Patent Application
20120048375
1. Field of the Invention
The present invention relates to a light-regulating film, and more particularly to a film used for a solar cell module.
2. Description of the Prior Art
Since such environmental protection problems as energy source shortage and greenhouse effect are increasingly serious, currently, countries are actively researching and developing various possible sustainable energy sources, and particularly, industries attach the most importance to solar power generation. As shown in
In order to reduce the cost of the solar power generation, currently, a common approach in the industry is to increase the power generation conversion efficiency of sunlight. However, when incident light 14 of the sun enters the solar cell module from air 16, is reflected in the module, and then reaches an interface between the transparent frontsheet and the air, if the face angle of reflected light 15 is smaller than a particular critical angle a for total internal reflection, the reflected light 15 would directly penetrate the module and cannot be absorbed and utilized again by a solar cell, and the increase of the conversion efficiency of the sunlight is also limited accordingly. Therefore, currently, the industry urgently needs to seek a technical solution for solving the foregoing problem, to achieve full utilization of the sunlight in the solar cell module.
Accordingly, the present invention is mainly directed to a film for increasing sunlight utilization and a module thereof.
In order to achieve the foregoing and other objectives, the present invention provides a film used for a solar cell module, and the film comprises: a substrate and at least one light-regulating layer, wherein the light-regulating layer comprises a fluoro resin and a plurality of light diffusing additives.
The present invention further provides a solar cell module including the foregoing film, and the solar cell module comprises: a transparent frontsheet; a backsheet; and one or more solar cells located between the transparent frontsheet and the backsheet, in which at least one of the transparent frontsheet and the backsheet includes the foregoing film.
When light enters a solar cell module, passes through a transparent frontsheet, and reaches a solar cell and a backsheet, due to reflection or scattering, the incident light turns into reflected light. Before the reflected light returns to the transparent frontsheet and again enters the air, at the interface between the transparent frontsheet and the air, there exists two possible circumstances, that is, the reflected light is returned into the cell module through total internal reflection or enters the air through refraction. If the face angle of the reflected light is larger than a particular critical angle a (if the transparent frontsheet is a glass sheet, the included angle relative to the normal of the surface of about 42 degrees), total internal reflection of the light happens, and the reflected light returns into the solar cell module and is effectively utilized once more. According to Snell's Law, when the incident light (that is, the reflected light) enters from a medium of a refractive index n1 to another medium of a refractive index n2, and refracted light is generated, the correlation between the incident light and the refracted light is as follows: n1 sin θ1=n2 sin θ2, where θ1 is an included angle between the incident light and the normal, and θ2 is an included angle between the refracted light and the normal.
As shown in
As shown in
−a<θ<a, and a=sin−1(1/n1),
where n1 is the refractive index of the material of the contact surface (the incident surface of the sunlight) between the transparent frontsheet and the air.
When the transparent frontsheet is glass (n1=1.51), a is about 42°.
Herein, a parameter of TIR ratio is defined as “a ratio of the amount (AT−Aθ) of the reflected light that cause TIR of a film used for the solar cell module to the total amount (AT) of the reflected light,” which refers to a percentage of the foregoing reflected light that cause TIR to all the reflected light, that is, satisfies the following formula:
TIR ratio=[(AT−Aθ)/AT]×100%.
When the TIR ratio of the film used for the solar cell module according to the present invention is larger than 10%, the power generation efficiency of the solar cell module can be apparently improved.
The film of the present invention may be transparent, translucent or opaque as required. The surface of a light-regulating layer of the film in the present invention may have a smooth structure or a concave-convex structure, and is preferably a surface having a concave-convex structure.
The shape of the light diffusing additives included in the light-regulating layer of the film of the present invention is not specially limited, and may be, for example, spherical, rhombus-shaped, elliptical, rice grain-shaped, polygonal spherical or biconvex-shaped, among which the spherical shape is preferred. The structure of the foregoing light diffusing additives may be, for example, a solid structure, a hollow structure, a porous structure or a combination thereof.
