CN218827172U

CN218827172U - Flexible solar cell front plate

Info

Publication number: CN218827172U
Application number: CN202223149059.6U
Authority: CN
Inventors: 吴培服; 吴迪; 孙化斌; 吴和坡; 高升
Original assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Current assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Priority date: 2022-11-25
Filing date: 2022-11-25
Publication date: 2023-04-07
Anticipated expiration: 2032-11-25

Abstract

The application discloses a flexible solar cell front plate which comprises a weather-resistant film on the outer side and a supporting base film on the inner side, wherein the weather-resistant film and the supporting base film are bonded into a whole through a bonding layer; the weather-resistant film comprises a weather-resistant film and a protective layer, wherein a plurality of saw-tooth stripes with isosceles triangle-shaped sections are formed on the surfaces of two sides of the weather-resistant film at equal intervals in parallel, a protective layer is formed on the surfaces of the saw-tooth stripes through vacuum sputtering, and the saw-tooth stripes on the surfaces of two sides of the weather-resistant film are perpendicular to each other; the supporting base film comprises a base material layer, two side surfaces of the base material layer are respectively provided with an online coating layer, and a barrier layer is formed by sputtering on the outer side of the online coating layer. The utility model provides a resistant time membrane in the front bezel outside has increased the whole adhesive force of resistant time membrane through the sawtooth stripe that its surface set up, has avoided the problem of the easy delaminating of resistant time membrane. The inner, supporting base film provides a stronger barrier.

Description

Flexible solar cell front panel

Technical Field

The present application relates to a flexible solar cell front sheet.

Background

The flexible solar cell is one of thin-film solar cells, and has the advantages of advanced technology, excellent performance, low cost and wide application. An important field of application of flexible solar energy is building integration of photovoltaics, which may be integrated in windows or roofs, exterior or interior walls. A solar cell photovoltaic module with a typical structure is composed of a front plate, a solar cell piece, an encapsulating material and a back plate. The solar cell photovoltaic module is generally applied to an outdoor environment and is subjected to tests such as wind, sun, rain, dust, abrasion and the like, so that the performance requirement on a front plate, namely a light receiving surface, is high, and the front plate needs to have high light transmittance, water resistance, UV resistance and certain mechanical strength.

CN 108091715A discloses a composite film for a solar cell front plate, which comprises a support layer and a PVDF coating coated on the support layer, wherein the PVDF coating is formed by spraying PVDF paint on the surface of the support layer, and the support layer is transparent PMMA. CN 111391457A discloses a front plate of a solar cell module, the front plate comprising: the light-transmitting film comprises a plurality of layers of light-transmitting films which are stacked in sequence, wherein each light-transmitting film is a fiber reinforced thermoplastic composite material film. In the prior art, the laminated front plate mainly uses a PMMA base material for light transmittance, and the structure after molding is fixed, difficult to bend, and poor in flexibility. The solar cell front plate of fixed knot constructs's sunshine utilization ratio is limited, unable make full use of oblique light, and in addition, above-mentioned prior art drops easily at the anti ultraviolet coating that the outside of front bezel provided, and weatherability is relatively poor.

CN 114447130A discloses a high light transmission flexible composite front plate. The high-light-transmission flexible composite front plate comprises a flexible front plate main body, wherein the flexible front plate main body consists of a substrate layer, a frosting layer and a water vapor barrier layer; the substrate layer is a transparent modified ETFE membrane; the frosted layer is compounded on the surface of the base material layer facing to the air side; the water vapor barrier layer is compounded on the surface of the substrate layer, which is opposite to the air side. The base material layer in the prior art adopts the fluorine-containing plastic film, the water permeability and the wear resistance of the base material layer are poor, particularly the surface energy is low, and the defects of high compounding difficulty, weak bonding and easy delamination exist. Moreover, because the market price of the ETFE membrane is very high, the ETFE membrane is difficult to bear in the cost of serving as a foundation support, and the defect of easy delamination is not a good choice.

CN 111933721A discloses an ultraviolet aging resistant front plate of a flexible solar cell module. This prior art front plate actually protects the multi-layer coating structure of its surface and does not relate to the front plate itself. In view of the requirement of high insulation of the flexible solar cell, the multilayer plating layer is not enough to ensure the insulation of water vapor and air, moreover, the more the coating layers, the lower the bonding strength between the coating layers, and the more the delamination is likely to occur.

Disclosure of Invention

The technical problem to be solved by the present application is to provide a flexible solar cell front sheet to reduce or avoid the aforementioned problems.

