Composite packaging adhesive film, preparation method thereof, photovoltaic module and photovoltaic system

Abstract

The invention relates to the technical field of photovoltaic cells, and discloses a composite packaging adhesive film, a preparation method thereof, a photovoltaic module and a photovoltaic system. The composite packaging adhesive film comprises a light conversion adhesive film layer, a blocking layer and a heterogeneous adhesive film bonding layer which are arranged in a stacked mode. A light guide structure is arranged on the surface of one side, close to the heterogeneous adhesive film bonding layer, of the blocking layer; the heterogeneous adhesive film bonding layer comprises two side edge areas and a middle area located between the two side edge areas in the TD direction, and the two side edge areas are made of water blocking materials. The light conversion layer and the bonding layer are separated through the blocking layer, migration of a light conversion material is blocked, and the water vapor blocking property is improved; secondary light utilization is realized by the light guide structure, and power gain is given to the assembly; the edge of the heterogeneous bonding layer is made of a water blocking material, edge water vapor invasion is further blocked, the design meets the requirements of ultraviolet resistance and water vapor resistance of the assembly at the same time, and the outdoor comprehensive weather resistance and reliability of the assembly are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic cell technology, and more specifically, to a composite encapsulating film and its preparation method, a photovoltaic module, and a photovoltaic system. Background Technology

[0002] Photovoltaic modules often face the problems of moisture sensitivity and ultraviolet light sensitivity in applications.

[0003] To address issues such as moisture intrusion and potential-induced degradation, existing technologies primarily employ two resin materials—EVA (ethylene-vinyl acetate copolymer) and POE (polyolefin elastomer, ethylene-α-olefin copolymer)—to prepare photovoltaic films. EVA is low-cost, has high light transmittance, and is manufactured using mature processes, but it lacks sufficient moisture barrier properties and long-term weather resistance. POE exhibits excellent resistance to potential-induced degradation and moisture barrier properties, but it is expensive, has a slow cross-linking speed, and suffers from slippage issues, limiting its large-scale application.

[0004] To address the problem of UV-induced degradation, a common solution is to add light-converting materials or UV absorbers to the film. However, light-converting materials are prone to migration and diffusion from the matrix resin, leading to unstable UV aging resistance; UV absorbers can alter the mechanical strength and cross-linking degree of EVA or POE, easily causing problems such as yellowing and bubbling under high temperature or UV aging conditions, affecting the long-term reliability of the module.

[0005] Therefore, how to effectively suppress the migration behavior of light-converting materials in the light-converting film, while improving the water vapor barrier performance of the encapsulating film, and thus improve the power output and long-term reliability of photovoltaic modules, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This application provides a composite encapsulating film, its preparation method, a photovoltaic module, and a photovoltaic system. By introducing a barrier layer with a light-guiding structure to separate the light-converting film layer and the film adhesive layer, not only is the problem of easy migration of the light-converting material in the light-converting film solved, but the overall water permeability barrier capability of the encapsulating film is also increased. Simultaneously, the introduction of the light-guiding structure can effectively couple light incident on the module gap region to the cell surface, realizing secondary light utilization and giving the module a power gain effect. Furthermore, the two edge regions of the constructed heterogeneous film adhesive layer are composed of water-blocking material, cutting off the water vapor intrusion path and significantly improving the edge water-blocking performance of the photovoltaic module. Therefore, through the synergistic design of the above structures, the composite encapsulating film of this invention can simultaneously meet the dual requirements of photovoltaic modules for UV aging resistance and water vapor corrosion resistance, significantly improving the overall weather resistance and long-term reliability of photovoltaic modules outdoors.

[0007] In a first aspect, a composite encapsulating film is provided, the composite encapsulating film comprising a light-converting film layer, a barrier layer, and a heterogeneous film adhesive layer stacked together.

[0008] The barrier layer has a light-guiding structure on the side surface near the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two edge regions and a middle region located between the two edge regions in the TD direction, and the two edge regions are made of water-blocking material.

[0009] This application separates the light-converting film layer and the adhesive film layer by introducing a barrier layer with a light-guiding structure. This not only solves the problem of easy migration of the light-converting material in the light-converting film, but also increases the overall water-permeability barrier capability of the encapsulation film. Simultaneously, the introduction of the light-guiding structure can effectively couple light incident on the module gap area to the cell surface, realizing secondary light utilization and giving the module a power gain effect. Furthermore, the two edge regions of the constructed heterogeneous adhesive film layer are composed of water-blocking material, cutting off the water vapor intrusion path and significantly improving the edge water-blocking performance of the photovoltaic module. Therefore, through the synergistic design of the above structures, the composite encapsulation film of this invention can simultaneously meet the dual requirements of photovoltaic modules for UV aging resistance and water vapor corrosion resistance, significantly improving the overall weather resistance and long-term reliability of photovoltaic modules outdoors.

[0010] In some embodiments, the material of the light-converting film layer includes a host resin and a light-converting agent.

[0011] In some embodiments, the mass content of the light-converting agent is 0.04-0.06% based on the mass of the main resin, for example, it may be 0.04%, 0.05% or 0.06%.

[0012] In some embodiments, the host resin includes any one or a combination of at least two of polyolefin elastomer resin, ethylene-vinyl acetate copolymer, or polyvinyl butyral.

[0013] In some embodiments, the light-converting agent includes any one or a combination of at least two of benzophenone light-converting agents, salicylate light-converting agents, benzotriazole light-converting agents, or triazine light-converting agents.

[0014] In some embodiments, the material of the barrier layer includes any one or a combination of at least two of polyethylene terephthalate, polypropylene, or polyethylene.

[0015] In some embodiments, the material of the barrier layer further includes an ultraviolet absorber.

[0016] In some embodiments, the ultraviolet absorber includes p-dimethylaminocinnamoyloxypropyltrimethoxysilane.

[0017] In some embodiments, the mass fraction of the ultraviolet absorber in the barrier layer is 0.05-0.15%, for example, it can be 0.05%, 0.1% or 0.15%.

[0018] In some embodiments, the material of the light guide structure includes any one of acrylic, epoxy resin, or polyurethane.

[0019] In some embodiments, the intermediate region of the heterogeneous adhesive film layer includes a host resin, which includes ethylene-vinyl acetate copolymer (EVA).

[0020] In some embodiments, the water-blocking material of the two side edge regions each independently comprises a polyolefin elastomer (POE) or a thermoplastic polyolefin (TPO).

[0021] In some embodiments, the light guide structure includes a plurality of triangular prism light guide units arranged at intervals along the TD direction.

[0022] In some embodiments, the cross-section of the triangular prism light guide unit is an isosceles triangle.

[0023] In some embodiments, the vertex angle of the isosceles triangle is 90°-120°, for example, it can be 90°, 100°, 110° or 120°.

[0024] In some embodiments, the height of the isosceles triangle is 10-50 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0025] In some embodiments, the surface of the heterogeneous adhesive film layer near the light guide structure conforms to the light guide structure.

[0026] In some embodiments, the thickness of the light-converting adhesive film layer is 100-400 μm, for example, it can be 100 μm, 200 μm, 300 μm or 400 μm.

