Super-reflective photovoltaic synergistic coating, preparation method and application thereof

Abstract

This invention belongs to the field of coating technology, specifically relating to a super-reflective photovoltaic enhancement coating, its preparation method, and its application. The coating raw materials include water-based acrylic resin, filler, titanium dioxide, dispersant, defoamer, and leveling agent; wherein the filler includes barium sulfate and / or core-shell particles, and the barium sulfate includes at least one of nano-sized barium sulfate, submicron-sized barium sulfate, micron-sized barium sulfate, and modified barium sulfate. The preparation method involves: adding the filler to deionized water, adding the dispersant, and dispersing; adding the water-based acrylic resin and stirring; adding titanium dioxide, defoamer, and leveling agent to adjust the fineness; adjusting the viscosity; and filtering to obtain the super-reflective photovoltaic enhancement coating. The coating is applied to photovoltaic modules. This invention's coating has the advantages of high reflectivity, full-band coverage, low cost, and stable performance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a super-reflective photovoltaic enhancement coating, its preparation method, and its application. Background Technology

[0002] With the rapid development of bifacial photovoltaic module technology, fully utilizing the reflected light received on the back of the module has become crucial for improving power generation efficiency. Current technologies mainly use white roofs or ordinary white paint to increase ground reflectivity, but this presents the following problems: 1. Low reflectivity: The solar reflectivity of traditional titanium dioxide (TiO2) based white coatings is only 85-90%, with 10-15% light energy loss. In addition, TiO2 absorbs ultraviolet rays, causing the coating surface to heat up, which reduces the heat dissipation effect of photovoltaic modules. 2. Incomplete band coverage: Single-size reflective fillers can only effectively scatter specific bands and cannot cover the entire spectrum of sunlight from ultraviolet to visible to infrared. 3. High cost: TiO2 is expensive, and a high amount needs to be added to achieve high reflectivity, resulting in high coating costs; 4. Insufficient adhesion: At high filler concentrations, it is difficult to balance the storage stability and film adhesion of the coating.

[0003] Therefore, developing a high-reflectivity, full-band coverage, low-cost, and stable super-reflective photovoltaic enhancement coating is of great significance for promoting the improvement of distributed photovoltaic power generation efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a super-reflective photovoltaic enhancement coating, its preparation method and application, thereby solving the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows: In a first aspect, a super-reflective photovoltaic enhancement coating, the raw materials of which include water-based acrylic resin, filler, titanium dioxide, dispersant, defoamer, and leveling agent; wherein the filler includes barium sulfate and / or core-shell particles, and the barium sulfate includes at least one of nano-sized barium sulfate, submicron-sized barium sulfate, micron-sized barium sulfate, and modified barium sulfate.

[0006] Preferably, the mass ratio of nano-sized barium sulfate, submicron-sized barium sulfate, and micron-sized barium sulfate is (25-40):(30-50):(20-30).

[0007] Preferably, the particle size of the nano-sized barium sulfate is 50-100 nm, the particle size of the submicron-sized barium sulfate is 0.5-1 μm, and the particle size of the micron-sized barium sulfate is 5-10 μm; the dispersant includes PVA (polyvinyl alcohol) and / or a wetting and dispersing agent.

[0008] It should be noted that by employing the above technical solution, barium sulfate particles of various sizes work synergistically to achieve unobstructed scattering coverage across the entire wavelength range from ultraviolet to near-infrared, resulting in a solar reflectance exceeding 98%. Furthermore, the particles of different sizes form an ordered packing structure in space: large particles form the framework, medium particles fill the gaps between large particles, and nanoparticles further fill the remaining pores. These three elements work together to form the densest packing, effectively reducing ineffective voids within the coating film, minimizing disordered light loss within the coating, and further improving reflectivity.

[0009] A preferred method for preparing modified barium sulfate includes the following steps: Nano-sized, submicron-sized, or micron-sized barium sulfate is dispersed in an aqueous ethanol solution, a silane coupling agent is added, the mixture is stirred at 60-90°C, filtered, and dried to obtain modified barium sulfate.

[0010] Preferably, the silane coupling agent includes at least one of KH-550, KH-560, and KH-570.

[0011] It should be noted that surface modification can improve the interfacial bonding force between barium sulfate and water-based acrylic resin, preventing filler agglomeration and sedimentation.

