CN115274897B - A highly reflective light-converting photovoltaic backsheet and double-sided photovoltaic modules - Google Patents

Abstract

The invention relates to the technical field of photovoltaic back plates, and discloses a high-reflection photovoltaic back plate and a double-sided photovoltaic module. The photovoltaic backboard comprises a fluorocarbon transparent coating, a down-conversion transparent base film, a down-conversion transparent coating, a high-reflection grid coating and an up-conversion transparent grid coating which are sequentially laminated from an air surface to a packaging adhesive film surface; wherein the down-conversion transparent base film is formed by co-extrusion of a PBT layer, a PET layer and a down-conversion film layer; wherein the down-conversion transparent coating is formed by coating and curing after fluorocarbon resin, acrylic resin, down-conversion nano material, curing agent and auxiliary agent are mixed into the down-conversion transparent coating; the down-conversion nano material is down-conversion nano inorganic photochromic material, and is quantum dot and Ce for generating photochromic for light energy with wavelength of 200-780nm and converting the photochromic material into visible light ³⁺ Doped fluoride and Eu ³⁺ At least one of the tellurate is doped. The photovoltaic backboard improves the double-sided rate and the power generation capacity of the double-sided photovoltaic module.

Description

A highly reflective light-converting photovoltaic backsheet and double-sided photovoltaic modules

technical field

The invention relates to the technical field of photovoltaic backplanes, in particular to a highly reflective light conversion photovoltaic backplane and a double-sided photovoltaic module.

Background technique

Efficient use of renewable energies such as solar, wind and tidal energy is one solution to sustainable energy use. The cost of semiconductor solar cell materials is relatively high, while spectral conversion materials have the advantages of low cost and simple process. Using spectral conversion materials to improve the power generation efficiency of photovoltaic cell modules (referred to as photovoltaic modules) can obtain higher marginal yields and reduce The cost per unit of power generation can be obtained to obtain more cost-effective photovoltaic modules. Therefore, spectral conversion materials used to improve the efficiency of solar cells have gradually become a hot topic of research. The use of spectral conversion layers for solar cells can overcome the inherent heat loss and spectral loss, which has great application potential. The spectral conversion material is applied to solar cells in the form of a spectral conversion layer, which can absorb solar photons that cannot be effectively used or captured, and convert them into photons in a high-response band. The advantage of the spectral conversion layer is that no modification of the standard solar cell architecture or intrinsic device materials is required, and the spectral conversion material can be scientifically selected for a specific type of solar cell.

At present, solar monocrystalline or polycrystalline solar cell modules on the market usually adopt the following structure, that is, front glass, packaging film (such as EVA layer), photovoltaic cells, and packaging film (such as EVA layer) are stacked sequentially from top to bottom. layer), backplane. In such a structure, the light transmittance of the front glass and the packaging film should be more concerned, which is generally required to be above 91%, so as to absorb as many photons as possible, so that the photovoltaic cells have higher conversion efficiency and power output; It is a fluorine-containing polymer composite material, which plays a protective role such as water blocking and insulation.

The power generation of photovoltaic modules is closely related to the spectral range and proportion absorbed by the surface of photovoltaic cells incident on the interior of photovoltaic modules. The spectral response of traditional single-polycrystalline silicon cells and the recently rapidly developed black silicon and backside cells all have a commonality, that is, to The conversion efficiency of the ultraviolet band is significantly lower than that of the visible light band, and the utilization rate of ultraviolet light is obviously low. Therefore, it is necessary to convert the ultraviolet band with low utilization rate into the visible band with higher utilization rate. Therefore, organic fluorescent dyes, organic-inorganic rare earth compounds, and up-conversion materials are tried to be applied in photovoltaic module materials in order to increase the power output of photovoltaic modules. For example, the prior art, such as CN107564984A, also provides a high weather resistance, high-gain solar cell backboard, assembly and preparation method, the solar cell backboard includes a light-directional reflection function and a light wave conversion function arranged on the substrate layer The adhesive inner layer is provided with a fine structure on the outer surface of the adhesive inner layer, and the light utilization rate of the solar energy transmitted to the front of the photovoltaic module is improved by the adhesive inner layer and the fine structure, and the output power is increased. However, the existing solar cell backsheet still has a low utilization rate of the light on the front and back of the photovoltaic module, so it is not effective in improving the light transmittance in the 380-1100nm band and the light reflectance in the 400-800nm band. Obviously, the bifacial rate of the existing solar cell backsheet applied to the double-sided photovoltaic module is low, which further affects the power generation and power generation efficiency of the double-sided photovoltaic module.

Contents of the invention

One of the purposes of the present invention is to overcome the deficiencies of the prior art and provide a highly reflective photo-converting photovoltaic backsheet to effectively solve the technical problem of low bifaciality of double-sided photovoltaic modules obtained by using the existing photovoltaic backsheet.

The second object of the present invention is to overcome the shortcomings of the prior art and provide a double-sided photovoltaic module with the highly reflective light-converting photovoltaic backplane.

Based on this, the present invention discloses a highly reflective photo-converting photovoltaic backplane, which includes a fluorocarbon transparent coating, a down-converting transparent base film, and a down-converting transparent coating layered sequentially from the air surface to the encapsulating film surface. , highly reflective mesh coating and up-converting transparent mesh coating;

Wherein, the transparent base film of the down-conversion is a composite base film formed by a three-layer co-extrusion process of a PBT layer, a PET layer and a down-conversion film layer;

Wherein, the down-conversion transparent coating is prepared by mixing fluorocarbon resin, acrylic resin, down-conversion nano-material, curing agent and auxiliary agent, and then coated and cured; the down-conversion nano-material It is a down-converting nano-inorganic photochromic material, which is a quantum dot, Ce ³⁺ doped fluoride and Eu ³⁺ doped tellurate that produces photochromic light energy with a wavelength of 200-780nm and converts it into visible light. at least one.