[0027] In some embodiments, the thickness of the barrier layer is 20-50 μm, for example, it can be 20 μm, 30 μm, 40 μm or 50 μm.

[0028] In some embodiments, the width of each side of the two edge regions in the TD direction is independently 10-50mm, for example, 10mm, 20mm, 30mm, 40mm or 50mm.

[0029] In some embodiments, the thickness of the heterogeneous adhesive film layer is 100-400 μm, for example, it can be 100 μm, 200 μm, 300 μm or 400 μm.

[0030] In a second aspect, a method for preparing a composite encapsulating film as described in the first aspect is provided, the method comprising the following steps: A barrier layer is provided, the barrier layer having opposing first and second surfaces.

[0031] A light guide structure is formed on the first surface of the barrier layer.

[0032] A light-converting adhesive film layer is formed on the second surface of the barrier layer.

[0033] A heterogeneous adhesive film layer is formed on the first surface of the barrier layer.

[0034] The light guiding structure is located between the barrier layer and the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two side edge regions and a middle region located between the two side edge regions in the TD direction, and the two side edge regions are made of water-blocking material.

[0035] In some embodiments, the method for forming the light guide structure includes: A UV-curable adhesive is applied to the first surface of the barrier layer, followed by rolling and UV curing.

[0036] In some embodiments, the method for forming the light-converting adhesive film layer includes: The main resin, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and then coated onto the second surface of the barrier layer. After curing, the light-converting adhesive film layer is formed.

[0037] In some embodiments, the method for forming the heterogeneous adhesive film layer includes: The main resin, initiator, crosslinking agent and coupling agent are mixed to obtain the intermediate region mixture; the water-blocking material, initiator, crosslinking agent and coupling agent are mixed to obtain the edge region mixture.

[0038] The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

[0039] In some embodiments, based on the mass of the main resin, the mass content of the initiator in the intermediate region mixture is 0.2-0.5%, for example, 0.2%, 0.3%, 0.4%, or 0.5%, the mass content of the crosslinking agent is 0.2-1.5%, for example, 0.2%, 0.5%, 1%, or 1.5%, and the mass content of the coupling agent is 0.1-1%, for example, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, or 1%.

[0040] In some embodiments, based on the mass of the water-blocking material, the mass content of the initiator in the edge region mixture is 0.2-0.5%, for example, 0.2%, 0.3%, 0.4%, or 0.5%, the mass content of the crosslinking agent is 0.2-1.5%, for example, 0.2%, 0.5%, 1%, or 1.5%, and the mass content of the coupling agent is 0.1-1%, for example, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, or 1%.

[0041] Thirdly, a photovoltaic module is provided, the photovoltaic module comprising a front glass panel, a front encapsulating film, a battery string layer, a rear encapsulating film and a back glass panel stacked sequentially, wherein the front encapsulating film is the composite encapsulating film described in the first aspect, or is prepared by the preparation method described in the second aspect.

[0042] Fourthly, a photovoltaic system is provided, the photovoltaic system comprising the photovoltaic modules as described in the third aspect. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the composite encapsulation film provided in Embodiment 1 of this application.

[0044] Figure 2 This is a schematic diagram of the fabrication process of the barrier layer with a light-guiding structure in the fabrication method provided in Embodiment 1 of this application.

[0045] Figure 3 This is a schematic diagram of the structure of the heterogeneous adhesive film bonding layer in the preparation method provided in Example 1 of this application.

[0046] Figure 4 This is a cross-sectional schematic diagram of the photovoltaic module provided in this application.

[0047] Figure 5 This is a top view of the photovoltaic module provided in this application.

[0048] Figure 6 This is a three-dimensional schematic diagram of the photovoltaic module provided in this application.

[0049] Figure 7 This is a schematic diagram of the photovoltaic system provided in this application.

[0050] The accompanying drawings are not drawn to scale.

[0051] Figure label: 1-Light conversion adhesive film layer; 2-Barrier layer; 3-Heterogeneous adhesive film bonding layer; 4-Light guiding structure; 5-POE adhesive film; 6-EVA adhesive film; 7-Front panel glass; 8-Front layer adhesive film; 9-Battery string layer; 10-Rear layer adhesive film; 11-Back panel glass; 12-Frame; 13-Gathering box; 14-Photovoltaic system; 15-Photovoltaic module. Detailed Implementation

[0052] The descriptions of specific structures or functions implemented according to the concept of this application disclosed in this specification are merely illustrative examples for explaining embodiments based on the concept of this application. Those skilled in the art will understand that embodiments based on the concept of this application can have various variations and forms, and are not limited to the embodiments described in this specification, but also include various modifications, equivalents, or substitutions made within the scope of the purpose, concept, and technology of this application.

[0053] In the description of this application, it should be understood that the use of terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicates the relative orientation or positional relationship between different components, and is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0054] Although the terms "first" or "second" may be used to describe various components or components, the components or components should not be limited by the terms. The terms above are used only for the purpose of distinguishing one component or component from another. For example, without departing from the scope of the claims according to the concept of this application, a first battery cell may be referred to as a second battery cell, and similarly, a second battery cell may be referred to as a first battery cell.

[0055] In this application, unless otherwise expressly specified and limited, the terms "connected," "fixed," "set," etc., should be interpreted broadly. For example, when one component is said to "connect" another component, it should be understood that it can be directly or indirectly connected to the other component, meaning that other components may also be present in between. Similarly, the terms "fixed" and "set" should be interpreted broadly in a similar way. Furthermore, the term "connected" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In this application, unless otherwise expressly specified and limited, the description of "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. The first feature being "below", "under", or "below" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0056] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0057] The researchers of this application have found that in traditional technologies, light-converting films are mainly produced by adding light-converting substances to the film matrix resin. Over time, the light-converting materials tend to migrate from the surface and diffuse into other structures, severely affecting the stability of the film's resistance to ultraviolet aging. To improve the light utilization rate at the gaps between batteries, reflective films with high reflectivity or light-guiding structures are generally pasted onto the front or back glass. However, this requires additional equipment and production steps. Currently, there are EPE films (which include EVA, POE, and EVA layers arranged from top to bottom) and EP films (which include EVA and POE layers arranged from top to bottom) that are co-extruded from EVA and POE through upper, middle, and lower layers, or POE and EVA layers arranged from top to bottom, that are co-extruded from EVA and POE through upper and lower layers. However, there is always an EVA layer with weak moisture barrier properties at the edges.

[0058] Therefore, how to effectively suppress the migration behavior of light-converting materials in the light-converting film, while improving the water vapor barrier performance of the encapsulating film, and thus improve the power output and long-term reliability of photovoltaic modules, has become a technical problem that urgently needs to be solved in this field.

[0059] Based on this, this application provides a composite encapsulating film and its preparation method, a photovoltaic module, and a photovoltaic system.

[0060] In one specific embodiment, a composite encapsulating film is provided, the composite encapsulating film comprising a light-converting film layer, a barrier layer, and a heterogeneous adhesive film layer stacked together.