In order to solve the technical problem, the application provides a flexible solar cell front plate, which comprises a weather-resistant film on the outer side and a supporting base film on the inner side, wherein the weather-resistant film and the supporting base film are bonded into a whole through a bonding layer; the weather-resistant film is composed of a PVDF (polyvinylidene fluoride) main body, a plurality of saw tooth stripes with isosceles triangle-shaped sections are formed on the surfaces of two sides of the weather-resistant film at equal intervals in parallel, a protective layer is formed on the surface of each saw tooth stripe through vacuum sputtering, and the saw tooth stripes on the surfaces of two sides of the weather-resistant film are perpendicular to each other; the supporting base film comprises a base material layer, two online coating layers are respectively arranged on the two side surfaces of the base material layer, and a barrier layer is formed on the outer sides of the online coating layers in a sputtering mode; the solar cell comprises a substrate layer and a plurality of solar cell panels, wherein the substrate layer comprises an inner layer film facing one side of each solar cell panel and an outer layer film far away from one side of each solar cell panel, the inner layer film is provided with a plurality of inner layer prism structures which are arranged in parallel at equal intervals and have isosceles trapezoid cross sections, the outer sides of the inner layer prism structures are provided with a refraction layer through vacuum sputtering, a sunken cavity between the outer layer film and the refraction layer is filled with an outer layer prism structure, and the outer layer film and the refraction layer are connected into a whole through the outer layer prism structure; the thickness of the weather-resistant film is 20-30 mu m; the thickness of the supporting base film is 100-200 μm.

Preferably, the length of the base of the isosceles triangle of the sawtooth stripe is 5-10 μm, the vertex angle is 45-135 degrees, and the height is 5-10 μm.

Preferably, the included angle between the length direction of the sawtooth stripes and the four rectangular sides of the weather-resistant film is 45 degrees.

Preferably, the length of the lower base of the isosceles trapezoid of the cross-section of the inner layer prism structure is 20 to 30 μm, the lower base angle is 30 to 60 degrees, and the height is 25 to 50 μm.

The utility model provides a weather-resistant film in the front bezel outside has increased the whole adhesive force of weather-resistant film through the sawtooth stripe that its surface set up, has avoided the easy problem of delaminating of weather-resistant film. Inboard support base film provides support protect function and stronger separation nature, and the substrate layer that supports the base film has improved the utilization ratio of sunshine through setting up the refraction layer between inlayer prism structure and outer prism structure.

Drawings

The drawings are only for purposes of illustrating and explaining the present application and are not to be construed as limiting the scope of the present application.

Figure 1 shows a schematic cross-sectional view of a flexible solar cell front sheet according to one embodiment of the present application.

Fig. 2 shows a schematic cross-sectional view of a weatherable film that can be used in the flexible solar cell front sheet of the present application, according to another embodiment of the present application.

Fig. 3 shows a schematic view of a weatherable film that can be used in the flexible solar cell front sheet of the present application, according to yet another embodiment of the present application.

Fig. 4 shows a schematic view of a support base film that can be used in a flexible solar cell front sheet according to an embodiment of the present application.

Fig. 5 shows a schematic of a support base film that can be used in a flexible solar cell front sheet of the present application, according to another embodiment of the present application.

Fig. 6 shows an exploded perspective schematic view of a substrate layer supporting a base film useful for a flexible solar cell front sheet according to yet another embodiment of the present application.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present application, embodiments of the present application will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

As shown in fig. 1, the present application proposes a flexible solar cell front panel, which comprises an outer weather-resistant film 100 and an inner support base film 200, wherein the weather-resistant film 100 and the support base film 200 are integrally bonded together by an adhesive layer 300. In a particular embodiment, the front plate has a total thickness of about 125-240 μm; the weatherable film 100 may have a thickness of about 20 to 30 μm; the thickness of the support base film 200 is about 100 to 200 μm; the thickness of the adhesive layer 300 is about 5-10 μm.

The outermost weatherable film 100 of the front panel mainly functions to reinforce, weather-proof, UV-resistant, moisture-proof, low dielectric constant, high breakdown voltage, etc., and preferably a PVDF film having a thickness of 20 to 30 μm may be used as the weatherable film 100, for example, a commercially available PVDF film having a thickness of 20 to 30 μm may be used, or a PVDF raw material particle having a mass content of 90% or more may be used, and an ultraviolet absorber, an abrasion-resistant filler, etc. are added to the PVDF film to form a PVDF film through melt co-extrusion and then biaxial stretching.

The supporting base film 200 is adjacent to the circuit side of the solar cell panel, and needs to provide a stronger barrier property to protect the internal circuit in addition to providing a stronger supporting protection function.

The bonding layer 300 may be a conventional EVA adhesive, or an ultraviolet light curing adhesive.

One weatherable film of the flexible solar cell front sheet of the present application is described in further detail below.

For weatherable film 100, some prior art weatherable films utilize a PVDF (polyvinylidene fluoride) coating and some utilize a fluoroplastic film. The PVDF coating is mainly made of bonding resin, the content of the PVDF is limited, and the weather-resistant effect is not as good as that of a weather-resistant film with the PVDF as the main body. However, the PVDF weather-resistant film has a problem of easy delamination due to low surface energy and insufficient adhesion, and the outer surface is not wear-resistant and easily adsorbs dust.

In view of the above, the present application proposes a weatherable film 100 for the front panel of the flexible solar cell of the present application, as shown in fig. 2 to 3, the weatherable film 100 in this embodiment is preferably mainly made of PVDF, wherein the mass content of PVDF in the weatherable film is greater than or equal to 90%, and in order to improve the performance of the weatherable film, an ultraviolet absorber, an abrasion-resistant filler, etc. may be added.