Preferably, the color of the quantum dots includes at least one of blue, green and red; the particle size of the quantum dots is 5-20nm, or the Ce ³⁺ doped fluoride and Eu ³⁺ doped The particle size of tellurate is 30-80nm.

Wherein, the quantum dots are: quantum dots such as cadmium selenide, zinc sulfide, zinc selenide, cadmium sulfide, indium phosphide, such as alloy quantum dots of cadmium zinc selenium, cadmium zinc selenium sulfur, phosphorus zinc indium sulfur, such as Core-shell quantum dots of cadmium selenide@zinc sulfide, indium phosphide@zinc sulfide, cadmium zinc selenium@zinc sulfide, cadmium zinc selenium sulfur@zinc sulfide.

Preferably, the down-conversion transparent coating used in the down-conversion transparent coating includes the following raw materials in parts by weight: 55-80 parts of FEVE resin, 10-35 parts of acrylic resin, 0.3-1 part of down-conversion nanomaterial, 5 parts of isocyanate curing agent -10 parts, 8-15 parts of solvent; the thickness of the down conversion transparent coating is 5-15 μm.

Preferably, the thickness of the PBT layer is 5-10 μm, the thickness of the PET layer is 255-265 μm, and the thickness of the down conversion film layer is 5-30 μm.

Preferably, the refractive index of the fluorocarbon transparent coating is 1.40-1.45, and the refractive index of the down-conversion transparent base film is 1.5-1.6.

Further preferably, the fluorocarbon transparent coating used in the fluorocarbon transparent coating includes the following raw materials in parts by weight: 20-45 parts of polytetrafluoroethylene resin, 15-30 parts of polyvinylidene fluoride resin, and 15-25 parts of acrylic resin , 6-10 parts of isocyanate curing agent, 5-12 parts of silica filler, 3-10 parts of propylene glycol methyl ether acetate solvent, 0.2-1 part of ultraviolet absorber, 0.1-1 part of antioxidant, 0.2-1 part of leveling agent 1 part, 0.4-2 parts of defoaming agent; the thickness of the fluorocarbon transparent coating is 15-25 μm.

Preferably, the high-reflection grid coating is prepared by mixing fluorocarbon resin, acrylic resin, titanium dioxide, curing agent and additives to form a white high-reflection grid coating, which is screen-printed and cured; The particle size of titanium dioxide is 300-600nm.

Further preferably, the high-reflection grid coating used for the high-reflection grid coating includes the following raw materials in parts by weight: 40-70 parts of fluorocarbon resin, 10-20 parts of acrylic resin, 20-50 parts of titanium dioxide, and isocyanate curing 4-5 parts of agent, 0.2-2 parts of leveling agent, 0.4-1 part of defoamer, 0.2-0.5 part of stabilizer, 0.3-1 part of antioxidant, 2-8 parts of solvent; The thickness of the layer is 5-15 μm.

Preferably, the up-conversion transparent grid coating is prepared by mixing fluorocarbon resin, acrylic resin, up-conversion nanomaterials, curing agent and additives, and then screen-printed and cured to form an up-conversion transparent grid coating; The up-conversion nano material is an up-conversion nano inorganic photochromic material, which is a material that produces photochromism for light energy with a wavelength of 980-1600nm and converts it into visible light.

Further preferably, the up-conversion nanomaterial is NaYF ₄ :Er ³⁺ /Yb ³⁺ , LiYF ₄ :Er ³⁺ /Yb ³⁺ , NaYF ₄ :Yb ³⁺ /Tm ³⁺ with a particle size of 5-20 nm , NaYF ₄ : Ho ³⁺ /Yb ³⁺ , Ho ³⁺ /Yb ³⁺ co-doped Gd ₂ O ₃ and E ³⁺ /Yb ³⁺ co-doped CeO ₂ nanowires.

Further preferably, the up-conversion transparent grid coating used in the up-conversion transparent grid coating includes the following raw materials in parts by weight: 50-80 parts of fluorocarbon resin, 10-40 parts of acrylic resin, 0.2-1 parts of up-conversion nanomaterial 1 part, 7-8 parts of isocyanate curing agent, 0.2-1 part of leveling agent, 0.2-0.5 part of defoamer, 0.4-1 part of stabilizer, 0.3-0.5 part of antioxidant, 18-28 parts of solvent; The thickness of the conversion transparent grid coat is 5-10 μm.

The invention also discloses a double-sided photovoltaic module, which comprises a photovoltaic front plate, a first encapsulation film, a photovoltaic battery sheet, a second encapsulation film and a photovoltaic back plate which are sequentially stacked from top to bottom. The board is a high-reflection photo-converting photovoltaic backplane as described above in the content of the present invention; the up-conversion transparent grid coating is pasted on the second encapsulation adhesive film, and the high-reflection grid coating and The grid position of the up-conversion transparent grid coating corresponds to the gap between two adjacent photovoltaic cells.

Compared with the prior art, the present invention at least includes the following beneficial effects:

The photovoltaic backplane of the present invention is provided through the above-mentioned fluorocarbon transparent coating, down-conversion transparent base film, down-conversion transparent coating, high-reflection grid coating and up-conversion transparent grid that are sequentially arranged from the air surface to the encapsulation film surface The combination of the coating can not only ensure the weather resistance and corrosion resistance of the photovoltaic backsheet, but also effectively utilize the light on the back of the double-sided photovoltaic module through the functions of anti-reflection, down-conversion, reflection, and up-conversion of sunlight. The ultraviolet light is converted into visible light, and the sunlight enters the photovoltaic cells from the back of the photovoltaic backplane, and the light transmitted from the front of the double-sided photovoltaic module is reflected back to improve the double-sided ratio of the double-sided photovoltaic module, and after up-conversion When the transparent grid coating is used, it can also convert infrared light into visible light and reflect it back to the surface of the photovoltaic cell of the double-sided photovoltaic module, which effectively solves the problem of low double-sided ratio of the double-sided photovoltaic module and improves the power generation of the double-sided photovoltaic module amount and power generation efficiency; moreover, the down-conversion transparent base film can improve the adhesion performance between it and the down-conversion transparent coating, and can also increase the thickness of the down-conversion layered structure, improve the transmittance of visible light, and More ultraviolet light is converted into visible light, which improves the utilization rate of light, further improves the power generation and power generation efficiency of double-sided photovoltaic modules, and can absorb part of ultraviolet light to protect the photovoltaic backplane.