[0012] Preferably, the method for preparing core-shell particles includes the following steps: Spherical barium sulfate microspheres were ultrasonically dispersed in ethanol, a silane coupling agent was added, and the mixture was stirred at 50-70℃. After the reaction was completed, the microspheres were centrifuged, washed, and dried to obtain activated barium sulfate core spheres. The activated barium sulfate core spheres were ultrasonically dispersed in water, a dispersant was added, and the mixture was stirred. Styrene monomer was added, and the mixture was pre-stirred at 60-80°C under nitrogen protection. Then an initiator was added, and the mixture was reacted at 60-80°C under nitrogen protection to obtain barium sulfate@PS (polystyrene) particles. Barium sulfate@PS particles were ultrasonically dispersed in ethanol, ammonia was added, and the mixture was stirred until homogeneous. TEOS (ethyl silicate) ethanol solution was slowly added dropwise. After the addition was complete, the reaction was stirred and the mixture was centrifuged. The particles were collected, washed, and barium sulfate@PS@SiO2 (silicon dioxide) three-layer core-shell particles were obtained. Barium sulfate@PS@SiO2 three-layer core-shell particles were dispersed in toluene, ultrasonically dispersed, stirred and soaked at 50-70℃, and the above steps were repeated with fresh toluene. The particles were then collected by centrifugation, washed, and dried to obtain the core-shell particles.

[0013] It should be noted that after hydrolysis, the siloxane group of the silane coupling agent condenses with the hydroxyl groups on the barium sulfate surface to form chemical bonds for anchoring. The terminal methacryloxy group extends outward, providing vinyl functional groups on the barium sulfate surface, which provide chemical bonding sites and compatibility for the subsequent polymerization of styrene monomers on its surface, ensuring uniform coating of the PS shell rather than self-nucleation. The dispersant keeps the activated barium sulfate core spheres uniformly suspended in the aqueous phase, and the styrene monomers tend to accumulate on the particle surface due to their hydrophobicity. The initiator initiates free radical polymerization, and the polystyrene chains grow and entangle on the particle surface, forming a uniform and dense PS shell, resulting in a well-defined barium sulfate@PS core-shell structure.

[0014] Ammonia water catalyzes the hydrolysis and condensation reaction of TEOS in an ethanol-water system. The silica oligomers generated by hydrolysis are adsorbed onto the surface of the PS shell through hydrogen bonding and electrostatic interaction, and then condense to form a cross-linked SiO2 network shell, thus obtaining a barium sulfate@PS@SiO2 three-layer structure.

[0015] Toluene is a good solvent for PS. Through repeated soaking and extraction, the PS intermediate layer is gently dissolved and removed, leaving the void between the SiO2 shell and the barium sulfate core. This method does not require high-temperature calcination, thus avoiding the collapse of the SiO2 shell pores and irreversible agglomeration between particles. It fully preserves the hollow structure and the porosity of the SiO2 shell, ultimately obtaining core-shell particles of barium sulfate@air@SiO2, with the air layer as the air layer.

[0016] The structure consists of high-refractive-index barium sulfate, low-refractive-index air, and medium-refractive-index SiO2. Light is reflected at each interface due to the abrupt change in refractive index, and the ultra-low refractive index of the air layer maximizes the reflectivity at each interface. The synergistic effect of these three interfaces causes multiple internal reflections of light within the hollow structure, extending the light path and increasing the number of scattering events.

[0017] Preferably, the spherical barium sulfate microspheres include at least one of small-core spherical barium sulfate microspheres, medium-core spherical barium sulfate microspheres, and large-core spherical barium sulfate microspheres; the particle size of the small-core spherical barium sulfate microspheres is 0.1-0.3 μm; the particle size of the medium-core spherical barium sulfate microspheres is 0.5-1.0 μm; and the particle size of the large-core spherical barium sulfate microspheres is 2-5 μm.

[0018] Furthermore, the preparation method of small-core spherical barium sulfate microspheres includes the following steps: Dissolve BaCl2 (barium chloride) in deionized water, add PVP (polyvinylpyrrolidone), stir to dissolve, and obtain BaCl2 solution; Dissolve Na2SO4 (sodium sulfate) in deionized water to obtain a Na2SO4 solution; Na2SO4 solution was pumped into BaCl2 solution while stirring, and the reaction was carried out at room temperature. After the reaction was completed, the mixture was aged, then centrifuged, washed, and dried to obtain small-core spherical barium sulfate microspheres.

[0019] It should be noted that PVP selectively adsorbs onto specific crystal planes, inhibiting anisotropic growth and guiding the grains towards a spherical shape. Rapid feeding combined with strong shear at 1200 rpm ensures that the crystal nuclei are fully dispersed before growth, ultimately yielding monodisperse spherical microspheres of 0.1-0.3 μm.