The material of the foregoing light diffusing additives may be, for example, glass, a metal oxide or plastic. The metal oxide may be, for example but is not limited to, TiO2, SiO2, ZnO, Al2O3, ZrO2 or a mixture thereof. The plastic may be, for example but is not limited to, an acrylate resin, a styrene resin, a urethane resin, a silicone resin or a mixture thereof. According to a preferred embodiment of the present invention, the material of the light diffusing additives is an acrylate resin, a silicone resin or a combination thereof.
The average particle size of the foregoing light diffusing additives is about 0.5 μm to 10 μm, preferably about 1 μm to 5 μm.
The content of the light diffusing additives is 5 wt % to 80 wt %, preferably 10 wt % to 60 wt % based on the total weight of the light-regulating layer.
The fluoro resin included in the light-regulating layer of the film used for the solar cell module according to the present invention comprises a copolymer of a fluoroolefin monomer and an alkyl vinyl ether monomer.
According to the present invention, the fluoroolefin monomer which may be used for forming the fluoro resin is well known to persons skilled in the art, which is, for example but not limited to, vinyl fluoride, vinylidene fluoride, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene or a mixture thereof, and preferably trifluorochloroethylene.
According to the present invention, the alkyl vinyl ether monomer which may be used for forming the fluoro resin is not specially limited, and may be one selected from the group consisting of a straight chain alkyl vinyl ether monomer, a side chain alkyl vinyl ether monomer, a cyclic alkyl vinyl ether monomer, and a hydroxyl alkyl vinyl ether monomer, and a mixture thereof.
Preferably, the alkyl in the alkyl vinyl ether has a carbon number of C2 to C11.
The fluoro resin used as a binder in the present invention provides an advantage of good weather resistance, and the content of the fluoro resin is 20 wt % to 95 wt %, preferably 40 wt % to 90 wt % based on the total weight of the light-regulating layer.
Optionally, a curing agent can be added to the light-regulating layer of the film used for the solar cell module according to the present invention, which plays the role of generating a chemical bond between molecules with the binder, so as to form crosslinking. The curing agent used in the present invention is well known to persons skilled in the art, and can be, for example, polyisocyanate.
The content of the foregoing curing agent is 0 wt % to 20 wt %, preferably 5 wt % to 10 wt % based on the total weight of the light-regulating layer.
Optionally, inorganic particles can be added to the light-regulating layer of the film used for the solar cell module, and the species of the inorganic particles may be, for example but is not limited to, aluminum nitride, magnesium oxide, silicon nitride, boron nitride, zinc oxide, silicon dioxide, titanium dioxide, zirconium oxide, iron oxide, aluminum oxide, calcium sulfate, barium sulphate or calcium carbonate or a mixture thereof, among which titanium dioxide is preferred.
The inorganic particles used in the light-regulating layer of the film used for the solar cell module of the present invention are used for color adjustment and for improving the reflection of the backsheet, and may also enable the backsheet to have an excellent ultraviolet absorption property. The inorganic particles optionally added to the light-regulating layer of the film used for the solar cell module of the present invention generally have a particle size of 0.01 μm to 20 μm, preferably 1 μm to 10 μm. The content of the inorganic particles used in the film of the present invention is 0 wt % to 75 wt %, preferably 1 wt % to 40 wt % based on the total weight of the light-regulating layer.
Optionally, conventional additives known to persons skilled in the art can be added to the light-regulating layer of the film used for the solar cell module according to the present invention.
The light-regulating layer of the film used for the solar cell module according to the present invention may be formed by, for example, but not limited to, knife coating, roller coating, micro gravure coating, flow coating, dip coating, spray coating, or curtain coating. According to an embodiment of the invention, the application method is roller coating.
The material of the substrate of the film used for the solar cell module according to the present invention may be, for example, glass, metal or resin. The resins useful for the present invention may include, but are not limited to, a polyester resin, such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN); a polyacrylate resin, such as polymethyl methacrylate (PMMA); a polyolefin resin, such as polyethylene (PE) or polypropylene (PP); a polycycloolefin resin; a polyimide resin; a polycarbonate resin; a polyurethane resin; polyvinyl chloride (PVC); triacetyl cellulose (TAC); or a polylactic acid, or a combination thereof, of which the polyester resin, polycarbonate resin, or a combination thereof is preferred and PET is more preferred.
