

[0072] The battery cells coated with a first carrier film and a second carrier film are arranged sequentially, and adjacent battery cells have a stacked region, such that there is a first carrier film and / or a second carrier film between adjacent battery cells in the stacked region.

[0073] Heating causes the first carrier film to bond to the front of the battery cell and pre-fixes the front solder ribbon to the front of the battery cell. The second carrier film is bonded to the back of the battery cell and the back solder ribbon is pre-fixed to the back of the battery cell, and adjacent battery cells are bonded together to obtain the initial battery string.

[0074] S202: Arrange multiple initial battery strings onto the front panel;

[0075] S203: The busbars are arranged between adjacent initial battery strings in an inter-string interconnection manner, with the busbars parallel to the short sides of the battery cells and electrically connected to the solder strips on the surfaces of adjacent battery cells in the same initial battery string, to obtain a battery string layer; wherein, a layout machine can be used to arrange the busbars between adjacent initial battery strings in an inter-string interconnection manner; the busbars can be laid out individually or pre-prepared on the backplate; they can be prepared as a whole or as parts assembled together.

[0076] Furthermore, this embodiment may also include, after step S203 and before step S102, fixing the inter-string busbars and battery strings with tape.

[0077] It should be noted that if the traditional solder ribbon interconnection method uses carrier film stringing technology, during the preparation process, the direction of the solder ribbon laying (requiring the placement of a pressure fixture) is consistent with the direction of the carrier film laying. In order to avoid the clamps pulling the solder ribbon, the pressure fixture needs to leave space for the pulling action. The pressure fixture at the edge cannot press the edge carrier film, resulting in differences in the heat bonding effect. This makes the inter-cell area a weak area of ​​reliability, and it is very easy to fail in aging tests such as TC. In this embodiment, the laying direction of the solder ribbon is changed, there is no solder ribbon end between the cells, and the direction of the pressure fixture is changed. This allows the range of the pressure fixture to be changed, improving the coating quality. This problem is solved from the component stringing direction, showing a significant advantage in reliability.

[0078] It should be noted that in existing technologies, lap welding is a high-temperature welding process. The welding process involves the heating machine directly contacting the busbar. To prevent defects such as cracking of the edge batteries, the busbar in current technology needs to be spaced out for the heating equipment. Therefore, the distance on both sides of the busbar cannot be effectively utilized, resulting in the inability to effectively adjust the size of some components. In this embodiment, the busbar in the length direction is eliminated, so there is naturally no need to leave a safe welding distance.

[0079] It should be noted that when the battery string adopts the above-mentioned carrier film stringing technology, using first and second carrier films of different thicknesses can result in different photovoltaic module structures. Different photovoltaic module structures require different fabrication methods, for example, the following two methods may be included:

[0080] (1) When the thickness of the first carrier film and / or the second carrier film is 50 μm to 200 μm, including the values ​​at both ends, step S202 may include: arranging multiple initial battery strings onto a front plate covered with a front adhesive film; step S102 may include: sequentially applying a back adhesive film and a back plate to the surface of the battery string layer facing away from the front plate. The overall steps of this method can be as follows: Figure 11 As shown.

[0081] (2) When the thickness of the first carrier film and / or the second carrier film is 0.4 mm to 0.6 mm, including both ends; and the first carrier film and / or the second carrier film are co-extruded films, and the pre-crosslinking degree of the co-extruded film on the side closer to the battery cell is higher than the pre-crosslinking degree of the co-extruded film on the side away from the battery cell, step S202 may include: directly arranging multiple initial battery strings onto the front panel; step S102 may include: directly applying a back panel to the surface of the battery string layer away from the front panel. The overall steps of this method can be as follows: Figure 12 As shown.

[0082] S102: A backplate is provided on the surface of the battery string layer away from the front plate to form a stacked structure.

[0083] S103: Lamination of the multilayer structure to tightly bond the solder strips and grid, and to tightly bond the solder strips and busbars, to obtain a photovoltaic module.

[0084] Furthermore, in this embodiment, after step S103, a frame can be installed on the photovoltaic module to protect the photovoltaic module.

