Preparation method and application of high-efficiency fixed-wavelength reflective film for silicon-based power generation

Abstract

This invention discloses a method for preparing and applying a high-efficiency fixed-wavelength reflective film for silicon-based power generation in the field of photovoltaic power generation enhancement materials. The method involves mixing and extruding a functional masterbatch made from cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, cerium-zirconium modified rutile titanium-silicon composite microspheres, rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, maleic anhydride-grafted polyethylene, and high-density polyethylene resin. This masterbatch is then co-extruded and blow-molded with low-density polyethylene, ethylene-octene copolymer, silicone masterbatch, polytetrafluoroethylene, antioxidants, UV absorbers, light stabilizers, calcined kaolin, and oxidized polyethylene wax to form a film. The film is then embossed, corona-treated, and wound to obtain the final product. This reflective film exhibits high diffuse reflectance, weather resistance, wear resistance, and anti-aging properties, and can be used in medium to large-scale photovoltaic power plants to improve the power generation efficiency of silicon-based photovoltaic modules.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic power generation enhancement materials technology, specifically relating to a method for preparing and applying a high-efficiency fixed-wavelength reflective film for silicon-based power generation. Background Technology

[0002] As photovoltaic power plants develop towards centralization, large-scale operation, and high efficiency, the power generation efficiency of silicon-based photovoltaic modules in actual operation depends not only on the conversion performance of the cells themselves, but also on the combined effects of the installation environment, ground reflection, light reception on the back of the module, hot spot control, and long-term outdoor stability. In medium and large-scale photovoltaic power plants, modules are typically installed in arrays, and there is a large amount of reusable solar radiation energy beneath the modules and between rows. If the surface material has low reflectivity, the portion of incident light not directly absorbed by the modules will be absorbed by the soil, gravel, grass, or ordinary weed control fabric and converted into heat, resulting in the loss of usable light energy. If highly reflective materials are used to reflect sunlight suitable for the response of silicon-based modules back to the front or back of the modules, the power generation revenue per unit area can be improved, especially suitable for bifacial modules, off-ground mounted modules, and large-area centralized power plants.

[0003] Existing solutions for improving surface reflectivity mainly include white coatings, reflective fabrics, aluminum foil, aluminized films, and ordinary plastic reflective films. White coatings are susceptible to erosion from rain, sediment buildup, UV aging, and substrate cracking during long-term outdoor use, resulting in rapid degradation of reflectivity. While ordinary reflective fabrics and plastic films are easy to install, they often rely solely on white fillers to generate broad scattering, making it difficult to achieve stable, efficient, and fixed-wavelength reflection enhancement within the effective spectral response range of silicon-based modules. Furthermore, their resistance to wear, dirt, aging, and thermal oxidation is insufficient. Aluminum foil and aluminized films possess strong specular reflectivity, but the concentrated reflection direction can easily lead to strong light spots and localized temperature increases on modules, increasing hot spots, aging of encapsulation materials, localized thermal stress on the glass, and power plant operation and maintenance risks. Especially in environments with strong sunlight, drought, high temperatures, and sandstorms, these specular reflective materials are not suitable as long-term enhancement materials for large-area application under modules.

[0004] Therefore, photovoltaic power plants urgently need a fixed-wavelength reflective film that can adapt to the effective response spectrum of silicon-based modules while also ensuring uniform diffuse reflection, weather resistance, processability, and reliability for large-area installation. This type of reflective film should use weather-resistant polyolefin materials such as high-density polyethylene as the matrix. Through inorganic reflective fillers, composite microspheres, surface modification of composite microspheres, and interface compatibility design with polyolefins, a multi-scale scattering interface is formed, allowing incident light to undergo uniform diffuse reflection on the surface and within the film material, thereby improving the effective light return rate suitable for silicon-based power generation. Simultaneously, it should avoid the localized heat problems caused by simple metallic mirror reflection. Furthermore, the stability of the film material under conditions of long-term outdoor exposure, diurnal temperature variations, rain erosion, mud and sand friction, and foot traffic during power plant maintenance should be improved through the use of antioxidants, UV absorbers, light stabilizers, wear-resistant and anti-fouling fillers, and embossed microtexture structures. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation, characterized by comprising the following steps: S1. By weight, 10.0-22.0 parts of dried cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, 4.0-12.0 parts of cerium-zirconium modified rutile titanium-silicon composite microspheres, 3.0-8.0 parts of rutile titanium dioxide, 6.0-15.0 parts of precipitated barium sulfate, 2.0-6.0 parts of hollow glass microspheres, 3.0-8.0 parts of light calcium carbonate, 2.0-5.0 parts of maleic anhydride-grafted polyethylene and 100.0 parts of high-density polyethylene resin are added to a high-speed mixer and mixed at 45-60℃. Then, the mixture is melt-extruded through a twin-screw extruder, cooled, and pelletized to obtain a fixed wavelength reflection functional masterbatch. S2. The fixed wavelength reflective masterbatch is mixed with 8.0-18.0 parts of dried low-density polyethylene, 3.0-8.0 parts of ethylene-octene copolymer, 0.3-1.0 parts of silicone masterbatch, 0.5-1.5 parts of polytetrafluoroethylene, 0.15-0.40 parts of antioxidant 1010, 0.10-0.35 parts of antioxidant 168, 0.20-0.60 parts of ultraviolet absorber, 0.30-0.90 parts of light stabilizer, 1.0-3.0 parts of calcined kaolin and 0.5-1.5 parts of oxidized polyethylene wax, and then co-extruded by blow molding to obtain a 2- or 3-layer film material. S3. Pass 2 or 3 layers of film material through a 70-95℃ embossing roller, then perform corona treatment, cool and shape, trim the edges, and rewind.

[0006] In this invention, the preparation of a high-efficiency fixed-wavelength reflective film for silicon-based power generation involves three steps: construction of a reflective masterbatch, polyolefin blending for film formation, and surface microtexturing. A fixed-wavelength reflective masterbatch is formed by high-speed mixing and melt extrusion of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, cerium-zirconium modified rutile titanium-silicon composite microspheres, rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, maleic anhydride-grafted polyethylene, and high-density polyethylene resin. Maleic anhydride-grafted polyethylene improves the interfacial bonding between inorganic particles and high-density polyethylene resin, resulting in more uniform dispersion of the cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and the cerium-zirconium modified rutile titanium-silicon composite microspheres within the high-density polyethylene resin matrix, reducing large particle agglomeration. Cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres provide a composite scattering interface formed by barium sulfate and magnesium fluoride. Cerium-zirconium modified rutile titanium-silicon composite microspheres provide a hollow scattering interface formed by hollow silica, rutile nano-titanium dioxide, and cerium and zirconium oxide modification layers. Together with rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, and light calcium carbonate, they construct a multi-scale diffuse reflection network. The fixed-wavelength reflective masterbatch is then blended with low-density polyethylene (LDPE), ethylene-octene copolymer, silicone masterbatch, polytetrafluoroethylene (PTFE), antioxidant 1010, antioxidant 168, UV absorber, light stabilizer, calcined kaolin, and oxidized polyethylene wax for blow molding. LPE and ethylene-octene copolymer improve the film's flexibility; silicone masterbatch and oxidized polyethylene wax improve melt processing and surface lubrication; PTFE enhances wear resistance and stain resistance; calcined kaolin further supplements diffuse reflection and shielding properties; and antioxidants 1010, 168, UV absorber, and light stabilizer delay thermo-oxidative and photo-aging. Embossing rollers create a micro-textured diffuse reflection structure on the film surface, and corona treatment improves the surface condition, ultimately resulting in a high-efficiency fixed-wavelength reflective film suitable for medium to large-scale photovoltaic power plants for silicon-based power generation.