Description of drawings

FIG. 1 is a schematic diagram of a partial cross-sectional structure of a highly reflective photo-converting photovoltaic backplane of this embodiment.

FIG. 2 is a schematic diagram of the front structure of a highly reflective photo-converting photovoltaic backplane of this embodiment.

Description of reference numerals: fluorocarbon transparent coating 1; down-converting transparent base film 2; PBT layer 21; PET layer 22; down-converting film layer 23; down-converting transparent coating 3; Convert Clear Mesh Coat 5.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

A highly reflective photo-converting photovoltaic backplane of this embodiment, as shown in Figure 1-2, is a multi-layer structure formed by coating and superposition, including a down-converting transparent base film 2, and a transparent base film stacked on the down-converting base film Fluorocarbon transparent coating 1 on the air side (i.e. the back side) of 2, and a down-conversion transparent coating layer 3 stacked on the encapsulation film surface (i.e. the front side) of the down-converted transparent base film 2; the down-conversion transparent coating layer 3 The front side is also provided with a highly reflective grid coating 4 and an up-conversion transparent grid coating 5 stacked in sequence.

Wherein, the transparent base film 2 of down-conversion is the composite base film that PBT layer 21, PET layer 22 and down-conversion film layer 23 form through three-layer co-extrusion process; The thickness of PBT layer 21 is 5-10 μ m, the thickness of PET layer 22 The thickness of the down conversion film layer 23 is 5-30 μm.

The production process of the down-converted transparent base film 2 is as follows: after drying the PBT colloidal particles, adding auxiliary agents such as antioxidant, hydrolysis-resistant auxiliary agent, and adhesion promoter, shaking well, to obtain the mixture 1; and After drying the PET colloidal particles, add additives such as antioxidant, hydrolysis-resistant additive, and UV absorber, and shake well to obtain Mixture 2; at the same time, after drying the PBT colloidal particles, add the following converted nanomaterials, anti- Oxygen agent, auxiliary agent of adhesion promoter, shake well to obtain compound 3; then add compound 1, compound 2 and compound 3 into the corresponding extruder respectively, and successively undergo three-layer co-extrusion and plasticization Forming, calendering and shaping with a three-roll calender, and winding with a coiler to obtain the down-converted transparent base film 2 . Wherein, the drying temperature of PBT colloidal particles and PET colloidal particles is 100-150°C, preferably 120°C.

In the process of preparing the down-conversion transparent base film 2, an adhesion promoter is usually added to the raw materials of the PBT layer 21 and the down-conversion film layer 23, so that the front and back sides of the down-conversion transparent base film 2 made It has good adhesion properties with down conversion clear coat 3 and fluorocarbon clear coat 1 respectively. And, because some raw materials are the same between the down-conversion thin film layer 23 and the down-conversion transparent coating layer 3, the adhesion performance between the down-conversion transparent base film 2 and the down-conversion transparent coating layer 3 can be further improved; and down conversion Adding a down-converting film layer 23 to the transparent base film 2 can also increase the thickness of the down-converted layered structure, increase the transmittance of visible light, and convert more ultraviolet light into visible light, improve light utilization efficiency, and improve dual The power generation and power generation efficiency of surface photovoltaic modules; and while converting ultraviolet light into visible light, it can also absorb part of ultraviolet light, so it can also protect the photovoltaic backplane to prevent the photovoltaic backplane from yellowing and aging due to ultraviolet rays.

Wherein, the thickness of the fluorocarbon transparent coating 1 is 15-25 μm. The fluorocarbon transparent coating 1 is: the fluorocarbon transparent coating is prepared by mixing polytetrafluoroethylene resin, polyvinylidene fluoride resin, acrylic resin, curing agent, ultraviolet absorber and auxiliary agent, and then coated and cured to shape.

Specifically, the fluorocarbon transparent coating used in the fluorocarbon transparent coating 1 includes the following raw materials in parts by weight: 20-45 parts of polytetrafluoroethylene resin, 15-30 parts of polyvinylidene fluoride resin, and 15-25 parts of acrylic resin , 6-10 parts of isocyanate curing agent, 5-12 parts of silica filler, 3-10 parts of propylene glycol methyl ether acetate solvent, 0.2-1 part of ultraviolet absorber, 0.1-1 part of antioxidant, 0.2-1 part of leveling agent 1 part, 0.4-2 parts of defoamer.

In order to reduce the cost and further improve the adhesive performance between the fluorocarbon transparent coating 1 and the down-conversion transparent base film 2, the fluorocarbon transparent coating 1 is formulated with polytetrafluoroethylene resin and polyvinylidene fluoride resin. An appropriate amount of acrylic resin is added as the main resin; these three main resins are combined with curing agent, ultraviolet absorber and additives, so that the obtained fluorocarbon transparent coating 1 can provide excellent weather resistance and corrosion resistance for photovoltaic backplanes sex.