Further, as shown in the figure, a plurality of equally spaced parallel saw-tooth stripes 11 with isosceles triangle cross-section are formed on both side surfaces of the weather-resistant film 100, and the saw-tooth stripes on both sides of the weather-resistant film 100 are identical. The weatherable film 100 is shown in an enlarged scale for easy viewing and understanding, the actual sawtooth streaks are relatively small in size, and the surface has only a small texture that is not easily perceived, and does not affect the overall light transmission of the weatherable film 100. In one particular embodiment, the weatherable film 100 has a maximum thickness of 20-30 μm.

The existing PVDF weather-resistant film has the problem of easy delamination when being bonded on the supporting base film 200 through an adhesive due to low surface energy and insufficient bonding force. In order to overcome the technical problem, the present application forms the sawtooth stripes 11 on the surface of the weather-resistant film 100, and the contact area with the adhesive layer 3 can be increased by the sawtooth stripes 11, for example, when the isosceles trapezoid of the sawtooth stripes 11 has an apex angle of 60 degrees, the sawtooth stripes 11 can double the surface area, thereby increasing the overall adhesion of the weather-resistant film 100 and avoiding the problem that the weather-resistant film 100 is easily delaminated.

It should be noted that, in practice, the overall adhesion of the weatherable film 100 only needs to be improved by providing the sawtooth stripes 11 on the inner side of the weatherable film 100, but since the stripes are very small and difficult to observe, and for the convenience of assembly operation, the inventors have chosen to form the same sawtooth stripes 11 on both surfaces of the weatherable film 100, so that both sides can be coated with the film, and the application range of the weatherable film can be improved. The inventor thinks that the originally located sawtooth stripes 11 do not assume any effect, however, in the actual laying experiment process, the inventor finds that if the scale of the sawtooth stripes 11 formed on the surface of the weather-resistant film 100 is smaller than a certain range, the surface of the weather-resistant film 100 can play a self-cleaning effect, the adhesion force of dust on the surface of the weather-resistant film 100 can be reduced, and the attached dust can be easily washed away by rainwater. For example, in one embodiment, it is preferable that the isosceles triangle of the sawtooth stripe 11 has a length of 5 to 10 μm, an apex angle of 45 to 135 degrees, a height of 5 to 10 μm, and a minimum gap between adjacent sawtooth stripes 11 of 0 to 5 μm. The formation of the same saw-tooth stripes on both side surfaces of the weather-resistant film 100 not only reduces the manufacturing cost, but also allows the saw-tooth stripes of this size range to be selected to achieve good adhesion on the inner side and excellent dust adsorption resistance on the outer side.

In addition, when the same sawtooth stripes 11 are formed on both sides, the sawtooth stripes 11 may reflect sunlight, thereby reducing the utilization rate of the solar cell. For example, when the flexible solar cell is integrated on a building, the direction of the flexible solar cell is not adjustable, and when the sun deflection angle is right perpendicular to one side surface of the sawtooth stripe 11, a part of light can be reflected by the surface, and this can be avoided by adjusting the installation angle of the sawtooth stripe 11 during installation, but the installation requirement is too high, and the operation is difficult in practice. In order to avoid the problem that the sunlight utilization rate is reduced due to the fact that the installation angle is not enough when the sawtooth stripes 11 on the two sides are arranged at the same time, the special design is provided, the sawtooth stripes 11 on the surfaces of the two sides of the weather-resistant film 100 are perpendicular to each other, and therefore the problem that the sunlight utilization rate is reduced due to the fact that reflection is formed on the two sides at the same time can be avoided.

In addition, the sawtooth stripes 11 on the surface of the weather-resistant film 100 can also make incident light converge towards the middle of the sawtooth stripes, so that the inclination angle of the light can deflect towards the direction perpendicular to the solar cell as much as possible to some extent, and the utilization rate of sunlight in an inclined state is improved. In addition, because the sawtooth stripes on the two sides of the weather-resistant film are perpendicular to each other, the light rays in different directions can be corrected to a certain extent, and the direction of the light rays can be modulated under the condition that the solar altitude angles are changed at different times after the weather-resistant film is laid and installed.

Further, in order to improve the adhesion of the weatherable film 100 and avoid delamination, the angle between the length direction of the sawtooth stripes 11 and the four rectangular sides of the weatherable film 100 is selected to be 45 degrees, as shown in fig. 3. In general, the solar cell panel is generally designed to be rectangular, four sides are perpendicular to each other, and if the length direction of the sawtooth stripes 11 is perpendicular to one pair of rectangular sides of the weatherable film 100, the other pair of rectangular sides will be parallel to the length direction of the sawtooth stripes 11. The longitudinal and width rigidities of the zigzag stripes 11 are different, and therefore the expansion rates are different, which causes the pair of rectangular sides of the weather-resistant film 100 to be easily warped and delaminated. The direction of sawtooth stripe 11 is turned to and is 45 degrees contained angles with four rectangle limits to this application, and then the rigidity difference of different directions that arouses because sawtooth stripe 11 can tend to averagely to the proportion of four rectangle limits diffusions, therefore can avoid the problem of resistant time film 100 delaminations that arouses because the setting of sawtooth stripe 11, has further improved resistant time film 100's structural performance.

