JP2010123682A - Solar cell protecting sheet and solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell protecting sheet which can efficiently allow the incidence of light upon an photoelectric converter of a solar cell, achieves excellent structural reproducibility and a handling property, and a solar cell module. <P>SOLUTION: A solar cell protecting sheet 5 has a permeable protective layer 12, a reflective structural layer 13, and an outer layer 6. The permeable protective layer 12 has optical transparency wherein its one plane is used as an optical incidence plane, and the other as an optical projection plane. The reflective structural layer 13 is formed at the side of the optical projection surface so that it has a reflective function to reflect light projected from the optical projection surface toward the permeable protective layer 12. The outer layer 6 is formed on a rear surface where the reflective structural layer 13 is located at an opposite side of the optical projection surface, and protects the reflective structural surface 13. A light reflection concavo-convex surface 13A having light reflectivity is prepared at least on one surface of front and reverse sides where the reflective structural layer 13 is located. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention has a structure, and the structure allows the light to be deflected in a specific direction by diffraction, scattering, diffusion, refraction, or reflection of light, and can protect the light that is originally lost. The present invention relates to a sheet and a solar cell module using the sheet.

  In recent years, various efforts have been made to suppress carbon dioxide emissions while interest from various countries both inside and outside Japan has increased. Increasing fossil fuel consumption leads to an increase in atmospheric carbon dioxide, and the greenhouse effect raises the Earth's temperature, significantly affecting the global environment. Various studies have been conducted on alternative energy to fossil fuels, but there is an increasing expectation for photovoltaic power generation, which is a clean energy source.

  A solar cell used for photovoltaic power generation uses a semiconductor having a pn junction as a photoelectric conversion unit that directly converts sunlight energy into electricity, and silicon is generally the best as a semiconductor constituting the pn junction. It is used. Generally, the above-mentioned silicon used for solar cells is divided into a crystalline type and an amorphous type.

  On these photoelectric conversion parts, generally a glass substrate such as transparent tempered glass is provided as a sealing substrate for protecting the photoelectric conversion parts from air and impurities.

  In addition, in this specification, what packaged the at least 1 solar cell containing such a photoelectric conversion part using the sealing material is called a solar cell module.

The solar cell module is configured by connecting small-sized solar cells with a plurality of electrodes. In silicon crystal solar cells, there is some space between adjacent solar cells. Further, in order to prevent the erosion of rainwater or the like at the end of the solar cell module, a blank portion where no solar cell is arranged is provided from several millimeters to several tens of millimeters.
Since there are no solar cells in these gaps and blank portions, even if light is irradiated on these areas, power generation is not performed and loss occurs.

  Conventionally, the following measures have been proposed for the loss of light poured into the gaps and margins of solar cells.

  For example, in a solar cell module having a crystalline solar cell (photoelectric conversion unit), a protective sheet placed on the back surface is used as a light reflecting material, light is returned to the solar cell side again, and a glass plate as a front plate is used. Some of them are totally reflected and reincident on the light receiving surface of the solar battery cell to increase the efficiency. Further, there is a structure in which a concavo-convex structure is provided on the protective sheet disposed on the back surface, the light reflected on the concavo-convex structure is easily scattered, the probability of guiding it to the light receiving surface of the solar cell is improved, and the efficiency is increased (Patent Document 1) And 2). Furthermore, there is also a configuration in which light is scattered by making irregularities on the protective sheet on the back surface, and the efficiency is improved by using a solar cell that has both surfaces as light receiving surfaces (see Patent Document 3).

  The manufacturing method of the protective sheet disposed on the back surface having the light reflecting function with the unevenness on the surface includes, for example, a random unevenness formed by vapor deposition when attaching the light reflecting material to the base material, or a material containing fine particles By forming the irregularities by randomly projecting the fine particles to the surface, or forming irregularities on the substrate with resin, applying a light reflecting material on the irregularities, or forming an uneven structure on the light reflecting material There is something to push. However, the random shape has poor reproducibility and is difficult to control quality, and it is difficult to provide light control functions such as scattering control. The structure in which the light reflecting material is applied on the concavo-convex structure is likely to fill the structure, or to cause uneven thickness such as dripping when applying the light reflecting material, and the performance is biased or the appearance is impaired.