In practice, the refractive index of the down-conversion transparent base film 2 is 1.5-1.6, while the refractive index of the fluorocarbon transparent coating 1 is 1.40-1.45, preferably 1.40-1.42, slightly lower than the down-conversion transparent base film 2 In this way, more sunlight can pass through the fluorocarbon transparent coating 1 and enter the photovoltaic backplane, so as to cooperate with the down-converting transparent base film 2, down-converting transparent coating 3, and high-reflection grid coating The layer 4 and the up-conversion transparent grid coating 5 improve the utilization rate of the light on the back of the double-sided photovoltaic module, increase the double-sided ratio of the double-sided photovoltaic module, and further improve the power generation and power generation efficiency of the double-sided photovoltaic module.

Wherein, the thickness of the down conversion transparent coating layer 3 is 8-20 μm, preferably 5-15 μm. The down-converting transparent coating 3 is: the down-converting transparent coating is prepared by mixing fluorocarbon resin, acrylic resin, down-converting nano-materials, curing agent and auxiliary agent, and then coated and cured.

Specifically, the down-converting transparent coating used in the down-converting transparent coating 3 includes the following raw materials in parts by weight: 55-80 parts of FEVE resin, 10-35 parts of acrylic resin, 0.3-1 part of down-converting nanomaterials, isocyanate curing agent 5-10 parts, solvent 8-15 parts.

The down-conversion nano-material used in the down-conversion thin film layer 23 and the down-conversion transparent coating 3 of the present embodiment is a down-conversion nano-inorganic photochromic material, which can produce photochromism for light with a wavelength of 200-780nm and will Light with a wavelength of 200-780nm is converted into at least one of quantum dots, Ce ³⁺ doped fluoride and Eu ³⁺ doped tellurate into visible light. The color of the quantum dot is at least one of blue, green and red; the quantum dot is specifically: quantum dots such as cadmium selenide, zinc sulfide, zinc selenide, cadmium sulfide, indium phosphide, and cadmium Alloy quantum dots of zinc selenium, cadmium zinc selenium sulfur, phosphorus zinc indium sulfur, and core-shell of cadmium selenide@zinc sulfide, indium phosphide@zinc sulfide, cadmium zinc selenium@zinc sulfide, cadmium zinc selenium sulfur@zinc sulfide Structured quantum dots.

In the down-conversion nanomaterial, the particle size of the quantum dot is 5-20nm, and the particle size of Ce ³⁺ doped fluoride and Eu ³⁺ doped tellurate is 30-80nm; thus, the down-conversion nanomaterial is nanometer-sized , therefore, the transparency and light transmission performance of the down-conversion transparent coating 3 and the down-conversion thin film layer 23 can be improved; moreover, the down-conversion transparent coating 3 can convert the ultraviolet light entering the photovoltaic backplane into visible light, which can improve the double-sided The power generation and power generation efficiency of the front and back of photovoltaic modules.

Wherein, the thickness of the highly reflective mesh coating 4 is 5-15 μm, preferably 5-10 μm. The high-reflection grid coating 4 is: a white high-reflection grid coating is prepared by mixing fluorocarbon resin, acrylic resin, titanium dioxide, curing agent and auxiliary agent, and then screen-printed and cured to shape. Among them, the particle size of the titanium dioxide is 300-600nm, and the titanium dioxide with an average particle size of 400nm is selected. In the case of the same addition amount, the high reflection grid coating 4 has a higher light reflectivity.

Specifically, the high-reflection grid coating used in the high-reflection grid coating 4 includes the following raw materials in parts by weight: 40-70 parts of fluorocarbon resin, 10-20 parts of acrylic resin, 20-50 parts of titanium dioxide, and isocyanate curing 4-5 parts of agent, 0.2-2 parts of leveling agent, 0.4-1 part of defoamer, 0.2-0.5 part of stabilizer, 0.3-1 part of antioxidant, 2-8 parts of solvent.

Wherein, the thickness of the up-conversion transparent grid coating 5 is 5-10 μm. The up-conversion transparent grid coating 5 is prepared by mixing fluorocarbon resin, acrylic resin, up-conversion nano-materials, curing agent and auxiliary agent, and then screen-printed and cured to form the up-conversion transparent grid coating.

Specifically, the up-conversion transparent grid coating used in the up-conversion transparent grid coating 5 includes the following raw materials in parts by weight: 50-80 parts of fluorocarbon resin, 10-40 parts of acrylic resin, and 0.2-1 parts of up-conversion nanomaterials. 1 part, 7-8 parts of isocyanate curing agent, 0.2-1 part of leveling agent, 0.2-0.5 part of defoamer, 0.4-1 part of stabilizer, 0.3-0.5 part of antioxidant, 18-28 parts of solvent.

The up-converting nanomaterial is an up-converting nano-inorganic photochromic material, which can produce photochromism for light with a wavelength of 980-1600nm and convert light with a wavelength of 980-1600nm into visible light; preferably: NaYF ₄ : Er ³⁺ /Yb ³⁺ , LiYF ₄ : Er ³⁺ /Yb ³⁺ , NaYF ₄ : Yb ³⁺ /Tm ³⁺ , NaYF ₄ : Ho ³⁺ /Yb ³⁺ , Ho ³⁺ /Yb ³⁺ At least one of doped Gd ₂ O ₃ and E ³⁺ /Yb ³⁺ co-doped CeO ₂ nanowires. The particle size of the up-conversion nano material is 5-20nm, like this, the up-conversion nano-material in the up-conversion transparent grid coating 5 is nanometer size, therefore, can ensure the excellent transparency and transparency of the up-conversion transparent grid coating 5 Light transmission performance.

