Inorganic radiation cooling coating for photovoltaic panels and preparation method thereof

Abstract

The present application discloses an inorganic radiation cooling coating for photovoltaic panels and a preparation method thereof, belonging to the field of energy conservation, environmental protection and new material technology. The upper surface of the photovoltaic panel is photovoltaic glass; the inorganic radiation cooling coating for the photovoltaic panel includes a ceramic particle layer; the ceramic particle layer includes inorganic nano-ceramic particles of at least two sizes; the inorganic nano-ceramic particles of at least two sizes are randomly stacked and fixed on the surface of the photovoltaic glass on the side away from the photovoltaic panel. The inorganic radiation cooling coating provided by the present application is thin in thickness and transparent in color. When applied to a photovoltaic glass panel, it can increase the emissivity of the atmospheric window (8‑13µm) on its surface by about 10%, thereby increasing the radiation cooling power of the photovoltaic panel and reducing the operating temperature of the photovoltaic panel; and the coating can increase the solar transmittance by about 5%, so that the photovoltaic cell receives more light, further improving the photoelectric conversion rate.

Description

Technical Field

[0001] The present application relates to an inorganic radiation cooling coating for photovoltaic panels and a preparation method thereof, belonging to the field of energy conservation, environmental protection and new material technology. Background Art

[0002] Reducing the use of fossil energy and the emission of warm and humid gases has become a global consensus. In 2020, my country formally proposed the strategic goals of reaching carbon peak before 2030 and achieving carbon neutrality before 2060. It is currently vigorously developing new energy such as wind energy, solar energy, bioenergy, geothermal energy, ocean energy, small hydropower and nuclear energy.

[0003] Photovoltaic panels convert solar energy into usable electricity and are currently the most common way to utilize solar energy. Currently, the conversion efficiency of silicon-based photovoltaics at room temperature (25°C) is approximately 20%, but this efficiency decreases by approximately 0.45% for every 1°C increase in temperature. For photovoltaic panels exposed to direct sunlight, the temperature can rise by up to 40°C, with a relative efficiency drop of approximately 18%. This temperature effect leads to a reduction in photoelectric conversion efficiency, which can seriously affect the actual production capacity of photovoltaic panels. Currently, mainstream photovoltaic glass produces surface reflection due to the large imaginary part of its refractive index, with an emissivity of less than 0.85 at the atmospheric window (8-13 µm).

[0004] To lower the operating temperature of photovoltaic panels, a layer of radiation cooling coating can be applied to the surface. However, the current radiation cooling coating is mainly a granular material dispersed in a polymer resin matrix organic coating. Although it has a radiation cooling effect, when applied to photovoltaic panels, there is a problem that the polymer resin matrix layer increases the reflection of sunlight and reduces the sunlight transmittance of the photovoltaic panel, which in turn restricts its conversion efficiency. Summary of the Invention

[0005] According to one aspect of the present application, an inorganic radiation cooling coating for photovoltaic panels is provided, which improves the photoelectric conversion efficiency of photovoltaic panels by changing the solar transmittance of photovoltaic panels, increasing the emissivity of the atmospheric window (8-13um), and reducing the surface temperature of photovoltaic panels.

[0006] This application adopts the following technical solutions:

[0007] An inorganic radiation cooling coating for a photovoltaic panel, wherein the upper surface of the photovoltaic panel is photovoltaic glass;

[0008] An inorganic radiative cooling coating for photovoltaic panels includes a layer of ceramic particles;

[0009] The ceramic particle layer includes inorganic nano-ceramic particles of at least two sizes;

[0010] The inorganic nano-ceramic particles of at least two sizes are randomly stacked and fixed on the surface of the photovoltaic glass facing away from the photovoltaic panel, and air gaps are formed between the inorganic nano-ceramic particles.

[0011] Optionally, the particle size of the inorganic nano-ceramic particles is 5-200 nm.

[0012] Optionally, the particle size of the inorganic nano-ceramic particles is selected from any value of 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, 200nm, or any range value therebetween.