  In addition, the protective sheet disposed on the back surface having the light reflection function with the unevenness on the front surface is incident from the surface opposite to the surface where the unevenness exists, and the incident surface from the surface where the unevenness exists. In some cases, it has been confirmed that the surface having high re-condensing efficiency on the light receiving surface of the cell due to total reflection from a glass plate or the like differs depending on the arrangement relationship between the protective sheet and the cell.

  In other words, depending on the arrangement of the cells of the solar cell module, it may be desirable to arrange a surface with the unevenness of the protective sheet on the light incident surface.

  On the other hand, a solar cell module manufacturer often obtains each member such as a glass plate, a protective sheet, and a sealing material arranged on the front surface from an outside contractor and assembles them to manufacture a solar cell module.

  However, the protective sheet having the unevenness on the surface as described above has a problem that dust and dust are easily caught when transported to a factory for assembly. If dust, dust, or other dust remains, it may not only cause troubles such as peeling between members, but it may also cause re-attachment to the solar cells due to the presence of dust between the irregularities of the protective sheet. Condensation performance may be reduced.

  Furthermore, the protective sheet with the unevenness on the surface as described above is slightly distorted due to friction, load, etc., because the uneven structure is exposed to the surface during the period from manufacture to assembly of the solar cell module. There is a possibility that defects such as scraping and scraping may occur, thereby reducing the re-condensing performance to the solar battery cell.

In addition, the protective sheet with irregularities on the surface as described above may deform the irregular structure due to heat applied in the assembly process of the solar cell module, thereby recondensing performance to the solar cells. May be lowered.
Japanese Utility Model Publication No. 62-101247 JP-A-10-284747 Japanese Patent No. 3670835

As described above, it is obvious that the power generation efficiency can be improved by reflecting light on the back side of the solar cell. In particular, thin-film solar cells have a large light absorption rate in the power generation section because of their thinness, and retroreflection on the back surface is important for improving the efficiency of power generation. Thin-film solar cells produce a power generation part with a thin film by a method such as vapor deposition. Therefore, the power generation part can be made thinner than a crystal system that uses a silicon wafer, and in terms of material cost and flexibility. This is an advantageous configuration. However, if it is a thin film, light incident on the light-receiving surface cannot be absorbed, and a transmitted light component is also generated. Therefore, the power generation efficiency is improved by providing a reflector on the back surface side for retroreflection or by devising to increase the optical path length inside the solar cell module by scattering.
Also, in order to obtain insulation and barrier properties in other types of solar cells, it is necessary to create a blank portion where no cells are arranged in the solar cell module, and much of the light poured into this blank portion is used for power generation. However, in order to improve the power generation efficiency around the area, a means for effectively utilizing the light poured into the blank area is desired. Many use protective sheets on the back side as reflective materials, or have irregularities on the surface. However, it is easy to get dust or dirt involved when transporting protective sheets, deformation of the uneven structure that occurs during storage and transportation, etc. Handling characteristics such as remain.

  Also, when the protective sheet placed on the back surface with light reflection function with unevenness on the front surface is incident from the surface where the unevenness exists, and from the surface opposite to the surface where the unevenness exists In order to achieve higher power generation efficiency, the above-mentioned problems must be solved because the surface with high re-condensing efficiency on the light receiving surface of the cell due to total reflection from a glass plate or the like depends on the arrangement relationship between the protective sheet and the cell There is a need to provide an optimal configuration according to the structure of the solar cell module while avoiding it.

  In the present invention, for the purpose of improving the light utilization efficiency, even when external light is incident from all directions, the light can be efficiently incident on the photoelectric conversion part of the solar cell, and the good concavo-convex structure reproducibility and the solar cell An object of the present invention is to provide a solar cell protective sheet and a solar cell module that can avoid deformation of the concavo-convex structure that can occur before the assembly of the module and achieve good handling properties, and that can manufacture a shape as designed.