In the photovoltaic backplane of the present embodiment, the highly reflective grid coating 4 and the up-conversion transparent grid coating 5 are coatings of a grid structure; Transparent mesh paint can greatly reduce the use of highly reflective mesh paint and up-conversion transparent mesh paint, saving costs. Moreover, the grid positions of the high-reflection grid coating 4 and the up-conversion transparent grid coating 5 correspond to the gap position between two adjacent photovoltaic cells, that is, only the grid corresponding to the gap position Positions are painted with a highly reflective mesh paint and an upconversion transparent mesh paint. Specifically, the sum of the projected areas of the highly reflective grid coating 4 on the surface of the down-conversion transparent coating 3 is 15-25%, preferably 20%, with the ratio of the area of the down-conversion transparent coating 3 surface; The ratio of the sum of the projected areas of the lattice coating 5 on the surface of the down-conversion transparent coating 3 to the area of the surface of the down-conversion transparent coating 3 is not less than 15%. In this way, the high-reflection grid coating 4 can effectively reflect the sunlight passing through the gaps on the front side of the photovoltaic cells, and the sunlight on the back side can also pass through the adjacent grids of the white high-reflection grid coating 4. Through the gap between them and into the photovoltaic cells from the back of the photovoltaic backsheet, the light utilization rate of the double-sided photovoltaic module is improved, and the power generation and power generation efficiency of the double-sided photovoltaic module are improved, while the up-conversion transparent grid coating 5. It can further effectively convert the light with a wavelength of 980-1600nm from the front and back to the green light with a wavelength of 550nm, and then reflect it back to the surface of the photovoltaic cell of the double-sided photovoltaic module, so that the double-sided rate of the double-sided photovoltaic module can be improved , to further improve the power generation and power generation efficiency of double-sided photovoltaic modules. The high reflection grid coating 4 and the up-conversion transparent grid coating 5 are formed by screen printing, so the grid shapes of the high reflection grid coating 4 and the up-conversion transparent grid coating 5 are the same as those of the screen printing. The shape of the mesh of the plate is consistent, and the shape of the mesh includes but is not limited to square, rectangle or other shapes.

To sum up, the photovoltaic backplane of this embodiment passes through the fluorocarbon transparent coating 1, the down-converting transparent base film 2, the down-converting transparent coating 3, and the high-reflection grid coating that are sequentially arranged from the air surface to the encapsulating film surface. The combination of layer 4 and up-conversion transparent grid coating 5 can not only ensure the weather resistance and corrosion resistance of the photovoltaic backplane, but also effectively utilize The light on the back of the double-sided photovoltaic module converts ultraviolet light into visible light, and makes sunlight enter the photovoltaic cell from the back of the photovoltaic backplane, and reflects back the light transmitted from the front of the double-sided photovoltaic module, improving the performance of the double-sided photovoltaic module. The double-sided rate, and after the up-converting transparent grid coating5, can also convert infrared light into visible light, reflect back to the surface of the photovoltaic cell of the double-sided photovoltaic module, effectively solve the problem of low double-sided ratio of double-sided photovoltaic modules problems, improve the power generation of double-sided photovoltaic modules, and further improve the power generation and power generation efficiency of double-sided photovoltaic modules; moreover, the up-conversion transparent grid coating 5, high-reflection grid coating 4, and down-conversion transparent coating In addition to fluorocarbon resin, the main resin of 3 and fluorocarbon transparent coating 1 is also matched with acrylic resin, which can reduce the cost and increase the interlayer adhesion performance to prevent interlayer detachment during long-term use.

A double-sided photovoltaic module in this embodiment includes a photovoltaic front sheet, a first packaging adhesive film, a photovoltaic cell sheet, a second packaging adhesive film, and a photovoltaic backplane that are stacked sequentially from top to bottom; the double-sided photovoltaic module It includes several photovoltaic cell sheets, and several photovoltaic cell sheets are distributed between the first encapsulation adhesive film and the second encapsulation adhesive film at intervals, and the photovoltaic cell sheet is a photovoltaic cell sheet capable of photovoltaic power generation on both the front and back sides; The photovoltaic backplane is a highly reflective photo-converting photovoltaic backplane described in this embodiment; the up-conversion transparent grid coating 5 is pasted on the second encapsulation adhesive film, and the high-reflection mesh The grid positions of the grid coating 4 and the up-conversion transparent grid coating 5 correspond to the gap between two adjacent photovoltaic cells.

Example 2

A highly reflective photo-converting photovoltaic backplane of this embodiment, refer to Embodiment 1 for details, and its difference from Embodiment 1 is:

Among them, the fluorocarbon transparent coating used in fluorocarbon transparent coating 1 includes the following raw materials in parts by weight: 30 parts of polytetrafluoroethylene resin, 25 parts of polyvinylidene fluoride resin, 20 parts of acrylic resin, 0.3 part of leveling agent, isocyanate 8 parts of curing agent, 0.4 part of defoamer, 0.2 part of ultraviolet absorber, 10 parts of silica filler, 5 parts of propylene glycol methyl ether acetate solvent, and 0.1 part of antioxidant. The thickness of the fluorocarbon transparent coating layer 1 is 22 μm.

Wherein, the total thickness of the down-conversion transparent base film 2 is 285 μm, and the thickness of the down-conversion film layer 23 is 20 μm.

Wherein, the down-conversion transparent coating used in the down-conversion transparent coating 3 includes the following raw materials in parts by weight: 60 parts of FEVE resin, 20 parts of acrylic resin, 0.5 part of down-conversion nanomaterial, 10 parts of isocyanate curing agent, and 9.5 parts of solvent. The down-conversion nanomaterials in the down-conversion transparent coating 3 and the down-conversion transparent base film 2 are blue light quantum dots with a core-shell structure of cadmium zinc selenium sulfur@zinc sulfide.

Wherein, the high-reflection grid coating used in the high-reflection grid coating 4 includes the following raw materials in parts by weight: 40 parts of FEVE resin, 20 parts of acrylic resin, 29 parts of titanium dioxide, 5 parts of isocyanate curing agent, and 1 part of leveling agent , 1 part of defoamer, 0.5 part of stabilizer, 1 part of antioxidant, 2.5 parts of solvent. The thickness of the highly reflective mesh coating 4 is 10 μm; the particle size of the titanium dioxide is 400 nm.