[0061] The barrier layer has a light-guiding structure on the side surface near the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two edge regions and a middle region located between the two edge regions in the TD direction, and the two edge regions are made of water-blocking material.

[0062] This application separates the light-converting film layer and the adhesive film layer by introducing a barrier layer with a light-guiding structure. This not only solves the problem of easy migration of the light-converting material in the light-converting film, but also increases the overall water-permeability barrier capability of the encapsulation film. Simultaneously, the introduction of the light-guiding structure can effectively couple light incident on the module gap area to the cell surface, realizing secondary light utilization and giving the module a power gain effect. Furthermore, the two edge regions of the constructed heterogeneous adhesive film layer are composed of water-blocking material, cutting off the water vapor intrusion path and significantly improving the edge water-blocking performance of the photovoltaic module. Therefore, through the synergistic design of the above structures, the composite encapsulation film of this invention can simultaneously meet the dual requirements of photovoltaic modules for UV aging resistance and water vapor corrosion resistance, significantly improving the overall weather resistance and long-term reliability of photovoltaic modules outdoors.

[0063] It should be noted that "TD direction" refers to the transverse direction, which is perpendicular to the direction of travel of the adhesive film during the production process, corresponding to the width direction of the adhesive film roll. In this invention, the TD direction specifically refers to the direction in which the heterogeneous adhesive film layer extends from one edge to the opposite edge. The adhesive film structure in this direction can be divided into two edge regions and a middle region located between them.

[0064] In some embodiments, the material of the light-converting film layer includes a host resin and a light-converting agent.

[0065] In this invention, by adding a light-converting agent to the main resin of the light-converting film layer, unlike the problem of easy migration of light-converting materials over time in traditional technologies, the presence of the barrier layer effectively prevents the migration of the light-converting agent and also improves the overall water vapor barrier capability of the composite encapsulation film.

[0066] In some embodiments, the mass content of the light-converting agent is 0.04-0.06% based on the mass of the main resin, for example, it may be 0.04%, 0.05% or 0.06%.

[0067] In this invention, the appropriate amount of light-converting agent can fully convert ultraviolet light with a wavelength of 200~380nm into a long wavelength band of 380~500nm, thereby reducing UV light damage to the solar cell.

[0068] In some embodiments, the host resin includes any one or a combination of at least two of polyolefin elastomer resin (POE), ethylene-vinyl acetate copolymer (EVA), or polyvinyl butyral.

[0069] In some embodiments, the light-converting agent includes any one or a combination of at least two of benzophenone-based light-converting agents, salicylate-based light-converting agents, benzotriazole-based light-converting agents, or triazine-based light-converting agents. For example, benzophenone-based light-converting agents may be 2-hydroxy-4-methoxybenzophenone, 4-hydroxybenzophenone, 4-methoxybenzophenone, or 4-methylbenzophenone, etc.; salicylate-based light-converting agents may be salicylic acid-o-phenanthroline-rare earth complexes, acetylsalicylic acid-rare earth complexes, or salicylic acid-europium complexes, etc.; and benzotriazole-based light-converting agents may be 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, methylenebis-benzotriazole tetramethylbutylphenol, etc.

[0070] In some embodiments, the material of the barrier layer includes any one or a combination of at least two of polyethylene terephthalate (PET), polypropylene (PP), or polyethylene (PE).

[0071] In this invention, the barrier layer uses the above-mentioned material, which helps to solve the problem of easy migration of light-converting materials in the light-converting film layer, and also helps to increase the overall water permeability barrier properties of the film.

[0072] In some embodiments, the material of the barrier layer further includes an ultraviolet absorber.

[0073] In some embodiments, the ultraviolet absorber includes p-dimethylaminocinnamoyloxypropyltrimethoxysilane.

[0074] In some embodiments, the mass fraction of the ultraviolet absorber in the barrier layer is 0.05-0.15%, for example, it can be 0.05%, 0.1% or 0.15%.

[0075] The present invention adds an appropriate amount of UV absorber to the barrier layer, which can further improve the UV resistance of the composite encapsulation film.

[0076] In some embodiments, the material of the light guide structure includes any one of acrylic, epoxy resin, or polyurethane.

[0077] The present invention provides a light-guiding structure of the material described above on the surface of the barrier layer near the heterogeneous adhesive film layer. This type of material can improve the light utilization rate at the gap between the batteries.

[0078] In some embodiments, the intermediate region of the heterogeneous adhesive film layer includes a host resin, which includes ethylene-vinyl acetate copolymer (EVA).

[0079] In some embodiments, the water-blocking material of the two side edge regions each independently comprises a polyolefin elastomer (POE) or a thermoplastic polyolefin (TPO).

[0080] In some embodiments, the light guide structure includes a plurality of triangular prism light guide units arranged at intervals along the TD direction.

[0081] It should be noted that "several" refers to two or more units. The specific number can be reasonably selected and adjusted according to the size of the light guide structure and the optical design requirements. For example, it can be 5, 10 or 20 units, as long as the triangular prism light guide units are arranged at intervals along the TD direction. This invention does not impose a specific limit on the specific number.

[0082] It should be noted that the projection of the triangular prism light guide unit in the thickness direction falls into the gap projection of the battery string.

[0083] In this invention, parallel arrangement of triangular prism light guide units can guide light from the gaps to the solar cells of the photovoltaic module through reflection and refraction, which is beneficial to improving the module power.

[0084] In some embodiments, the cross-section of the triangular prism light guide unit is an isosceles triangle.

[0085] In some embodiments, the vertex angle of the isosceles triangle is 90°-120°, for example, it can be 90°, 100°, 110° or 120°.

[0086] In some embodiments, the height of the isosceles triangle is 10-50 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0087] It should be noted that "height" is defined as the vertical distance from the vertex of an isosceles triangle to its opposite side (base) in the cross-section of the triangle, which is also the protrusion height of the triangular prism light guide unit in the direction perpendicular to the plane of the barrier layer.

[0088] In this invention, the cross-section of the triangular prism light guide unit is defined as an isosceles triangle with a vertex angle of 90°-120°, and its height is defined as 10-50μm. The triangular prism light guide unit with the above parameters working together can better scatter the incident light at the gap between the battery strings onto the battery cells on both sides, thereby improving the light utilization rate.

[0089] It should be noted that the vertex angle of an isosceles triangle can be obtained by observing the cross-section of the composite encapsulating film with a scanning electron microscope (SEM) and measuring it using image analysis software. The height of the isosceles triangle can be obtained by measuring the vertical distance from the vertex to the bottom edge using the same cross-sectional SEM image.

[0090] In some embodiments, the surface of the heterogeneous adhesive film layer near the light guide structure conforms to the light guide structure.

[0091] In some embodiments, the thickness of the light-converting adhesive film layer is 100-400 μm, for example, it can be 100 μm, 200 μm, 300 μm or 400 μm.

[0092] In this invention, an appropriate thickness of the light-converting adhesive film layer is used to provide UV protection for the battery cells while reducing costs.

[0093] It should be noted that the thickness of the light-converting adhesive film layer can be obtained by observing the cross-section of the composite encapsulating film using SEM and measuring it with image analysis software.