In order to solve the above-mentioned problems, the solar cell protective sheet according to claim 1 of the present invention is light transmissive and has one surface as a light incident surface and the other surface as a light exit surface. A protective layer, a reflective structure layer that is provided on the light exit surface side and has a reflective function of reflecting light emitted from the light exit surface toward the transparent protective layer, and the reflective structure layer includes the light exit surface; An outer layer which is provided on the back side located on the opposite side and protects the reflective structure layer, and the reflective structure layer has light reflectivity on at least one of the front surface and the back surface located on the light emitting surface side. An uneven surface for reflecting light is provided.
In other words, by providing the protective sheet with a light-reflective uneven surface (relief structure) having light reflectivity, the light that is retroreflected by the protective sheet increases the probability of reaching the light-receiving surface of the solar battery cell, thereby improving efficiency. Can be improved. In addition, since the surface on which the light-reflective surface (relief structure) is formed is located inside the protective sheet, there is no structure on both surfaces of the protective sheet, and it is caused by friction before the solar cell module is assembled. Scratches and structural deformation, and dust entrainment in the structure are reduced, and handling is excellent. Furthermore, the surface on which the relief structure is formed can be a light receiving surface or a surface opposite to the light receiving surface.
Even when the surface on which the relief structure is formed is the surface opposite to the light-receiving surface, the structural layer having the reflective function is covered with the transparent protective layer and the outer layer, so emphasis is placed on moldability and optical properties. This makes it possible to select materials.

In the solar cell protective sheet according to claim 2 of the present invention, a barrier layer having a water vapor permeability in the range of 0 to 0.5 g / m ² is provided between the transmissive protective layer and the reflective structure layer. It is characterized by having.
By forming the barrier layer, it is possible to prevent water vapor from penetrating into the solar cell module, and to prevent corrosion of electrodes used in the solar cell module and deterioration of the sealing resin. If the water vapor transmission rate exceeds the above range, it is not desirable because corrosion of the electrode or deterioration of the sealing resin may occur. Further, by arranging the transparent protective layer between the reflective protective layer and the reflective structural layer, for example, when a metal is used for a part of the reflective structural layer, the electrode is protected when the solar cell module is assembled. By penetrating, it is possible to enhance the effect of preventing the phenomenon of short circuit.

Moreover, the solar cell protective sheet which concerns on Claim 3 of this invention has a barrier layer whose water vapor permeability is the range of 0-0.5 g / m < ² > between the said reflective structure layer and the said outer layer. Features.
By forming the barrier layer, it is possible to prevent water vapor from penetrating into the solar cell module, and to prevent corrosion of electrodes used in the solar cell module and deterioration of the sealing resin. If the water vapor transmission rate exceeds the above range, it is not desirable because corrosion of the electrode or deterioration of the sealing resin may occur. Further, by disposing between the reflective structure layer and the previous outer layer, it is possible to suppress the absorption of light until the incident light reaches the reflective structure layer as much as possible.

Moreover, the solar cell protective sheet which concerns on Claim 4 of this invention is characterized by the shape of the said uneven surface for light reflection being a V-shaped groove, a polygonal pyramid shape, or these reverse type | molds.
The prism shape as described above has good reflectivity. For example, an aspherical lens having a high aspect ratio has a scattering property, but light is absorbed by the structure, which may cause a decrease in retroreflectance. Further, the V-shaped groove structure is a structure in which a V-shape that is convex downward with respect to the plane is dug, and the reverse type is formed with a V-shape that is convex upward with respect to the plane. It is a structure. In addition, the polygonal pyramid shape is a structure in which a polygonal pyramid that is convex upward with respect to a plane is formed, and the inverse type is a structure in which a polygonal pyramid that is convex downward with respect to a plane is dug. It is.

In the solar cell protective sheet according to claim 5 of the present invention, the shape of the uneven surface for light reflection is composed of a plurality of convex portions and a plurality of concave portions, and the apex angle of the convex portions is 120 ° to 135 °. It is included in the range of °.
By setting the apex angle within the above-mentioned angle range, when the refractive index of the sealing resin and glass used in the solar cell module is about 1.5, total reflection is performed at the interface between the glass and air, and the reflected light Can be prevented from entering the relief structure. On the other hand, when the angle exceeds 135 °, total reflection is less likely to occur at the interface between the glass and the air, so that there is a high possibility that the re-condensing efficiency is lowered. In addition, when the angle is less than 120 °, there is a high possibility that a part of the light reflected by the relief structure collides with the relief structure, and the possibility that the re-condensing efficiency decreases.