[0007] According to a preferred embodiment of the present invention, in step S1, the temperatures of each zone of the twin-screw extruder are as follows: zone 1 temperature is 155-165℃, zone 2 temperature is 170-180℃, zone 3 temperature is 180-190℃, zone 4 temperature is 190-200℃, and the die head temperature is 195-205℃.

[0008] According to a preferred embodiment of the present invention, in step S2, the ultraviolet absorber is ultraviolet absorber UV-326; the light stabilizer is light stabilizer 944; the extruder barrel temperature of the co-extrusion blow molding process is 160-205℃, the die temperature is 195-210℃, and the cooling air temperature is 18-28℃.

[0009] According to a preferred embodiment of the present invention, the preparation steps of the cerium-yttrium modified magnesium fluoride coated barium sulfate microspheres include: A1. By weight, add 18.0-24.0 parts of barium chloride dihydrate, 0.20-0.60 parts of cerium nitrate hexahydrate, 0.10-0.40 parts of yttrium nitrate hexahydrate, and 1.0-2.0 parts of sodium citrate to 120.0-160.0 parts of deionized water and stir at 25-35℃ to obtain a barium salt mixture; dissolve 12.0-18.0 parts of anhydrous sodium sulfate in 80.0-120.0 parts of deionized water and add it dropwise to the barium salt mixture at 35-45℃, control the pH to 4.5-5.5 with dilute hydrochloric acid, and age at 45-55℃ to obtain a suspension; A2. Add 2.0-3.0 parts of magnesium nitrate hexahydrate and 0.5-1.2 parts of polyvinylpyrrolidone to the suspension, heat to 55-65℃, add dropwise an aqueous solution containing 0.9-1.5 parts of ammonium fluoride, adjust the pH to 5.0-5.5 with dilute ammonia, and react at 60-70℃; filter, wash successively with deionized water and ethanol, dry at 80-90℃, and then calcine at 380-440℃ to obtain cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres; A3. Disperse 10.0-15.0 parts of cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres in 80.0-120.0 parts of anhydrous ethanol, add 0.8-1.5 parts of γ-methacryloyloxypropyltrimethoxysilane and 0.2-0.5 parts of deionized water, adjust the pH to 4.5-5.0 with glacial acetic acid, react at 50-60℃, filter, and dry to obtain vinylsilanized composite microspheres; A4. Add 10.0-15.0 parts of vinyl silanized composite microspheres, 2.0-4.0 parts of maleic anhydride-grafted polyethylene wax, 0.05-0.15 parts of dicumyl peroxide and 30.0-50.0 parts of xylene to the reactor. Under nitrogen protection, heat to 115-125℃ to react, cool, filter, wash with ethanol, vacuum dry at 80-90℃, pulverize and sieve.

[0010] In this invention, the preparation of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres is completed in three sequential steps: inorganic precipitation, surface deposition, and organic interface modification. Barium chloride dihydrate dissolves in deionized water to form a barium salt mixture. Cerium nitrate hexahydrate and yttrium nitrate hexahydrate remain dispersed under the action of sodium citrate, which simultaneously mitigates local enrichment of metal ions and reduces crystal nucleus aggregation. After anhydrous sodium sulfate aqueous solution is added dropwise to the barium salt mixture, sulfate ions combine with barium ions to form insoluble barium sulfate crystal nuclei. The weakly acidic environment controlled by dilute hydrochloric acid reduces the formation of carbonate byproducts, making the formation process of barium sulfate crystal nuclei more stable. The cerium and yttrium components provided by cerium nitrate hexahydrate and yttrium nitrate hexahydrate participate in the modification during the growth and aging of barium sulfate crystal nuclei through surface adsorption and defect site enrichment. After adding magnesium nitrate hexahydrate and polyvinylpyrrolidone to the suspension, polyvinylpyrrolidone adsorbs onto the particle surface, improving dispersion and providing an interface for magnesium fluoride deposition. After adding an aqueous solution containing ammonium fluoride, magnesium ions combine with fluoride ions to form insoluble magnesium fluoride. The weakly acidic to near-neutral conditions maintained by dilute ammonia water inhibited the formation of magnesium hydroxide byproducts, causing magnesium fluoride to tend to deposit on the surface of barium sulfate particles containing cerium and yttrium components. After washing, drying, and calcination, the polyvinylpyrrolidone residue was decomposed and removed, and the barium sulfate, cerium-yttrium modified components, and magnesium fluoride coating layer were more tightly bonded, resulting in cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres. Subsequently, γ-methacryloxypropyltrimethoxysilane is hydrolyzed in an alcohol-water system regulated by glacial acetic acid. The silanol groups condense with the hydroxyl groups on the surface of the composite microspheres to generate vinyl silanized composite microspheres. Dicumyl peroxide is thermally decomposed in xylene to generate free radicals, which initiate the grafting and coating of the main chain free radicals of maleic anhydride-grafted polyethylene wax with the vinyl groups on the surface of the vinyl silanized composite microspheres, thereby improving the interfacial compatibility between cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and high-density polyethylene resin.

[0011] According to a preferred embodiment of the present invention, in step A1, the aging time at 45-55°C is 60-90 minutes.

[0012] According to a preferred embodiment of the present invention, in step A2, the calcination time at 380-440°C is 1.5-2.5 hours.

[0013] According to a preferred embodiment of the present invention, the preparation steps of the cerium-zirconium modified rutile titanium-silicon composite microspheres include: B1. By weight, 10.0-15.0 parts of carboxylated monodisperse polystyrene microspheres, 80.0-120.0 parts of anhydrous ethanol, 20.0-35.0 parts of deionized water and 3.0-6.0 parts of ammonia water are added to a reactor and stirred at 25-30°C; 0.3-0.8 parts of polyvinylpyrrolidone are added, and 6.0-10.0 parts of tetraethyl orthosilicate are added dropwise. The mixture is reacted at 30-40°C, centrifuged, washed, dried, and then calcined at 500-550°C to obtain hollow silica microspheres. B2. Add 8.0-12.0 parts of hollow silica microspheres and 4.0-7.0 parts of rutile nano-titanium dioxide to a mixture of 100.0-140.0 parts of deionized water and 30.0-50.0 parts of ethanol, add 0.5-1.0 parts of polyvinylpyrrolidone, and disperse by ultrasonication; then add 0.20-0.50 parts of zirconium oxynitrate hydrate, 0.10-0.30 parts of cerium nitrate hexahydrate, and 1.0-2.5 parts of urea, and react at 90-95℃; filter, wash, dry, and then calcine at 450-500℃ to obtain hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres; B3. Add 10.0-15.0 parts of hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres to 100.0-150.0 parts of toluene, add 0.8-1.5 parts of γ-methacryloyloxypropyltrimethoxysilane, react at 80-90℃ under nitrogen protection, filter, and vacuum dry to obtain methacryloylated composite microspheres; B4. Add 10.0-15.0 parts of methacrylamide composite microspheres, 1.0-2.0 parts of 2,2,6,6-tetramethyl-4-piperidin methacrylate, 1.5-3.0 parts of octadecyl methacrylate, 0.04-0.10 parts of azobisisobutyronitrile, and 80.0-120.0 parts of toluene to a reactor. Under nitrogen protection, react at 65-75℃. After the reaction is complete, filter, wash alternately with ethanol and toluene, vacuum dry at 80-90℃, pulverize, and sieve.