[0094] In some embodiments, the thickness of the barrier layer is 20-50 μm, for example, it can be 20 μm, 30 μm, 40 μm or 50 μm.

[0095] In this invention, by using an appropriate barrier layer thickness, the migration of the light-converting agent can be effectively prevented and the water vapor resistance can be improved.

[0096] It should be noted that the thickness of the barrier layer can be obtained by observing the cross-section of the composite encapsulating film using SEM and measuring it with image analysis software.

[0097] In some embodiments, the width of each side of the two edge regions in the TD direction is independently 10-50mm, for example, 10mm, 20mm, 30mm, 40mm or 50mm.

[0098] In this invention, with a suitable width, the water-blocking material can block the intrusion of external moisture, protect the battery cells, and will not adversely affect the photoelectric performance of the module.

[0099] It should be noted that the aforementioned single-sided width can be obtained by observing the cross-section of the composite encapsulating film using a scanning electron microscope (SEM) and measuring it using image analysis software.

[0100] In some embodiments, the thickness of the heterogeneous adhesive film layer is 100-400 μm, for example, it can be 100 μm, 200 μm, 300 μm or 400 μm.

[0101] It should be noted that the thickness of the heterogeneous adhesive film layer can be obtained by observing the cross-section of the composite encapsulation film using a scanning electron microscope (SEM) and measuring it using image analysis software.

[0102] In another specific embodiment, a method for preparing the composite encapsulating film as described above is provided, the method comprising the following steps: A barrier layer is provided, the barrier layer having opposing first and second surfaces.

[0103] A light guide structure is formed on the first surface of the barrier layer.

[0104] A light-converting adhesive film layer is formed on the second surface of the barrier layer.

[0105] A heterogeneous adhesive film layer is formed on the first surface of the barrier layer.

[0106] The light guiding structure is located between the barrier layer and the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two side edge regions and a middle region located between the two side edge regions in the TD direction, and the two side edge regions are made of water-blocking material.

[0107] In some embodiments, the method for forming the light guide structure includes: A UV-curable adhesive is applied to the first surface of the barrier layer, followed by rolling and UV curing.

[0108] In some embodiments, the method for forming the light-converting adhesive film layer includes: The main resin, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and then coated onto the second surface of the barrier layer. After curing, the light-converting adhesive film layer is formed.

[0109] For example, the initiator may be tert-butyl peroxide-2-ethylhexyl carbonate (TBEC), etc. The crosslinking agent may be triallyl isocyanurate, etc. The coupling agent may be γ-methacryloyloxypropyltrimethoxysilane, etc.

[0110] In some embodiments, the method for forming the heterogeneous adhesive film layer includes: The main resin, initiator, crosslinking agent and coupling agent are mixed to obtain the intermediate region mixture; the water-blocking material, initiator, crosslinking agent and coupling agent are mixed to obtain the edge region mixture.

[0111] The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

[0112] For example, the initiator may be tert-butyl peroxide-2-ethylhexyl carbonate (TBEC), etc. The crosslinking agent may be triallyl isocyanurate, etc. The coupling agent may be γ-methacryloyloxypropyltrimethoxysilane, etc.

[0113] In some embodiments, based on the mass of the main resin, the mass content of the initiator in the intermediate region mixture is 0.2-0.5%, for example, 0.2%, 0.3%, 0.4%, or 0.5%, the mass content of the crosslinking agent is 0.2-1.5%, for example, 0.2%, 0.5%, 1%, or 1.5%, and the mass content of the coupling agent is 0.1-1%, for example, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, or 1%.

[0114] In some embodiments, based on the mass of the water-blocking material, the mass content of the initiator in the edge region mixture is 0.2-0.5%, for example, 0.2%, 0.3%, 0.4%, or 0.5%, the mass content of the crosslinking agent is 0.2-1.5%, for example, 0.2%, 0.5%, 1%, or 1.5%, and the mass content of the coupling agent is 0.1-1%, for example, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, or 1%.

[0115] In another specific embodiment, a photovoltaic module is provided, the photovoltaic module comprising a front glass panel, a front encapsulating film, a battery string layer, a rear encapsulating film and a back glass panel stacked sequentially, wherein the front encapsulating film is a composite encapsulating film as described above.

[0116] It should be noted that a photovoltaic module is a device that directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. In addition to the above structure, it also includes a frame surrounding the aforementioned laminated structure and a junction box located on one side of the back glass.

[0117] For example, the front glass may be made of a material with excellent light transmittance, impact resistance, corrosion resistance, and weather resistance, and may optionally include at least one of the following materials: tempered glass, plexiglass, transparent ceramics, organic fibers, or polymers. In some embodiments, the front glass may include at least one of an insulating barrier layer, a fluorinated weather-resistant layer, and a transition adhesive layer.

[0118] Backing glass typically needs to possess insulation, water resistance, aging resistance, weather resistance, and corrosion resistance. It can optionally include at least one of the following: tempered glass, acrylic glass, metal backing, or composite backing with PET film as the substrate. Among these, PET-based composite backing can be selected from various types, such as composite (e.g., TPT / KPK, TPE / KPE), coated (e.g., TPC, KPC, CPC), and co-extruded (e.g., PO), depending on the needs of different applications.

[0119] It is understandable that the choice of materials for the front and back glass does not affect each other, and the same or different materials can be selected depending on the different application scenarios of the components (such as residential photovoltaics and building-integrated photovoltaics).

[0120] The battery string layer comprises multiple battery strings, which can be combined in series, parallel, or series-parallel configurations to achieve current collection and output. Further, each battery string is formed by sequentially connecting multiple battery cells via connectors. In some embodiments, at least a portion of the connector is electrically connected to the back electrode of one battery cell, and at least another portion of the connector is electrically connected to the front or back electrode of another battery cell to form a battery string. The connector may optionally include conductive elements such as solder strips, busbars, or metal clips. In some embodiments, to improve welding performance, oxidation resistance, and weather resistance, the connector material may preferably be a highly conductive metal material, such as at least one of silver, copper, tin, and nickel, or an alloy thereof. In some embodiments, to balance conductivity and cost control, the connector material may also be at least one of metal-clad composite materials such as silver-coated copper, copper-coated silver, copper-coated aluminum, aluminum-coated copper, tin-plated copper, or nickel-plated copper. The electrical connection may be selected from one of the following methods: laser welding, spot welding, bonding, ultrasonic welding, resistance welding, or brazing.

[0121] The solar cell may include a semiconductor substrate, a first emitter of a first conductivity type, and a second emitter of a second conductivity type. It is understood that one of the first and second conductivity types is P-type, and the other is N-type. The semiconductor substrate may include an N-type silicon substrate or a P-type silicon substrate. N-type silicon substrates are typically formed by doping with Group V elements such as phosphorus, arsenic, or antimony, and have the characteristic that the majority charge carriers are electrons; P-type silicon substrates are typically formed by doping with Group III elements such as boron, gallium, or aluminum, and have the characteristic that the majority charge carriers are holes.