[0013] Optionally, the inorganic radiation cooling coating for photovoltaic panels comprises:

[0014] First-size inorganic nano-ceramic particles with a particle size of L1, L1 = X nm;

[0015] The particle size is L2 second size inorganic nano ceramic particles, Xnm<L2≤X+30nm;

[0016] The particle size is L3 third size inorganic nano ceramic particles, X+30nm<L3≤X+60nm;

[0017] Where X is 5~140.

[0018] Optionally, the thickness of the ceramic particle layer is 10-100 μm.

[0019] Optionally, the thickness of the ceramic particle layer is selected from any value of 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm, or any range therebetween.

[0020] Optionally, the inorganic nano-ceramic particles are selected from at least one of SiO2, TiO2, and Al2O3.

[0021] The inorganic nano-ceramic material used in this application has strong molecular vibrations at the atmospheric window (8-13 µm) and can efficiently absorb mid- and far-infrared light. The layer of inorganic nano-ceramic particles and visible light transparent coating applied to the surface of the photovoltaic glass in this application can suppress the surface reflection of the photovoltaic glass in the atmospheric window band. The particle size of the nano-ceramic particles is much smaller than the wavelength of visible light (400-780nm), so they will not block or scatter visible light, and can maintain the high transmittance of the photovoltaic glass. The ceramic layer formed by stacking particles of multiple sizes can reduce the equivalent refractive index of this interface due to the presence of air gaps, making the refractive index of the photovoltaic glass surface closer to the refractive index of air, thereby reducing sunlight reflection and increasing sunlight transmittance, allowing photovoltaic panels to obtain more solar energy.

[0022] According to another aspect of the present application, a method for preparing the inorganic radiation cooling coating for photovoltaic panels is provided, comprising the following steps:

[0023] S1, adding inorganic nano-ceramic particles of at least two sizes into ethanol and stirring for 1 to obtain a nano-ceramic particle dispersion;

[0024] S2, adding a film-forming aid and a leveling agent to the nano-ceramic particle dispersion prepared in step S1, and stirring for II to obtain a nano-ceramic coating;

[0025] S3. Spray or scrape the nano-ceramic coating in step S2 on the surface of the photovoltaic glass to form an inorganic radiation cooling coating for photovoltaic panels after drying.

[0026] During the drying process, the solvent evaporates and the paint solidifies to form a coating.

[0027] Optionally, in step S2, before spraying or scraping the surface of the photovoltaic glass, the photovoltaic glass is surface cleaned and then sprayed or scraped with an adhesion promoter.

[0028] Optionally, in step S1, the weight ratio of the inorganic nano-ceramic particles to ethanol is 1:3-9.

[0029] In this application, ethanol may be anhydrous ethanol.

[0030] Optionally, in step S2, the content of the film-forming aid in the nano-ceramic coating is 1-2 wt%, and the content of the leveling agent is 0.5-1 wt%.

[0031] Optionally, in step S2, the content of the film-forming aid in the nano-ceramic coating is selected from any value of 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, or any range therebetween.

[0032] Optionally, in step S2, the content of the leveling agent in the nano-ceramic coating is any value among 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, or any range therebetween.

[0033] In the present application, the specific selection range of the film-forming aid, leveling agent, and adhesion promoter is not particularly limited, and those skilled in the art can select and adjust them according to needs.

[0034] Optionally, the stirring conditions I include: a stirring rate of 600-800 r / min and a stirring time of 30-40 min.

[0035] Optionally, the stirring conditions II include: a stirring rate of 600-800 r / min and a stirring time of 30-40 min.

[0036] Optionally, in step S3, the thickness of the spraying and scraping coating is independently 20-60 μm.

[0037] The beneficial effects of this application include:

[0038] The inorganic radiation cooling coating for photovoltaic panels provided in this application is thin and transparent. When applied on a photovoltaic glass panel, it can increase the emissivity of the atmospheric window (8-13 µm) on its surface by about 10%, thereby improving the radiation cooling power of the photovoltaic panel and reducing the operating temperature of the photovoltaic panel; and the coating can increase the solar transmittance by about 5%, allowing the photovoltaic cell to receive more light and further improving the photoelectric conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of the inorganic radiation cooling coating used for photovoltaic panels in an embodiment of the present application.

