Photovoltaic encapsulant film and method of making same, photovoltaic module

Abstract

The application relates to the technical field of photovoltaic cells, in particular to a photovoltaic encapsulating adhesive film and a preparation method thereof and a photovoltaic module. The photovoltaic encapsulating adhesive film comprises a first adhesive film layer, the first adhesive film layer comprises a thermoplastic resin matrix and long glass fibers distributed in the thermoplastic resin matrix, the long glass fibers are arranged in a direction along the plane of the first adhesive film layer, the length of the long glass fibers is 6 mm-15 mm, and the diameter of the long glass fibers is 5 microns-18 microns. The photovoltaic encapsulating adhesive film provided in the embodiment of the application can inhibit the melt flow of the photovoltaic encapsulating adhesive film by mixing the long glass fibers arranged in a direction into the thermoplastic resin matrix in the first adhesive film layer, reduce the shrinkage of the photovoltaic encapsulating adhesive film in a hot-pressing process, reduce the deviation of a wire and the breakage of the long glass fibers in the hot-pressing process, and then improve the efficiency of the photovoltaic module and the product yield.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and in particular to photovoltaic encapsulation films and their preparation methods, and photovoltaic modules. Background Technology

[0002] Perovskite-silicon tandem solar cells can break through the efficiency limit of monocrystalline silicon cells and represent the mainstream route for next-generation high-efficiency photovoltaics. To further achieve silver-free cells and reduce thermal damage, the industry has introduced a busbar-less (OBB) structure, which uses multiple wires to replace the traditional busbar and employs an integrated coating process for encapsulation. In this integrated coating process, a thermal lamination process is required, using an encapsulating film to bond and fix the wires to the solar cell.

[0003] Because perovskite materials are highly sensitive to crosslinking agents (such as peroxides and amines) commonly used in thermosetting encapsulation films and are prone to chemical decomposition, thermoplastic resin encapsulation films are usually used.

[0004] However, traditional thermoplastic resin encapsulation films are prone to melting at lamination temperatures (100℃~140℃), which causes the viscosity of the encapsulation film to drop sharply (the fluidity usually increases by 300%). This causes the conductors to shift with the flow of the film (the offset can reach 0.5 mm~1 mm), resulting in misalignment between the cells and increased series resistance, which in turn significantly reduces the efficiency and yield of photovoltaic modules. Summary of the Invention

[0005] Based on this, embodiments of this application provide a photovoltaic encapsulating film and its preparation method, as well as a photovoltaic module, which can suppress the melt flow of the photovoltaic encapsulating film, reduce wire offset, and improve the efficiency and product yield of the photovoltaic module.

[0006] In a first aspect, this application provides a photovoltaic encapsulation film, which includes a first film layer. The first film layer includes a thermoplastic resin matrix and long glass fibers distributed within the thermoplastic resin matrix. The long glass fibers are oriented along the plane of the first film layer, and the length of the long glass fibers is 6 mm to 15 mm, and the diameter of the long glass fibers is 5 μm to 18 μm.

[0007] In some embodiments, the mass ratio of thermoplastic resin matrix to long glass fiber is 100:(10~20).

[0008] In some embodiments, the long glass fibers satisfy at least one of the following conditions: (1) the distribution density of the long glass fibers is 5 fibers / mm to 20 fibers / mm; (2) the length of the long glass fibers is 8 mm to 12 mm.

[0009] In some embodiments, the first film layer also includes a silane coupling agent.

[0010] Optionally, the silane coupling agent includes one or more of KH550, KH560 and KH570.

[0011] Optionally, the mass ratio of the thermoplastic resin matrix to the silane coupling agent is 100:(0.2~0.8).

[0012] In some embodiments, the photovoltaic encapsulation film further includes a second encapsulation layer, which is stacked with the first encapsulation layer, and the material of the second encapsulation layer includes a thermoplastic resin.

[0013] Optionally, the thickness of the first adhesive film layer is 0.05 mm to 0.15 mm, and the thickness of the second adhesive film layer is 0.5 mm to 0.7 mm.

[0014] In some embodiments, the thermoplastic resin matrix material includes at least one of polyolefin elastomers, maleic anhydride-grafted polyolefin elastomers, thermoplastic polyolefins, ethylene-vinyl acetate copolymers, and polyurethanes.

[0015] In some embodiments, the orientation is along the length or width of the first adhesive film layer.

[0016] A second aspect of this application provides a method for preparing a photovoltaic encapsulating film, the method comprising the following steps: mixing and melting a thermoplastic resin matrix with long glass fibers, and then casting the mixture to form a first film layer, such that the long glass fibers are oriented along the plane of the first film layer, the length of the long glass fibers being 6 mm to 15 mm, and the diameter of the long glass fibers being 5 μm to 18 μm.

[0017] Optionally, the melting temperature of the casting process is 190℃~210℃, and the cooling temperature of the casting process is 20℃~40℃.