[0122] The solar cell can employ a grid line design with no main grid (OBB), multiple main grid (MBB), or super-multiple main grid (SMBB). In some embodiments, the grid line material can be selected as at least one of silver-based conductive paste or silver-coated copper composite paste. The paste uses highly conductive metal powder as the conductive substrate, and the substrate can be selected as at least one of silver powder, copper powder, or silver-coated copper composite powder. To improve the ohmic contact performance, conductivity, and long-term weather resistance of the electrodes, a composite functional layer can be formed on the surface of the substrate or in the grid line structure. The functional layer material includes at least one of glass powder, organic carrier, nickel-based material, or tin-based alloy.

[0123] It is understood that the solar cell can be at least one of the following commonly used in the art: tunnel oxide passivated contact (TOPCon) cell, intrinsic thin-film heterojunction (HJT) cell, back contact (BC) cell, perovskite / tandem cell, etc.

[0124] The frame surrounds the periphery of the stacked structure and is typically made of aluminum alloy or steel alloy. In some embodiments, the frame may also be a fiberglass frame or a plastic frame. The inner side of the frame usually has grooves for filling with sealant to achieve a sealed bond with the stacked components formed by the front glass, front adhesive film, battery string layers, rear adhesive film, and back glass, thereby blocking moisture and buffering external impacts. In some embodiments, the frame can be assembled using corner brackets.

[0125] The junction box is located on one side of the back glass panel and is electrically connected to the terminals of the bus electrodes in the battery string layer via a lead-out busbar for energy extraction. The junction box typically includes a housing and cover made of weather-resistant insulating material, conductive connecting tabs disposed within the housing, and one or more bypass diodes. The bypass diodes are connected in parallel with sub-units of the battery string. The electrical leads of the junction box include photovoltaic-specific connectors and cables. The cables preferably use tinned copper cores as conductive wires and cross-linked polyethylene as insulating sheaths. In some embodiments, the interior of the junction box may also be filled and encapsulated with potting compound to achieve insulation, thermal conductivity, moisture protection, and fixation.

[0126] In another specific embodiment, a photovoltaic system 14 is provided, the structural schematic diagram of which is shown below. Figure 7 As shown, the photovoltaic system 14 includes the photovoltaic module 15 as described above.

[0127] It should be noted that photovoltaic systems can be applied to photovoltaic power plants, such as ground-mounted power plants, rooftop power plants, and water-based power plants, as well as to equipment or devices that use solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, solar buildings, and so on.

[0128] It is understandable that the application scenarios of photovoltaic (PV) systems are not limited to this; that is to say, PV systems can be applied in all fields that require solar energy for power generation. Taking a PV power generation system as an example, a PV system can include a PV array, a combiner box, and an inverter. The PV array can be an array combination of multiple PV modules; for example, multiple PV modules can form multiple PV arrays. The PV array is connected to the combiner box, which can collect the current generated by the PV array. The collected current flows through the inverter and is converted into AC power required by the mains power grid before being connected to the mains power grid to realize solar power supply.

[0129] Example 1 This embodiment provides a composite encapsulating film, the structural schematic diagram of which is shown below. Figure 1 As shown, it includes a light-converting adhesive film layer 1, a barrier layer 2, and a heterogeneous adhesive film layer 3, which are stacked together.

[0130] The barrier layer 2 has a light guiding structure 4 on the side surface near the heterogeneous adhesive film layer 3; the heterogeneous adhesive film layer 3 includes two side edge regions and a middle region located between the two side edge regions in the TD direction, and the two side edge regions are made of water-blocking material.

[0131] The material of the light-converting film layer 1 includes a main resin and a light-converting agent. The main resin is POE, and the light-converting agent is 2-hydroxy-4-methoxybenzophenone. Based on the mass of the main resin, the mass content of the light-converting agent is 0.05%. The thickness of the light-converting film layer 1 is 300 μm.

[0132] The barrier layer 2 is made of PET and has a thickness of 25 μm; the light guide structure 4 is made of acrylic acid; the light guide structure 4 includes a plurality of triangular prism light guide units arranged at intervals along the TD direction, and the projection of the triangular prism light guide unit in the thickness direction falls into the gap projection of the battery string; the cross-section of the triangular prism light guide unit is an isosceles triangle with a vertex angle of 120° and a height of 10 μm.

[0133] The surface of the heterogeneous adhesive film layer 3 near the light guide structure 4 is conformal to the light guide structure 4; the middle region of the heterogeneous adhesive film layer 3 is an EVA adhesive film 6; the two side edge regions are both POE adhesive films 5; the single-sided width of the two side edge regions in the TD direction is 30mm; the thickness of the heterogeneous adhesive film layer 3 is 300μm.

[0134] This embodiment also provides a method for preparing the above-mentioned composite encapsulating film, the method comprising the following steps: (1) A PET roll with a thickness of 25 μm is provided as a barrier layer, the barrier layer having a first surface and a second surface opposite to each other.

[0135] (2) Reference Figure 2 The process flow diagram shown illustrates the formation of a light guide structure on the first surface of the barrier layer, the method comprising: S1. Unwind the PET roll to obtain a barrier layer, and coat the first surface of the barrier layer with UV-curable adhesive to obtain the coated barrier layer.

[0136] S2. Roll-press and UV-cur the coated barrier layer to form the light guide structure on the first surface of the barrier layer.

[0137] The UV-curable adhesive is acrylic acid.

[0138] (3) Forming a light-converting adhesive film layer on the second surface of the barrier layer, the method comprising: POE, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and stirred thoroughly. The mixture is then coated onto the second surface of the barrier layer using a coating equipment. After curing, the light-converting adhesive film layer is formed.

[0139] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, the coupling agent is γ-methacryloxypropyltrimethoxysilane, and the light-converting agent is 2-hydroxy-4-methoxybenzophenone; based on the mass of the POE, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, the mass content of the coupling agent is 1%, and the mass content of the light-converting agent is 0.05%.

[0140] (4) A heterogeneous adhesive film layer is formed on the first surface of the barrier layer. A schematic diagram of the structure of the heterogeneous adhesive film layer is shown below. Figure 3 As shown, the method includes: EVA, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the middle region mixture; POE, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the edge region mixture.

[0141] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, and the coupling agent is γ-methacryloyloxypropyltrimethoxysilane; in the intermediate region mixture, based on the mass of EVA, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, and the mass content of the coupling agent is 1%; in the edge region mixture, based on the mass of POE, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, and the mass content of the coupling agent is 1%.

[0142] The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

[0143] Example 2 This embodiment provides a composite encapsulation film, which includes a light-converting adhesive film layer, a barrier layer, and a heterogeneous adhesive film layer stacked together.

[0144] The barrier layer has a light-guiding structure on the side surface near the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two edge regions and a middle region located between the two edge regions in the TD direction, and the two edge regions are made of water-blocking material.

[0145] The material of the light-converting film layer includes a main resin and a light-converting agent. The main resin is POE, and the light-converting agent is a salicylic acid-o-phenanthroline-rare earth complex. Based on the mass of the main resin, the mass content of the light-converting agent is 0.05%. The thickness of the light-converting film layer is 300 μm.