[0014] In this invention, the preparation of cerium-zirconium modified rutile titanium-silicon composite microspheres uses carboxylated monodisperse polystyrene microspheres as sacrificial templates. Hollow silica microspheres are first formed, and then combined with rutile nano-titanium dioxide and cerium and zirconium components. After the carboxylated monodisperse polystyrene microspheres are dispersed in a system of anhydrous ethanol, deionized water, and ammonia, polyvinylpyrrolidone is adsorbed on the carboxylated surface, enhancing the dispersion stability of the microspheres. After the addition of tetraethyl orthosilicate, hydrolysis and condensation occur under ammonia catalysis, and the generated silica gradually deposits on the surface of the carboxylated monodisperse polystyrene microspheres, forming composite particles with the carboxylated monodisperse polystyrene microspheres as the core and silica as the shell. After centrifugation, washing, and drying, the microspheres enter the calcination stage. The carboxylated monodisperse polystyrene microsphere template is decomposed and removed by heat, leaving the silica shell, forming hollow silica microspheres. Hollow silica microspheres and rutile nano-titanium dioxide were dispersed in a mixture of deionized water and ethanol with the aid of polyvinylpyrrolidone. The rutile nano-titanium dioxide adhered to the outer surface of the hollow silica microspheres and the interparticle interfaces. After the addition of zirconium oxynitrate hydrate, cerium nitrate hexahydrate, and urea, the urea slowly hydrolyzed under heating conditions, releasing alkaline components. The zirconium and cerium components gradually deposited on the surfaces of the hollow silica microspheres and rutile nano-titanium dioxide as hydroxyl precursors, avoiding the formation of a large number of free particles due to instantaneous precipitation. After drying and calcination, the zirconium and cerium hydroxyl precursors were converted into corresponding oxide modified layers, yielding hollow silica-cerium-zirconium modified rutile titanium dioxide composite microspheres. The composite microspheres react with γ-methacryloxypropyltrimethoxysilane in toluene. The methoxy group of the silane condenses with the hydroxyl group on the surface of the composite microspheres to form methacrylated composite microspheres. Azobisisobutyronitrile decomposes upon heating to generate free radicals, which initiates surface graft copolymerization of methacrylyl groups, 2,2,6,6-tetramethyl-4-piperidin methacrylate, and octadecyl methacrylate on the surface of the methacrylated composite microspheres. This results in the cerium-zirconium modified rutile titanium-silicon composite microspheres simultaneously possessing an inorganic diffuse reflection structure, a photostable interface, and a long-chain alkyl compatible interface.

[0015] According to a preferred embodiment of the present invention, in step B1, the reaction time at 30-40°C is 4-6 hours, and the calcination time at 500-550°C is 2-3 hours.

[0016] According to a preferred embodiment of the present invention, in step B2, the calcination time at 450-500°C is 1.5-2.5 hours.

[0017] The present invention also provides the application of the high-efficiency fixed-wavelength reflective film for silicon-based power generation prepared by the method described above in improving the power generation efficiency of medium and large-scale photovoltaic power plants.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, cerium-zirconium modified rutile titanium-silicon composite microspheres, rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, and calcined kaolin to form a multi-layered diffuse reflection structure inside the membrane material. The cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres have a stable inorganic reflection interface, and the cerium-zirconium modified rutile titanium-silicon composite microspheres have a hollow scattering structure and a weather-resistant modified interface. Together with rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, and calcined kaolin, they improve the reflectivity of the membrane material for the effective response light of silicon-based photovoltaic modules and reduce the risk of localized heating caused by concentrated reflected light irradiation. (2) In this invention, barium sulfate microspheres coated with cerium-yttrium modified magnesium fluoride, cerium-zirconium modified rutile titanium-silicon composite microspheres, rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, maleic anhydride-grafted polyethylene, and high-density polyethylene resin are first prepared into a fixed wavelength reflective functional masterbatch, so that the inorganic reflective components are fully dispersed in the high-density polyethylene resin. Maleic anhydride-grafted polyethylene improves the interfacial bonding between inorganic particles and high-density polyethylene resin, reduces particle agglomeration and uneven reflection, so that the obtained fixed wavelength reflective functional masterbatch has a stable reflective component distribution and adaptability to subsequent film formation processing; (3) In this invention, a fixed wavelength reflective masterbatch is blended with low-density polyethylene, ethylene-octene copolymer, silicone masterbatch, polytetrafluoroethylene, antioxidant 1010, antioxidant 168, ultraviolet absorber, light stabilizer, calcined kaolin, and oxidized polyethylene wax, and then blow-molded into a film. Low-density polyethylene and ethylene-octene copolymer improve the flexibility of the film material, silicone masterbatch and oxidized polyethylene wax improve processing fluidity and film surface smoothness, polytetrafluoroethylene improves wear resistance and stain resistance, and antioxidant 1010, antioxidant 168, ultraviolet absorber and light stabilizer improve outdoor heat and oxygen aging resistance and light aging resistance. After the film material is embossed with a roller to form a micro-textured surface, the diffuse reflection uniformity is improved, making it suitable for laying under or between rows of medium and large photovoltaic power station modules. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The drawings are only used to illustrate the implementation methods and are not intended to limit the present invention.

[0020] Figure 1 The transmission spectrum scan of the high-efficiency fixed-wavelength reflective film for silicon-based power generation prepared in Example 1.