Wherein, the up-conversion transparent grid coating used in the up-conversion transparent grid coating 5 includes the following raw materials in parts by weight: 55 parts of FEVE resin, 10 parts of acrylic resin, 1 part of up-conversion nanomaterial, 8 parts of isocyanate curing agent, flow 0.5 parts of leveling agent, 0.5 parts of defoamer, 1 part of stabilizer, 0.5 parts of antioxidant, 24.5 parts of solvent. The up-converting transparent mesh coating 5 has a thickness of 10 μm. The up-conversion nanomaterial is LiYF ₄ :Er ³⁺ /Yb ³⁺ .

A method for preparing a highly reflective photo-converting photovoltaic backplane in this embodiment: first coat a layer of fluorocarbon transparent coating on the back of the down-converting transparent base film 2, and after curing, apply The front side of the conversion film layer 23 is coated with a down-conversion transparent coating, and is cured in multiple ovens at different temperatures to obtain a transparent photovoltaic backplane. The MEK test data of the transparent photovoltaic backplane is greater than 300 times; The grid coil is sliced for subsequent grid screen printing. The screen printing is to selectively print a highly reflective grid coating on the front side of the down-converting clear coat 3, after curing, and then coat the highly reflective grid coating The front side of 4 is screen-printed to convert the transparent grid coating, and after curing, the highly reflective light-converting photovoltaic backsheet of this embodiment is obtained.

Example 3

A highly reflective photo-converting photovoltaic backplane and its preparation method in this embodiment refer to Example 2, and its difference from Example 2 lies in:

The down-conversion transparent coating used in the down-conversion transparent coating 3 includes the following raw materials in parts by weight: 65 parts of FEVE resin, 18 parts of acrylic resin, 1 part of down-conversion nanomaterial, 8 parts of isocyanate curing agent, and 12 parts of solvent. The down-conversion nano material in the down-conversion transparent coating 3 and the down-conversion transparent base film 2 is alloy quantum dots of phosphorus, zinc, indium and sulfur.

Example 4

A kind of highly reflective photo-converting photovoltaic backplane and its preparation method of this embodiment refer to Embodiment 2, and its difference from Embodiment 2 is:

The high-reflection grid coating used in the high-reflection grid coating 4 includes the following raw materials in parts by weight: 50 parts of FEVE resin, 15 parts of acrylic resin, 35 parts of titanium dioxide, 5 parts of isocyanate curing agent, 1.5 parts of leveling agent, 1 part of foaming agent, 0.5 part of stabilizer, 0.8 part of antioxidant, and 7 parts of solvent; wherein, the particle size of titanium dioxide is 500 nm.

Example 5

A kind of highly reflective photo-converting photovoltaic backplane and its preparation method of this embodiment refer to Embodiment 2, and its difference from Embodiment 2 is:

The up-conversion transparent grid coating used for the up-conversion transparent grid coating 5 includes the following raw materials in parts by weight: 60 parts of FEVE resin, 20 parts of acrylic resin, 1 part of up-conversion nanomaterial, 8 parts of isocyanate curing agent, leveling agent 1 part, 0.5 part of defoamer, 1 part of stabilizer, 0.5 part of antioxidant, 28 parts of solvent; wherein, the up-conversion nanomaterial is Ho ³⁺ /Yb ³⁺ co-doped Gd ₂ O ₃ .

Comparative example 1

A photovoltaic backplane and its preparation method in this comparative example, specifically refer to Example 2. The difference between it and Example 2 is that the down-conversion transparent base film 2 of Example 2 is replaced with a transparent base film 2 that does not have a down-conversion function. The base film, that is, the transparent base film is a composite base film formed by a three-layer co-extrusion process of a PBT layer, a PET layer and a PBT layer; The material is replaced by a solvent; the particle diameter of the titanium dioxide in the highly reflective grid coating 4 used in the high reflection grid coating of embodiment 2 is 400nm, and the titanium dioxide of 1.5 μm is replaced by the titanium dioxide of the particle diameter; The up-conversion nano-material in the up-conversion transparent grid coating used in transparent grid coating 5 was replaced with solvent; thus, a photovoltaic backplane of this comparative example was obtained.

Comparative example 2

A kind of photovoltaic backplane of this comparative example and preparation method thereof, specifically refer to embodiment 2, and its difference with embodiment 2 is: the particles in the highly reflective grid coating used in the high reflective grid coating 4 of embodiment 2 Diameter is that the titanium dioxide of 400nm is replaced by the titanium dioxide that particle diameter is 1.5 μ m; The up-conversion nano material in the used up-conversion transparent grid coating 5 of the up-conversion transparent grid coating 5 of embodiment 2 is replaced with solvent; A photovoltaic backplane of the comparative example.

Comparative example 3

A photovoltaic backplane and its preparation method in this comparative example, specifically refer to Example 2. The difference between it and Example 2 is that the down-conversion transparent base film 2 of Example 2 is replaced with a transparent base film 2 that does not have a down-conversion function. The base film, that is, the transparent base film is a composite base film formed by a three-layer co-extrusion process of a PBT layer, a PET layer and a PBT layer; The material is replaced with a solvent; the up-conversion nanomaterial in the up-conversion transparent grid coating 5 used in the up-conversion transparent grid coating 5 of Example 2 is replaced with a solvent; a photovoltaic backplane of this comparative example is obtained.