[0020] Furthermore, the preparation method of the core-centered spherical barium sulfate microspheres includes the following steps: Dissolve BaCl2 in deionized water, add PVP and EDTA (ethylenediaminetetraacetic acid), stir to dissolve, and obtain BaCl2 solution; Dissolve Na2SO4 in deionized water to obtain a Na2SO4 solution; Na2SO4 solution was pumped into BaCl2 solution while stirring. After the addition was completed at room temperature, stirring continued. Then the reaction mixture was transferred to a hydrothermal reactor and hydrothermally treated at 50-70℃. After the reaction was completed, the mixture was cooled to room temperature, aged, centrifuged, washed, and dried to obtain spherical barium sulfate microspheres with a central core.

[0021] It should be noted that EDTA and Ba 2+ Formation of complexes reduces free Ba 2+ The concentration was adjusted to allow nucleation and growth to proceed gradually, resulting in a larger number of primary particles. Subsequent hydrothermal treatment, without stirring, allowed the smaller particles to dissolve preferentially due to their high surface energy, while the solute redeposited on the surface of the larger particles. This resulted in more uniform and spherical particles, ultimately yielding 0.5-1.0 μm spherical microspheres.

[0022] Furthermore, the preparation method of large-core spherical barium sulfate microspheres includes the following steps: Add BaCl2, Na2SO4, and PVP to deionized water, stir, and transfer the mixture to a hydrothermal reactor. Place the reactor in an oven, heat it to 160-200℃, keep it at that temperature, close the oven, and allow the reactor to cool naturally to room temperature in the air. Open the reactor, pour out the supernatant, transfer the precipitate to a centrifuge tube, centrifuge, wash, and dry to obtain large-core spherical barium sulfate microspheres.

[0023] It should be noted that when all reactants are mixed at once and placed in a high-temperature, hydrothermal, sealed environment, the initially irregularly shaped barium sulfate particles will dissolve and recrystallize. The high temperature provides sufficient energy to overcome the lattice barrier, and PVP, acting as a morphology-directing agent, adsorbs onto specific crystal faces, guiding the recrystallization to grow along a spherical morphology. By maintaining the temperature, 2-5 μm spherical microspheres are obtained.

[0024] Secondly, a method for preparing a super-reflective photovoltaic enhancement coating includes the following steps: Add the filler to deionized water, add the dispersant, and disperse at 1500-2000 rpm at room temperature; add water-based acrylic resin and stir for 15-20 minutes; add titanium dioxide, defoamer, and leveling agent to adjust the fineness; adjust the viscosity, filter, and obtain the super-reflective photovoltaic enhancement coating.

[0025] Thirdly, a super-reflective photovoltaic enhancement coating is applied to photovoltaic modules, and the super-reflective photovoltaic enhancement coating is used in conjunction with the photovoltaic modules.

[0026] Preferably, the super-reflective photovoltaic enhancement coating is applied to the roof or ground below the bifacial photovoltaic module, with a coating thickness of 200-400μm and a coating area of ​​not less than 1.2 times the area of ​​the photovoltaic module.

[0027] The beneficial effects of this invention are: 1. This invention employs a compound of three barium sulfate particles with different sizes: nano-sized barium sulfate with a particle size of 50-100 nm, primarily scattering ultraviolet (200-400 nm) sunlight; submicron-sized barium sulfate with a particle size of 0.5-1 μm, primarily scattering visible (400-700 nm) sunlight; and micron-sized barium sulfate with a particle size of 5-10 μm, primarily scattering infrared (700-2500 nm) sunlight. The synergistic effect of these three particle sizes achieves highly efficient reflection of sunlight across the entire wavelength range. The solar reflectivity can reach over 98.1%, which is 8-13 percentage points higher than traditional TiO2 coatings (85-90%).

[0028] 2. The market price of barium sulfate is only about 1 / 3 of that of TiO2. Moreover, this invention reduces the raw material cost by 20-25% while ensuring high reflectivity through high concentration filling and particle size optimization.

[0029] 3. Barium sulfate does not absorb ultraviolet light and its high reflectivity reduces photothermal conversion, which can lower the surface temperature of the coating and further reduce the operating temperature of photovoltaic modules, thereby improving power generation efficiency.

[0030] 4. Through surface silane modification treatment, the high-content filler system still maintains good storage stability and coating adhesion, and its outdoor service life can reach more than 10 years.

[0031] 5. The water-based system contains no VOCs, and barium sulfate is an inert and non-toxic material that meets green building standards, making it environmentally friendly and safe.