[0018] Optionally, the thermoplastic resin matrix includes a first thermoplastic resin matrix and a second thermoplastic resin matrix; the step of mixing the thermoplastic resin matrix with long glass fibers specifically includes: impregnating the long glass fibers in the first thermoplastic resin matrix, such that the first thermoplastic resin matrix coats the surface of the long glass fibers, to obtain a long glass fiber prepreg; mixing the long glass fiber prepreg with the second thermoplastic resin matrix; the first thermoplastic resin matrix is ​​selected from one or more of maleic anhydride-grafted polyolefin elastomers and polyethylene with a degree of polymerization of 500 to 5000; the second thermoplastic resin matrix is ​​selected from one or more of polyolefin elastomers, thermoplastic polyolefins, ethylene-vinyl acetate copolymers, and polyurethanes.

[0019] A third aspect of this application provides a photovoltaic module, comprising: a cell string including a plurality of cells, at least a portion of which are perovskite-silicon tandem cells; a ribbon cable electrically connected to adjacent cells in the cell string, such that adjacent cells in the cell string are connected in series, the ribbon cable including a plurality of wires arranged at intervals; a photovoltaic encapsulating film provided in the first aspect, attached to the outer side of the ribbon cable away from the cell string, fixing the ribbon cable to the cell string; and a cover plate disposed on the side of the photovoltaic encapsulating film away from the cell string; wherein, a first encapsulating film layer is disposed close to the ribbon cable, and the arrangement direction of the long glass fibers has an angle α with the arrangement direction of the wires, 0° < α < 180°.

[0020] Optionally, α can be 80° to 100°.

[0021] The photovoltaic encapsulation film provided in this application embodiment incorporates oriented long glass fibers into a thermoplastic resin matrix in the first film layer. The long glass fibers are sufficiently long (6 mm to 15 mm) to form a continuous rigid skeleton at hot pressing temperature. Compared to short glass fibers, this better suppresses the relaxation and slippage of polymer molecular chains in a specific direction. The diameter of the long glass fibers is in the range of 5 μm to 18 μm, giving each long glass fiber good flexibility and resistance to bending deformation, and adapting to the diameter of the wire. The surface of the long glass fibers forms a strong chemical bond and physical adsorption with the polymer molecular chains. The molten polymer molecular chains are "anchored" to the surface of each fiber, making the long glass fibers and polymer composite into a whole. This effectively resists directional shear flow during lamination. The slippage and diffusion of molecular chains need to overcome huge frictional resistance, which restricts the free movement space of the polymer molecular chains, thereby suppressing the melt flow of the photovoltaic encapsulation film, reducing the shrinkage rate of the photovoltaic encapsulation film during hot pressing, reducing the displacement of the wires and the breakage of the long glass fibers during hot pressing, and thus improving the efficiency and product yield of the photovoltaic module.

[0022] When the mass ratio of thermoplastic resin matrix to long glass fiber is 100:(10~20), the distribution density of long glass fiber can be effectively increased, further improving the anti-flow properties of photovoltaic encapsulation film in the molten state, suppressing the problem of wire misalignment during hot pressing, and improving the compressive strength of photovoltaic encapsulation film while reducing the breakage of long glass fiber.

[0023] When the first layer of the photovoltaic encapsulating film covers the conductive wire, the three-dimensional network skeleton formed by the interlocking of the oriented long glass fibers and the conductive wire weaves into a macroscopic network that encapsulates the conductive wire, generating a stronger "pinning effect." This further restricts the movement of molecular chains, directly anchoring the conductive wire mechanically. This suppresses thermal shrinkage deformation caused during the lamination process, significantly reducing the shrinkage rate. The continuous three-dimensional network skeleton formed by long glass fibers is more effective than short glass fibers in resisting directional shear flow and shrinkage stress during hot pressing. It constructs a rigid network that mechanically locks the conductive wire, significantly increases melt viscosity, and achieves anisotropic anti-shrinkage capabilities. This enhances the viscosity and anti-shrinkage performance of the thermoplastic film in the molten state, reduces the thermal displacement of the conductive wire during hot pressing, and enables integrated and stable coating of grid-less perovskite tandem cells, improving the efficiency and yield of photovoltaic modules. Attached Figure Description

[0024] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0025] Figure 1 This is a schematic diagram showing the directional arrangement of long glass fibers in the first film layer of the encapsulating film in one embodiment.

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of a photovoltaic module in one embodiment.

[0027] Figure 3 This is a schematic diagram of the cross-sectional structure of a photovoltaic module in another embodiment.

[0028] Figure 4 This is a schematic diagram illustrating the directional arrangement between the long glass fibers in the first encapsulant layer and the conductors in the conductor layer of a photovoltaic module in one embodiment.

[0029] Reference numerals: 1. Photovoltaic module; 100. Battery string; 110. Ribbon cable; 111. Wire; 120. Photovoltaic encapsulation film; 121. First encapsulation layer; 1211. Thermoplastic resin matrix; 1212. Long glass fiber; 122. Second encapsulation layer; 130. Cover plate. Detailed Implementation

[0030] Reference will now be made to detailed embodiments of this application, one or more of which are described below. Each example is provided for explanation and not for limitation of this application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to this application without departing from its scope or spirit. For example, features described or illustrated as part of one embodiment may be used in another embodiment to produce further embodiments.

[0031] Therefore, this application is intended to cover such modifications and variations falling within the scope of the appended claims and their equivalents. Other objects, features, and aspects of this application are disclosed in or will be apparent from the following detailed description. It will be understood by those skilled in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of this application.

