A solar cell back panel and preparation method thereof, and photovoltaic module

Abstract

The invention relates to a solar cell backboard and a preparation method thereof, and a photovoltaic module. The backboard comprises an ethylene-vinyl alcohol copolymer (EVOH) layer located in an inner layer and modified polyvinylidene fluoride layers (PVDF) located on both sides of the EVOH layer, maleic anhydride and glycidyl methacrylate are grafted onto polyvinylidene fluoride molecular chains by melt extrusion grafting, maleic anhydride, glycidyl methacrylate monomers and hydroxyl groups of ethylene-vinyl alcohol copolymer polymer chains are chemically reacted to increase the compatibility of polyvinylidene fluoride and ethylene-vinyl alcohol copolymer, and a three-layer co-extrusion method is used to obtain the solar cell backboard, without the need for glue for bonding, and the ethylene-vinyl alcohol polymer is a high-barrier polymer material with excellent water vapor barrier performance, so that the obtained solar cell backboard has excellent water vapor barrier performance, can be widely used in high-temperature and high-humidity environments of industrial roofs, and has good development prospects in the field of solar cell backboards.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules, and in particular relates to a solar cell back panel and a preparation method thereof, and a photovoltaic module. Background Art

[0002] Polyvinylidene fluoride has good weather resistance, chemical resistance and processability and is widely used in the field of solar cell backplane film. Currently, PVDF / PET / PVDF backplane is widely used. As a double-sided fluorine-containing composite backplane, it has excellent resistance to environmental erosion, UV aging and moisture and heat. At the same time, it has obvious cost advantages over the widely used TPT (PVF / PET / PVF) backplane in the market. Therefore, with the continuous expansion of the solar energy market, its demand is also increasing. However, its structure is a three-layer composite film, and the interfacial bonding strength is improved by coating adhesives between the layers. In the later use process, it faces the problem of interface detachment, which will reduce the battery life. In addition, the adhesive contains solvents, which will cause environmental pollution during the production process. In addition, PVDF also has poor surface tension, poor adhesion with ethylene-vinyl acetate (EVA) film, and insufficient water vapor barrier performance, which makes it difficult to be used in high temperature and high humidity environments. These problems limit the wide application of PVDF in the field of solar cell backplanes.

[0003] Ethylene-vinyl alcohol copolymer (EVOH) is one of the three major high barrier polymer materials. It has excellent barrier properties against water vapor. However, the EVOH molecular chain contains hydroxyl groups that are easy to absorb moisture. It is generally located in the inner layer and is widely used in the field of food and pharmaceutical packaging. However, it has not been widely used in the field of solar photovoltaic backplanes. The melting point of EVOH is similar to that of PVDF, which creates conditions for the blending and modification of the two. However, PVDF and EVOH are incompatible. PVDF is a hydrophobic polymer and EVOH is a hydrophilic polymer. It is necessary to add a compatibilizer or graft modification on the surface of PVDF to promote the compatibility of the two. Summary of the invention

[0004] Purpose of the invention: In view of the problems and shortcomings in the prior art, the present invention proposes a solar cell backplane and a preparation method thereof, and a photovoltaic module.

[0005] To achieve the above object, the present invention provides a method for preparing a solar cell back sheet, comprising the following steps:

[0006] S1, putting polyvinylidene fluoride particles, glycidyl methacrylate, a free radical initiator, and a free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain a PVDF-g-GMA special material;

[0007] S2, putting polyvinylidene fluoride particles, maleic anhydride monomer, free radical initiator, and free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain PVDF-g-MAH special material;

[0008] S3, the PVDF-g-GMA special material obtained in S1, ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in S2 are co-extruded and cast to obtain a PVDF co-extruded EVOH solar cell back panel.

[0009] Furthermore, the addition ratio of glycidyl methacrylate in S1 is 3% to 10% of the total mass of glycidyl methacrylate and polyvinylidene fluoride;

[0010] In the step S2, the addition ratio of maleic anhydride monomer is 3% to 10% of the total mass of maleic anhydride and polyvinylidene fluoride.

[0011] Furthermore, the free radical initiator is benzoyl peroxide, and the free radical stabilizer is 9-vinylanthracene.

[0012] Furthermore, the addition ratio of benzoyl peroxide and 9-vinyl anthracene in S1 is 0.025% to 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the addition ratio of benzoyl peroxide and 9-vinyl anthracene in S2 is 0.025% to 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride.

[0013] Furthermore, the temperatures of the various sections of the twin-screw extruders in S1 and S2 are 185°C, 190°C, 190°C, 190°C, 185°C, respectively.