[0146] The barrier layer is made of PET and has a thickness of 50 μm; the light guide structure is made of epoxy resin; the light guide structure includes several triangular prism light guide units arranged in parallel along the TD direction, the cross-section of the triangular prism light guide unit is an isosceles triangle with a vertex angle of 90° and a height of 50 μm.

[0147] The surface of the heterogeneous adhesive film layer closest to the light guide structure is conformal to the light guide structure; the middle region of the heterogeneous adhesive film layer is an EVA film; the two side edge regions are both POE films; the single-sided width of the two side edge regions in the TD direction is 30mm; the thickness of the heterogeneous adhesive film layer is 300μm.

[0148] This embodiment also provides a method for preparing the above-mentioned composite encapsulating film, the method comprising the following steps: (1) A PET roll with a thickness of 50 μm is provided as a barrier layer, the barrier layer having a first surface and a second surface opposite to each other.

[0149] (2) Forming a light-guiding structure on the first surface of the barrier layer, the method comprising: S1. Unwind the PET roll to obtain a barrier layer, and coat the first surface of the barrier layer with UV-curable adhesive to obtain the coated barrier layer.

[0150] S2. Roll-press and UV-cur the coated barrier layer to form the light guide structure on the first surface of the barrier layer.

[0151] The UV-curable adhesive is epoxy resin.

[0152] (3) Forming a light-converting adhesive film layer on the second surface of the barrier layer, the method comprising: POE, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and stirred thoroughly. The mixture is then coated onto the second surface of the barrier layer using a coating equipment. After curing, the light-converting adhesive film layer is formed.

[0153] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, the coupling agent is γ-methacryloxypropyltrimethoxysilane, and the light-converting agent is a salicylic acid-o-phenanthroline-rare earth complex; based on the mass of the POE, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, the mass content of the coupling agent is 1%, and the mass content of the light-converting agent is 0.05%.

[0154] (4) Forming a heterogeneous adhesive film layer on the first surface of the barrier layer, the method comprising: EVA, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the middle region mixture; POE, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the edge region mixture.

[0155] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, and the coupling agent is γ-methacryloyloxypropyltrimethoxysilane; in the intermediate region mixture, based on the mass of EVA, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, and the mass content of the coupling agent is 1%; in the edge region mixture, based on the mass of POE, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, and the mass content of the coupling agent is 1%.

[0156] The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

[0157] Example 3 This embodiment provides a composite encapsulation film, which includes a light-converting adhesive film layer, a barrier layer, and a heterogeneous adhesive film layer stacked together.

[0158] The barrier layer has a light-guiding structure on the side surface near the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two edge regions and a middle region located between the two edge regions in the TD direction, and the two edge regions are made of water-blocking material.

[0159] The material of the light-converting film layer includes a main resin and a light-converting agent. The main resin is POE, and the light-converting agent is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. Based on the mass of the main resin, the mass content of the light-converting agent is 0.05%. The thickness of the light-converting film layer is 400 μm.

[0160] The barrier layer is made of PP and has a thickness of 35 μm; the light guide structure is made of polyurethane; the light guide structure includes several triangular prism light guide units arranged side by side along the TD direction, the cross-section of the triangular prism light guide unit is an isosceles triangle with a vertex angle of 100° and a height of 30 μm.

[0161] The surface of the heterogeneous adhesive film layer closest to the light guide structure is conformal to the light guide structure; the middle region of the heterogeneous adhesive film layer is an EVA film; the two side edge regions are both POE films; the single-sided width of the two side edge regions in the TD direction is 40mm; the thickness of the heterogeneous adhesive film layer is 400μm.

[0162] This embodiment also provides a method for preparing the above-mentioned composite encapsulating film, the method comprising the following steps: (1) A PP roll with a thickness of 35 μm is provided as a barrier layer, the barrier layer having a first surface and a second surface opposite to each other.

[0163] (2) Forming a light-guiding structure on the first surface of the barrier layer, the method comprising: S1. Unwind the PET roll to obtain a barrier layer, and coat the first surface of the barrier layer with UV-curable adhesive to obtain the coated barrier layer.

[0164] S2. Roll-press and UV-cur the coated barrier layer to form the light guide structure on the first surface of the barrier layer.

[0165] The UV-curable adhesive is polyurethane.

[0166] (3) Forming a light-converting adhesive film layer on the second surface of the barrier layer, the method comprising: POE, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and stirred thoroughly. The mixture is then coated onto the second surface of the barrier layer using a coating equipment. After curing, the light-converting adhesive film layer is formed.

[0167] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, the coupling agent is γ-methacryloxypropyltrimethoxysilane, and the light-converting agent is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; based on the mass of the POE, the mass content of the initiator is 0.5%, the mass content of the crosslinking agent is 1.5%, the mass content of the coupling agent is 1%, and the mass content of the light-converting agent is 0.05%.

[0168] (4) Forming a heterogeneous adhesive film layer on the first surface of the barrier layer, the method comprising: EVA, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the middle region mixture; POE, initiator, crosslinking agent and coupling agent are mixed and stirred thoroughly to obtain the edge region mixture.

[0169] Wherein, the initiator is TBEC, the crosslinking agent is triallyl isocyanurate, and the coupling agent is γ-methacryloyloxypropyltrimethoxysilane; in the intermediate region mixture, based on the mass of EVA, the mass content of the initiator is 0.3%, the mass content of the crosslinking agent is 1%, and the mass content of the coupling agent is 0.5%; in the edge region mixture, based on the mass of POE, the mass content of the initiator is 0.3%, the mass content of the crosslinking agent is 1%, and the mass content of the coupling agent is 0.5%.

[0170] The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

[0171] Example 4 The difference between this embodiment and Embodiment 1 is that the material of the barrier layer further includes an ultraviolet absorber. That is, the barrier layer is made by mixing PET material and ultraviolet absorber and then performing melt extrusion and molding. The ultraviolet absorber is p-dimethylaminocinnamoyloxypropyltrimethoxysilane. The mass fraction of the ultraviolet absorber in the barrier layer is 0.1%.

[0172] The remaining preparation methods and parameters are consistent with those in Example 1.

[0173] Example 5 The difference between this embodiment and Embodiment 1 is that the thickness of the barrier layer is 15 μm.

[0174] The remaining preparation methods and parameters are consistent with those in Example 1.

[0175] Example 6 The difference between this embodiment and Embodiment 1 is that the thickness of the barrier layer is 55 μm.

[0176] The remaining preparation methods and parameters are consistent with those in Example 1.

[0177] Example 7 The difference between this embodiment and Embodiment 1 is that the triangular prism light guide unit is replaced with a hemispherical light guide unit.

[0178] The remaining preparation methods and parameters are consistent with those in Example 1.

[0179] Example 8 The difference between this embodiment and Embodiment 1 is that the vertex angle of the isosceles triangle is 40°.

[0180] The remaining preparation methods and parameters are consistent with those in Example 1.

[0181] Example 9 The difference between this embodiment and Embodiment 1 is that the vertex angle of the isosceles triangle is 150°.

[0182] The remaining preparation methods and parameters are consistent with those in Example 1.

[0183] Example 10 The difference between this embodiment and Embodiment 1 is that the height of the isosceles triangle is 5μm.