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0034] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0035] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] Perovskite-silicon tandem solar cells can break through the efficiency limit of monocrystalline silicon cells and represent the mainstream route for next-generation high-efficiency photovoltaics. To further achieve silver-free cells and reduce thermal damage, the industry has introduced a busbar-less (OBB) structure, which uses multiple wires to replace the traditional busbar and employs an integrated coating process for encapsulation. In this integrated coating process, a thermal lamination process is required, using an encapsulating film to bond and fix the wires to the solar cell.

[0038] Because perovskite materials are highly sensitive to crosslinking agents (such as peroxides and amines) commonly used in thermosetting encapsulation films and are prone to chemical decomposition, thermoplastic resin encapsulation films are usually used.

[0039] However, traditional thermoplastic resin encapsulation films are prone to melting at lamination temperatures (100℃~140℃), which causes the viscosity of the encapsulation film to drop sharply (the fluidity usually increases by 300%). This causes the conductors to shift with the flow of the film (the offset can reach 0.5 mm~1 mm), resulting in misalignment between the cells and increased series resistance, which in turn significantly reduces the efficiency and yield of photovoltaic modules.

[0040] The applicant's research found that although modifying thermoplastic resin encapsulating films with inorganic fillers or short glass fibers can improve the general mechanical properties of the encapsulating films (such as overall stiffness and tear resistance) and achieve isotropic low shrinkage, it is difficult to effectively suppress the local and directional shear deformation caused by melt flow during the lamination process of the encapsulating film, resulting in wire misalignment.

[0041] Therefore, combining Figures 1 to 4 As shown, in a first aspect of this application, a photovoltaic encapsulation film 120 is provided. The photovoltaic encapsulation film 120 includes a first film layer 121. The first film layer 121 includes a thermoplastic resin matrix 1211 and long glass fibers 1212 distributed within the thermoplastic resin matrix 1211. The long glass fibers 1212 are oriented along the planar direction of the first film layer 121. The length of the long glass fibers 1212 is 6 mm to 15 mm, and the diameter of the long glass fibers 1212 is 5 μm to 18 μm.

[0042] The photovoltaic encapsulating film 120 provided in this application embodiment incorporates oriented long glass fibers 1212 into the first film layer 121 within a thermoplastic resin matrix 1211. The long glass fibers 1212 are sufficiently long (6 mm to 15 mm) to form a continuous rigid framework under hot-pressing conditions. Compared to short glass fibers, this better suppresses the relaxation and slippage of polymer molecular chains in specific directions. The diameter of the long glass fibers 1212 is between 5 μm and 18 μm. Within the μm range, the single long glass fiber 1212 is endowed with good flexibility and the ability to withstand bending deformation, and is adapted to the diameter of the wire 111. The surface of the long glass fiber 1212 forms a strong chemical bond and physical adsorption with the polymer molecular chain. The molten polymer molecular chain is "anchored" to the surface of each fiber, making the long glass fiber 1212 and the polymer composite into a whole. This effectively resists the directional shear flow during the lamination process. The slippage and diffusion of the molecular chain need to overcome huge frictional resistance, which restricts the free movement space of the polymer molecular chain, thereby inhibiting the melt flow of the photovoltaic encapsulation film 120, reducing the shrinkage rate of the photovoltaic encapsulation film 120 during the hot pressing process, reducing the displacement of the wire 111 and the breakage of the long glass fiber 1212 during the hot pressing process, and thus improving the efficiency and product yield of the photovoltaic module 1.

[0043] When the first encapsulant layer 121 of the photovoltaic encapsulant film 120 covers the conductor 111, the three-dimensional network skeleton formed by the oriented long glass fibers 1212 overlapping with the conductor 111 weaves into a macroscopic network that encapsulates the conductor 111, generating a stronger "pinning effect." This further restricts the movement of molecular chains and directly anchors the conductor 111 mechanically, suppressing thermal shrinkage deformation caused during the lamination process and significantly reducing the shrinkage rate. The continuous three-dimensional network skeleton formed by the long glass fibers 1212 is more effective than short glass fibers in resisting directional shear flow and shrinkage stress during hot pressing. It constructs a rigid network that mechanically locks the conductor 111, significantly increases melt viscosity, and achieves anisotropic anti-shrinkage capability. This enhances the viscosity and anti-shrinkage performance of the thermoplastic film in the molten state, reduces the thermal displacement problem of the conductor 111 during hot pressing, and achieves integrated and stable coating of the gridless perovskite silicon tandem cell, improving the efficiency and product yield of the photovoltaic module 1.

[0044] For example, the length of the long glass fiber 1212 can be, but is not limited to, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm.