In order to improve the resistance of the weather-resistant film 100 against wind and sand erosion, in another embodiment of the present application, a protective layer 12 is formed on the surface of the sawtooth pattern 11 on the surface of the weather-resistant film 100 by vacuum sputtering, and preferably, the protective layer 12 is made of silicon dioxide and has a thickness of 1 to 3 μm.

Examples 1 to 6

Weatherable films were prepared according to the following parameters (detailed preparation method is further detailed below).

In examples 1 to 3, the included angles between the sawtooth stripes and the rectangular sides of the weather-resistant film are both 45 degrees, and in examples 4 to 6, the included angles between the sawtooth stripes and the rectangular sides of the weather-resistant film are both 0/90 degrees, that is, the included angles between the sawtooth stripes and one pair of rectangular sides are 0 degree, and the included angles between the sawtooth stripes and the other pair of rectangular sides are 90 degrees.

Comparative examples 1 to 6

Comparative examples 1-6 used PVDF films without jagged stripes as weatherable films with the following parameters.

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The weatherable films of examples 1 to 6 and comparative examples 1 to 6 were respectively adhered to the surface of a 188 μm PET support base film, and the parametric properties of the examples in which the weatherable film was measured were compared as follows.

It can be seen through the performance parameter contrast of above-mentioned embodiment that the resistant membrane of waiting of the flexible solar cell front bezel that can be used to this application can show promotion adhesion property and avoid the layering under the condition that has the sawtooth stripe, can improve the luminousness of oblique light simultaneously, can increase the contact angle of surface simultaneously, has improved automatically cleaning ability, possesses excellent anti dust adsorptivity.

The support base film of the flexible solar cell front sheet of the present application is described in further detail below.

As shown in fig. 1, the support base film 200 may be made of a PET film having a visible light transmittance of more than 85%, and may have a single-layer or multi-layer structure formed by biaxial stretching. The PET film can provide excellent insulation, water resistance, mechanical properties, and dimensional stability. However, for solar cells, especially for CI (G) S flexible solar cells, which are the mainstream products, the requirements for front plates are high due to the process characteristics of the solar cells, such as stronger barrier property for protecting the internal circuits, and the barrier property is usually 10 ^-3 g/m ² Day level. The general idea behind enhancing the barrier properties is to increase the thickness of the material, which results in increased material costs, while increasing the unit weight and decreasing the flexibility of the material, too thick a material also results in slippage leakage when the edges of the sheet are bent. The traditional packaging process in China is difficult to achieve the required barrier property, and even in Japan with the strongest packaging process, the flexible solar cell still does not reach the level of large-scale mass production, so that the cost of the traditional flexible solar cell sold in the market is high, and the actual service life of the flexible solar cell is slightly insufficient compared with that of a crystalline silicon solar cell due to the limitation of the packaging process.

In view of this, in one embodiment of the support base film 200 shown in fig. 4, the support base film 200 includes a substrate layer 21, an in-line coating layer 22 is formed on both surfaces of the substrate layer 21, and a barrier layer 23 is formed on the outer side of the in-line coating layer 22 by sputtering. The substrate layer 21 has a thickness of about 100 to 200 μm, and may be formed of, for example, 188 μm biaxially oriented PET film having a single layer structure, or may be formed by laminating a plurality of films (as will be described in further detail below). The barrier layer 23 is preferably composed of silicon dioxide; the thickness was 200nm.

The barrier property of the substrate layer 21 can be improved by arranging the barrier layer 23, the thickness of the substrate layer 21 does not need to be increased, and the adaptability of the flexible solar cell is improved. In order to improve the surface smoothness and the adhesion of the barrier layer 23, it is preferable to perform an in-line coating process on both surfaces of the base material layer 21 before the formation of the barrier layer 23 by sputtering, and to form an in-line coating layer 22 having a thickness of preferably 0.1 to 0.3 μm on each of both sides.

The online coating can be directly through online coating machine with the coating of chemical article on the substrate layer in the production process of substrate layer 21, and online coating can be directly formed in the later stage of the production process of substrate layer, need not launch the operation again with the coiled material, and the coating forms evenly, fast, efficient, and is with low costs.

In one embodiment, the primer solution constituting the in-line coating layer 22 may be applied to the slab before or during the stretching of the polyester film constituting the substrate layer 21, and then the primer solution applied to the surface of the slab is cured to form the in-line coating layer 22 at a high temperature during the stretching process as the slab is stretched to a film having a desired thickness and the thickness is reduced.

In one embodiment, the in-line coating layer 22 is formed by uniformly mixing acrylic resin, silica nanoparticles having a particle size of 5 to 10nm, 1, 4-dioxane, polyethylene oxide, and ethylene-vinyl acetate copolymer into a primer solution, and then curing by in-line coating.

Specifically, the mass ratios of the components of the online coating layer 22 are, respectively, acrylic resin: silica nanoparticles: 1, 4-dioxane: polyethylene oxide: the ethylene-vinyl acetate copolymer is 100: (10-15): (20 to 30): (10-15): (5-10). Wherein the ethylene-vinyl acetate copolymer can be ethylene-vinyl acetate copolymer which is sold by Mitsui corporation of Japan and has the trade name of Evaflex 550, and the mass percentage of the contained vinyl acetate polymer is 14 percent.