In the solar cell protective sheet according to claim 6 of the present invention, the uneven surface for light reflection is configured by providing a reflective film having light reflectivity on the uneven shape provided in the reflective structure layer. It is characterized by being.
By forming the reflective structure layer as described above, the uneven surface for light reflection (relief structure) can be mass-produced by, for example, extrusion molding, embossing using a plate with a relief structure, UV molding, etc., and stable. Thus, the same relief structure can be formed. As a result, it is possible to stably produce the reflective structure layer.
In the solar cell protective sheet according to claim 7 of the present invention, the reflective structure layer is composed of a light reflective layer having light reflectivity, and the uneven surface for light reflection is composed of the surface of the light reflective layer. It is characterized by being.

In the solar cell protective sheet according to claim 8 of the present invention, the reflective film is a metal.
By using a metal for the reflection film, it becomes possible to increase the re-condensing efficiency of the reflected light by the specular reflection.

The solar cell protective sheet according to claim 9 of the present invention is characterized in that an antioxidant layer is formed on the reflective film.
By forming the antioxidant layer on the reflective film, it is possible to prevent the reflective film from being oxidized and to prevent deterioration of the reflective performance. In addition, by making the antioxidant layer a thin film layer of an inorganic oxide, not only the oxygen blocking effect but also water vapor blocking can be achieved.

Moreover, the solar cell protective sheet which concerns on Claim 10 of this invention is characterized by the said reflecting film containing at least 1 type of diffusion filler mixing material.
By using a material containing a diffusing filler for the reflective film, the reflection angle of light can be adjusted by the relief structure, and the scattering property of this reflected light can be adjusted by the diffusing filler. That is, it is possible to realize stable reflectivity regardless of the incident angle of light.

Moreover, the solar cell module which concerns on Claim 11 of this invention uses the solar cell protection sheet in any one of Claim 1-10, It is characterized by the above-mentioned.
By employing the solar cell protective sheet according to any one of claims 1 to 10 for a solar cell module, light can be efficiently incident on the photoelectric conversion part of the solar cell, and good reproducibility can be obtained. A solar cell module can be provided.

In the present invention, by forming the reflective structure layer, light can be efficiently incident on the photoelectric conversion portion of the solar cell, and the concavo-convex structure of the reflective structure layer has a relief structure that allows easy shape reproduction. By having a good concavo-convex structure reproducibility, and disposing the reflective structure layer between the transmissive protective layer and the outer layer, it is possible to avoid the deformation of the concavo-convex structure that may occur before the assembly of the solar cell module and good It is possible to provide a solar cell protective sheet and a solar cell module capable of realizing excellent handling properties and manufacturing a shape as designed.
In addition, by using the protective sheet and reusing light of a light emitting element such as an LED or an EL element, the light use efficiency can be improved, and a light emitting element with high light emission efficiency can be provided.

First, the solar cell module according to the present invention will be described.
FIG. 1 is a schematic view according to a uniform state of the solar cell module of the present invention. The light beam 1 refers to sunlight or light from artificial lighting such as room light. The front plate 2 receives the external light 1 and is made of a general transparent material having high light transmittance. Specifically, a resin sheet such as tempered glass or PEN (polyethylene naphthalate) is used. Yes.
The thickness of the front plate 2 is about 5 mm for tempered glass and several tens to several hundreds μm for a resin sheet.

  The light 1 incident on the front plate 2 enters the filler 3. The filler 3 has a role of sealing the solar battery cell, and a material having a high light transmittance is used to transmit the external light 1 incident from the front plate 2, and EVA (ethylene vinyl vinyl) having flame retardancy is used. Acetate) is widely used.