[0032] 6. Existing reflective fillers are solid particles, allowing light to undergo only a single reflection at the particle surface. This invention introduces a core-shell hollow structure into the field of photovoltaic reflective coatings, constructing a microstructure of a high-refractive-index core, a low-refractive-index air layer, and a medium-refractive-index shell, enabling multiple internal reflections of light. This invention uses PS as a sacrificial template and solvent extraction to create pores, avoiding the structural damage risk of traditional high-temperature calcination methods and completely preserving the shell microstructure. Detailed Implementation

[0033] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0035] Unless otherwise specified, the equipment and materials used in the embodiments can be readily obtained from commercial companies.

[0036] Example 1 A method for preparing a super-reflective photovoltaic enhancement coating, the specific steps of which are as follows: Prepare the ingredients: Ethanol aqueous solution: Ethanol and water are prepared at a mass ratio of 7:3; Silane coupling agent: KH-550; Dispersant: BYK-190; Waterborne acrylic resin: 45% solids content, Alberdingk AC 2714 is a good choice; Defoamer: BYK-024; Leveling agent: BYK-333.

[0037] Preparation using the above raw materials: 1. Surface modification of fillers: 15 kg of 80 nm nano-sized barium sulfate, 22.5 kg of 0.8 μm submicron-sized barium sulfate, and 12.5 kg of 8 μm micron-sized barium sulfate were weighed and dispersed separately in 70 L of ethanol aqueous solution. 0.5 kg of silane coupling agent was added to each, and the mixture was stirred at 75 °C for 3 hours. After filtration and drying at 120 °C for 2 hours, three types of modified barium sulfate were obtained. The three types of modified barium sulfate were mixed to obtain a modified multi-particle-size barium sulfate composite filler.

[0038] 2. Coating preparation: Add 50 kg of modified multi-size barium sulfate composite filler to 80 kg of deionized water, add 0.8 kg of dispersant, and disperse at 1800 rpm for 35 minutes at room temperature; add 30 kg of waterborne acrylic resin and stir for 18 minutes; add 8 kg of rutile TiO2, 0.4 kg of defoamer, and 0.3 kg of leveling agent, and grind with a sand mill for 45 minutes until the fineness is ≤20 μm; adjust the viscosity to 90 seconds (25℃) with a Forte 4 cup, filter and package with a 200-mesh filter to obtain sample S1.

[0039] Example 2 The difference from Example 1 lies in the mass ratio of barium sulfate with multiple particle sizes: In step 1, the filler surface modification: 18 kg of 60 nm nano-sized barium sulfate, 20 kg of 0.6 μm submicron-sized barium sulfate, and 12 kg of 6 μm micron-sized barium sulfate were weighed, with a total amount of 50 kg. The mass ratio of the three was 36:40:24. The remaining steps were exactly the same as in Example 1, resulting in sample S2.

[0040] Example 3 The difference from Example 1 lies in the amount of barium sulfate added: In step 2, coating preparation: 60 kg of modified multi-particle-size barium sulfate composite filler was added to 96 kg of deionized water, 0.8 kg of dispersant was added, and the mixture was dispersed at 1800 rpm for 35 minutes at room temperature; 28 kg of waterborne acrylic resin was added, and the remaining steps were exactly the same as in Example 1, to obtain sample S3.

[0041] Example 4 The specific steps for preparing spherical barium sulfate microspheres are as follows: Prepare the ingredients: Polyvinylpyrrolidone: PVP, K30.

[0042] Preparation using the above raw materials: 1. Preparation of small-core spherical barium sulfate microspheres with a particle size of 0.1-0.3 μm: Dissolve 0.1 mol BaCl2 in 500 mL of deionized water, add 2 g PVP, and stir magnetically until completely dissolved to obtain a BaCl2 solution.

[0043] Dissolve 0.1 mol Na2SO4 in 500 mL of deionized water to obtain a Na2SO4 solution.

[0044] Na2SO4 solution was pumped into BaCl2 solution at a rate of 20 mL / min while stirring at 1200 rpm. The reaction was carried out at room temperature. After the reaction was completed, the mixture was aged for 30 minutes and then centrifuged at 8000 rpm for 10 minutes. The precipitate was washed three times with deionized water and once with ethanol, and then dried under vacuum at 60℃ for 12 hours to obtain small-core spherical barium sulfate microspheres with a particle size D50 of 0.18 μm.

[0045] 2. Preparation of spherical barium sulfate microspheres with a core diameter of 0.5-1.0 μm: Dissolve 0.2 mol BaCl2 in 500 mL of deionized water, add 2 g PVP and 0.5 g EDTA, and stir magnetically until completely dissolved to obtain a BaCl2 solution.

[0046] Dissolve 0.1 mol Na2SO4 in 500 mL of deionized water to obtain a Na2SO4 solution.