Comparative example 4

A photovoltaic backplane and its preparation method in this comparative example, specifically refer to Example 2. The difference between it and Example 2 is that the down-conversion transparent base film 2 of Example 2 is replaced with a transparent base film 2 that does not have a down-conversion function. The base film, that is, the transparent base film is a composite base film formed by a three-layer co-extrusion process of a PBT layer, a PET layer and a PBT layer; The material is replaced by a solvent; the titanium dioxide with a particle diameter of 400nm in the highly reflective grid coating 4 used in embodiment 2 is replaced with titanium dioxide with a particle diameter of 1.5 μm; that is, a part of this comparative example A photovoltaic backplane.

Performance Testing

The light transmittance of the transparent part and the light reflectance of the grid part are tested for the photovoltaic backsheets of Examples 2-4 and Comparative Examples 1-4, and the test data are shown in Table 1-2 below:

Table 1 Light transmittance and light reflectance

It can be seen from Table 1 that: the light transmittance of the transparent part of the photovoltaic backsheet in the 380-1100nm band and the light reflectance of the grid part in the 400-800nm band of the photovoltaic backsheets of Examples 2-5 are excellent.

Table 2 Light transmittance and light reflectance

It can be seen from Table 2 that compared with Comparative Examples 1-4, the light transmittance of the transparent part of the photovoltaic backsheet of Example 2 in the 380-1100nm band is as high as 93.5%, and the net of the photovoltaic backsheet of Example 2 is as high as 93.5%. The light reflectance of the lattice part in the 400-800nm band is as high as 77.5%, and the light transmittance in the 380-1100nm band and the light reflectance in the 400-800nm band of the photovoltaic backsheet in Example 2 are the best.

In order to further investigate the power generation and power generation gain of the double-sided photovoltaic modules produced by the photovoltaic backsheet of the present invention, we made the photovoltaic backsheets of Example 2 and Comparative Examples 1-4 into different types of double-sided photovoltaic modules , to track the power generation for a period of 7 months; among them, in order to reduce the difference between double-sided photovoltaic modules, we made 24 pieces of each double-sided photovoltaic module, using the same type of inverter, and counted the inverters of each group The generating capacity of the generator is shown in Table 3 below:

Table 3 Power generation data of different types of double-sided photovoltaic modules (unit: KW.h)

It can be seen from Data Table 3 that the monthly power generation of the double-sided photovoltaic module in Example 2 is the highest, and compared with Comparative Examples 1-4, the average monthly power generation of the double-sided photovoltaic module in Example 2 has increased by 3 -5KW.h.

Table 4 Power generation gain of different types of bifacial photovoltaic modules

time Comparative example 1 (control group) Comparative example 2 Comparative example 3 Comparative example 4 Example 2 December 0.00% 0.09% 0.23% 0.18% 0.63% January 0.00% 0.10% 0.31% 0.24% 0.79% February 0.00% 0.11% 0.30% 0.24% 0.80% March 0.00% 0.10% 0.30% 0.20% 0.75% April 0.00% 0.11% 0.29% 0.22% 0.81% May 0.00% 0.12% 0.29% 0.22% 0.82% June 0.00% 0.10% 0.25% 0.25% 0.74% average 0.00% 0.11% 0.28% 0.22% 0.76%

It can be seen from the data table 4 that, compared with the control group, after the photovoltaic backsheet of comparative example 2 is provided with a down-conversion transparent base film and a down-conversion transparent coating in sequence, the average power generation of the double-sided photovoltaic module for 7 months is only Increased by 0.11%; after the photovoltaic backplane of comparative example 3 was provided with a high-reflection grid coating, the average power generation of the double-sided photovoltaic module in 7 months was only increased by 0.28%; the photovoltaic backplane of comparative example 4 was set with up-conversion transparency After the grid coating, the average power generation of the double-sided photovoltaic module in 7 months was only increased by 0.22%; while the photovoltaic backplane of Example 2 was provided with a down-conversion transparent base film 2, a down-conversion transparent coating 3, a high After reflective grid coating 4 and up-conversion transparent grid coating 5, the average power generation of its double-sided photovoltaic modules increased by 0.76% in 7 months.

It can be seen that in the photovoltaic backplane of the present invention, by sequentially setting the transparent base film 2 for down conversion, the down conversion transparent coating 3, the highly reflective grid coating 4 and the up conversion transparent grid coating 5 for synergy, it can effectively improve the The power generation and power generation efficiency of double-sided photovoltaic modules. From a theoretical point of view, in the photovoltaic backplane of the present invention, the addition of the down-conversion transparent base film 2 and the down-conversion transparent coating 3 can improve the transmittance of visible light, and can also convert ultraviolet light into visible light, further Improve the power generation of double-sided photovoltaic modules; the introduction of the highly reflective grid coating 4 can make the sunlight that would have been wasted directly passing through the gaps between photovoltaic cells be reflected by the highly reflective grid coating 4 Secondary utilization improves the average power generation of double-sided photovoltaic modules; and the introduction of the up-conversion transparent grid coating 5 can reflect part of the light first, and convert the transmitted infrared light into visible light. After the light passes through The highly reflective grid coating 4 reflects again to improve the power generation of the double-sided photovoltaic module.

Having described preferred embodiments of embodiments of the present invention, additional changes and modifications to these embodiments can be made by those skilled in the art once the basic inventive concept is appreciated. Therefore, the appended claims are intended to be interpreted to cover the preferred embodiment and all changes and modifications which fall within the scope of the embodiments of the present invention.

The technical solution provided by the present invention has been introduced in detail above, and the principles and implementation methods of the present invention have been explained by using specific examples in this paper. The description of the above embodiments is only used to help understand the method and core idea of the present invention; At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be construed as limiting the present invention.