[0040] Figure 2 This is a comparison chart of the infrared emissivity spectra of different coatings in Test Example 1 of this application.

[0041] Figure 3 This is a comparison chart of solar transmittance spectra of different coatings in Test Example 1 of this application. DETAILED DESCRIPTION

[0042] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0043] Unless otherwise specified, all raw materials and reagents used in this application were purchased from commercial sources and used directly without treatment. The instruments and equipment used adopted the protocols and parameters recommended by the manufacturers.

[0044] Unless otherwise specified, the technical means used in the embodiments of the present invention are conventional means well known to those skilled in the art.

[0045] The atmospheric window emissivity is measured using a Fourier transform infrared spectrometer with an integrating sphere. The equipment performance must meet the following requirements: the infrared spectrometer's wavelength range must be no less than 3μm to 25μm; the integrating sphere's inner diameter must be no less than 60mm, and its inner wall must be made of highly reflective material; the standard plate must be a polytetrafluoroethylene plate or a gold mirror (certified by the metrology department and within the validity period). The atmospheric window emissivity measurement range is 0.05 to 0.99, with a detection accuracy of 0.01 or higher.

[0046] The atmospheric window emissivity refers to the provisions of 4.3 in JGJ / T287-2014, and the result of the atmospheric transmission window band (8-13) μm is taken and calculated according to formula (1), where G λ The selection of λ is shown in Table A.1 in Appendix A of AJGJ / T287-2014. The atmospheric window (8-13) μm emissivity of three samples should be tested, and the arithmetic mean value should be taken as the final result.

[0047] Formula (1).

[0048] The test method for solar transmittance refers to the provisions of 5.1.1 of GB / T 2680-2021, taking the results of the visible light band (380nm~780nm), and calculating according to formula (2), using D λ V( λ )Δ λ The values ​​of the corresponding bands can be found in Table 1 of the GB / T 2680-2021 standard. The solar transmittance of three tests should be tested and the arithmetic average should be taken as the final result.

[0049] Formula (2).

[0050] The test of photoelectric conversion efficiency is to test the output power of photovoltaic panels of samples with different serial numbers and compare the changes in photoelectric conversion efficiency.

[0051] Example 1:

[0052] (1) Silica (SiO2) particles were selected as ceramic particles. 50 g of SiO2 particles were weighed, including 30 g of particles with a diameter of 5-20 nm, 15 g of particles with a diameter of 20-50 nm, and 5 g of particles with a diameter of 50-80 nm. 440 g of anhydrous ethanol was added and stirred at a rate of 600-800 r / min for 30-40 min to obtain a nano-silica dispersion.

[0053] (2) Add 5 g of film-forming aid (Dow alcohol ester twelve) and 5 g of leveling agent (Dow RM2020NPR) to the nano-silicon oxide dispersion, and stir at a rate of 600-800 r / min for 5-10 min to obtain a nano-silicon oxide coating;

[0054] (3) Clean the surface of photovoltaic glass with glass cleaner;

[0055] (4) Spray or scrape the adhesion promoter (Hengying 952) evenly on the upper surface of the photovoltaic glass, and then evenly spray the nano-ceramic coating with a thickness of 30 μm;

[0056] (5) After the solvent evaporates, an inorganic nano-silicon oxide radiation cooling layer will be formed on the surface of the photovoltaic glass.

[0057] The coating obtained in Example 1 is recorded as coating 1, and the corresponding glass is recorded as sample 1.

[0058] Example 2:

[0059] (1) Silica (SiO2) particles were selected as ceramic particles. 50 g of SiO2 particles were weighed, including 5 g of particles with a diameter of 5-20 nm, 30 g of particles with a diameter of 20-50 nm, and 15 g of particles with a diameter of 50-80 nm. 440 g of anhydrous ethanol was added and stirred at a rate of 600-800 r / min for 30-40 min to obtain a nano-silica aqueous dispersion.