[0047] Na2SO4 solution was pumped into BaCl2 solution at a rate of 5 mL / min while stirring at 1200 rpm. After the addition was completed at room temperature, stirring was continued for 10 minutes. The reaction mixture was then transferred to a hydrothermal reactor and hydrothermally treated at 60°C for 2 hours without stirring. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and aged for 30 minutes. Then, it was centrifuged at 8000 rpm for 10 minutes, washed three times with deionized water and once with ethanol, and vacuum dried at 60°C for 12 hours to obtain spherical barium sulfate microspheres with a core and a particle size D50 of 0.72 μm.

[0048] 3. Preparation of macronuclear spherical barium sulfate microspheres with a particle size of 2-5 μm: Add 0.1 mol BaCl2, 0.1 mol Na2SO4, and 5 g PVP to 80 mL of deionized water and stir magnetically for 10 minutes. Transfer the mixture to a hydrothermal reactor, place the reactor in an oven, heat to 180°C, and maintain the temperature for 4 hours. Turn off the oven and allow the reactor to cool naturally to room temperature in the air. Open the reactor, pour out the supernatant, transfer the precipitate to a centrifuge tube, centrifuge at 8000 rpm for 10 minutes, wash three times with deionized water and once with ethanol, and vacuum dry at 60°C for 12 hours to obtain large-core spherical barium sulfate microspheres with a particle size D50 of 3.5 μm.

[0049] Example 5 The specific steps for preparing small core-shell particles are as follows: Prepare the ingredients: Styrene monomer: St, polymerization grade; Initiator: Azobisisobutyronitrile (AIBN); Dispersants: Polyvinyl alcohol, PVA; Spherical barium sulfate microspheres: Small-core spherical barium sulfate microspheres prepared in Example 4; Silane coupling agent: KH-570.

[0050] Preparation using the above raw materials: 5g of spherical barium sulfate microspheres were ultrasonically dispersed in 100mL of ethanol, and 0.5g of KH-570 was added. The mixture was stirred at 60℃ for 2 hours. After the reaction was completed, the mixture was centrifuged, and the precipitate was washed three times with ethanol and dried under vacuum to obtain activated barium sulfate core spheres.

[0051] 2g of activated barium sulfate core spheres were ultrasonically dispersed in 200mL of water, 0.5g of PVA was added, and the mixture was stirred for 15 minutes. Then, 4g of styrene monomer was added, and the mixture was pre-stirred at 70℃ for 30 minutes under nitrogen protection. Finally, 0.05g of AIBN was added, and the mixture was reacted at 70℃ for 8 hours under nitrogen protection to obtain barium sulfate@PS particles. Barium sulfate@PS has a core-shell structure, meaning the core is barium sulfate and the shell is polystyrene (PS).

[0052] 2g of barium sulfate@PS particles were ultrasonically dispersed in 150mL of ethanol at 300W for 10min. 3mL of 28wt% ammonia was added and stirred at 400rpm until homogeneous. TEOS ethanol solution was slowly added dropwise at 0.5mL / min, with a TEOS:ethanol ratio of 1:10 v / v. After the addition was complete, the reaction was stirred for another 6 hours. After the reaction, the particles were centrifuged at 3000rpm for 10min, collected, and washed three times with deionized water and once with ethanol to obtain barium sulfate@PS@SiO2 three-layer core-shell particles. The structure from the inside out consisted of barium sulfate, polystyrene (PS), and silicon dioxide (SiO2).

[0053] 2g of barium sulfate@PS@SiO2 three-layer core-shell particles were dispersed in 50mL of toluene and ultrasonically dispersed for 10min. The particles were then stirred and soaked at 60℃ for 24 hours. The toluene was replaced with fresh toluene, and the above steps were repeated twice for a total of 3 extractions. The particles were then collected by centrifugation and washed three times each with toluene, ethanol, and deionized water. The particles were then dried under vacuum at 40℃ to obtain a small-core barium sulfate@air@SiO2 hollow structure.

[0054] Example 6 Core-shell particles were prepared. Unlike Example 5, the spherical barium sulfate microspheres were prepared using the core-shell barium sulfate microspheres prepared in Example 4. The rest were the same as in Example 5, resulting in a core-shell barium sulfate@air@SiO2 hollow structure.

[0055] Example 7 Large core-shell particles were prepared. Unlike Example 5, the spherical barium sulfate microspheres were prepared using the large core spherical barium sulfate microspheres prepared in Example 4. The rest were the same as in Example 5, resulting in a large core barium sulfate@air@SiO2 hollow structure.