[0045] For example, the diameter of the long glass fiber 1212 can be, but is not limited to, 5 μm, 8 μm, 11 μm, 14 μm, or 18 μm. The diameter of the long glass fiber 1212 ranges from 5 μm to 18 μm. On one hand, it is suitable for the diameter of the conductor 111 (less than 0.2 mm, with a fine cylindrical surface). The diameter of the long glass fiber 1212 is significantly smaller than that of the conductor 111. During hot pressing, the small-diameter long glass fiber 1212 can conform to and tightly adhere to the fine cylindrical surface of the conductor 111. Multiple long glass fibers 1212 can form a densely wrapped three-dimensional network around the conductor 111, generating efficient mechanical interlocking and a "pinning effect" with the conductor 111, thereby firmly anchoring the conductor 111 and effectively suppressing its thermal displacement. This achieves effective adhesion and mechanical interlocking between the long glass fiber 1212 and the conductor 111. On the other hand, it allows a single long glass fiber 1212 to possess both good flexibility and sufficient rigidity. If the diameter of the long glass fiber 1212 is too large (e.g., exceeding 18 μm), it will not be suitable for the conductor 111. If the diameter of the long glass fiber 1212 is too small (e.g., less than 5 μm), the fiber stiffness is too low, and the monofilament is too soft to form an effective mechanical skeleton to resist wire deflection. Therefore, a diameter range of 5 μm to 18 μm is a preferred balance range that provides sufficient rigidity to the long glass fiber 1212 while ensuring that it can conform to the flow of the adhesive film and withstand bending deformation without breaking. In some embodiments, the mass ratio of thermoplastic resin matrix 1211 to long glass fiber 1212 is 100:(10~20). Exemplarily, the mass ratio of thermoplastic resin matrix 1211 to long glass fiber network 1212 can be, but is not limited to, 100:10, 100:12, 100:14, 100:16, 100:18, or 100:20. Thus, when the mass ratio of thermoplastic resin matrix 1211 to long glass fiber 1212 is within the above range, the distribution density of long glass fiber 1212 can be effectively increased, further improving the anti-flow properties of photovoltaic encapsulation film 120 in the molten state, suppressing the misalignment of wire 111 during hot pressing, and simultaneously enhancing the compressive strength of photovoltaic encapsulation film 120 and reducing the breakage of long glass fiber 1212.

[0046] Furthermore, the distribution density of the long glass fibers 1212 is 5 fibers / mm to 20 fibers / mm. For example, the distribution density of the long glass fibers 1212 can be, but is not limited to, 5 fibers / mm, 10 fibers / mm, 15 fibers / mm, or 20 fibers / mm. Thus, the high distribution density of the long glass fibers 1212 can significantly restrict the free movement space of the thermoplastic resin molecular chains. The slippage and diffusion of the molecular chains need to overcome enormous frictional resistance, thereby suppressing the melt flow of the photovoltaic encapsulation film 120, reducing the offset of the wires 111 and the breakage of the long glass fibers during hot pressing, and ensuring that the photovoltaic encapsulation film 120 can still provide uniform elastic support in the molten state, thereby improving the efficiency and product yield of the photovoltaic module 1.

[0047] In this article, "the distribution density of long glass fiber 1212" refers to the number of long glass fibers 1212 passing through a virtual measurement line per unit length in a direction perpendicular to the length direction of the long glass fiber.

[0048] In some embodiments, the first encapsulating film layer 121 further includes a silane coupling agent. Thus, the silane coupling agent can chemically anchor the molecular chains of the thermoplastic resin matrix 1211 to the long glass fibers, effectively preventing the slippage of the resin molecular chains and significantly improving the shear flow properties of the photovoltaic encapsulating film 120 in the molten state, thereby increasing the peel strength between the photovoltaic encapsulating film 120 and the encapsulation interface.

[0049] Optionally, the silane coupling agent includes one or more of KH550, KH560 and KH570.

[0050] Optionally, the mass ratio of thermoplastic resin matrix 1211 to silane coupling agent is 100:(0.2~0.8). Exemplarily, the mass ratio of thermoplastic resin matrix 1211 to silane coupling agent can be, but is not limited to, 100:0.2, 100:0.3, 100:0.4, 100:0.5, 100:0.6, 100:0.7, or 100:0.8.

[0051] In some implementations, such as Figure 3 As shown, the photovoltaic encapsulation film 120 also includes a second film layer 122, which is stacked with the first film layer 121. The material of the second film layer 122 includes thermoplastic resin.

[0052] Optionally, the thickness of the first adhesive layer 121 is 0.05 mm to 0.15 mm, and the thickness of the second adhesive layer 122 is 0.5 mm to 0.7 mm. For example, the thickness of the first adhesive layer 121 can be, but is not limited to, 0.05 mm, 0.1 mm, or 0.15 mm; the thickness of the second adhesive layer 122 can be, but is not limited to, 0.5 mm, 0.6 mm, or 0.7 mm. The thickness of the first adhesive layer 121, being 0.05 mm to 0.15 mm, is slightly smaller than or close to the diameter of the wire 111 (<0.2 mm). During hot pressing, the wire 111 can be pressed into the first adhesive layer 121 and contact the surface of the battery cell, so that the wire 111 and the long glass fiber 1212 coexist in an extremely thin space, resulting in good interlocking effect. The second adhesive layer 122 is used to bond the first adhesive layer 121 to the cover plate 130. The thickness of the second encapsulant layer 122 is 0.5 mm to 0.7 mm, which can improve the mechanical strength of the photovoltaic encapsulant film 120 and thus improve the reliability of the photovoltaic module 1.

[0053] In some embodiments, the thermoplastic resin matrix 1211 is made of at least one of polyolefin elastomer (POE), maleic anhydride-grafted polyolefin elastomer, thermoplastic polyolefin (TPO), ethylene-vinyl acetate copolymer (EVA), and polyurethane.