[0014] Furthermore, the temperatures of the various sections of the three-layer co-extrusion in S3 are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0015] Further, before S1, including:

[0016] The polyvinylidene fluoride and ethylene-vinyl alcohol copolymer are dried at 60-80° C. for 12-24 hours and then cooled to room temperature.

[0017] On the other hand, the present invention provides a solar cell back panel, which is prepared by the above-mentioned preparation method.

[0018] On the other hand, the present invention provides a photovoltaic module, which includes a photovoltaic module layer structure, and the photovoltaic module layer structure includes a light-receiving surface packaging layer, a light-receiving surface packaging film layer, a battery string, a backlight surface packaging film layer, and the above-mentioned solar cell backplane laminated together.

[0019] Beneficial effects:

[0020] In the present application, EVOH replaces the polyethylene terephthalate (PET) layer in the solar cell backplane used in the market. At the same time, in order to improve the compatibility of the two and reduce the use of adhesives, the present invention grafts methacrylate and maleic anhydride on the PVDF molecular chain respectively by melt grafting, and adopts a three-layer co-extrusion method to obtain the solar cell backplane, wherein the PVDF grafted with glycidyl methacrylate is located in the outer layer. Since glycidyl methacrylate is a hydrophobic group, the grafting does not impair its water vapor barrier ability. The PVDF grafted with maleic anhydride is located in the inner layer. Maleic anhydride can chemically react with the ester group of EVA to improve its adhesion. Moreover, glycidyl methacrylate and maleic anhydride can both chemically react with the hydroxyl group of the EVOH molecular chain. There is no need to use adhesives. The prepared solar panel can be widely used in high-humidity environments such as offshore solar power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a method for preparing a solar cell back panel in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the technical problem solved by the present invention, the technical solution adopted and the technical effect achieved more clearly, the technical solution of the present invention is further explained below through specific implementation methods.

[0023] The present invention provides a method for preparing a solar cell back sheet, comprising the following steps:

[0024] S1, putting polyvinylidene fluoride particles, glycidyl methacrylate, a free radical initiator, and a free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain a PVDF-g-GMA special material;

[0025] S2, putting polyvinylidene fluoride particles, maleic anhydride monomer, free radical initiator, and free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain PVDF-g-MAH special material;

[0026] S3, the PVDF-g-GMA special material obtained in S1, ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in S2 are co-extruded and cast to obtain a PVDF co-extruded EVOH solar cell back panel.

[0027] Furthermore, the addition ratio of glycidyl methacrylate in S1 is 3% to 10% of the total mass of glycidyl methacrylate and polyvinylidene fluoride;

[0028] In the step S2, the addition ratio of maleic anhydride monomer is 3% to 10% of the total mass of maleic anhydride and polyvinylidene fluoride.

[0029] Furthermore, the free radical initiator is benzoyl peroxide, and the free radical stabilizer is 9-vinylanthracene.

[0030] Furthermore, the addition ratio of benzoyl peroxide and 9-vinyl anthracene in S1 is 0.025% to 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the addition ratio of benzoyl peroxide and 9-vinyl anthracene in S2 is 0.025% to 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride.

[0031] Furthermore, the temperatures of the various sections of the twin-screw extruders in S1 and S2 are 185°C, 190°C, 190°C, 190°C, 185°C, respectively.

[0032] Furthermore, the temperatures of the various sections of the three-layer co-extrusion in S3 are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0033] Further, before S1, including:

[0034] The polyvinylidene fluoride and ethylene-vinyl alcohol copolymer are dried at 60-80° C. for 12-24 hours and then cooled to room temperature.

[0035] On the other hand, the present invention provides a solar cell back panel, which is prepared by the above-mentioned preparation method.

[0036] On the other hand, the present invention provides a photovoltaic module, which includes a photovoltaic module layer structure, and the photovoltaic module layer structure includes a light-receiving surface packaging layer, a light-receiving surface packaging film layer, a battery string, a backlight surface packaging film layer, and the above-mentioned solar cell backplane laminated together.

[0037] Preferably, the light-receiving surface encapsulation layer includes any one of the following materials: PVF, PVDF, and ETFE.

[0038] The light-receiving surface encapsulation film layer and the backlight surface encapsulation film layer include any one of the following materials: EVA, POE, and PVB.