[0056] Example 8 A method for preparing a super-reflective photovoltaic enhancement coating, the specific steps of which are as follows: Prepare the ingredients: Ethanol aqueous solution: Ethanol and water are prepared at a mass ratio of 7:3; Silane coupling agent: KH-550; Dispersant: BYK-190; Waterborne acrylic resin: 45% solids content, Alberdingk AC 2714 is a good choice; Defoamer: BYK-024; Leveling agent: BYK-333.

[0057] Preparation using the above raw materials: 8 kg of rutile TiO2, 0.4 kg of defoamer, and 0.3 kg of leveling agent were mixed at low speed of 300 rpm for 15 minutes. The mixture was pretreated to a fineness of ≤20 μm using a three-roll mill to obtain a slurry. 15 kg of small-core-shell particles, 22.5 kg of medium-core-shell particles, and 12.5 kg of large-core-shell particles were weighed and added to 80 kg of deionized water. 0.8 kg of dispersant was added and the mixture was dispersed at high speed of 1800 rpm for 35 minutes at room temperature. 30 kg of water-based acrylic resin was added and stirred for 18 minutes. The slurry was added and mixed. The viscosity was adjusted to 90 seconds (25℃) using a Forecast-4 cup filter. The mixture was filtered through a 200-mesh filter and packaged to obtain sample S4.

[0058] Comparative Example 1 The specific steps for traditional TiO2-based white coatings are as follows: Prepare the ingredients: Dispersant: BYK-190; Waterborne acrylic resin: 45% solids content, Alberdingk AC 2714 is a good choice; Defoamer: BYK-024; Leveling agent: BYK-333; Barium sulfate: 1μm submicron grade barium sulfate.

[0059] Preparation using the above raw materials: Add 40 kg of rutile TiO2 and 15 kg of barium sulfate to 80 kg of deionized water, add 0.8 kg of dispersant, and disperse at 1800 rpm for 35 minutes; add 30 kg of water-based acrylic resin and stir for 18 minutes; add 0.4 kg of defoamer and 0.3 kg of leveling agent, and grind with a sand mill for 45 minutes until the fineness is ≤20 μm; adjust the viscosity to 90 seconds (25℃) with a Forte 4 cup, filter with a 200-mesh filter and package to obtain sample D1.

[0060] Comparative Example 2 The specific steps for producing a high-concentration barium sulfate coating with a single particle size are as follows: Prepare the ingredients: Dispersant: BYK-190; Waterborne acrylic resin: 45% solids content, Alberdingk AC 2714 is a good choice; Defoamer: BYK-024; Leveling agent: BYK-333; Barium sulfate: 0.8μm submicron grade barium sulfate.

[0061] Preparation using the above raw materials: Add 50 kg of barium sulfate to 80 kg of deionized water, add 0.8 kg of dispersant, and disperse at 1800 rpm for 35 minutes at room temperature; add 30 kg of water-based acrylic resin and stir for 18 minutes; add 8 kg of rutile TiO2, 0.4 kg of defoamer, and 0.3 kg of leveling agent, and grind with a sand mill for 45 minutes until the fineness is ≤20 μm; adjust the viscosity to 90 seconds (25℃) with a Forte 4 cup, filter with a 200-mesh filter, and package to obtain sample D2.

[0062] Performance testing 1. Reflectivity Test A UV-Vis-NIR spectrophotometer (equipped with an integrating sphere) was used as the testing instrument. Coating samples S1-D2 were coated onto the surface of an aluminum plate, with a dry film thickness controlled at 300 μm to prepare coating samples. Solar reflectance (TSR) was calculated according to ASTM E903 standard, and solar reflectance index (SRI) was calculated according to ASTM E1980 standard. The test results are as follows: Sample S1: TSR=98.3%, SRI=118; Sample S2: TSR=97.8%, SRI=116; Sample S3: TSR=98.5%, SRI=119; Sample S4: TSR=99.1%, SRI=122; Sample D1: TSR=88.5%, SRI=102; Sample D2: TSR=91.2%, SRI=108.

[0063] 2. Surface temperature test Aluminum plates coated with samples S1-D2 were placed under a solar simulator with an irradiation intensity of 1000 W / m². 2 The coating was continuously irradiated for 1 hour. The surface temperature of the coating was measured using an infrared thermal imager. The results showed: The surface temperature of the coating on sample S1 was 42.1℃. The surface temperature of the coating on sample S2 was 42.5℃. The surface temperature of the coating on sample S3 was 41.8℃. The surface temperature of the coating on sample S4 was 41.3℃. Surface temperature of coating on sample D1: 49℃; The surface temperature of the coating on sample D2 was 46.5℃.