[0054] In some embodiments, the orientation is along the length or width of the first adhesive film layer 121. This facilitates intersection with the wires in the photovoltaic module during use, improving production efficiency.

[0055] In some embodiments, the first film layer 121 and the second film layer 121 further include antioxidants.

[0056] Optionally, in the first film layer 121 and the second film layer 122, the antioxidants are independently selected from one or more of hindered phenolic antioxidants (such as antioxidant 1010, antioxidant 1076) and phosphite antioxidants (such as antioxidant 168, trioctyl phosphite).

[0057] Optionally, in the first adhesive film layer 121, the mass ratio of the thermoplastic resin matrix 1211 to the antioxidant is 100:(0.1~0.4). Exemplarily, the mass ratio of the thermoplastic resin matrix 1211 to the antioxidant can be, but is not limited to, 100:0.1, 100:0.2, 100:0.3, or 100:0.4.

[0058] In some embodiments, the first film layer 121 and the second film layer 122 further include an ultraviolet absorber.

[0059] Optionally, in the first film layer 121 and the second film layer 122, the ultraviolet absorber is independently selected from one or more of benzotriazole ultraviolet absorbers (such as UV-326, UV-329), benzophenone ultraviolet absorbers (such as UV-531, BP12), triazine ultraviolet absorbers, and benzoxazinone ultraviolet absorbers (such as Chiguard 380W).

[0060] Optionally, the mass ratio of the thermoplastic resin matrix 1211 to the ultraviolet absorber is 100:(0.05~0.5). Exemplarily, the mass ratio of the thermoplastic resin matrix 1211 to the ultraviolet absorber can be, but is not limited to, 100:0.05, 100:0.1, 100:0.2, 100:0.3, 100:0.4, or 100:0.5.

[0061] A second aspect of this application provides a method for preparing a photovoltaic encapsulating film 120. The method includes the following steps: mixing and melting a thermoplastic resin matrix 1211 with long glass fibers 1212, and then casting the mixture to form a first encapsulating film layer 120, such that the long glass fibers 1212 are oriented along the plane of the first encapsulating film layer 120, the length of the long glass fibers 1212 is 6 mm to 15 mm, and the diameter of the long glass fibers 1212 is 5 μm to 18 μm.

[0062] The photovoltaic encapsulation film 120 provided in this application embodiment utilizes the flow characteristics of the melt in the flow field during the casting process to guide the long glass fibers 1212 to be oriented along the flow direction, thereby achieving enhanced viscosity and improved anti-shrinkage performance of the thermoplastic film in the molten state.

[0063] In this article, "casting" refers to the process of extruding molten material into a thin film using rollers and then using rapid cooling to transform it from a molten state into a solid film, thus obtaining a continuous film.

[0064] In some embodiments, prior to the step of mixing the thermoplastic resin matrix 1211 with the long glass fiber 1212, the method further includes: surface treatment of the long glass fiber 1212 with a silane coupling agent. Specifically, the surface treatment method includes one or more of spraying, impregnation, and coating. Thus, the silane coupling agent can improve the wettability of the surface of the long glass fiber 1212, further enhancing the interfacial bonding force between the long glass fiber 1212 and the thermoplastic resin matrix 1211.

[0065] In some embodiments, the thermoplastic resin matrix 1211 includes a first thermoplastic resin matrix and a second thermoplastic resin matrix. The step of mixing the thermoplastic resin matrix 1211 with the long glass fiber 1212 specifically includes: impregnating the long glass fiber 1212 in the first thermoplastic resin matrix, such that the first thermoplastic resin matrix coats the surface of the long glass fiber 1211, to obtain a long glass fiber prepreg; and mixing the long glass fiber prepreg with the second thermoplastic resin matrix. Thus, through prepreg, a continuous and uniform first thermoplastic resin matrix is ​​coated on the surface of the long glass fiber 1212, which can significantly enhance the wettability of the long glass fiber 1212 and improve the interfacial bonding force between the long glass fiber 1212 and the thermoplastic resin matrix 1211, thereby improving the overall anti-flow and anti-shrinkage properties of the photovoltaic encapsulation film 120.

[0066] Optionally, the first thermoplastic resin matrix is ​​selected from one or more of maleic anhydride-grafted polyolefin elastomers and polyethylene with a degree of polymerization of 500 to 5000. Thus, the first thermoplastic resin matrix is ​​selected as a low-viscosity thermoplastic resin with good melt flowability, which can quickly penetrate to the surface of the long glass fiber 1212, so that the surface of each fiber is completely covered by the resin.

[0067] Optionally, the second thermoplastic resin matrix is ​​selected from one or more of polyolefin elastomers, thermoplastic polyolefins, ethylene-vinyl acetate copolymers, and polyurethanes.

[0068] In some embodiments, the melt temperature for tape casting is 190°C to 210°C. Exemplarily, the melt temperature for tape casting can be, but is not limited to, 190°C, 195°C, 200°C, 205°C, and 210°C.

[0069] In some embodiments, the cooling temperature for casting is 20°C to 40°C. Exemplarily, the cooling temperature for casting can be, but is not limited to, 20°C, 25°C, 30°C, 35°C, or 40°C.