[0021] Figure 2 This is a physical image of the high-efficiency fixed-wavelength reflective film for silicon-based power generation prepared in Example 1. Detailed Implementation

[0022] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0023] Example 1: This example provides a method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation, including the following steps: S1. 16.0g of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, 8.0g of cerium-zirconium modified rutile titanium-silicon composite microspheres, 5.5g of rutile titanium dioxide, 10.5g of precipitated barium sulfate, 4.0g of hollow glass microspheres, 5.5g of light calcium carbonate, 3.5g of maleic anhydride-grafted polyethylene, and 100.0g of high-density polyethylene resin were dried at 80℃ for 3h, then added to a high-speed mixer and mixed at 52.5℃ and 800r / min for 10min. Subsequently, the mixture was melt-extruded, cooled, and pelletized using a twin-screw extruder to obtain a fixed wavelength reflection functional masterbatch. The temperature of the twin-screw extruder was 160℃ in zone 1, 175℃ in zone 2, 185℃ in zone 3, 195℃ in zone 4, 200℃ at the die head, 180r / min at the screw speed, and 3mm in pellet length. S2. The fixed wavelength reflective masterbatch, along with 13.0g of low-density polyethylene, 5.5g of ethylene-octene copolymer, 0.65g of silicone masterbatch, 1.0g of polytetrafluoroethylene, 0.275g of antioxidant 1010, 0.225g of antioxidant 168, 0.40g of UV absorber, 0.60g of light stabilizer, 2.0g of calcined kaolin, and 1.0g of oxidized polyethylene wax, dried at 80℃ for 3h, are added to a mixer and mixed at 300r / min for 10min. A co-extrusion blow molding process is then used to obtain a 3-layer film material. The extruder barrel temperature is 182.5℃, the die temperature is 202.5℃, the cooling air temperature is 23℃, the blow-up ratio is 2.0, the traction ratio is 4.0, the traction speed is 8m / min, and the total thickness of the 3-layer film material is 0.40mm. S3. The three-layer film material is treated with an embossing roller at 82.5℃, with an embossing roller pressure of 0.5MPa and an embossing roller linear speed of 8m / min. Then, it is subjected to corona treatment. The surface tension of the film material after corona treatment is 40mN / m. After cooling and shaping, the edges are trimmed and the film is wound up to obtain a high-efficiency fixed wavelength reflective film for silicon-based power generation.

[0024] Preparation steps of cerium-yttrium modified magnesium fluoride coated barium sulfate microspheres: A1. Add 21.0g of barium chloride dihydrate, 0.40g of cerium nitrate hexahydrate, 0.25g of yttrium nitrate hexahydrate, and 1.50g of sodium citrate to 140.0g of deionized water and stir at 30℃ and 300r / min for 40min to obtain a barium salt mixture. Add 15.0g of anhydrous sodium sulfate to 100.0g of deionized water and stir at 25℃ and 300r / min for 20min until completely dissolved to obtain anhydrous sodium sulfate aqueous solution. Add the anhydrous sodium sulfate aqueous solution dropwise to the barium salt mixture at 40℃ at a rate of 1.5mL / min, using 1mol / L dilute hydrochloric acid to control the pH at 5.0 during the dropwise addition. After the dropwise addition is complete, age the solution at 50℃ and 300r / min for 75min to obtain a suspension. A2. Add 2.50g magnesium nitrate hexahydrate and 0.85g polyvinylpyrrolidone to the suspension, stir at 300r / min for 20min, and heat to 60℃; dissolve 1.20g ammonium fluoride in 30.0g deionized water to obtain an aqueous solution containing ammonium fluoride, and add the aqueous solution containing ammonium fluoride to the suspension at a dropping rate of 1.0mL / min. During the dropping process, adjust the pH to 5.25 with dilute ammonia water. After the dropping is completed, react at 65℃ and 300r / min for 105min; after the reaction is completed, filter, wash the filter cake 3 times with deionized water and 2 times with ethanol, dry at 85℃ for 8h, then calcine at 410℃ for 2.0h, and naturally cool to 25℃ to obtain cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres; A3. 12.5g of cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres were dispersed in 100.0g of anhydrous ethanol and stirred at 300r / min for 30min. 1.15g of γ-methacryloyloxypropyltrimethoxysilane and 0.35g of deionized water were added. The pH was adjusted to 4.75 with glacial acetic acid. The reaction was carried out at 55℃ and 300r / min for 2.5h. After the reaction was completed, the mixture was filtered. The filter cake was washed twice with anhydrous ethanol and dried at 75℃ for 6h to obtain vinylsilanized composite microspheres. A4. 12.5g of vinylsilanized composite microspheres, 3.0g of maleic anhydride-grafted polyethylene wax, 0.10g of dicumyl peroxide and 40.0g of xylene were added to a reactor and stirred at 300r / min for 10min. Nitrogen gas was then introduced to purge the mixture for 15min. The mixture was heated to 120℃ under nitrogen protection and reacted for 2.5h. The mixture was then cooled to 25℃, filtered, washed three times with ethanol, vacuum dried at 85℃ for 7h, pulverized, and passed through a 300-mesh sieve to obtain cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres.

[0025] Preparation steps of cerium-zirconium modified rutile titanium-silicon composite microspheres: B1. 12.5g of carboxylated monodisperse polystyrene microspheres, 100.0g of anhydrous ethanol, 27.5g of deionized water and 4.5g of ammonia were added to a reactor and stirred at 27.5℃ and 300r / min for 25min. 0.55g of polyvinylpyrrolidone was added and stirring was continued for 20min. 8.0g of tetraethyl orthosilicate was added dropwise over 30min. After the addition was complete, the reaction was carried out at 35℃ and 300r / min for 5h. The mixture was centrifuged, and the precipitate was washed three times with ethanol and twice with deionized water. It was dried at 80℃ for 6h and then calcined at 525℃ for 2.5h. After natural cooling to 25℃, hollow silica microspheres were obtained. B2. 10.0 g of hollow silica microspheres and 5.5 g of rutile nano-titanium dioxide were added to a mixture of 120.0 g of deionized water and 40.0 g of ethanol, and 0.75 g of polyvinylpyrrolidone was added. The mixture was ultrasonically dispersed at 300 W for 25 min. Then, 0.35 g of zirconium oxynitrate hydrate, 0.20 g of cerium nitrate hexahydrate and 1.75 g of urea were added, and the mixture was reacted at 92.5 °C and 300 r / min for 4 h. After the reaction was completed, the mixture was filtered, and the filter cake was washed 3 times with deionized water and 2 times with ethanol. It was dried at 80 °C for 6 h, and then calcined at 475 °C for 2.0 h. After natural cooling to 25 °C, hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres were obtained. B3. 12.5g of hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres were added to 125.0g of toluene and stirred at 300r / min for 20min. 1.15g of γ-methacryloyloxypropyltrimethoxysilane was added and nitrogen gas was introduced for 15min to replace the precipitate. The reaction was carried out at 85℃ and 300r / min for 3.5h under nitrogen protection. The mixture was filtered, washed twice with toluene, and dried under vacuum at 85℃ for 7h to obtain methacryloylated composite microspheres. B4. 12.5g of methacrylamide composite microspheres, 1.50g of 2,2,6,6-tetramethyl-4-piperidin methacrylate, 2.25g of octadecyl methacrylate, 0.07g of azobisisobutyronitrile, and 100.0g of toluene were added to a reactor. The mixture was stirred at 300r / min for 10min, purged with nitrogen for 15min, and reacted at 70℃ and 300r / min under nitrogen protection for 5h. After the reaction was completed, the mixture was filtered, washed twice each with ethanol and toluene, dried under vacuum at 85℃ for 7h, pulverized, and passed through a 300-mesh sieve to obtain cerium-zirconium modified rutile titanium-silicon composite microspheres.