[0064] The surface temperature of the coatings (S1-S4) of this invention is 6.5℃-7.7℃ lower than that of the traditional coating (D1), and the temperature reduction effect of the coatings of this invention is significant.

[0065] 3. Photovoltaic application testing Under standard test conditions (AM1.5 spectrum, irradiance 1000 W / m²) 2 Under an ambient temperature of 25℃, bifacial photovoltaic modules (nominal power 400 W) were mounted on substrates coated with samples S1, S4, and D1, respectively. The module tilt angle was set to 30°, and the back side was 1.5 m above the ground. The overall power generation efficiency and back side gain of the modules were tested, and the results are as follows: When mounted on the sample S1 coated substrate, the back-side gain of the component is 18.5%, and the overall efficiency is improved by 14.2%. When mounted on the sample S4 coated substrate, the back-side gain of the component was 21.3%, and the overall efficiency was improved by 16.8%. When mounted on the sample D1 coated substrate, the back-side gain of the component was 8.3%, and the overall efficiency was improved by 6.1%.

[0066] 4. Storage stability test Samples S1, S2, S3, S4, and D2 were sealed and stored in a 50℃ constant temperature oven, and the sedimentation was observed periodically. The test results showed that: Samples S1, S2, S3, and S4 showed no hard precipitate after 6 months of storage, and their reflectivity did not decrease after being stirred evenly. Sample D1 showed obvious stratification after 3 months of storage, and a small amount of soft precipitate appeared at the bottom after 6 months of storage, which could be redispersed after stirring.

[0067] Sample D2 showed obvious stratification after 1 month of storage and formed a hard precipitate that could not be redispersed after 3 months of storage.

[0068] 5. Adhesion Test The adhesion of each coating was tested using the cross-cut adhesion test according to ASTM D3359 standard. The rating results are as follows: Samples S1, S2, S3, and S4 showed an adhesion grade of 5B to the steel plate substrate, with smooth cut edges and no peeling. The adhesion grade of samples D1 and D2 to the steel plate substrate is 4B, and slight peeling occurs at the intersection of the cuts.

[0069] 6. Outdoor stability test Aluminum plates coated with samples S1, S4, and D1 respectively were combined with bifacial photovoltaic modules to form a system, which was then continuously operated in an outdoor environment in Shanghai for 12 months. The solar reflectance of the coatings and the power generation efficiency of the modules were tested monthly. The test results are as follows: Sample S1: Reflectivity degradation: After 12 months, the solar reflectance decreased from the initial 98.3% to 97.5%, a degradation of less than 1%; Improved power generation efficiency: The overall power generation efficiency of the system remains stable between 13% and 15%; Coating appearance: No chalking, peeling or obvious discoloration was observed in the film.

[0070] Sample S4: Reflectivity degradation: After 12 months, the solar reflectance decreased from the initial 99.1% to 98.2%, a degradation of less than 1%. Improved power generation efficiency: The overall power generation efficiency of the system remains stable between 15% and 16%; Coating appearance: No chalking, peeling or obvious discoloration was observed in the film.

[0071] Sample D1: Reflectivity degradation: After 12 months, the solar reflectance decreased from the initial 88.5% to 86.8%, a degradation of less than 2%. Improved power generation efficiency: The overall power generation efficiency of the system remains stable between 5% and 6%; Coating appearance: The film layer is slightly powdery and the edges are slightly raised.

[0072] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A super-reflective photovoltaic enhancement coating, characterized in that, The raw materials include water-based acrylic resin, filler, titanium dioxide, dispersant, defoamer, and leveling agent; wherein the filler includes barium sulfate and / or core-shell particles, and the barium sulfate includes at least one of nano-sized barium sulfate, submicron-sized barium sulfate, micron-sized barium sulfate, and modified barium sulfate.

2. The super-reflective photovoltaic enhancement coating according to claim 1, characterized in that, The composition comprises nano-sized barium sulfate, submicron-sized barium sulfate, and micron-sized barium sulfate, in a mass ratio of (25-40):(30-50):(20-30); the nano-sized barium sulfate has a particle size of 50-100 nm, the submicron-sized barium sulfate has a particle size of 0.5-1 μm, and the micron-sized barium sulfate has a particle size of 5-10 μm; the dispersant includes PVA and / or a wetting and dispersing agent.

3. The super-reflective photovoltaic enhancement coating according to claim 1, characterized in that, The preparation method of modified barium sulfate includes the following steps: Nano-sized, submicron-sized, or micron-sized barium sulfate is dispersed in an aqueous ethanol solution, a silane coupling agent is added, the mixture is stirred at 60-90°C, filtered, and dried to obtain modified barium sulfate.