[0070] Combination Figures 1 to 4As shown, in a third aspect of this application, a photovoltaic module 1 is provided. The photovoltaic module 1 includes a cell string 100, a ribbon cable 110, a photovoltaic encapsulating film 120 provided in the first aspect, and a cover plate 130. The cell string 100 includes a plurality of cells (not shown in the figure), at least some of which are perovskite silicon tandem cells. The ribbon cable 110 is electrically connected to adjacent cells in the cell string 100, such that adjacent cells in the cell string 100 are connected in series. The ribbon cable 110 includes a plurality of wires 111 arranged at intervals. The ribbon cable 110 is used to replace grid lines to connect adjacent cells in series. The plurality of wires 111 are electrically connected to the electrode layers of the cells, serving to collect and conduct current. The photovoltaic encapsulating film 120 is attached to the outside of the ribbon cable 110 and the cell string 100, fixing the ribbon cable 110 to the cell string 100. The cover plate 130 is disposed on the side of the photovoltaic encapsulating film 120 away from the cell string 100. The first adhesive film layer 121 is disposed close to the ribbon cable 110, and the arrangement direction of the long glass fiber 1212 has an angle α with the arrangement direction of the wire 111, where 0° < α < 180°.

[0071] It is understandable that, since the offset of the conductor 111 mainly occurs in the in-plane direction during the lamination process, when the angle α between the arrangement direction of the long glass fiber 1212 and the arrangement direction of the conductor 111 satisfies 0° < α < 180° (i.e. they are not parallel to each other), the long glass fiber 1212 can resist the lateral shear force of the resin and suppress the offset of the conductor 111.

[0072] Furthermore, the angle α between the arrangement direction of the long glass fibers 1212 and the arrangement direction of the conductor 111 is 80°~100°. Thus, the arrangement direction of the long glass fibers 1212 and the arrangement direction of the conductor 111 are in a positional relationship that is perpendicular or approximately perpendicular to each other. The long glass fibers 1212 can resist the lateral shear force of the resin with the maximum stress-bearing cross section, and further resist the deflection of the conductor 111.

[0073] In some embodiments, the cover plate 130 includes a first cover plate located on the light-receiving surface of the photovoltaic module 1 and a second cover plate located on the back surface of the photovoltaic module 1. The first cover plate and the second cover plate may be the same or different, and are independently selected from a glass substrate, a quartz substrate, a polymethyl methacrylate substrate, and a polyethylene terephthalate substrate.

[0074] A fourth aspect of this application provides a method for manufacturing a photovoltaic module 1, the method comprising the following steps: providing a battery string 100 with a ribbon cable 110, the battery string 100 comprising a plurality of battery cells, at least a portion of which are perovskite-silicon tandem cells, the ribbon cable 110 electrically connecting adjacent battery cells in the battery string 100 such that adjacent battery cells in the battery string 100 are connected in series, the ribbon cable 110 comprising a plurality of wires 111 arranged at intervals; stacking the battery string 100, the photovoltaic encapsulating film 120 provided in the first aspect, and a cover plate 130, the photovoltaic encapsulating film 120 being attached to the outside of the ribbon cable 110 and the battery string 100, fixing the ribbon cable 110 to the battery string 100, the first encapsulating film layer 121 being disposed close to the ribbon cable 110, the arrangement direction of the long glass fibers 1212 having an angle α with the arrangement direction of the wires 111, 0°<α<180°, and then performing a lamination process to obtain a photovoltaic module.

[0075] Optionally, the lamination temperature is 100°C to 160°C. For example, the lamination temperature can be, but is not limited to, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, or 160°C.

[0076] Optionally, the lamination process pressure is 60 kPa to 90 kPa. For example, the lamination process pressure can be, but is not limited to, 60 kPa, 70 kPa, 80 kPa, or 90 kPa.

[0077] The present application will be further described below with reference to specific embodiments and comparative examples.

[0078] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0079] Example 1

[0080] This embodiment provides a photovoltaic encapsulation film and its preparation method, and a photovoltaic module and its preparation method.

[0081] Photovoltaic encapsulation film:

[0082] (1) Provide the following components and parts by weight of raw materials: 98 parts TPO, 2 parts maleic anhydride grafted POE, 15 parts long glass fiber (diameter of 10 μm), 0.5 parts silane coupling agent KH-550, 0.2 parts antioxidant 1010 and 0.1 parts ultraviolet absorber UV-326.

[0083] (2) KH-550 was prepared into an ethanol solution with a concentration of 2wt% and sprayed onto long glass fibers. The solution was dried at 80°C. Continuous long glass fiber bundles were passed through an impregnation tank filled with molten maleic anhydride-grafted POE to allow the maleic anhydride-grafted POE to fully penetrate. The solution was then dried to obtain long glass fiber prepreg tape.

[0084] (3) Cut the long glass fiber prepreg tape into long glass fiber prepreg segments with a length of 10 mm.

[0085] (4) Long glass fiber prepreg fragments, TPO, antioxidant 1010 and UV-326 are fed into a twin-screw extruder, heated to 200°C in the extruder to a molten state, and then fed into a casting machine for casting. The mixture is then cooled at 30°C to form a first film layer with a thickness of 0.1 mm. During this process, the long glass fibers are guided to align along the length of the first film layer.