[0026] Example 2: The difference between this example and Example 1 is that this example provides a method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation, including the following steps: S1. 10.0g of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, 4.0g of cerium-zirconium modified rutile titanium-silicon composite microspheres, 3.0g of rutile titanium dioxide, 6.0g of precipitated barium sulfate, 2.0g of hollow glass microspheres, 3.0g of light calcium carbonate, 2.0g of maleic anhydride-grafted polyethylene, and 100.0g of high-density polyethylene resin were dried at 70℃ for 2h, then added to a high-speed mixer and mixed at 45℃ for 8min. Subsequently, the mixture was melt-extruded, cooled, and pelletized using a twin-screw extruder to obtain a fixed wavelength reflection functional masterbatch. The temperature of the twin-screw extruder was 155℃ in zone 1, 170℃ in zone 2, 180℃ in zone 3, 190℃ in zone 4, and 195℃ at the die head. S2. The fixed wavelength reflective masterbatch is mixed with 8.0g of low-density polyethylene, 3.0g of ethylene-octene copolymer, 0.3g of silicone masterbatch, 0.5g of polytetrafluoroethylene, 0.15g of antioxidant 1010, 0.10g of antioxidant 168, 0.20g of ultraviolet absorber, 0.30g of light stabilizer, 1.0g of calcined kaolin, and 0.5g of oxidized polyethylene wax after being dried at 70℃ for 2h. The mixture is then co-extruded using a blow molding process to obtain a two-layer film material. The extruder barrel temperature is 160℃, the die temperature is 195℃, and the cooling air temperature is 18℃. S3. The two layers of film are passed through a 70°C embossing roller, then subjected to corona treatment, cooled and shaped, trimmed, and wound up to obtain a high-efficiency fixed-wavelength reflective film for silicon-based power generation.

[0027] Preparation steps of cerium-yttrium modified magnesium fluoride coated barium sulfate microspheres: A1. Add 18.0g of barium chloride dihydrate, 0.20g of cerium nitrate hexahydrate, 0.10g of yttrium nitrate hexahydrate and 1.0g of sodium citrate to 120.0g of deionized water and stir at 25℃ for 30min to obtain a barium salt mixture; dissolve 12.0g of anhydrous sodium sulfate in 80.0g of deionized water and add it dropwise to the barium salt mixture at 35℃ at a dropping rate of 1.0mL / min. During the dropping process, use dilute hydrochloric acid to control the pH at 4.5. After the dropping is completed, age at 45℃ for 60min to obtain a suspension. A2. Add 2.0 g magnesium nitrate hexahydrate and 0.5 g polyvinylpyrrolidone to the suspension, heat to 55 °C, add an aqueous solution containing 0.9 g ammonium fluoride dropwise, adjust the pH to 5.0 with dilute ammonia, and react at 60 °C for 90 min. After the reaction is complete, filter, wash the filter cake with deionized water and ethanol in sequence, dry at 80 °C, and then calcine at 380 °C for 1.5 h to obtain cerium yttrium modified barium sulfate-magnesium fluoride composite microspheres. A3. 10.0g of cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres were dispersed in 80.0g of anhydrous ethanol, 0.8g of γ-methacryloyloxypropyltrimethoxysilane and 0.2g of deionized water were added, the pH was adjusted to 4.5 with glacial acetic acid, the reaction was carried out at 50℃ for 2h, filtered, and dried at 70℃ to obtain vinylsilanized composite microspheres; A4. 10.0g of vinylsilanized composite microspheres, 2.0g of maleic anhydride-grafted polyethylene wax, 0.05g of dicumyl peroxide and 30.0g of xylene were added to a reactor. The mixture was heated to 115℃ under nitrogen protection and reacted for 2h. After cooling, the mixture was filtered, washed with ethanol, and vacuum dried at 80℃ for 6h. The microspheres were then pulverized and sieved to obtain cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres.

[0028] Preparation steps of cerium-zirconium modified rutile titanium-silicon composite microspheres: B1. 10.0g of carboxylated monodisperse polystyrene microspheres, 80.0g of anhydrous ethanol, 20.0g of deionized water and 3.0g of ammonia were added to a reactor and stirred at 25°C for 20min. 0.3g of polyvinylpyrrolidone was added, followed by dropwise addition of 6.0g of tetraethyl orthosilicate. The mixture was reacted at 30°C for 4h, centrifuged, washed, dried, and then calcined at 500°C for 2h to obtain hollow silica microspheres. B2. 8.0 g of hollow silica microspheres and 4.0 g of rutile nano-titanium dioxide were added to a mixture of 100.0 g of deionized water and 30.0 g of ethanol, and 0.5 g of polyvinylpyrrolidone was added. The mixture was ultrasonically dispersed for 20 min. Then, 0.20 g of zirconium oxynitrate hydrate, 0.10 g of cerium nitrate hexahydrate and 1.0 g of urea were added, and the mixture was reacted at 90 °C for 3 h. The mixture was filtered, washed, dried, and then calcined at 450 °C for 1.5 h to obtain hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres. B3. 10.0g of hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres were added to 100.0g of toluene, and 0.8g of γ-methacryloyloxypropyltrimethoxysilane were added. The mixture was reacted at 80℃ for 3h under nitrogen protection, filtered, and dried under vacuum at 80℃ to obtain methacryloylated composite microspheres. B4. 10.0 g of methacrylamide composite microspheres, 1.0 g of 2,2,6,6-tetramethyl-4-piperidin methacrylate, 1.5 g of octadecyl methacrylate, 0.04 g of azobisisobutyronitrile, and 80.0 g of toluene were added to a reactor and reacted at 65 °C for 4 h under nitrogen protection. After the reaction was completed, the mixture was filtered, washed alternately with ethanol and toluene, dried under vacuum at 80 °C for 6 h, pulverized, and sieved to obtain cerium-zirconium modified rutile titanium-silicon composite microspheres.

[0029] Example 3: The difference between this example and Example 1 is that this example provides a method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation, including the following steps: S1. 22.0g of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, 12.0g of cerium-zirconium modified rutile titanium-silicon composite microspheres, 8.0g of rutile titanium dioxide, 15.0g of precipitated barium sulfate, 6.0g of hollow glass microspheres, 8.0g of light calcium carbonate, 5.0g of maleic anhydride-grafted polyethylene, and 100.0g of high-density polyethylene resin were dried at 85℃ for 4h, then added to a high-speed mixer and mixed at 60℃ for 12min. Subsequently, the mixture was melt-extruded, cooled, and pelletized using a twin-screw extruder to obtain a fixed wavelength reflection functional masterbatch. The temperature of the twin-screw extruder was 165℃ in zone 1, 180℃ in zone 2, 190℃ in zone 3, 200℃ in zone 4, and 205℃ at the die head. S2. The fixed wavelength reflective masterbatch is mixed with 18.0g of low-density polyethylene, 8.0g of ethylene-octene copolymer, 1.0g of silicone masterbatch, 1.5g of polytetrafluoroethylene, 0.40g of antioxidant 1010, 0.35g of antioxidant 168, 0.60g of ultraviolet absorber, 0.90g of light stabilizer, 3.0g of calcined kaolin, and 1.5g of oxidized polyethylene wax, which have been dried at 85℃ for 4h. The mixture is then co-extruded using a blow molding process to obtain a 3-layer film material. The extruder barrel temperature is 205℃, the die temperature is 210℃, and the cooling air temperature is 28℃. S3. The three layers of film are passed through a 95°C embossing roller, then subjected to corona treatment, cooled and shaped, trimmed, and wound up to obtain a high-efficiency fixed-wavelength reflective film for silicon-based power generation.