The light 1 transmitted through the filler 3 enters the solar battery cell 4. The solar battery cell 4 has a function of converting light incident on the light receiving portion into electricity by photoelectric effect, and is a single crystal silicon type, a polycrystalline silicon type, a thin film silicon type, CIGS (Cu · In · Ga · Se compound) ) There are many types such as thin film type.
A plurality of solar cells 4 are connected by electrodes to form a module.

  The light 1 transmitted through the solar battery cell 4 enters the protective sheet 5 through the filler 3. The protective sheet 5 has a function of reflecting incident light toward the light receiving surface by a reflection structure layer 13 described later. The reflected light is further reflected at the interface between the front plate 2 and the atmosphere, etc., and is applied to the light receiving surface of the solar battery cell 4 for photoelectric conversion, thereby improving the light utilization efficiency.

FIG. 2 is a side view showing an example of the configuration of the protective sheet 5 of the solar cell according to the present embodiment. The protective sheet 5 includes an outer layer 6, an intermediate layer 7, a gas barrier layer 8, a base material 9, a structural layer 10, a reflective film 11, an intermediate layer 7, and a permeable protective layer 12.
In the present embodiment, the reflective structure layer 13 is configured by the structural layer 10 and the reflective film 11.

The outer layer 6 is provided on the back surface side where the reflective structure layer 13 is located on the opposite side of the light emitting surface of the transmissive protective layer 12 and protects the reflective structure layer 13.
In view of being installed outdoors, it is desirable that the outer layer 6 has weather resistance such as water resistance and durability against ultraviolet rays. For example, a polyethylene resin such as polyethylene terephthalate resin (PET resin), a polypropylene resin, Methacrylic resin, polymethylpentene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile- (poly) styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride Resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyarylphthalate resin, silicone resin, polysulfone resin, polyphenylene Sulfide Resins, polyethersulfone resins, triethylene naphthalate resins, polyether imide resins, Epokishin resins, polyurethane resins, acetal resins, cellulose resins and the like.
Among the above resins, polyimide resins, polycarbonate resins, polyester resins, fluorine resins, polylactic acid resins are those having high heat resistance, strength, weather resistance, durability, gas barrier properties against water vapor and the like. preferable.

  Examples of the polyester-based resin include polyethylene terephthalate and polyethylene naphthalate. Among these polyester-based resins, polyethylene terephthalate is particularly preferable because it has a good balance between various functions such as heat resistance and weather resistance, and price.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), perfluoroalkoxy resin (PFA) made of a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP). ), Copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether and hexafluoropropylene (EPE), copolymer of tetrafluoroethylene and ethylene or propylene (ETFE), polychlorotrifluoroethylene resin (PCTFE), ethylene and chlorotrifluoroethylene Copolymer (ECTFE), vinylidene fluoride resin (PVDF), vinyl fluoride resin (PVF), and the like. Among these fluororesins, polyvinyl fluoride resin (PVF) and a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE) which are excellent in strength, heat resistance, weather resistance and the like are particularly preferable.

  Examples of the above-mentioned cyclic polyolefin-based resin include polymerizing cyclic dienes such as a) cyclopentadiene (and derivatives thereof), dicyclopentadiene (and derivatives thereof), cyclohexadiene (and derivatives thereof), norbornadiene (and derivatives thereof), and the like. And b) a copolymer obtained by copolymerizing the cyclic diene with one or more olefinic monomers such as ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. It is done. Among these cyclic polyolefin resins, cyclopentadiene (and derivatives thereof), dicyclopentadiene (and derivatives thereof) or norbornadiene (and derivatives thereof) such as polymers having excellent strength, heat resistance, and weather resistance are particularly preferred. preferable.

  In addition, as a formation material of the outer layer 6, the above-mentioned synthetic resin can be used 1 type or in mixture of 2 or more types. In addition, various additives and the like can be mixed in the forming material of the outer layer 6 for the purpose of improving and modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, and the like. Examples of the additive include a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing fiber, a reinforcing agent, an antistatic agent, a flame retardant, a flame retardant, a foaming agent, and an antifungal agent. And pigments. The method for forming the outer layer 6 is not particularly limited, and known methods such as an extrusion method, a cast forming method, a T-die method, a cutting method, and an inflation method are employed.