[0039] Beneficial effects:

[0040] In the present application, EVOH replaces the polyethylene terephthalate (PET) layer in the solar cell backplane used in the market. At the same time, in order to improve the compatibility of the two and reduce the use of adhesives, the present invention grafts methacrylate and maleic anhydride on the PVDF molecular chain respectively by melt grafting, and adopts a three-layer co-extrusion method to obtain the solar cell backplane, wherein the PVDF grafted with glycidyl methacrylate is located in the outer layer. Since glycidyl methacrylate is a hydrophobic group, the grafting does not impair its water vapor barrier ability. The PVDF grafted with maleic anhydride is located in the inner layer. Maleic anhydride can chemically react with the ester group of EVA to improve its adhesion. Moreover, glycidyl methacrylate and maleic anhydride can both chemically react with the hydroxyl group of the EVOH molecular chain. There is no need to use adhesives. The prepared solar panel can be widely used in high-humidity environments such as offshore solar power generation.

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in combination with embodiments.

[0042] Embodiment 1:

[0043] A method for preparing a solar cell back sheet, comprising:

[0044] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain polyvinylidene fluoride grafted glyceryl methacrylate special material (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 3:97, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.025% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, 185°C respectively;

[0045] (2) Dry polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene are melt-reacted and extruded in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 3:97, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.025% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0046] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0047] Further, before S1, including:

[0048] The polyvinylidene fluoride and ethylene-vinyl alcohol copolymer are dried at 60-80° C. for 12-24 hours and then cooled to room temperature.

[0049] Embodiment 2:

[0050] A method for preparing a solar cell back sheet, comprising:

[0051] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain polyvinylidene fluoride grafted glyceryl methacrylate special material (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.1% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, 185°C respectively;

[0052] (2) Melt reaction extrusion granulation of dried polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.1% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, 185°C respectively;

[0053] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0054] Embodiment 3:

[0055] A method for preparing a solar cell back sheet, comprising:

[0056] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain a special material for polyvinylidene fluoride grafted with glyceryl methacrylate (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, 185°C respectively;

[0057] (2) Dry polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene are melt-reacted and extruded in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0058] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0059] Embodiment 4:

[0060] A method for preparing a solar cell back sheet, comprising:

[0061] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain a special material for polyvinylidene fluoride grafted with glyceryl methacrylate (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 10:90, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.10% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0062] (2) Melt reaction extrusion granulation of dried polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 10:90, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.10% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0063] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0064] Embodiment 5:

[0065] A solar cell back panel is prepared according to the following steps:

[0066] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain a special material for polyvinylidene fluoride grafted with glyceryl methacrylate (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 10:90, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0067] (2) Melt reaction extrusion granulation of dried polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 10:90, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0068] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0069] Embodiment 6:

[0070] A solar cell back panel is prepared according to the following steps:

[0071] (1) Dry polyvinylidene fluoride particles, glycidyl methacrylate (GMA), free radical initiator benzoyl peroxide, free radical stabilizer 9-vinyl anthracene, and melt reaction extrusion granulation in a twin-screw extruder to obtain a special material for polyvinylidene fluoride grafted with glyceryl methacrylate (PVDF-g-GMA). The mass ratio of glycidyl methacrylate to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, 185°C respectively;

[0072] (2) Dry polyvinylidene fluoride particles, maleic anhydride monomer (MAH), free radical initiator benzoyl peroxide, and free radical stabilizer 9-vinyl anthracene are melt-reacted and extruded in a twin-screw extruder to obtain polyvinylidene fluoride grafted maleic anhydride special material (PVDF-g-MAH). The mass ratio of maleic anhydride to polyvinylidene fluoride is 5:95, the addition ratio of benzoyl peroxide and 9-vinyl anthracene is 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride, and the temperatures of each section of the twin-screw melt grafting granulation are 185°C, 190°C, 190°C, 190°C, 190°C, and 185°C respectively;

[0073] (3) The PVDF-g-GMA special material obtained in step (1), the dried ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material obtained in step (2) are subjected to three-layer co-extrusion casting to obtain a PVDF co-extruded EVOH solar cell backplane, wherein the temperatures of each section of the three-layer co-extrusion casting machine are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

[0074] Comparative Example 1

[0075] Conventional PVDF / PET / PVDF backsheets purchased on the market were used for comparison.

[0076] The adhesion and water vapor transmission rate performance tests of Examples 1 to 6 and Comparative Example 1 with EVA were carried out according to the following standards:

[0077] Adhesion with EVA: The test method is peel strength test. Use a knife to cut a 1cm wide strip between the back panel and the EVA, and make sure to cut through it. Use a tensile testing machine to pull the peeling layer in a 180° direction at a speed of 100mm / min. Take points when the material is peeled off at a uniform speed and take the minimum value. The peel strength between the EVA and the back panel is determined to be 40N / cm to be qualified.