Claims (12)

1. A highly reflective light-converting photovoltaic backplane, characterized in that it comprises a fluorocarbon transparent coating layered sequentially from the air surface to the encapsulation film surface, a down-conversion transparent base film, a down-conversion transparent coating, Highly reflective grid coat and up-converting transparent grid coat; Wherein, the transparent base film of the down-conversion is a composite base film formed by a three-layer co-extrusion process of a PBT layer, a PET layer and a down-conversion film layer; Wherein, the down-conversion transparent coating is prepared by mixing fluorocarbon resin, acrylic resin, down-conversion nano-material, curing agent and auxiliary agent, and then coated and cured; the down-conversion nano-material It is a down-converting nano-inorganic photochromic material, which is a quantum dot, Ce ³⁺ doped fluoride and Eu ³⁺ doped tellurate that produces photochromic light energy with a wavelength of 200-780nm and converts it into visible light. at least one. 2. A kind of highly reflective photo-conversion photovoltaic backplane according to claim 1, characterized in that, the color of the quantum dots includes at least one of blue, green and red; the particle diameter of the quantum dots 5-20nm, or the particle size of the Ce ³⁺ doped fluoride and Eu ³⁺ doped tellurate is 30-80nm. 3. A kind of highly reflective photo-converting photovoltaic backboard according to claim 1, characterized in that, the down-conversion transparent coating used in the down-conversion transparent coating comprises the following raw materials in parts by weight: 55-80 parts of FEVE resin , 10-35 parts of acrylic resin, 0.3-1 part of down-conversion nano material, 5-10 parts of isocyanate curing agent, 8-15 parts of solvent; the thickness of the down-conversion transparent coating is 5-15 μm. 4. A highly reflective photo-converting photovoltaic backplane according to claim 1, wherein the thickness of the PBT layer is 5-10 μm, the thickness of the PET layer is 255-265 μm, and the down conversion The thickness of the film layer is 5-30 μm. 5. A highly reflective photo-converting photovoltaic backplane according to claim 1, wherein the refractive index of the fluorocarbon transparent coating is 1.40-1.45, and the refractive index of the down-conversion transparent base film is The rate is 1.5-1.6. 6. A kind of highly reflective photo-converting photovoltaic backplane according to claim 5, characterized in that, the fluorocarbon transparent coating used in the fluorocarbon transparent coating comprises the following raw materials in parts by weight: polytetrafluoroethylene resin 20 -45 parts, polyvinylidene fluoride resin 15-30 parts, acrylic resin 15-25 parts, isocyanate curing agent 6-10 parts, silica filler 5-12 parts, propylene glycol methyl ether acetate solvent 3-10 parts, UV 0.2-1 part of absorbent, 0.1-1 part of antioxidant, 0.2-1 part of leveling agent, 0.4-2 part of defoamer; the thickness of the fluorocarbon transparent coating is 15-25 μm. 7. A highly reflective photo-converting photovoltaic backplane according to claim 1, characterized in that the highly reflective grid coating is mixed with fluorocarbon resin, acrylic resin, titanium dioxide, curing agent and auxiliary agent After the white high-reflection grid paint is made, it is screen-printed and solidified; the particle size of the titanium dioxide is 300-600nm. 8. A kind of highly reflective photo-converting photovoltaic backplane according to claim 7, characterized in that, the high reflective grid coating used in the highly reflective grid coating comprises the following raw materials in parts by weight: fluorocarbon resin 40 -70 parts, 10-20 parts of acrylic resin, 20-50 parts of titanium dioxide, 4-5 parts of isocyanate curing agent, 0.2-2 parts of leveling agent, 0.4-1 part of defoamer, 0.2-0.5 parts of stabilizer, 0.3-1 part of oxygen agent, 2-8 parts of solvent; the thickness of the high reflection grid coating is 5-15 μm. 9. A kind of highly reflective photo-converting photovoltaic backplane according to claim 1, characterized in that, the up-conversion transparent grid coating is made of fluorocarbon resin, acrylic resin, up-conversion nano-material, curing agent and After the additives are mixed to make an up-conversion transparent grid coating, it is screen-printed and solidified; the up-conversion nanomaterial is an up-conversion nano-inorganic photochromic material, which generates light for light energy with a wavelength of 980-1600nm. A material that changes color and converts it into visible light. 10. A kind of highly reflective photo-conversion photovoltaic backplane according to claim 9, characterized in that, the up-conversion nanomaterial is NaYF ₄ :Er ³⁺ /Yb ³⁺ , LiYF with a particle diameter of 5-20nm ₄ :Er ³⁺ /Yb ³⁺ , NaYF ₄ :Yb ³⁺ /Tm ³⁺ , NaYF ₄ :Ho ³⁺ /Yb ³⁺ , Ho ³⁺ /Yb ³⁺ co-doped Gd ₂ O ₃ and E ³⁺ /Yb ³⁺ at least one of the CeO ₂ nanowires co-doped. 11. A kind of highly reflective photo-converting photovoltaic backplane according to claim 9, characterized in that, the up-conversion transparent grid coating used in the up-conversion transparent grid coating comprises the following raw materials in parts by weight: fluorocarbon 50-80 parts of resin, 10-40 parts of acrylic resin, 0.2-1 part of up-conversion nanomaterials, 7-8 parts of isocyanate curing agent, 0.2-1 part of leveling agent, 0.2-0.5 parts of defoamer, 0.4-0 parts of stabilizer 1 part, 0.3-0.5 part of antioxidant, 18-28 parts of solvent; the thickness of the up-conversion transparent mesh coating is 5-10 μm. 12. A double-sided photovoltaic module, comprising a photovoltaic front plate, a first encapsulation film, a photovoltaic cell sheet, a second encapsulation film and a photovoltaic back plate, which are sequentially stacked from top to bottom, characterized in that the photovoltaic The backboard is a highly reflective photo-converting photovoltaic backboard according to any one of claims 1-11; the up-conversion transparent grid coating is attached to the second encapsulation film, and the high The grid positions of the reflective grid coating and the up-conversion transparent grid coating correspond to the gap between two adjacent photovoltaic cells.

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