  The outer layer 6 may contain an ultraviolet stabilizer or a polymer having an ultraviolet stabilizing group bonded to a molecular chain. By this ultraviolet stabilizer or ultraviolet stabilizer, radicals generated by ultraviolet rays, active oxygen and the like are inactivated, and the ultraviolet stability and weather resistance of the protective sheet 5 can be improved. As the UV stabilizer or UV stabilizer, a hindered amine UV stabilizer or a hindered amine UV stabilizer having high stability to UV is preferably used.

  The intermediate layer 7 desirably has good adhesion to the two layers in contact with the intermediate layer 7 and is used to supplement various characteristics such as durability and cushioning properties. For example, silicone resin is used. By providing the intermediate layer 7, it is possible to compensate for performance that is insufficient with only the other layers. For example, a silicone resin is used to improve durability, cushioning properties, and the like. In particular, in the case of a solar cell used outdoors, the heat rise of the solar cell during sunshine is remarkable, and the protective sheet made from the resin material is warped, which may cause an unexpected failure of the solar cell. In addition, a metal layer may be used to have a high barrier property that is important for maintaining high power generation efficiency.

The gas barrier layer 8 is desirably a material having excellent water vapor barrier properties. Specifically, the water vapor permeability is desirably in the range of 0 to 0.5 g / m ² . Examples of materials that can be used for the gas barrier layer 8 include aluminum foil, alumina, silica, and the like.

  The substrate 9 desirably has high adhesion to the material forming the structural layer 10. Moreover, when the reflective film 11 is located on the outer layer 6 side with respect to the base material 9, it is desired that the transmittance is high.

  The material forming the structural layer 10 desirably has high adhesion to the base material 9. When the structural layer 10 is located closer to the outer layer 6 than the base material 9, it is desirable that the permeability is high. Examples of the material used for the structural layer 10 include a polymer composition and a metal. When a polymer composition is used for the structural layer 10, in addition to the polymer composition, for example, a curing agent, a plasticizer, a dispersant, various leveling agents, an ultraviolet absorber, an antioxidant, a viscosity modifier, a lubricant, light A stabilizer and the like may be appropriately blended.

  The above-mentioned polymer composition is not particularly limited. For example, poly (meth) acrylic resin, polyurethane resin, fluorine resin, silicone resin, polyimide resin, epoxy resin, polyethylene resin, polypropylene Resin, methacrylic resin, polymethylpentene resin, cyclic polyolefin resin, acrylonitrile- (poly) styrene copolymer (AS resin), polystyrene resin such as acrylonitrile-butadiene-styrene copolymer (ABS resin), Polyvinyl chloride resin, polycarbonate resin, polyester resin, polyamide resin, polyamideimide resin, polyaryl phthalate resin, polysulfone resin, polyphenylene sulfide resin, polyether sulfone resin, reethylene naphthalene DOO-based resins, polyether imide resins, acetal resins, cellulose resins and the like, can be used as a mixture of these polymers alone or in combination.

  Examples of the polyol that is a raw material for the polyurethane resin include a polyol obtained by polymerizing a monomer component containing a hydroxyl group-containing unsaturated monomer, a polyester polyol obtained under conditions of excess hydroxyl group, and the like. These can be used alone or in admixture of two or more.

  Examples of the hydroxyl group-containing unsaturated monomer include (a) 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, homoallyl alcohol, Keihi Hydroxyl group-containing unsaturated monomers such as alcohol and crotonyl alcohol, (b) for example ethylene glycol, ethylene oxide, propylene glycol, propylene oxide, butylene glycol, butylene oxide, 1,4-bis (hydroxymethyl) cyclohexane, phenylglycidyl Dihydric alcohols or epoxy compounds such as ether, glycidyl decanoate, Plaxel FM-1 (manufactured by Daicel Chemical Industries, Ltd.) and, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, Tonsan, and the like hydroxyl group-containing unsaturated monomers obtained by reaction of an unsaturated carboxylic acid such as itaconic acid. One or more selected from these hydroxyl group-containing unsaturated monomers can be polymerized to produce a polyol.