4. The super-reflective photovoltaic enhancement coating according to claim 1, characterized in that, The preparation method of core-shell particles includes the following steps: Spherical barium sulfate microspheres were ultrasonically dispersed in ethanol, a silane coupling agent was added, and the mixture was stirred at 50-70℃. After the reaction was completed, the microspheres were centrifuged, washed, and dried to obtain activated barium sulfate core spheres. Activated barium sulfate core spheres were ultrasonically dispersed in water, a dispersant was added, and the mixture was stirred. Styrene monomer was added, and the mixture was pre-stirred at 60-80°C under nitrogen protection. Then, an initiator was added, and the mixture was reacted at 60-80°C under nitrogen protection to obtain barium sulfate@PS particles. Barium sulfate@PS particles were ultrasonically dispersed in ethanol, ammonia was added, and the mixture was stirred until homogeneous. TEOS ethanol solution was slowly added dropwise. After the addition was complete, the reaction was stirred and the reaction was continued. After the reaction, the particles were centrifuged, collected, and washed to obtain barium sulfate@PS@SiO2 three-layer core-shell particles. Barium sulfate@PS@SiO2 three-layer core-shell particles were dispersed in toluene, ultrasonically dispersed, stirred and soaked at 50-70℃, and the above steps were repeated with fresh toluene. The particles were then collected by centrifugation, washed, and dried to obtain the core-shell particles.

5. The super-reflective photovoltaic enhancement coating according to claim 4, characterized in that, Spherical barium sulfate microspheres include at least one of small-core spherical barium sulfate microspheres, medium-core spherical barium sulfate microspheres, and large-core spherical barium sulfate microspheres; the particle size of small-core spherical barium sulfate microspheres is 0.1-0.3 μm; the particle size of medium-core spherical barium sulfate microspheres is 0.5-1.0 μm; and the particle size of large-core spherical barium sulfate microspheres is 2-5 μm.

6. The super-reflective photovoltaic enhancement coating according to claim 5, characterized in that, The preparation method of small-core spherical barium sulfate microspheres includes the following steps: Dissolve BaCl2 in deionized water, add PVP, stir to dissolve, and obtain BaCl2 solution; Dissolve Na2SO4 in deionized water to obtain a Na2SO4 solution; Na2SO4 solution was pumped into BaCl2 solution while stirring, and the reaction was carried out at room temperature. After the reaction was completed, the mixture was aged, then centrifuged, washed, and dried to obtain small-core spherical barium sulfate microspheres.

7. The super-reflective photovoltaic enhancement coating according to claim 5, characterized in that, The preparation method of spherical barium sulfate microspheres with a central core includes the following steps: BaCl2 was dissolved in deionized water, PVP and EDTA were added, and the mixture was stirred to dissolve, thus obtaining a BaCl2 solution. Dissolve Na2SO4 in deionized water to obtain a Na2SO4 solution; Na2SO4 solution was pumped into BaCl2 solution while stirring. After the addition was completed at room temperature, stirring continued. Then the reaction mixture was transferred to a hydrothermal reactor and hydrothermally treated at 50-70℃. After the reaction was completed, the mixture was cooled to room temperature, aged, centrifuged, washed, and dried to obtain spherical barium sulfate microspheres with a central core.

8. The super-reflective photovoltaic enhancement coating according to claim 5, characterized in that, The preparation method of large-core spherical barium sulfate microspheres includes the following steps: Add BaCl2, Na2SO4, and PVP to deionized water, stir, and transfer the mixture to a hydrothermal reactor. Place the reactor in an oven, heat it to 160-200℃, keep it at that temperature, close the oven, and allow the reactor to cool naturally to room temperature in the air. Open the reactor, pour out the supernatant, transfer the precipitate to a centrifuge tube, centrifuge, wash, and dry to obtain large-core spherical barium sulfate microspheres.

9. A method for preparing a super-reflective photovoltaic enhancement coating according to any one of claims 1-8, characterized in that, Includes the following steps: Add the filler to deionized water, add the dispersant, and disperse at 1500-2000 rpm at room temperature; add the water-based acrylic resin and stir for 15-20 minutes; add titanium dioxide, defoamer, and leveling agent to adjust the fineness; The viscosity was adjusted and the mixture was filtered to obtain a super-reflective photovoltaic enhancement coating.

10. A super-reflective photovoltaic enhancement coating according to any one of claims 1-8, applied to a photovoltaic module, characterized in that, Super-reflective photovoltaic enhancement coatings are used in conjunction with photovoltaic modules.