According to the weight ratio of the raw materials in the following table, on-line coating layers are respectively prepared on the two side surfaces of a single-layer 188-micron biaxially oriented PET film, and then a layer of barrier layer made of silicon dioxide is respectively sputtered on the outer sides of the on-line coating layers.

As a comparison, barrier layers of 200nm thick silica were formed by sputtering directly on both side surfaces of a single layer of 188 μm biaxially oriented PET film as comparative examples. The 180 degree peel force (N/25 mm) of the barrier layers of examples 7-11 was measured to be 34.5%, 36.2%, 35.1%, 34.8%, and 36.1% higher than the comparative examples, respectively.

Further, as shown in fig. 5, the present application provides a schematic structural diagram of a support base film for a front sheet of a flexible solar cell in accordance with another embodiment, and similar to the embodiment shown in fig. 4, the support base film 200 of this embodiment also includes a substrate layer 21, an on-line coating layer 22 is respectively disposed on both sides of the substrate layer 21, and a barrier layer 23 is formed on the outside of the on-line coating layer 22 by sputtering. Unlike the embodiment shown in fig. 4, the substrate layer 21 of the present embodiment is formed by laminating a plurality of films, and the on-line coating layer 22 and the barrier layer 23 may have the same structure and composition as those of the previous embodiment. Only the substrate layer 21 of the multilayer composite structure of the present embodiment will be described in detail below.

As shown in fig. 5-6, the substrate layer 21 of this embodiment includes an inner layer film 1 facing one side of the solar cell (not shown in the figure) and an outer layer film 2 away from one side of the solar cell, wherein, a plurality of inner layer prism structures 3 with isosceles trapezoid cross sections and arranged in parallel at equal intervals are formed on the inner layer film 1, a layer of refraction layer 4 is formed on the outer side of the inner layer prism structures 3 through vacuum sputtering, an outer layer prism structure 5 is filled in a hollow cavity between the outer layer film 2 and the refraction layer 4, and the outer layer film 2 and the refraction layer 4 are connected into a whole through the outer layer prism structure 5.

The inner layer film 1 and the outer layer film 2 can be made of PET with visible light transmittance of more than 85%, and the PET film with a double-layer structure can provide excellent insulativity, water resistance, mechanical properties and dimensional stability. Two layers of prism structures which are nested with each other are formed between the inner layer film 1 and the outer layer film 2, the two layers of prism structures are separated by the sputtered refraction layer 4, a channel between the two layers of prism structures is lengthened, and the water resistance and the air tightness are enhanced.

In a particular embodiment, the refractive index of each of the inner and

outer prism structures

3 and 5 is less than the refractive index of the refractive layer 4. For example, the refractive layer 4 may be made of Nb having a refractive index of 2.01 to 2.48 ₂ O ₅ And (4) forming. The outer prism structure 5 may be made of uv curable acrylic resin with a refractive index of preferably 1.4-1.6 (small amounts of high refractive index particles may be added to adjust the overall refractive index, e.g., 1% -5% of lead fluoride nanoparticles, as desired). The inner prism structure 3 may be made of the same material as the outer prism structure 5, i.e., may be made of a uv curable acrylic resinPreferably 1.4-1.6 (again, small amounts of high refractive index particles may be added as required to adjust the overall refractive index, for example 1% -5% lead fluoride nanoparticles).

As mentioned above, since the flexible solar cell can be integrated in a window or a roof, an outer wall or an inner wall, and the orientation of the flexible solar cell is fixed after installation, the efficiency of the flexible solar cell is greatly affected by the direction of the sunlight, generally the efficiency of the direct sunlight is the greatest, but the time is short, and the direction of the sunlight is inclined for a large period of time. The utility model provides a set up and formed inlayer prismatic structure and outer prismatic structure in the substrate layer 21, one deck refraction layer has been set up between the two, when the light slope shines on prismatic structure's trapezoidal edge, because there are irradiation angle and refracting index difference, make the light that the incidence got into inlayer prismatic structure can assemble to prismatic structure's middle part, make the inclination of light can deflect to the direction of the perpendicular to solar wafer of trying to the best in a certain degree, thereby the utilization ratio of sunshine has been improved. In addition, for the flexible solar cell laid on the roof, the efficiency of the stripes of the prism structure pointing to the south and north directions is better, and the utilization rate of light rays in the morning, evening and east-west directions can be improved. To the flexible solar cell who lays in perpendicular wall, the efficiency of the stripe pointing to east and west direction of prism structure is better, can promote the utilization ratio of the light that shines on the wall from the top slope when noon sunshine is strongest.

Regarding the prism structure and the principle of converging light by the sawtooth stripes, the inventor uses the prism film technology in the backlight plate in the field of liquid crystal displays for reference. Since the field of operation of the applicant coincided with years of development on liquid crystal displays, the inventors were able to derive elicitations from the field of liquid crystal displays that vary widely in field, but such elicitations should not be considered obvious to a person of ordinary skill in the solar cell field, since the solar cell field differs considerably from the liquid crystal display field. For example, in the field of liquid crystal displays, light is refracted only from air into prisms, and there is a large difference in refractive index between air and prisms, so that an additional refractive layer is not required. In the solar cell field of the present application, the problems of the sealing property, the waterproof property and the like of the package need to be considered, and the air cannot exist in the substrate layer 21, so that the prism structure is applied to the solar cell field, and the material layers do not have a large refractive index difference, and the prism film technology in the backlight plate in the liquid crystal display field is applied to the solar cell field, so that the technical effect of light convergence cannot be directly obtained.