  The polyols described above are ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, ethyl hexyl acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, N-butyl methacrylate, tert-butyl methacrylate, ethyl hexyl methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, styrene, vinyl toluene, 1-methylstyrene, acrylic acid, methacrylic acid, acrylonitrile, vinyl acetate, vinyl propionate, stearin Vinyl acid, allyl acetate, diallyl adipate, diallyl itaconate, diethyl maleate, vinyl chloride, vinylidene chloride, acrylamide, N-methylol acrylamide, N-butyl One or more ethylenically unsaturated monomers selected from xymethyl acrylamide, diacetone acrylamide, ethylene, propylene, isoprene and the like, and a hydroxyl group-containing non-functional group selected from the above (a) and (b) It can also be produced by polymerizing a saturated monomer.

  The number average molecular weight of a polyol obtained by polymerizing a monomer component containing a hydroxyl group-containing unsaturated monomer is from 1,000 to 500,000, preferably from 5,000 to 100,000. The hydroxyl value is 5 or more and 300 or less, preferably 10 or more and 200 or less, more preferably 20 or more and 150 or less.

  The polyester polyol obtained under the condition of excess hydroxyl group is (c), for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl. Glycol, hexamethylene glycol, decamethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane, hexanetriol, glycerin, pentaerythritol, cyclohexanediol, hydrogenated bisphenol A, bis (hydroxymethyl) Polyhydric alcohols such as cyclohexane, hydroquinone bis (hydroxyethyl ether), tris (hydroxyethyl) isosinurate, xylylene glycol, and (d) maleic acid, for example. Polybasic acids such as fumaric acid, succinic acid, adipic acid, sebacic acid, azelaic acid, trimetic acid, terephthalic acid, phthalic acid, and isophthalic acid, and polyvalent acids such as propanediol, hexanediol, polyethylene glycol, and trimethylolpropane It can be produced by reacting under conditions where the number of hydroxyl groups in the alcohol is greater than the number of carboxyl groups of the polybasic acid.

  The number average molecular weight of the polyester polyol obtained under the above hydroxyl group-excess conditions is 500 or more and 300,000 or less, preferably 2000 or more and 100,000 or less. The hydroxyl value is 5 or more and 300 or less, preferably 10 or more and 200 or less, more preferably 20 or more and 150 or less.

  The polyol used as the polymer material of the polymer composition is obtained by polymerizing the above-described polyester polyol and a monomer component containing the above-mentioned hydroxyl group-containing unsaturated monomer, and is a (meth) acryl unit. Etc. are preferred. When such a polyester polyol or acrylic polyol is used as a polymer material, the weather resistance is high, and yellowing of the structural layer 10 can be suppressed. In addition, any one of this polyester polyol and acrylic polyol may be used, and both may be used.

  The number of hydroxyl groups in the above-described polyester polyol and acrylic polyol is not particularly limited as long as it is 2 or more per molecule, but if the hydroxyl value in the solid content is 10 or less, the number of crosslinking points decreases, and the solvent resistance Film properties such as heat resistance, water resistance, heat resistance and surface hardness tend to decrease.

  Further, by adding a filler to the material forming the structural layer 10, it is possible to impart scattering properties and reduce the influence of the re-condensing efficiency due to the incident angle of external light. Moreover, it becomes possible to improve heat resistance by containing a filler. Examples of the material used for the filler include acrylic, acrylic styrene, silicon oxide, titanium oxide, zinc sulfide, and aluminum oxide.

The light reflecting uneven surface 13A formed on the reflective structure layer 13 (structure layer 10) is a structure for reflecting incident light in a specific direction. Examples include a weight shape, a diffraction grating, a microlens, and an aspheric lens.
The light reflecting uneven surface 13 </ b> A may be formed over the entire region of the reflective structure layer 13, or may be formed only at a location corresponding to the solar battery cell 4.

  As a method of forming the light reflecting uneven surface 13A formed on the reflective structural layer 13 (structural layer 10), a plastic raw material is fed into a heating cylinder with a screw or a plunger, heated and fluidized, and passed through a tip die. There is an extrusion method in which a long product is formed by giving a shape and cooling and solidifying it with water or air.