According to an embodiment of the present invention, the transparent frontsheet in the solar cell module may be the film of the present invention, the backsheet in the solar cell module of the present invention may also be the film of the present invention, or both the transparent frontsheet and the backsheet are respectively the films. According to the present invention, a single surface of the substrate of the film has the light-regulating layer, or two surfaces of the substrate of the film respectively have the light-regulating layers. When the film is the transparent frontsheet, the substrate of the light-regulating film is a transparent substrate.
The construction of the film used for the solar cell module according to the present invention and the module thereof is exemplified hereinafter with reference to the drawings, which is not intended to limit the scope of the present invention. Modifications and changes which may be easily achieved by persons of ordinary skill in the art are included in the disclosure of the specification.
The foregoing film is located in the backsheet, and the light scattering phenomenon occurring when the sunlight 56 is incident to the film 54 may increase the quantity of the reflected light of the TIR and raise the utilization of the sunlight, so as to improve the photoelectric conversion efficiency.
The foregoing film is located in the frontsheet, and the light scattering phenomenon occurring when the sunlight 86 is incident to the film 84 may increase the reflected light of the TIR of the solar cell module and raise the utilization of the sunlight, so as to improve the photoelectric conversion efficiency of the solar cell module.
According to another embodiment of the present invention, as shown in
The following examples are provided to further illustrate the present invention, and not intended to limit the scope of the present invention. Modifications and variations achieved by persons skilled in the art without departing from the spirit of the present invention shall fall within the scope of the present invention.
A Tedlar/PET/Tedlar (TPT) lamination structure was manufactured by placing polyethylene terephthalate (PET) (O321E188, Mitsubishi Company) with the thickness of 188 μm between two polyvinyl fluoride layers (with the thickness of 25 μm, Tedlar® PV2001, DuPont Company), and then performing a vacuum hot-pressing procedure.
79.64 grams of a fluoro resin (Eterflon 4101-50 provided by Eternal Company, having a solids content of 50%, and being a trifluorochloroethylene and alkyl vinyl ether copolymer resin) was taken and added to a plastic bottle, then 6.79 grams of a solvent (butyl acetate) was added under high speed stirring, then 13.57 grams of a curing agent (Desmodur 3390 provided by Bayer Company, having a solids content of about 75%, and being an isocyanate curing agent) was added, and a coating with a solids content of about 50% and a total weight of about 100 grams was formulated. With an RDS coating rod #35, the coating was applied onto one side of a PET (O321E188, Mitsubishi Company) substrate, and a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C.
30.72 grams of a fluoro resin (Eterflon 4101-50 provided by Eternal Company, having a solids content of 50%, and being a trifluorochloroethylene and alkyl vinyl ether copolymer resin) was taken and added in a plastic bottle, then 33.33 grams of a solvent (butyl acetate) and 30.72 grams of light diffusing additives (Tospearl 120E provided by GE Toshiba Silicones Company, being silicone resin solid spherical particulates with an average particle size of 2 μm) were sequentially added under high speed stirring, and finally 5.23 grams of a curing agent (Desmodur 3390 provided by Bayer Company, having a solids content of about 75%, and being an isocyanate curing agent) was added, so that a coating with the solids content of about 50% and the total weight of about 100 grams was formulated. With an RDS coating rod #35, the coating was applied onto one side of a PET (O321E188, Mitsubishi Company) substrate, and a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C.
The steps in Preparation Example 3 were repeated, except that the amounts of the fluoro resin, the solvent, the light diffusing additives, and the curing agent were changed to 23.5 grams, 37.25 grams, 35.25 grams, and 4 grams, respectively.
44.33 grams of a fluoro resin (Eterflon 4101-50 provided by Eternal Company, having a solids content of 50%, and being a trifluorochloroethylene and alkyl vinyl ether copolymer resin) was taken and added in a plastic bottle, then 25.94 grams of a solvent (butyl acetate) and 22.17 grams of an inorganic particle TiO2 (R-902 provided by DuPont Company) were sequentially added under high speed stirring, and finally 7.56 grams of a curing agent (Desmodur 3390 provided by Bayer Company, having a solids content of about 75%, and being an isocyanate curing agent) was added, so that a coating with the solids content of about 50% and the total weight of about 100 grams was formulated. With an RDS coating rod #35, the coating was applied onto one side of a PET (O321E188, Mitsubishi Company) substrate, and a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C.