In addition, since the substrate layer 21 in the solar cell field needs to consider the sealing property, in the case where air is not present, it needs to consider the problem of manufacturing cost while providing a different interface material to form an integral body. The arrangement of two layers of prism structures with different refractive indexes is feasible, however, in consideration of the problem of light transmission, two materials with small light transmission difference and large refractive index difference are difficult to find, and the processing process of the two materials with large property difference has large difference, so that the defect of large cost is brought, and the matching problem of special equipment is also required to be considered, so that the arrangement is not advisable in the practical application process.

Therefore, the two layers of prism structures in the application can be prepared from materials with the same or similar properties, for example, the two layers of prism structures can be prepared from ultraviolet curing acrylic resin commonly used for prism films of liquid crystal display back plates, the processing technology of the two layers of prism structures formed by the two layers of prism structures is the same, the two layers of prism structures can be molded by the same set of ultraviolet curing equipment, and the two layers of prism structures have the same or similar light transmission and refractive indexes, so that the refractive layers can be prepared from materials with the proper refractive index range conveniently. In addition, it should be emphasized that since the solar cell needs to maintain a considerable transmittance, it is difficult to change the refractive index of the bulk material by adding a high refractive index material to the two-layered prism structure, because the difference between the refractive index of the added high refractive index material and the refractive index of the bulk material is large, which causes a defect in index matching and leads to a decrease in the light transmittance of the material.

In another modified embodiment, the inner prism structure 3 may be made of uv-curable acrylic resin with uv-excited phosphor added, and the refractive index thereof is preferably 1.6-1.7 (small amount of high refractive index particles may be added therein to adjust the overall refractive index, for example, 1% -5% of lead fluoride nanoparticles, as required). The ultraviolet light excited fluorescent powder in the inner layer prism structure 3 is preferably 3-5% by mass. In the embodiment, a proper amount of ultraviolet light is added to excite the commercial fluorescent powder, so that spectrum regulation and control can be performed on the ultraviolet light converged into the inner layer prism structure, and the ultraviolet light harmful to the solar cell is converted into visible light with longer wavelength, so that the technical effects of effectively preventing ultraviolet radiation and improving the light utilization efficiency are achieved.

It should be noted that the commonly used uv excited phosphors in the market usually emit red light, and are typically one or a mixture of silicate, aluminate, nitride and fluoride phosphor materials. The ultraviolet light excited fluorescent powder preferably adopts a fluoride fluorescent powder material, and has the advantages that the refractive index of the fluoride fluorescent powder material is slightly higher than that of ultraviolet light cured acrylic resin, so that the light transmittance of a prism structure prepared by the original ultraviolet light cured acrylic resin can be kept under the condition that a small amount of the fluorescent powder material is added by 3-5% (mass percentage), and the light transmittance of the material in a visible light range is weakened under the condition that the difference between the refractive index of the fluorescent material and the refractive index of a body material is large, so that the light conversion of a solar cell is not facilitated. In addition, a small amount of high refractive index fine particles may be added thereto as needed to adjust the overall refractive index, for example, 1% to 5% (mass percentage) of lead fluoride nanoparticles may be added.

This modified embodiment can further convert the ultraviolet ray in the light that assembles to the long wave visible light that can supply solar cell panel to utilize on utilizing prism structure to assemble the basis of light through add ultraviolet ray excitation phosphor powder in inlayer prism structure 3, can further improve the utilization ratio of light to reduce the harm of ultraviolet ray to solar cell panel. Of course, the addition of ultraviolet light excitation phosphor will reduce the whole light transmissivity of substrate layer 21, therefore does not suggest adding ultraviolet light excitation phosphor in outer prismatic structure 5, and because the ultraviolet light excitation phosphor that adds in inner prismatic structure 3 can convert the light of assembling, can offset the influence to the light transmissivity to a certain extent, therefore this embodiment of improvement is the scheme of compromising efficiency, obtains great sunshine utilization ratio through lower cost, can effectively prevent ultraviolet light to solar cell panel's harm simultaneously.

Examples 6 to 11

The substrate layer of the support base film for the front sheet of the flexible solar cell was prepared according to the parameters of the following table.

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Comparative examples 12 to 14

Comparative examples 12-14 used a monolayer PET film as the substrate layer, with the following parameters.

The parametric properties of the examples were measured and compared as follows.

As can be seen from the comparison of the performance parameters of the embodiment, the insulating property, the light transmission property, the mechanical property, the ultraviolet light blocking property, the size stability and the like of the base material layer of the front panel of the flexible solar cell are greatly improved, and the ultraviolet light transmission rate of the improved example added with the fluorescent powder is greatly reduced.

The method for manufacturing the flexible solar cell front sheet of the present application is described in further detail below with reference to the accompanying drawings.