[0060] (2) Add 5 g of film-forming aid (Dow alcohol ester twelve) and 5 g of leveling agent (Dow RM2020NPR) to the nano-silicon oxide dispersion, and stir at a rate of 600-800 r / min for 5-10 min to obtain a nano-silicon oxide coating;

[0061] (3) Clean the surface of photovoltaic glass with glass cleaner;

[0062] (4) Spray or scrape the adhesion promoter (Hengying 952) evenly on the upper surface of the photovoltaic glass, and then evenly spray the nano-ceramic coating with a thickness of 50 μm;

[0063] (5) After the solvent evaporates, an inorganic nano-silicon oxide radiation cooling layer will be formed on the surface of the photovoltaic glass.

[0064] The coating obtained in Example 2 is recorded as coating 2, and the corresponding glass is recorded as sample 2.

[0065] Example 3:

[0066] (1) Alumina (Al2O3) particles were selected as ceramic particles. 50 g of particles were weighed, including 30 g of particles with a diameter of 5-20 nm, 15 g of particles with a diameter of 20-50 nm, and 5 g of particles with a diameter of 50-80 nm. 440 g of anhydrous ethanol was added and stirred at a rate of 600-800 r / min for 30-40 min to obtain a nano-alumina dispersion.

[0067] (2) Add 5 g of film-forming aid (Dow alcohol ester twelve) and 5 g of leveling agent (Dow RM2020NPR) to the nano-alumina dispersion, and stir at a rate of 600-800 r / min for 5-10 min to obtain a nano-alumina coating;

[0068] (3) Clean the surface of photovoltaic glass with glass cleaner;

[0069] (4) Spray or scrape the adhesion promoter (Hengying 952) evenly on the upper surface of the photovoltaic glass, and then evenly spray the nano-ceramic coating with a thickness of 30 μm;

[0070] (5) After the solvent evaporates, an inorganic nano-aluminum oxide radiation cooling layer will be formed on the surface of the photovoltaic glass.

[0071] The coating obtained in Example 3 is recorded as coating 3, and the corresponding glass is recorded as sample 3.

[0072] Example 4:

[0073] (1) Alumina (Al2O3) particles were selected as ceramic particles. 50 g of particles were weighed, including 5 g of particles with a diameter of 5-20 nm, 30 g of particles with a diameter of 20-50 nm, and 15 g of particles with a diameter of 50-80 nm. 440 g of anhydrous ethanol was added and stirred at a rate of 600-800 r / min for 30-40 min to obtain a nano-alumina dispersion.

[0074] (2) Add 5 g of film-forming aid (Dow alcohol ester twelve) and 5 g of leveling agent (Dow RM2020NPR) to the nano-alumina dispersion, and stir at a rate of 600-800 r / min for 5-10 min to obtain a nano-alumina coating;

[0075] (3) Clean the surface of photovoltaic glass with glass cleaner;

[0076] (4) Spray or scrape the adhesion promoter (Hengying 952) evenly on the upper surface of the photovoltaic glass, and then evenly spray the nano-ceramic coating with a thickness of 50 μm;

[0077] (5) After the solvent evaporates, an inorganic nano-aluminum oxide radiation cooling layer will be formed on the surface of the photovoltaic glass.

[0078] The coating obtained in Example 4 is recorded as coating 4, and the corresponding glass is recorded as sample 4.

[0079] Example 5:

[0080] (1) Titanium oxide (TiO2) particles were selected as ceramic particles. 50 g of the particles were weighed, including 5 g of particles with a diameter of 5-20 nm, 30 g of particles with a diameter of 20-50 nm, and 15 g of particles with a diameter of 50-80 nm. 440 g of anhydrous ethanol was added and stirred at a rate of 600-800 r / min for 30-40 min to obtain a nano-titanium oxide dispersion.

[0081] (2) Add 5 g of film-forming aid (Dow alcohol ester twelve) and 5 g of leveling agent (Dow RM2020NPR) to the nano titanium oxide dispersion, and stir at a rate of 600-800 r / min for 5-10 min to obtain a nano titanium oxide coating;

[0082] (3) Clean the surface of photovoltaic glass with glass cleaner;

[0083] (4) Spray or scrape the adhesion promoter (Hengying 952) evenly on the upper surface of the photovoltaic glass, and then evenly spray the nano-ceramic coating with a thickness of 50 μm;

[0084] (5) After the solvent evaporates, an inorganic nano-titanium oxide radiation cooling layer will be formed on the surface of the photovoltaic glass.