[0086] (5) A TPO film with a thickness of 0.6 mm (containing the following parts by weight of raw materials: 100 parts TPO, 0.2 parts antioxidant 1010 and 0.1 parts UV absorber UV-326) is used as the second encapsulant layer and laminated with the first encapsulant layer to form a photovoltaic encapsulant film.

[0087] Photovoltaic modules:

[0088] (1) A battery string with ribbon cables on both sides is provided. The battery string includes multiple battery cells, all of which are perovskite-silicon tandem cells. The ribbon cables are electrically connected to adjacent battery cells in the battery string, so that adjacent battery cells in the battery string are connected in series. The ribbon cables include multiple wires arranged at intervals. The wires are arranged in a directional orientation along the width direction of the battery string.

[0089] (2) A multilayer structure is formed by sequentially stacking the following layers: a first glass substrate, the aforementioned photovoltaic encapsulating film, and a battery string with cables on both sides. The photovoltaic encapsulating film and the second glass substrate are attached to the outside of the cables and the battery string, fixing the cables to the battery string. The first layer of the photovoltaic encapsulating film is positioned close to the cables, and the angle α between the direction of the long glass fibers and the direction of the wires is approximately 90° (perpendicular to each other).

[0090] (3) The above-mentioned stacked structure is sent into a laminator for lamination and encapsulation; then lamination and encapsulation is carried out at a temperature of 130°C and a pressure of 75 kPa to obtain a solar cell module.

[0091] Example 2

[0092] In this embodiment, the photovoltaic encapsulating film and its preparation method, as well as the photovoltaic module and its preparation method, are basically the same as in Example 1, except that:

[0093] Photovoltaic encapsulation film:

[0094] In step (1), the diameter of the long glass fiber is 5 μm and the weight is 20 parts.

[0095] In step (4), the long glass fiber prepreg tape is cut into long glass fiber prepreg segments with a length of 8 mm.

[0096] Example 3

[0097] In this embodiment, the photovoltaic encapsulating film and its preparation method, as well as the photovoltaic module and its preparation method, are basically the same as in Example 1, except that:

[0098] Photovoltaic encapsulation film:

[0099] In step (1), the diameter of the long glass fiber is 18 μm and the weight is 10 parts.

[0100] In step (4), the long glass fiber prepreg tape is cut into long glass fiber prepreg segments with a length of 12 mm.

[0101] Comparative Example 1

[0102] In this comparative example, the photovoltaic encapsulating film and its preparation method, as well as the photovoltaic module and its preparation method, are basically the same as in Example 1, except that:

[0103] Photovoltaic encapsulation film:

[0104] In step (1), the raw material does not contain glass fiber and does not include the glass fiber treatment steps in steps (2) to (4).

[0105] In step (4), TPO, antioxidant 1010 and UV-326 are directly fed into a twin-screw extruder, heated to 200°C in the extruder until they are in a molten state, and then fed into a casting machine. Finally, they are cooled at 30°C to obtain a film with a thickness of 0.1 mm.

[0106] Comparative Example 2

[0107] In this comparative example, the adhesive film and its preparation method, and the solar cell module and its preparation method are basically the same as in Example 1, except that:

[0108] Photovoltaic encapsulation film:

[0109] In step (1), the long glass fiber is replaced with a short glass fiber (10 μm in diameter and 3 mm in length), and step (3) is not included.

[0110] In step (4), TPO, short glass fiber, antioxidant 1010 and UV-326 are directly fed into a twin-screw extruder, heated to 200°C in the extruder to a molten state, and then fed into a casting machine. Finally, the extruder is cooled at 30°C to obtain a first film layer with a thickness of 0.1 mm.

[0111] The key parameters of Examples 1-4 and Comparative Example 2 are summarized in Table 1.

[0112] Table 1

[0113]

[0114] Performance testing

[0115] (1) Heat shrinkage rate of the film

[0116] A square sample of 30cm (longitudinal, MD) × 30cm (transverse, TD) was cut from the first adhesive film layer of each embodiment and comparative example. Reference line segments of 20±1cm in length were drawn on both the transverse and longitudinal sides of the sample. The measurements were recorded using vernier calipers and denoted as X1. The first adhesive film layer was placed on a similar tempered glass embossed surface used in the production line (with the smooth side of the first adhesive film layer close to the glass), and placed in an oven at 120±1℃ for 3 minutes. After cooling, the length of the line segment after heating was retested and denoted as X2. The shrinkage rate δ of the carrier film was calculated using the following formula:

[0117] δ = (1 - X2 / X1) × 100%;

[0118] Calculate the average value of 10 sets of data.

[0119] (2) Deviation of conductor position

[0120] Calculate the center displacement of the conductor before and after lamination. Randomly select 10 observation points on the component and calculate the average offset distance (unit: mm).

[0121] (3) Electroluminescence (EL) defect rate of photovoltaic modules

[0122] Testing was conducted according to IEC TS 62941:2016, "Guideline for detecting microcracks in photovoltaic modules". Defect rate = (number of defective cells / total number of tested cells) × 100%.

[0123] The test results are shown in Table 2.