As described above, the flexible solar cell front panel of the present application includes the weather-resistant film 100 on the outer side and the support base film 200 on the inner side, and the weather-resistant film 100 and the support base film 200 are integrally bonded to each other by the adhesive layer 300. The weather-resistant film 100 is mainly made of PVDF, a plurality of saw tooth stripes 11 which are arranged in parallel at equal intervals and have isosceles triangle-shaped cross sections are formed on the surfaces of two sides of the weather-resistant film 100, a protective layer 12 is formed on the surface of each saw tooth stripe 11 through vacuum sputtering, and the saw tooth stripes 11 on the surfaces of two sides of the weather-resistant film 100 are perpendicular to each other. The support base film 200 comprises a base material layer 21, wherein an online coating layer 22 is respectively arranged on two side surfaces of the base material layer 21, and a barrier layer 23 is formed on the outer side of the online coating layer 22 in a sputtering mode. The substrate layer 21 is including facing inner film 1 of solar wafer one side and keeping away from outer membrane 2 of solar wafer one side, wherein, inner film 1 is last to be formed with a plurality of equidistant parallel arrangement's cross-section and is isosceles trapezoid's inner prismatic structure 3, and the inner prismatic structure 3 outside is formed with one deck refraction layer 4 through vacuum sputtering, and it has outer prismatic structure 5 to fill in the sunken cavity between outer membrane 2 and the refraction layer 4, and outer membrane 2 is connected as an organic wholely through outer prismatic structure 5 with refraction layer 4. In order to save cost and reduce working procedures, the preparation method adopts PET films with the same thickness as the inner layer film 1 and the outer layer film 2.

Further, the manufacturing method of the present application includes a manufacturing step of the weather-resistant film 100, a manufacturing step of the support base film 200, and an adhesion step of the support base film 200 and the weather-resistant film 100.

Wherein the preparation of the weatherable film 100 comprises:

first, a PVDF film composed mainly of PVDF is provided. The PVDF film can be a PVDF film with the thickness of 20-30 μm sold in the market, or a PVDF raw material particle with the mass content of more than or equal to 90 percent is added with an ultraviolet absorber, an abrasion-resistant filler and the like, and the PVDF film is formed by melt co-extrusion and then two-way stretching.

Then, a plurality of equally spaced saw-tooth stripes 11 having isosceles triangle-shaped cross sections are formed on both side surfaces of the PVDF film by hot press molding. For example, the cured zigzag stripes 11 can be obtained on the PVDF film by passing the heated PVDF film between two rollers disposed one above the other and having a pattern matching the shape of the zigzag stripes, and then air-cooling or water-cooling the PVDF film. Wherein the longitudinal directions of the patterns matching with the shape of the sawtooth stripes of the two roll surfaces which are opposite up and down are arranged perpendicular to each other, so that the sawtooth stripes 11 which are perpendicular to each other can be formed on the two side surfaces of the PVDF film. For example, the pattern direction of the two roller surfaces forms an angle of 45 degrees with the advancing direction of the PVDF film, so that the sawtooth stripes 11 forming an angle of 45 degrees with the four rectangular sides of the weather-resistant film can be formed.

Thereafter, a protective layer 4 is formed on the sawtooth stripes 11 by vacuum sputtering. For example, a silicon dioxide layer having a thickness of 1-3 μm may be formed on the sawtooth pattern 11 by vacuum sputtering, and since the thickness of the protective layer 12 is relatively very thin, the protective layer 12 is not shown in fig. 3, and the protective layer 12 in fig. 2 is enlarged for easy understanding.

The preparation of the support base film 200 includes:

firstly, using PET slices as raw materials for preparing a PET film, obtaining a single-layer thick sheet through melt extrusion, longitudinally stretching the single-layer thick sheet into a film after preheating, coating a mixture of components forming the on-line coating layer on one side of the film through a coating machine after longitudinally stretching, then transversely stretching, sizing, cooling and rolling to form the on-line coating layer 22 on the surface of the film, and then sputtering and forming a layer of barrier layer 23 formed by silicon dioxide on the outer side of the on-line coating layer 22 to obtain an inner layer film 1 and an outer layer film 2 with the on-line coating layer 22 and the barrier layer 23 for later use. Wherein, the thickness of the inner layer film 1 and the outer layer film 2 is preferably 40-60 μm, and the visible light transmittance is 85% -95%.

Then, on the side of the inner layer film 1 where the on-line coating layer 22 and the barrier layer 23 are not formed, a plurality of inner layer prism structures 3 having an isosceles trapezoid cross section, which are arranged in parallel at equal intervals, are formed by curing. For example, a roller with a pattern matching the shape of the inner prism structure may be used, the ultraviolet curable acrylic resin may be applied to the roller, the inner film 1 may be pressed and rolled along the surface of the roller, the ultraviolet curable acrylic resin may be pressed onto the inner film 1 according to the shape of the inner prism structure, and then the ultraviolet curable acrylic resin may be cured by irradiating ultraviolet light, so as to form the inner prism structure 3 having a desired shape on the inner film 1, where the refractive index of the formed inner prism structure 3 is 1.4 to 1.6. Or in another embodiment, the ultraviolet curing acrylic resin added with the ultraviolet excited phosphor may be formed into the inner prism structure 3 according to the same process, and the refractive index thereof is 1.6-1.7. The length of the lower base of the isosceles trapezoid of the cross section of the inner-layer prism structure 3 is 20-30 μm, the lower base angle is 30-60 degrees, the height is 25-50 μm, and the minimum gap between adjacent inner-layer prism structures 3 is 50-100 μm.