[0184] The remaining preparation methods and parameters are consistent with those in Example 1.

[0185] Example 11 The difference between this embodiment and Embodiment 1 is that the height of the isosceles triangle is 55 μm.

[0186] The remaining preparation methods and parameters are consistent with those in Example 1.

[0187] Example 12 The difference between this embodiment and Embodiment 1 is that the single-sided width of the two edge regions of the heterogeneous adhesive film layer in the TD direction is 5mm.

[0188] The remaining preparation methods and parameters are consistent with those in Example 1.

[0189] Comparative Example 1 The difference between this comparative example and Example 1 is that no barrier layer is provided.

[0190] The remaining preparation methods and parameters are consistent with those in Example 1.

[0191] Comparative Example 2 The difference between this comparative example and Example 1 is that no light guide structure is provided.

[0192] The remaining preparation methods and parameters are consistent with those in Example 1.

[0193] Comparative Example 3 The difference between this comparative example and Example 1 is that the heterogeneous adhesive film layer is replaced with an EPE film co-extruded from the upper, middle and lower layers. The EPE film includes an EVA layer, a POE layer and an EVA layer stacked along the thickness direction.

[0194] The remaining preparation methods and parameters are consistent with those in Example 1.

[0195] Performance testing A photovoltaic module 15 is fabricated based on the composite encapsulating film provided in the above embodiments and comparative examples, and its cross-sectional schematic diagram, top view schematic diagram and three-dimensional schematic diagram are shown below. Figure 4 , Figure 5 and Figure 6 As shown, the photovoltaic module 15 includes a front glass panel 7, a front encapsulating film 8, a cell string layer 9, a rear encapsulating film 10, and a back glass panel 11, which are stacked sequentially. The front encapsulating film 8 is the composite encapsulating film provided in the above embodiments and comparative examples. The cell string layer 9 is a TOPCon cell string layer. The rear encapsulating film 10 is an ethylene-vinyl acetate copolymer film (EVA film). In addition to the above structures, it also includes a frame 12 surrounding the stacked structure and a junction box 13 located on one side of the back glass panel 11.

[0196] Performance testing steps for photovoltaic modules: I. Preparatory work before testing 1. Visual inspection, including: Inspect the appearance of the photovoltaic modules for scratches, damage, cracks, or other defects.

[0197] 2. Surface cleaning, including: Wipe the component surface with ultrapure water, ethanol or isopropanol to remove fingerprints, dust and organic residues; After drying the components with nitrogen, let them stand for 10 minutes to avoid surface contamination affecting optical properties.

[0198] 3. Temperature equilibrium, including: The temperature of the components was stabilized at 25℃±0.5℃ using a constant temperature stage, and this temperature condition was maintained during the test.

[0199] 4. Equipment calibration, including: The light source spectrum was calibrated using a standard reference cell to conform to the AM1.5G standard spectral conditions, with a calibration wavelength range of 300 nm to 1200 nm. The irradiance uniformity deviation in the test area does not exceed ±2%, and the measurement error of the temperature sensor used is less than ±0.1℃.

[0200] II. Testing Equipment and Conditions 1. Core equipment IV tester: Keysight B2900A series, with a voltage resolution of 0.1mV and a current resolution of 0.1μA; Solar simulator: Class AAA compliant, with selectable pulsed or steady-state light source (Wacom WXS-200S-20 model). Temperature control console: Temperature regulation is achieved based on a thermoelectric cooling (TEC) module, with a control accuracy of ±0.2℃; Spectral response instrument: equipped with a quantum efficiency (QE) testing system (Bentham PVE300).

[0201] 2. Standard Test Conditions (STC) Irradiance: 1000W / m 2 (AM1.5G standard spectrum); Temperature: 25℃±1℃ (real-time monitoring via TEC module); Light spot uniformity: The uniformity of the light spot covering the effective area of ​​the battery is >95%.

[0202] III. Parameter Testing Procedures 1. IV Characteristics (Voc, Isc, Pmax, FF) Testing Test equipment: solar simulator, IV tester and four-wire probe.

[0203] step: (1) Sample placement: Place the photovoltaic module in the center of the light spot of the simulator, and use a light shield to block the edge of the cell by 5mm to avoid light leakage at the edge; (2) IV scan: Apply a scan voltage from -0.5V to Voc+0.5V through an IV tester, set the scan step size to 10mV, and record the IV characteristic curve of the battery simultaneously; (3) Parameter extraction: Extract the open-circuit voltage Voc (voltage when current = 0) and short-circuit current Isc (current when voltage = 0) from the IV curve; (4) Power and fill factor calculation: Calculate the maximum power point on the IV curve (Pmax=Vmpp×Impp).

[0204] 2. UV aging resistance test The testing steps include: (1) Initial performance characterization: Before testing, the photovoltaic modules are inspected for appearance, maximum power, and insulation resistance, and initial performance data are recorded.

[0205] (2) Installation and irradiation: Install the photovoltaic modules inside the ultraviolet test chamber and adjust the light source spectrum and irradiance (280-385nm wavelength, not exceeding 250W / m). 2 ).

[0206] (3) Dose accumulation: Pretreatment stage: Continuous irradiation until the total irradiation dose in the 280-385nm wavelength band reaches 15kWh / m 2 Furthermore, the irradiation dose in the 280-320nm band reaches 5kWh / m². 2 .

[0207] UVID assessment phase: Continue irradiation until the total irradiation dose reaches 60 or 120 kWh / m² 2 Of this, the UVB band accounts for 3%-10% of the total irradiance.

[0208] (4) Final performance retest: After the target dose is reached, the photovoltaic module is removed and cooled to room temperature. Then, the performance indicators in step (1) are retested to compare the performance changes before and after irradiation.

[0209] The test results are shown in Table 1.

[0210] Table 1

[0211] analyze: As shown in Table 1, this application separates the light-converting film layer and the adhesive film layer by introducing a barrier layer with a light-guiding structure. This not only solves the problem of easy migration of the light-converting material in the light-converting film, but also increases the overall water permeability barrier capability of the encapsulation film. Simultaneously, the introduction of the light-guiding structure can effectively couple light incident on the module gap area to the cell surface, realizing secondary light utilization and giving the module a power gain effect. Furthermore, the two edge regions of the constructed heterogeneous adhesive film layer are composed of water-blocking materials, cutting off the water vapor intrusion path and significantly improving the edge water-blocking performance of the photovoltaic module. Therefore, through the synergistic design of the above structures, the composite encapsulation film of this invention can simultaneously meet the dual requirements of photovoltaic modules for UV aging resistance and water vapor corrosion resistance, significantly improving the overall weather resistance and long-term reliability of photovoltaic modules outdoors.

[0212] As can be seen from the comparison between Example 1 and Examples 5-6, if the thickness of the barrier layer is too small, the moisture barrier capacity of the component will decrease and the damp heat aging performance will decrease; if the thickness of the barrier layer is too large, it will affect the overall light transmittance of the film and reduce the initial power.