44.33 grams of a fluoro resin (Eterflon 4101-50 provided by Eternal Company, having a solids content of 50%, and being a trifluorochloroethylene and alkyl vinyl ether copolymer resin) was taken and added in a plastic bottle, then 25.94 grams of a solvent (butyl acetate), 17.73 grams of an inorganic particle TiO2 (R-902 provided by DuPont Company), and 4.43 grams of light diffusing additives (Tospearl 120E provided by GE Toshiba Silicones Company, being silicone resin solid spherical particulates with the average particle size of 2 μm) were sequentially added under high speed stirring, and finally 7.56 grams of a curing agent (Desmodur 3390 provided by Bayer Company, having a solids content of about 75%, and being an isocyanate curing agent) was added, so that a coating with the solids content of about 50% and the total weight of about 100 grams was formulated. With an RDS coating rod #35, the coating was applied onto one side of a PET (O321E188, Mitsubishi Company) substrate, and a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C.
The steps in Preparation Example 6 were repeated, except changing both the added quantities of TiO2 and the light diffusing additives to 11.08 grams.
The steps in Preparation Example 5 were repeated, except that the added quantities of the fluoro resin, the solvent, TiO2, and the curing agent were changed to 30.72 grams, 33.33 grams, 30.72 grams, and 5.24 grams respectively.
The steps in Preparation Example 6 were repeated, except that the added quantities of the fluoro resin, the solvent, TiO2, the light diffusing additives, and the curing agent were changed to 30.72 grams, 33.33 grams, 23.04 grams, 7.68 grams, and 5.24 grams respectively.
The steps in Preparation Example 9 were repeated, except that both the added quantities of TiO2 and the light diffusing additives were changed to 15.36 grams.
The steps in Preparation Example 9 were repeated, except that the added quantities of TiO2 and the light diffusing additives were changed to 7.68 grams and 23.04 grams respectively.
The steps in Preparation Example 5 were repeated, except that the added quantities of the fluoro resin, the solvent, TiO2, and the curing agent were changed to 23.5 grams, 37.25 grams, 35.25 grams, and 4.01 grams respectively.
The steps in Preparation Example 6 were repeated, except that the added quantities of the fluoro resin, the solvent, TiO2, the light diffusing additives, and the curing agent were changed to 23.5 grams, 37.25 grams, 29.37 grams, 5.88 grams, and 4.00 grams respectively.
The steps in Preparation Example 13 were repeated, except that the added quantities of TiO2 and the light diffusing additives were changed to 23.5 grams and 11.75 grams respectively.
The steps in Preparation Example 13 were repeated, except that both the added quantities of TiO2 and the light diffusing additives were changed to 17.62 grams.
The steps in Preparation Example 13 were repeated, except that the added quantities of TiO2 and the light diffusing additives were changed to 11.75 grams and 23.5 grams respectively.
The steps in Preparation Example 13 were repeated, except that the added quantities of TiO2 and the light diffusing additives were changed to 5.87 grams and 29.37 grams respectively.
A coating of the same formula as that in Preparation Example 3 was applied onto the uncoated side of the substrate of Preparation Example 3, a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C., and a film coated on double sides was formed.
A coating of the same formula as that in Preparation Example 7 was applied onto the uncoated side of the substrate in Preparation Example 7, a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C., and a film with coated on double sides was formed.
A coating of the same formula as that in Preparation Example 11 was applied onto the uncoated side of the substrate in Preparation Example 11, a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C., and a film coated on double sides was formed.
A coating of the same formula as that in Preparation Example 17 was applied onto the uncoated side of the substrate in Preparation Example 17, a coating layer (light-regulating layer) with the film thickness of about 25 μm was obtained after drying for 2 minutes at 120° C., and a film coated on double sides was formed.