[0124] Table 2

[0125]

[0126] As shown in Table 2, comparing Examples 1-3 and Comparative Examples 1-2, it can be seen that the encapsulant film provided in this application has a lower thermal shrinkage rate, and the photovoltaic module provided in this application has a lower wire position deviation and a lower defect rate (i.e., a higher yield).

[0127] Comparing Example 1 and Comparative Example 2, it can be seen that Comparative Example 2 uses short glass fibers with a length of 3 mm, which is much shorter than the wire size. During the flow of the encapsulant melt, these fibers cannot form an effective spatial barrier to resist the movement of the wire. Furthermore, the short glass fibers mainly provide isotropic reinforcement, with limited effect on suppressing the relaxation and slippage of polymer molecular chains in specific directions. In contrast, Example 1 uses long glass fibers with a length of 10 mm, which are on the same order of magnitude as or even longer than the wire size. This allows for the formation of a macroscopic network that encapsulates the wire, directly anchoring it. Simultaneously, the long glass fibers can suppress the movement of molecular chains, thereby significantly reducing the thermal shrinkage rate of the encapsulant film and the positional deviation of the wire, thus reducing the defect rate of the photovoltaic module.

[0128] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0129] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A photovoltaic encapsulating film, characterized in that, The first adhesive film layer includes a thermoplastic resin matrix and long glass fibers distributed within the thermoplastic resin matrix. The long glass fibers are oriented along the plane of the first adhesive film layer, and the length of the long glass fibers is 6 mm to 15 mm, and the diameter of the long glass fibers is 5 μm to 18 μm.

2. The photovoltaic encapsulating film according to claim 1, characterized in that, The mass ratio of the thermoplastic resin matrix to the long glass fiber is 100:(10~20).

3. The photovoltaic encapsulating film according to claim 2, characterized in that, The long glass fiber satisfies at least one of the following conditions: (1) The distribution density of the long glass fibers is 5 fibers / mm to 20 fibers / mm; (2) The length of the long glass fiber is 8 mm to 12 mm.

4. The photovoltaic encapsulating film according to claim 1, characterized in that, The first adhesive film layer also includes a silane coupling agent; Optionally, the silane coupling agent includes one or more of KH550, KH560, and KH570; Optionally, the mass ratio of the thermoplastic resin matrix to the silane coupling agent is 100:(0.2~0.8).

5. The photovoltaic encapsulating film according to claim 1, characterized in that, The photovoltaic encapsulation film further includes a second film layer, which is stacked with the first film layer, and the material of the second film layer includes thermoplastic resin.

6. The photovoltaic encapsulating film according to claim 5, characterized in that, The thickness of the first adhesive film layer is 0.05 mm to 0.15 mm, and the thickness of the second adhesive film layer is 0.5 mm to 0.7 mm.

7. The photovoltaic encapsulating film according to any one of claims 1 to 6, characterized in that, The thermoplastic resin matrix material includes at least one of polyolefin elastomer, maleic anhydride-grafted polyolefin elastomer, thermoplastic polyolefin, ethylene-vinyl acetate copolymer, and polyurethane.

8. The photovoltaic encapsulating film according to any one of claims 1 to 6, characterized in that, The directional arrangement is along the length or width of the first adhesive film layer.

9. A method for preparing a photovoltaic encapsulating film, characterized in that, Includes the following steps: A thermoplastic resin matrix is ​​mixed with long glass fibers and melted, then cast to form a first film layer, such that the long glass fibers are oriented along the plane of the first film layer, the length of the long glass fibers is 6 mm to 15 mm, and the diameter of the long glass fibers is 5 μm to 18 μm. Optionally, the melting temperature of the casting process is 190℃~210℃, and the cooling temperature of the casting process is 20℃~40℃. Optionally, the thermoplastic resin matrix includes a first thermoplastic resin matrix and a second thermoplastic resin matrix; the step of mixing the thermoplastic resin matrix with long glass fibers specifically includes: impregnating the long glass fibers in the first thermoplastic resin matrix, such that the first thermoplastic resin matrix covers the surface of the long glass fibers, to obtain a long glass fiber prepreg. The long glass fiber prepreg is mixed with the second thermoplastic resin matrix; The first thermoplastic resin matrix is ​​selected from one or more of maleic anhydride-grafted polyolefin elastomer and polyethylene with a degree of polymerization of 500 to 5000. The second thermoplastic resin matrix is ​​selected from one or more of polyolefin elastomers, thermoplastic polyolefins, ethylene-vinyl acetate copolymers, and polyurethanes.

10. A photovoltaic module, characterized in that, include: A battery string, comprising multiple battery cells, at least some of which are perovskite-silicon tandem cells; A ribbon cable is electrically connected to adjacent battery cells in the battery string, so that adjacent battery cells in the battery string are connected in series. The ribbon cable includes multiple wires arranged in a spaced and oriented manner. The photovoltaic encapsulating film as described in any one of claims 1 to 8 is attached to the outside of the ribbon cable and the battery string to fix the ribbon cable to the battery string; A cover plate is disposed on the side of the photovoltaic encapsulation film away from the battery string; in, The first adhesive film layer is disposed close to the ribbon cable, and the arrangement direction of the long glass fibers and the arrangement direction of the wires have an angle α, 0°<α<180°; Optionally, α can be 80° to 100°.

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