[0078] Water vapor transmission rate test: According to GB / T 21529-2008 standard, the test was conducted using the W3 / 330 water vapor transmission rate test system. The test area was 108 mm x 108 mm, the test temperature was 40°C, the test humidity was 90%, and three samples were tested for each solar cell back panel to take the average value.

[0079] The water vapor transmission rate test results of the solar cell back sheet and the EVA adhesion test results are shown in Table 1 below:

[0080] Table 1

[0081]

[0082] It can be seen from the table that the water vapor permeability of the solar cell backsheets prepared in Examples 1 to 6 is significantly lower than that of conventional PVDF backsheets on the market, and the adhesion to the EVA film is significantly enhanced.

[0083] Beneficial effects:

[0084] In the present application, EVOH replaces the polyethylene terephthalate (PET) layer in the solar cell backplane used in the market. At the same time, in order to improve the compatibility of the two and reduce the use of adhesives, the present invention grafts methacrylate and maleic anhydride on the PVDF molecular chain respectively by melt grafting, and adopts a three-layer co-extrusion method to obtain the solar cell backplane, wherein the PVDF grafted with glycidyl methacrylate is located in the outer layer. Since glycidyl methacrylate is a hydrophobic group, the grafting does not impair its water vapor barrier ability. The PVDF grafted with maleic anhydride is located in the inner layer. Maleic anhydride can chemically react with the ester group of EVA to improve its adhesion. Moreover, glycidyl methacrylate and maleic anhydride can both chemically react with the hydroxyl group of the EVOH molecular chain. There is no need to use adhesives. The prepared solar panel can be widely used in high-humidity environments such as offshore solar power generation.

[0085] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a solar cell back sheet, characterized in that: The following steps are involved: S1, putting polyvinylidene fluoride particles, glycidyl methacrylate, a free radical initiator, and a free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain a PVDF-g-GMA special material; S2, putting polyvinylidene fluoride particles, maleic anhydride monomer, free radical initiator, and free radical stabilizer into a twin-screw extruder for melt extrusion and granulation to obtain PVDF-g-MAH special material; S3, co-extruding and casting the PVDF-g-GMA special material, ethylene-vinyl alcohol copolymer particles, and the PVDF-g-MAH special material to obtain a PVDF co-extruded EVOH solar cell back sheet; The addition ratio of glycidyl methacrylate in S1 is 3% to 10% of the total mass of glycidyl methacrylate and polyvinylidene fluoride; The addition ratio of maleic anhydride monomer in step S2 is 3% to 10% of the total mass of maleic anhydride and polyvinylidene fluoride; The free radical initiator is benzoyl peroxide, and the free radical stabilizer is 9-vinyl anthracene; The addition ratio of benzoyl peroxide and 9-vinyl anthracene in S1 is 0.025% to 0.15% of the total mass of glycidyl methacrylate and polyvinylidene fluoride, and the addition ratio of benzoyl peroxide and 9-vinyl anthracene in S2 is 0.025% to 0.15% of the total mass of maleic anhydride and polyvinylidene fluoride; The PVDF grafted with glycidyl methacrylate is located in the outer layer, and the PVDF grafted with maleic anhydride is located in the inner layer.

2. The method for preparing a solar cell back sheet according to claim 1, characterized in that: The temperatures of the various sections of the twin-screw extruders in S1 and S2 were 185°C, 190°C, 190°C, 190°C, 185°C, respectively.

3. The method for preparing a solar cell back sheet according to claim 1, characterized in that: The temperatures of the various sections of the three-layer co-extrusion in S3 are 180°C, 190°C, 210°C, 220°C, 220°C, 220°C, and 200°C, respectively.

4. The method for preparing a solar cell back sheet according to claim 1, characterized in that: Prior to S1, this included: The polyvinylidene fluoride and ethylene-vinyl alcohol copolymer are dried at 60-80° C. for 12-24 hours and then cooled to room temperature.

5. A solar cell back sheet, characterized in that: The preparation method is described in any one of claims 1 to 4.

6. A photovoltaic module, characterized in that: The photovoltaic module comprises a photovoltaic module layer structure, and the photovoltaic module layer structure comprises a light-receiving surface encapsulation layer, a light-receiving surface encapsulation film layer, a battery string, a backlight surface encapsulation film layer, and the solar cell back panel as claimed in claim 5 which are laminated together.

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