The steps in Preparation Example 3 were repeated, except that the added quantities of the fluoro resin, the solvent, the light diffusing additives, and the curing agent were changed to 32.73 grams, 32.24 grams, 29.45 grams, and 5.58 grams respectively.
As shown in
The steps in Example 1A were repeated, except replacing Preparation Example 3 with Preparation Example 4, Preparation Example 6, Preparation Example 7, Preparation Example 9, Preparation Example 10, Preparation Example 11, Preparation Example 13, Preparation Example 14, Preparation Example 15, Preparation Example 16, and Preparation Example 17, respectively.
The steps in Example 1A were repeated, except that the backsheet was placed with the coating layer facing downward.
The steps in Example 1B were repeated, except replacing Preparation Example 3 with Preparation Example 4, Preparation Example 6, Preparation Example 7, Preparation Example 9, Preparation Example 10, Preparation Example 11, Preparation Example 13, Preparation Example 14, Preparation Example 15, Preparation Example 16, and Preparation Example 17, respectively.
The steps in Example 1A were repeated, except replacing Preparation Example 3 with Preparation Examples 18 to 21, respectively.
Preparation Example 22 (with the coating surface facing upward) was attached to an upper surface of the tempered glass in Example 12A, so as to obtain the solar cell module.
Preparation Example 22 (with the coating surface facing downward) was attached to an upper surface of the tempered glass in Example 12A, so as to obtain the solar cell module.
The steps in Example 1A were repeated, except changing Preparation Example 3 to Preparation Example 1.
The steps in Example 1A were repeated, except changing Preparation Example 3 to Preparation Example 2.
The steps in Example 1B were repeated, except changing Preparation Example 3 to Preparation Example 2.
The steps in Example 1A were repeated, except changing Preparation Example 3 to Preparation Example 5.
The steps in Example 1B were repeated, except changing Preparation Example 3 to Preparation Example 5.
The steps in Example 1A were repeated, except changing Preparation Example 3 to Preparation Example 8.
The steps in Example 1B were repeated, except changing Preparation Example 3 into Preparation Example 8.
The steps in Example 1A were repeated, except changing Preparation Example 3 to Preparation Example 12.
The steps in Example 1B were repeated, except changing Preparation Example 3 to Preparation Example 12.
<Test Methods>
1. A ratio of the reflected light (AT-Aθ) of the TIR to the total reflected light (AT) of the film, that is, a TIR ratio, was obtained; as shown in
TIR ratio=[(AT−Aθ)/AT]×100%,
so that the TIR ratio was obtained, where θ is a critical angle for generating the TIR, −a<θ<a, a=sin−1 (1/n1), and n1 is the refractive index of the material of the contact surface (the incident surface of the sunlight) between the transparent frontsheet and the air. Test results are as shown in Table 1, Table 2, and Table 3.
2. A test of the efficiency (η) of the solar cell module was performed, in which a solar simulator (Model: 92193A-1000, Newport Company) was used under the condition of AM1.5 luminance to irradiate the solar cell module to be tested, an I-V characteristic curve was measured, and then the efficiency (η=Pmax/Pin) of the solar cell module was calculated. Test results are as shown in Table 1, Table 2, and Table 3.
An optical characteristic (TIR ratio) of a film in a preparation example and the module power generation efficiency (η) measured after the film is mounted to the backsheet of the solar cell module are as shown in Table 1, in which the T/R value is a weight ratio of TiO2 (inorganic particle) to the fluoropolymer (solids content) after the coating layer is cured, and the B/R value is a weight ratio of the light diffusing additives to the fluoropolymer (solids content) after the coating layer is cured.
In the example of the single-sided coating layer (light-regulating layer) as shown in Table 1, the TIR value of a film in a preparation example is increased with the raise of the content of the light diffusing additives in the coating layer (Preparation Examples 2 to 4, Preparation Examples 5 to 7, Preparation Examples 8 to 11, and Preparation Examples 12 to 17), and meanwhile, when the film is mounted to the backsheet of the solar cell module, the corresponding module power generation efficiency η is also increased accordingly.
Both
It can be clearly seen from Table 2 and
It can be seen from Table 3 and
| Number | Date | Country | Kind |
|---|---|---|---|
| 099138379 | Aug 2010 | TW | national |