[0030] Preparation steps of cerium-yttrium modified magnesium fluoride coated barium sulfate microspheres: A1. Add 24.0g of barium chloride dihydrate, 0.60g of cerium nitrate hexahydrate, 0.40g of yttrium nitrate hexahydrate, and 2.0g of sodium citrate to 160.0g of deionized water and stir at 35℃ for 45min to obtain a barium salt mixture; dissolve 18.0g of anhydrous sodium sulfate in 120.0g of deionized water and add it dropwise to the barium salt mixture at 45℃ at a dropping rate of 2.0mL / min. During the dropping process, use dilute hydrochloric acid to control the pH at 5.5. After the dropping is completed, age at 55℃ for 90min to obtain a suspension. A2. Add 3.0g magnesium nitrate hexahydrate and 1.2g polyvinylpyrrolidone to the suspension, heat to 65℃, add an aqueous solution containing 1.5g ammonium fluoride dropwise, adjust the pH to 5.5 with dilute ammonia, and react at 70℃ for 120min. After the reaction is complete, filter, wash the filter cake with deionized water and ethanol in sequence, dry at 90℃, and then calcine at 440℃ for 2.5h to obtain cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres. A3. 15.0g of cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres were dispersed in 120.0g of anhydrous ethanol, 1.5g of γ-methacryloyloxypropyltrimethoxysilane and 0.5g of deionized water were added, the pH was adjusted to 5.0 with glacial acetic acid, the reaction was carried out at 60℃ for 3h, filtered, and dried at 80℃ to obtain vinylsilanized composite microspheres; A4. 15.0g of vinylsilanized composite microspheres, 4.0g of maleic anhydride-grafted polyethylene wax, 0.15g of dicumyl peroxide and 50.0g of xylene were added to a reactor. The mixture was heated to 125℃ under nitrogen protection and reacted for 3h. After cooling, the mixture was filtered, washed with ethanol, and dried under vacuum at 90℃ for 8h. The mixture was then pulverized and sieved to obtain cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres.

[0031] Preparation steps of cerium-zirconium modified rutile titanium-silicon composite microspheres: B1. 15.0 g of carboxylated monodisperse polystyrene microspheres, 120.0 g of anhydrous ethanol, 35.0 g of deionized water and 6.0 g of ammonia were added to a reactor and stirred at 30 °C for 30 min. 0.8 g of polyvinylpyrrolidone was added, and 10.0 g of tetraethyl orthosilicate was added dropwise. The mixture was reacted at 40 °C for 6 h, centrifuged, washed, dried, and then calcined at 550 °C for 3 h to obtain hollow silica microspheres. B2. 12.0 g of hollow silica microspheres and 7.0 g of rutile nano-titanium dioxide were added to a mixture of 140.0 g of deionized water and 50.0 g of ethanol, and 1.0 g of polyvinylpyrrolidone was added. The mixture was ultrasonically dispersed for 30 min. Then, 0.50 g of zirconium oxynitrate hydrate, 0.30 g of cerium nitrate hexahydrate and 2.5 g of urea were added, and the mixture was reacted at 95 °C for 5 h. The mixture was filtered, washed, dried, and then calcined at 500 °C for 2.5 h to obtain hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres. B3. Add 15.0g of hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres to 150.0g of toluene, add 1.5g of γ-methacryloyloxypropyltrimethoxysilane, react at 90℃ for 4h under nitrogen protection, filter, and vacuum dry at 90℃ to obtain methacryloylated composite microspheres. B4. 15.0 g of methacrylamide composite microspheres, 2.0 g of 2,2,6,6-tetramethyl-4-piperidin methacrylate, 3.0 g of octadecyl methacrylate, 0.10 g of azobisisobutyronitrile, and 120.0 g of toluene were added to a reactor and reacted at 75 °C for 6 h under nitrogen protection. After the reaction was completed, the mixture was filtered, washed alternately with ethanol and toluene, dried under vacuum at 90 °C for 8 h, pulverized, and sieved to obtain cerium-zirconium modified rutile titanium-silicon composite microspheres.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres are not added, and 16.0g of precipitated barium sulfate is used instead of 16.0g of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres in step S1. The rest is the same as in Example 1.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that cerium-zirconium modified rutile titanium-silicon composite microspheres are not added, and 8.0g of rutile titanium dioxide is used instead of 8.0g of cerium-zirconium modified rutile titanium-silicon composite microspheres in step S1. The rest is the same as in Example 1.

[0034] Comparative Example 3 The difference between this comparative example and Example 1 is that cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and cerium-zirconium modified rutile titanium-silicon composite microspheres are not added; in step S1, 16.0g of precipitated barium sulfate is used instead of 16.0g of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, and 8.0g of rutile titanium dioxide is used instead of 8.0g of cerium-zirconium modified rutile titanium-silicon composite microspheres, and the rest is the same as in Example 1.

[0035] In accordance with national and industry standard testing specifications, a series of standardized tests were conducted on the high-efficiency fixed-wavelength reflective films for silicon-based power generation prepared by the preparation methods of the high-efficiency fixed-wavelength reflective films for silicon-based power generation described in Examples 1-3 and Comparative Examples 1-3.

[0036] The high-efficiency fixed-wavelength reflective films for silicon-based power generation prepared in Examples 1-3 and Comparative Examples 1-3 were used as samples. Each group was cut into flat films of 300mm×300mm. Before the test, the samples were placed in an environment of 23°C and 50% relative humidity for 24 hours. Before the test, the surface dust was removed with a lint-free cloth and the surface was kept free of wrinkles and obvious scratches.

[0037] During the average spectral reflectance test, the reflective surface of the sample is oriented towards the incident window of the integrating sphere. A UV-Vis-NIR spectrophotometer with an integrating sphere is used for the test, with a barium sulfate standard white plate as a reference. The test wavelength range is 400-1100 nm, the scanning interval is 5 nm, and the incident angle is 8°. Five positions are selected for each sample: center, top, bottom, left, and right. The reflectance of each test position in the range of 400-1100 nm is read and the average value is calculated. The average value of the five positions is then taken as the average spectral reflectance, with the unit being 0.5.

[0038] When testing visible light reflectance, the same testing equipment, reference white board, incident angle, and sampling method as the average spectral reflectance are used. The reflectance of each scanning point in the range of 400-700nm is read and the average value is calculated. The average value of 5 positions is then taken as the visible light reflectance, and the unit is .

[0039] When testing near-infrared reflectance, the same testing equipment, reference white board, incident angle, and sampling method as the average spectral reflectance are used. The reflectance of each scanning point in the range of 800-950nm is read and the average value is calculated. The average value of 5 positions is then taken as the near-infrared reflectance, and the unit is .