[0085] The coating obtained in Example 5 is recorded as Coating 5, and the corresponding glass is recorded as Sample 5.

[0086] The schematic diagram of the structure of the inorganic radiation cooling coating for photovoltaic panels obtained in Examples 1 to 5 is as follows: Figure 1 As shown, ceramic particles of three sizes are randomly stacked on the surface of photovoltaic glass.

[0087] Test Example 1:

[0088] Ordinary photovoltaic glass was taken without any treatment and recorded as sample 6.

[0089] The infrared emissivity spectra and solar transmittance spectra of glass samples 1 to 6 were tested and compared. The results are as follows: Figure 2 、 Figure 3 It can be found that after applying different coatings on the surface, the infrared emissivity and solar transmittance of photovoltaic glass are increased.

[0090] Comparing the atmospheric window (8-13 μm) emissivity and the corresponding photoelectric conversion efficiency changes of different samples, the results shown in Table 1 below are obtained. This comparison shows that the inorganic radiative cooling coating provided by the present invention can increase the atmospheric window (8-13 μm) emissivity of the photovoltaic glass surface by approximately 10%, thereby improving the radiative cooling power of the photovoltaic panel and reducing the operating temperature of the photovoltaic panel. In addition, the coating can increase the solar transmittance by approximately 5%, allowing the photovoltaic cell to receive more light and further improving the photoelectric conversion efficiency. The coating has great application prospects in the field of photovoltaic power generation.

[0091] Table 1: Comparison of photoelectric conversion efficiency of different samples

[0092]

[0093] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An inorganic radiation cooling coating for photovoltaic panels, characterized in that: The upper surface of the photovoltaic panel is photovoltaic glass; An inorganic radiative cooling coating for photovoltaic panels includes a layer of ceramic particles; The ceramic particle layer includes inorganic nano-ceramic particles of three sizes; The three sizes of inorganic nano-ceramic particles are randomly stacked and fixed on the surface of the photovoltaic glass facing away from the photovoltaic panel, and air gaps are formed between the inorganic nano-ceramic particles; The particle size of the inorganic nano-ceramic particles is 5 to 200 nm; The inorganic radiation cooling coating for photovoltaic panels comprises: First-size inorganic nano-ceramic particles with a particle size of L1, L1 = X nm; The particle size is L2 second size inorganic nano ceramic particles, Xnm<L2≤X+30nm; The particle size is L3 third size inorganic nano ceramic particles, X+30nm<L3≤X+60nm; Where X is 5~140; The inorganic nano-ceramic particles are selected from at least one of SiO2, TiO2, and Al2O3; The method for preparing the inorganic radiation cooling coating for photovoltaic panels comprises the following steps: S1. Adding inorganic nano-ceramic particles of three sizes into ethanol and stirring for 1 minute to obtain a nano-ceramic particle dispersion; S2, adding a film-forming aid and a leveling agent to the nano-ceramic particle dispersion prepared in step S1, and stirring for II to obtain a nano-ceramic coating; S3, spraying or scraping the nano-ceramic coating in step S2 on the surface of the photovoltaic glass to form an inorganic radiation cooling coating for the photovoltaic panel after drying; In step S1, the weight ratio of the inorganic nano-ceramic particles to the ethanol is 1:3-9; In step S2, in the nano-ceramic coating, the content of the film-forming aid is 1-2 wt%, and the content of the leveling agent is 0.5-1 wt%.

2. The inorganic radiation cooling coating for photovoltaic panels according to claim 1, characterized in that: The thickness of the ceramic particle layer is 10-100 μm.

3. The inorganic radiation cooling coating for photovoltaic panels according to claim 1, characterized in that: The stirring conditions include: a stirring rate of 600-800 r / min and a stirring time of 30-40 min; The stirring conditions of II include: a stirring rate of 600-800 r / min and a stirring time of 30-40 min.

4. The inorganic radiation cooling coating for photovoltaic panels according to claim 1, characterized in that: In step S3, the thickness of the spray coating and the scraping coating is independently 20-60 μm.

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