[0213] A comparison of Examples 1 and 7 shows that if the triangular prism light guide unit is replaced with a hemispherical light guide unit, the efficiency of light utilization in the gaps of the battery string will decrease, and the initial power will decrease.

[0214] As can be seen from the comparison between Example 1 and Examples 8-9, if the degree of the vertex angle of the isosceles triangle is too small, the incident light scattering effect of the gap between the battery strings will be worse, and the power of the photovoltaic module will be reduced; if the degree of the vertex angle of the isosceles triangle is too large, the incident light scattering effect of the gap between the battery strings will be worse, and the power of the photovoltaic module will be reduced.

[0215] As can be seen from the comparison between Example 1 and Examples 10-11, if the height of the isosceles triangle is too small, the incident light scattering effect of the gap between the battery strings will be worse, and the power of the photovoltaic module will be reduced; if the height of the isosceles triangle is too large, the incident light scattering effect of the gap between the battery strings will be worse, and the power of the photovoltaic module will be reduced.

[0216] A comparison of Example 1 and Example 12 shows that if the single-sided width of the two edge regions of the non-homogeneous adhesive film layer in the TD direction is too small, the moisture barrier capability of the component edge will be reduced, and the power attenuation will be greater after humid heat aging.

[0217] As can be seen from the comparison between Example 1 and Comparative Example 1, if no barrier layer is provided, the light conversion agent will migrate as the aging test proceeds, thereby reducing the protection of the battery and increasing the power decay.

[0218] As can be seen from the comparison between Example 1 and Comparative Example 2, if a light guide structure is not provided, the light at the gaps in the battery string cannot be utilized, and the initial power of the component is reduced.

[0219] As can be seen from the comparison between Example 1 and Comparative Example 3, if the non-homogeneous adhesive film layer is replaced with EPE adhesive film, the moisture barrier at the edge of the component cannot be guaranteed, and the power attenuation increases after humid heat aging.

Claims

1. A composite encapsulating film, characterized in that, The composite encapsulation film includes a light-converting adhesive film layer, a barrier layer, and a heterogeneous adhesive film layer stacked together. The barrier layer has a light-guiding structure on the side surface near the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two edge regions and a middle region located between the two edge regions in the TD direction, and the two edge regions are made of water-blocking material.

2. The composite encapsulating film according to claim 1, characterized in that, The material of the light-converting film layer includes a main resin and a light-converting agent; Based on the mass of the main resin, the mass content of the light-converting agent is 0.04-0.06%.

3. The composite encapsulating film according to claim 2, characterized in that, The main resin includes any one or a combination of at least two of polyolefin elastomer resin, ethylene-vinyl acetate copolymer, or polyvinyl butyral ester. The light-converting agent includes any one or a combination of at least two of the following: benzophenone light-converting agents, salicylate light-converting agents, benzotriazole light-converting agents, or triazine light-converting agents.

4. The composite encapsulating film according to claim 1, characterized in that, The barrier layer is made of any one or a combination of at least two of polyethylene terephthalate, polypropylene, or polyethylene.

5. The composite encapsulating film according to claim 4, characterized in that, The material of the barrier layer also includes an ultraviolet absorber; The ultraviolet absorber includes p-dimethylaminocinnamoyloxypropyltrimethoxysilane; The mass fraction of the ultraviolet absorber in the barrier layer is 0.05-0.15%.

6. The composite encapsulating film according to claim 1, characterized in that, The material of the light guide structure includes any one of acrylic, epoxy resin or polyurethane.

7. The composite encapsulating film according to claim 1, characterized in that, The middle region of the heterogeneous adhesive film layer includes a main resin, which includes an ethylene-vinyl acetate copolymer. And / or, the water-blocking material in the two side edge regions each independently comprises a polyolefin elastomer or a thermoplastic polyolefin.

8. The composite encapsulating film according to claim 1, characterized in that, The light guide structure includes several triangular prism light guide units arranged at intervals along the TD direction.

9. The composite encapsulating film according to claim 8, characterized in that, The cross-section of the triangular prism light guide unit is an isosceles triangle; The vertex angle of the isosceles triangle is 90°-120°. The height of the isosceles triangle is 10-50 μm.

10. The composite encapsulating film according to claim 1, characterized in that, The surface of the heterogeneous adhesive film layer near the light guide structure conforms to the light guide structure.

11. The composite encapsulating film according to claim 1, characterized in that, The thickness of the optical transfer adhesive film layer is 100-400 μm; And / or, the thickness of the barrier layer is 20-50 μm; And / or, the width of each side of the two edge regions in the TD direction is independently 10-50mm; And / or, the thickness of the heterogeneous adhesive film layer is 100-400 μm.

12. A method for preparing a composite encapsulating film, characterized in that, The preparation method includes the following steps: A barrier layer is provided, the barrier layer having opposing first and second surfaces; A light guide structure is formed on the first surface of the barrier layer; A light-converting adhesive film layer is formed on the second surface of the barrier layer; A heterogeneous adhesive film layer is formed on the first surface of the barrier layer; The light guiding structure is located between the barrier layer and the heterogeneous adhesive film layer; the heterogeneous adhesive film layer includes two side edge regions and a middle region located between the two side edge regions in the TD direction, and the two side edge regions are made of water-blocking material.

13. The preparation method according to claim 12, characterized in that, The method for forming the light guide structure includes: A UV-curable adhesive is applied to the first surface of the barrier layer, followed by rolling and UV curing.

14. The preparation method according to claim 12, characterized in that, The method for forming the optical transfer adhesive film layer includes: The main resin, initiator, crosslinking agent, coupling agent and light-converting agent are mixed and then coated onto the second surface of the barrier layer. After curing, the light-converting adhesive film layer is formed.

15. The preparation method according to claim 12, characterized in that, The method for forming the heterogeneous adhesive film layer includes: The main resin, initiator, crosslinking agent, and coupling agent are mixed to obtain the intermediate region mixture; the water-blocking material, initiator, crosslinking agent, and coupling agent are mixed to obtain the edge region mixture. The intermediate region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD, and the edge region mixture is coated onto a predetermined area of ​​the first surface of the barrier layer along a direction perpendicular to TD. After curing, the heterogeneous adhesive film layer is formed.

16. The preparation method according to claim 15, characterized in that, In the intermediate region mixture, based on the mass of the main resin, the mass content of the initiator is 0.2-0.5%, the mass content of the crosslinking agent is 0.2-1.5%, and the mass content of the coupling agent is 0.1-1%.

17. The preparation method according to claim 15, characterized in that, In the edge region mixture, based on the mass of the water-blocking material, the mass content of the initiator is 0.2-0.5%, the mass content of the crosslinking agent is 0.2-1.5%, and the mass content of the coupling agent is 0.1-1%.

18. A photovoltaic module, characterized in that, The photovoltaic module includes a front glass panel, a front encapsulating film, a battery string layer, a rear encapsulating film, and a back glass panel, which are stacked in sequence. The front encapsulating film is the composite encapsulating film according to any one of claims 1-11, or is prepared by the preparation method according to any one of claims 12-17.

19. A photovoltaic system, characterized in that, The photovoltaic system includes the photovoltaic module as described in claim 18.

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