[0040] During the test of the retention rate of average spectral reflectance after ultraviolet aging, the sample was placed in an ultraviolet aging chamber and irradiated with a 340nm ultraviolet lamp at an intensity of 0.76W / m². 2 The blackboard temperature was 63℃ and the condensation temperature was 50℃. One cycle consisted of 8 hours of UV irradiation and 4 hours of condensation, with a cumulative aging time of 1000 hours. After aging, the sample was placed in an environment of 23℃ and 50% relative humidity for 24 hours. The average spectral reflectance after aging was then measured according to the average spectral reflectance test method. The average spectral reflectance retention rate after UV aging was calculated as "average spectral reflectance after aging ÷ average spectral reflectance before aging × 100%", with the unit being .

[0041] During the wear resistance test, the sample was fixed on the platform of the wear resistance testing machine with the reflective surface facing upwards. A rubber grinding wheel was used for abrasion, with a load of 500g and 500 abrasion cycles. After abrasion, the surface dust was removed with a lint-free cloth, and the average spectral reflectance after abrasion was measured according to the average spectral reflectance test method. The average spectral reflectance retention rate after abrasion was calculated as "average spectral reflectance after abrasion ÷ average spectral reflectance before abrasion × 100%", with the unit being 0.5%.

[0042] During the power generation gain test, silicon-based photovoltaic modules of the same specifications were selected. The reflective films prepared in Examples 1-3 and Comparative Examples 1-3 were laid on the ground directly below the modules, with the reflective surface facing upwards and kept flat. Silicon-based photovoltaic modules of the same specifications without reflective films were used as blank controls. The tilt angle, orientation, height above the ground, and test period of the modules were kept consistent, and the solar irradiance was 800-1000 W / m². 2 Under the condition that the ambient temperature fluctuation does not exceed 5℃, the test is conducted continuously for 6 hours. The output power of the module is recorded once every 10 minutes. The average output power of the module with the reflective film and the average output power of the blank control module are calculated respectively. The power generation gain is calculated by dividing "average output power of the module with the reflective film - average output power of the blank control module" by the average output power of the blank control module and then multiplying by 100%. The unit is .

[0043] The performance test data above are shown in Table 1.

[0044] .

[0045] As can be seen from the above, Examples 1-3 show significant advantages over Comparative Examples 1-3 in terms of average spectral reflectance, visible light reflectance, near-infrared light reflectance, average spectral reflectance retention rate after ultraviolet aging, average spectral reflectance retention rate after wear resistance, and power generation gain. This indicates that the present invention can solve the problems of insufficient effective spectral reflectance of existing reflective films, low utilization rate of the near-infrared band, attenuation of reflective performance after outdoor aging, decrease in reflective performance after wear, and limited actual power generation gain.

[0046] Specifically, the average spectral reflectance of Examples 1-3 was 77.83-82.36%, which was higher than that of Comparative Example 1 (73.95%), Comparative Example 2 (75.46%), and Comparative Example 3 (70.28%). Among them, the average spectral reflectance of Example 1 reached 80.04%, indicating that the multi-scale reflectance system formed by components such as cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and cerium-zirconium modified rutile titanium-silicon composite microspheres can improve the overall spectral reflectance of the film material.

[0047] The visible light reflectance of Examples 1-3 was 82.74-87.10%, which was significantly higher than that of Comparative Example 1 (79.20%), Comparative Example 2 (80.12%), and Comparative Example 3 (75.18%). This indicates that the synergistic effect of rutile titanium dioxide, precipitated barium sulfate, hollow glass microspheres, light calcium carbonate, calcined kaolin, cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, and cerium-zirconium modified rutile titanium-silicon composite microspheres can improve the diffuse reflection utilization effect in the visible light region.

[0048] In Comparative Example 3, the visible light reflectance decreased most significantly after the simultaneous removal of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and cerium-zirconium modified rutile titanium-silicon composite microspheres, indicating that the visible light reflectance of the above components is not simply additive, but rather has a composite enhancement effect.

[0049] The near-infrared reflectance of Examples 1-3 was 74.58-79.62%, which is a significant improvement compared to 68.40% of Comparative Example 1, 72.55% of Comparative Example 2, and 64.90% of Comparative Example 3. In particular, the near-infrared reflectance of Comparative Example 1 was significantly reduced after the addition of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, indicating that the microspheres play a key role in enhancing the reflection in the near-infrared response region of silicon-based photovoltaic modules.

[0050] Comparative Example 2, without the addition of cerium-zirconium modified rutile titanium-silicon composite microspheres, also showed a lower near-infrared reflectance than Examples 1-3, indicating that the hollow scattering interface formed by the cerium-zirconium modified rutile titanium dioxide composite microspheres also promotes near-infrared reflection.

[0051] The average spectral reflectance retention rate of Examples 1-3 after UV aging was 92.60-94.50%, which was higher than that of Comparative Example 1 (89.20%), Comparative Example 2 (87.60%), and Comparative Example 3 (82.40%). Among them, Comparative Example 2 showed a more significant decrease. This indicates that the cerium-zirconium modified rutile titanium-silicon composite microspheres, combined with antioxidant 1010, antioxidant 168, UV absorber, and light stabilizer, can improve the UV aging resistance stability of the film material and reduce the problem of reflectance decay during long-term outdoor use.

[0052] The average spectral reflectance retention rate after wear resistance in Examples 1-3 was 90.40-92.80%, which was higher than that of Comparative Example 1 (87.50%), Comparative Example 2 (88.20%), and Comparative Example 3 (82.70%). This indicates that the cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres and the cerium-zirconium modified rutile titanium-silicon composite microspheres are stably dispersed in high-density polyethylene resin. Combined with polytetrafluoroethylene and oxidized polyethylene wax, they can improve the reflectance retention ability of the film surface after wear resistance, and adapt to the wind, sand, dust and maintenance trampling environment in the ground laying of photovoltaic power stations.

[0053] Ultimately, the power generation gain of Examples 1-3 was 5.20-6.40%, which was significantly higher than that of Comparative Example 1 (3.70%), Comparative Example 2 (4.30%), and Comparative Example 3 (2.50%). This indicates that the improved spectral reflectance, near-infrared reflectance, aging resistance, and wear resistance of the present invention can be converted into an actual increase in the output power of silicon-based photovoltaic modules.

[0054] Therefore, Examples 1-3, compared with Comparative Examples 1-3, demonstrate that the present invention, through the synergistic design of cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, cerium-zirconium modified rutile titanium-silicon composite microspheres, calcined kaolin, and polyolefin weather-resistant film-forming system, solves the technical problems of insufficient reflection efficiency, poor fixed wavelength response, insignificant near-infrared reflection enhancement, performance degradation after outdoor service, and limited power generation gain of medium and large-scale photovoltaic power plants in existing photovoltaic reflective films.