Thereafter, a refractive layer 4 is formed on the inner prism structure 3 by vacuum sputtering. For example, a layer of Nb having a refractive index of 2.01 to 2.48 and a thickness of 0.5 to 2 μm can be formed on the inner layer prism structure 3 by vacuum sputtering ₂ O ₅ Since the thickness of the refractive layer 4 is formed to be relatively very thin, the refractive layer 4 is not shown in fig. 4, and the refractive layer 4 is enlarged in fig. 3 for easy understanding. It should be noted that the refraction layer 4 mainly provides the function of interfacial refraction, and plays a certain role of insulation while ensuring light transmission. In addition, since the inner layer prism structures 3 protrude from the surface of the inner layer film 1 during sputtering, the thickness of the refractive layer 4 formed on the surface of the inner layer prism structures 3 is slightly thicker, and the refractive layer 4 formed on the surface of the inner layer film 1 between the inner layer prism structures 3 is slightly thinner. The refractive layer 4 on the surface of the inner film 1 does not contribute to the convergence of light, and mainly functions as an insulator, and the refractive layer 4 having a thickness of 0.5 to 2 μm does not affect the light transmittance.

And then, filling ultraviolet curing acrylic resin in the concave cavity on the outer side of the refraction layer 4, and attaching an outer layer film 2 on one side far away from the solar cell piece to the outer sides of the refraction layer 4 and the filled ultraviolet curing acrylic resin, wherein the side, on which the online coating layer 22 and the barrier layer 23 are not formed, of the outer layer film 2 faces the refraction layer 4 for attachment. Preferably, when filling ultraviolet curing acrylic resin in the sunken cavity in the outside of refraction layer 4, scrape the resin outside the top of refraction layer 4 through the scraper blade for the ultraviolet curing acrylic resin who fills flushes with the top of refraction layer 4, and it is more firm to eliminate the space and guarantee bonding between each layer of laminating. Since the thickness of the refractive layer 4 is relatively very thin, the thickness of the filled uv curable acrylic resin is almost equal to that of the inner prism structure 3.

Then, irradiating ultraviolet light through one side of the barrier layer 23 of the outer film 2 to cure the filled ultraviolet light curing acrylic resin to form an outer prism structure 5, and at the same time of curing the outer prism structure 5, connecting the outer film 2 and the refraction layer 4 into a whole through the outer prism structure 5, thereby preparing the support base film 200.

The bonding step of the support base film 200 and the weather-resistant film 100 includes: one side of the outer layer film 2 supporting the base film 200 is integrally bonded to the weather-resistant film 100 through the adhesive layer 300.

It should be understood by those skilled in the art that although the present application has been described in terms of several embodiments, not every embodiment includes every implementation of an independent aspect. The description is thus given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including all technical equivalents which are encompassed by the claims and are to be interpreted as combined with each other in a different embodiment so as to cover the scope of the present application.

The above description is only illustrative of the present invention and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations that may be made by those skilled in the art without departing from the spirit and principles of this application shall fall within the scope of this application.

Claims

1. A flexible solar cell front plate comprises a weather-resistant film on the outer side and a supporting base film on the inner side, wherein the weather-resistant film and the supporting base film are bonded into a whole through a bonding layer; the weather-resistant film is characterized in that a plurality of saw-tooth stripes with isosceles triangle-shaped sections are formed on the surfaces of two sides of the weather-resistant film at equal intervals in parallel, a protective layer is formed on the surface of each saw-tooth stripe, and the saw-tooth stripes on the surfaces of two sides of the weather-resistant film are mutually perpendicular; the supporting base film comprises a base material layer, two side surfaces of the base material layer are respectively provided with an online coating layer, and the outer side of the online coating layer is provided with a blocking layer; the solar cell comprises a substrate layer and a plurality of solar cell panels, wherein the substrate layer comprises an inner layer film facing one side of each solar cell panel and an outer layer film far away from one side of each solar cell panel, a plurality of inner layer prism structures which are arranged in parallel at equal intervals and have isosceles trapezoid-shaped cross sections are formed on the inner layer film, a refraction layer is formed on the outer side of each inner layer prism structure through vacuum sputtering, an outer layer prism structure is filled in a hollow cavity between each outer layer film and the refraction layer, and the outer layer films and the refraction layers are connected into a whole through the outer layer prism structures; the thickness of the weather-resistant film is 20-30 μm; the thickness of the supporting base film is 100-200 μm.

2. The front plate according to claim 1, wherein the isosceles triangle of the saw-tooth stripe has a length of a base of 5-10 μm, an apex angle of 45-135 degrees and a height of 5-10 μm.

3. The front panel according to claim 2, wherein the lengthwise direction of the sawtooth pattern is at an angle of 45 degrees to the four rectangular sides of the weatherable film.

4. The front plate according to claim 3, wherein the isosceles trapezoid of the cross-section of the inner layer prism structure has a length of a lower base of 20 to 30 μm, a lower base angle of 30 to 60 degrees, and a height of 25 to 50 μm.