[0085] Based on the above embodiments, in the photovoltaic module of this application, a busbar is provided on the side of the cell along the arrangement direction perpendicular to the cell. The front solder strip of one cell and the back solder strip of another cell are connected to the same busbar. The solder strips on the surface of adjacent cells are connected by the busbar, thereby realizing the series connection of adjacent cells in the same cell string. This can effectively avoid the problem of cell cracking caused by inter-cell stress.

[0086] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. A battery string, characterized in that, include: A plurality of battery cells arranged sequentially along a first direction, a busbar connecting adjacent battery cells, and a solder strip disposed on the surface of the battery cells and connected to the busbar; the solder strip includes a front solder strip and a back solder strip disposed on both sides of the battery cells. The busbar is disposed on the side of the battery cell along a second direction perpendicular to the first direction, and the solder strip extends beyond the edge of the battery cell along the second direction and is connected to the corresponding busbar; the front solder strip of one of the adjacent battery cells and the back solder strip of the other battery cell are connected to the same busbar, so that the adjacent battery cells are electrically connected.

2. The battery string according to claim 1, characterized in that, The solar cell is a gridless solar cell; the solar cell includes fine grids extending along the first direction.

3. The battery string according to claim 1, characterized in that, The battery cell is rectangular in shape, including a short side extending along the first direction and a long side extending along the second direction.

4. The battery string according to any one of claims 1 to 3, characterized in that, Also includes: A first carrier film and a second carrier film; the first carrier film is bonded to the front side of the battery cell and covers the front solder strip of the battery cell; The second carrier film is bonded to the back of the battery cell and covers the back solder strip of the battery cell.

5. The battery string according to claim 4, characterized in that, The thickness of the first carrier membrane and / or the second carrier membrane is 50 μm to 200 μm, including the values ​​at both ends; Alternatively, the thickness of the first carrier film and / or the second carrier film is 0.4 mm to 0.6 mm, including the values ​​at both ends; the first carrier film and / or the second carrier film are co-extruded films, and the pre-crosslinking degree of the co-extruded film on the side closer to the battery cell is higher than the pre-crosslinking degree of the co-extruded film on the side away from the battery cell.

6. The battery string according to claim 4, characterized in that, There are stacked areas between adjacent battery cells; The first carrier film and / or the second carrier film on the opposite side of the adjacent battery cells extend into the stacked region.

7. The battery string according to claim 4, characterized in that, The solder strip is a low-temperature solder strip, which includes tin-bismuth-silver system solder strip or tin-bismuth-lead system solder strip.

8. The battery string according to claim 1, characterized in that, The length of the welding strip extending beyond the edge of the battery cell is 1mm to 2mm, including the values ​​at both ends.

9. A photovoltaic module, characterized in that, include: A backplate, a battery string layer, and a front plate are arranged sequentially along the thickness direction; The battery string layer includes a plurality of battery strings as described in any one of claims 1 to 8.

10. The photovoltaic module according to claim 9, characterized in that, The front panel has a raised structure on the side surface near the battery string layer; the position of the raised structure corresponds to the position of the busbar.

11. The photovoltaic module according to claim 9, characterized in that, The busbar includes an edge busbar and an inter-string busbar; the edge busbar is located on the side of the edge of the battery string that is away from the adjacent battery string; the inter-string busbar is located between the adjacent battery strings; The inter-string busbar includes a low-temperature plating layer, a copper substrate, a support layer, and a reflective layer arranged sequentially along the thickness direction. The support layer is configured as an insulating layer. The inter-string busbar also includes an insulating material layer that penetrates the low-temperature plating layer and the copper substrate. The insulating material layer separates the low-temperature plating layer and the copper substrate to form two mutually insulated conductive parts. The two conductive parts are used to realize the electrical connection of adjacent cells in different battery strings.

12. The photovoltaic module according to claim 11, characterized in that, The width of the edge busbar is 2mm to 4mm, including the values ​​at both ends; The width of the inter-string busbar is 6mm to 8mm, including the values ​​at both ends; the width of the inter-string busbar is greater than the spacing between adjacent battery strings.

13. The photovoltaic module according to claim 11, characterized in that, The support layer is a PET layer; the reflective layer has a triangular pyramidal prism structure formed on the surface opposite to the PET layer.

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