Claims

1. A method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation, characterized in that, Includes the following steps: S1. By weight, 10.0-22.0 parts of dried cerium-yttrium modified magnesium fluoride-coated barium sulfate microspheres, 4.0-12.0 parts of cerium-zirconium modified rutile titanium-silicon composite microspheres, 3.0-8.0 parts of rutile titanium dioxide, 6.0-15.0 parts of precipitated barium sulfate, 2.0-6.0 parts of hollow glass microspheres, 3.0-8.0 parts of light calcium carbonate, 2.0-5.0 parts of maleic anhydride-grafted polyethylene and 100.0 parts of high-density polyethylene resin are added to a high-speed mixer and mixed at 45-60℃. Then, the mixture is melt-extruded through a twin-screw extruder, cooled, and pelletized to obtain a fixed wavelength reflection functional masterbatch. S2. The fixed wavelength reflective masterbatch is mixed with 8.0-18.0 parts of dried low-density polyethylene, 3.0-8.0 parts of ethylene-octene copolymer, 0.3-1.0 parts of silicone masterbatch, 0.5-1.5 parts of polytetrafluoroethylene, 0.15-0.40 parts of antioxidant 1010, 0.10-0.35 parts of antioxidant 168, 0.20-0.60 parts of ultraviolet absorber, 0.30-0.90 parts of light stabilizer, 1.0-3.0 parts of calcined kaolin and 0.5-1.5 parts of oxidized polyethylene wax, and then co-extruded by blow molding to obtain a 2- or 3-layer film material. S3. Pass 2 or 3 layers of film material through a 70-95℃ embossing roller, then perform corona treatment, cool and shape, trim the edges, and rewind.

2. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 1, characterized in that, In step S1, the temperatures of each zone of the twin-screw extruder are as follows: Zone 1 temperature is 155-165℃, Zone 2 temperature is 170-180℃, Zone 3 temperature is 180-190℃, Zone 4 temperature is 190-200℃, and the die head temperature is 195-205℃.

3. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 1, characterized in that, In step S2, the ultraviolet absorber is ultraviolet absorber UV-326; the light stabilizer is light stabilizer 944; the extruder barrel temperature for the co-extrusion blow molding process is 160-205℃, the die temperature is 195-210℃, and the cooling air temperature is 18-28℃.

4. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to any one of claims 1-3, characterized in that, The preparation steps of the cerium-yttrium modified magnesium fluoride coated barium sulfate microspheres include: A1. By weight, add 18.0-24.0 parts of barium chloride dihydrate, 0.20-0.60 parts of cerium nitrate hexahydrate, 0.10-0.40 parts of yttrium nitrate hexahydrate, and 1.0-2.0 parts of sodium citrate to 120.0-160.0 parts of deionized water and stir at 25-35℃ to obtain a barium salt mixture; dissolve 12.0-18.0 parts of anhydrous sodium sulfate in 80.0-120.0 parts of deionized water and add it dropwise to the barium salt mixture at 35-45℃, control the pH to 4.5-5.5 with dilute hydrochloric acid, and age at 45-55℃ to obtain a suspension; A2. Add 2.0-3.0 parts of magnesium nitrate hexahydrate and 0.5-1.2 parts of polyvinylpyrrolidone to the suspension, heat to 55-65℃, add dropwise an aqueous solution containing 0.9-1.5 parts of ammonium fluoride, adjust the pH to 5.0-5.5 with dilute ammonia, and react at 60-70℃; filter, wash successively with deionized water and ethanol, dry at 80-90℃, and then calcine at 380-440℃ to obtain cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres; A3. Disperse 10.0-15.0 parts of cerium-yttrium modified barium sulfate-magnesium fluoride composite microspheres in 80.0-120.0 parts of anhydrous ethanol, add 0.8-1.5 parts of γ-methacryloyloxypropyltrimethoxysilane and 0.2-0.5 parts of deionized water, adjust the pH to 4.5-5.0 with glacial acetic acid, react at 50-60℃, filter, and dry to obtain vinylsilanized composite microspheres; A4. Add 10.0-15.0 parts of vinyl silanized composite microspheres, 2.0-4.0 parts of maleic anhydride-grafted polyethylene wax, 0.05-0.15 parts of dicumyl peroxide and 30.0-50.0 parts of xylene to the reactor. Under nitrogen protection, heat to 115-125℃ to react, cool, filter, wash with ethanol, vacuum dry at 80-90℃, pulverize and sieve.

5. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 4, characterized in that, In step A1, the aging time at 45-55℃ is 60-90 minutes.

6. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 4, characterized in that, In step A2, the calcination time at 380-440℃ is 1.5-2.5h.

7. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to any one of claims 1-3, characterized in that, The preparation steps of the cerium-zirconium modified rutile titanium-silicon composite microspheres include: B1. By weight, 10.0-15.0 parts of carboxylated monodisperse polystyrene microspheres, 80.0-120.0 parts of anhydrous ethanol, 20.0-35.0 parts of deionized water and 3.0-6.0 parts of ammonia water are added to a reactor and stirred at 25-30°C; 0.3-0.8 parts of polyvinylpyrrolidone are added, and 6.0-10.0 parts of tetraethyl orthosilicate are added dropwise. The mixture is reacted at 30-40°C, centrifuged, washed, dried, and then calcined at 500-550°C to obtain hollow silica microspheres. B2. Add 8.0-12.0 parts of hollow silica microspheres and 4.0-7.0 parts of rutile nano-titanium dioxide to a mixture of 100.0-140.0 parts of deionized water and 30.0-50.0 parts of ethanol, add 0.5-1.0 parts of polyvinylpyrrolidone, and disperse by ultrasonication; then add 0.20-0.50 parts of zirconium oxynitrate hydrate, 0.10-0.30 parts of cerium nitrate hexahydrate, and 1.0-2.5 parts of urea, and react at 90-95℃; filter, wash, dry, and then calcine at 450-500℃ to obtain hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres; B3. Add 10.0-15.0 parts of hollow silica-cerium zirconium modified rutile titanium dioxide composite microspheres to 100.0-150.0 parts of toluene, add 0.8-1.5 parts of γ-methacryloyloxypropyltrimethoxysilane, react at 80-90℃ under nitrogen protection, filter, and vacuum dry to obtain methacryloylated composite microspheres; B4. Add 10.0-15.0 parts of methacrylamide composite microspheres, 1.0-2.0 parts of 2,2,6,6-tetramethyl-4-piperidin methacrylate, 1.5-3.0 parts of octadecyl methacrylate, 0.04-0.10 parts of azobisisobutyronitrile, and 80.0-120.0 parts of toluene to a reactor. Under nitrogen protection, react at 65-75℃. After the reaction is complete, filter, wash alternately with ethanol and toluene, vacuum dry at 80-90℃, pulverize, and sieve.

8. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 7, characterized in that, In step B1, the reaction time is 4-6 hours at 30-40℃ and the calcination time is 2-3 hours at 500-550℃.

9. The method for preparing a high-efficiency fixed-wavelength reflective film for silicon-based power generation according to claim 7, characterized in that, In step B2, the calcination time at 450-500℃ is 1.5-2.5h.

10. The application of the high-efficiency fixed-wavelength reflective film for silicon-based power generation prepared by the method of any one of claims 1-3 in improving the power generation efficiency of medium and large-scale photovoltaic power plants.

Images