  Further, as another uneven surface 13A for reflecting light, for example, a relief pattern is drawn on a resin or the like by an electron beam, or a relief pattern is formed by cutting a bite or the like, and the relief pattern thus formed is converted into a metal plate by electroforming. The relief pattern can be reproduced in large quantities by producing an original plate by, for example, causing the pattern to be transferred to the thermoplastic resin by an embossing method. Further, instead of transferring to the thermoplastic resin by an embossing molding method, the pattern may be transferred by a molding method using an ultraviolet curable resin.

  In this example, the surface of the reflective structural layer 13 (structural layer 10) where the light reflecting uneven surface 13A is formed faces the transparent protective layer 12, but may face the outer layer 6. .

  The reflective film 11 is a layer having a function of reflecting incident light. The material used for the reflective film 11 is not particularly limited as long as it has reflectivity and can be deposited. For example, aluminum (Al), silver (Ag) nickel (Ni), tin (Sn), Examples of the metal include zirconium (Zr). Further, a high refractive index material such as zinc sulfide may be included. Among these, aluminum has a high reflectance in the ultraviolet, visible, and near infrared regions, and it is possible to prevent internal erosion by forming an oxide film on the surface. Moreover, there exists an advantage that it has high water vapor | steam barrier property. Further, silver has an advantage that the reflectance is higher than that of aluminum in the visible and near infrared regions. Gold absorbs on the short wavelength side of the visible region, but has a higher reflectance than aluminum at wavelengths of 600 nm or longer. In addition, these three metals are desirable as materials used for the reflective film 11 because they have an advantage that they are hardly eroded.

  When the reflective film 11 is formed, it is formed by vapor-depositing a metal along the light reflecting uneven surface 13A. The means for depositing the reflective film 11 is not particularly limited as long as a metal can be deposited without causing deterioration of the structural layer 10 such as shrinkage and yellowing. (A) Vacuum deposition method, sputtering method, ion plate Chemical vapor deposition methods (Physical Vapor Deposition method; PVD method), (b) Plasma chemical vapor deposition method, thermal chemical vapor deposition method, photochemical vapor deposition method, etc. A phase growth method (Chemical Vapor Deposition method; CVD method) is employed. Among these vapor deposition methods, a vacuum vapor deposition method and an ion plating method that can form a high-quality reflective layer 4 with high productivity are preferable.

  The reflective film 11 may have a single layer structure or a multilayer structure of two or more layers. Thus, by making the reflective film 11 have a multilayer structure, the deterioration of the structural layer 10 is reduced by reducing the thermal burden applied during vapor deposition, and the adhesion between the structural layer 10 and the reflective film 11 is further improved. Can do. At this time, a metal oxide layer may be provided on the metal film. The vapor deposition conditions in the physical vapor deposition method and the chemical vapor deposition method are appropriately designed according to the resin type of the structural layer 10 and the substrate 9, the thickness of the reflective film 11, and the like.

  The lower limit of the thickness of the reflective film 11 is preferably 10 nm, and particularly preferably 20 nm. On the other hand, the upper limit of the thickness of the reflective film 11 is preferably 200 nm, and particularly preferably 100 nm. If the thickness of the reflective film 11 is smaller than the lower limit of 10 nm, the light incident on the reflective film 11 cannot be sufficiently reflected. Even if the thickness is 20 nm or more, the light reflected by the reflective film 11 does not increase. On the other hand, when the thickness of the reflective film 11 exceeds the upper limit of 200 nm, cracks that can be visually confirmed occur in the reflective film 11, and cracks that cannot be visually confirmed occur if the thickness is 100 nm or less.

  Further, the outer surface of the reflective film 11 may be subjected to a top coat process. Thus, by performing a top coat process on the outer surface of the reflective film 11, the reflective film 11 is sealed and protected, and deterioration over time can be suppressed.

  Examples of the topcoat agent used in the above-described topcoat treatment include a polyester topcoat agent, a polyamide topcoat agent, a polyurethane topcoat agent, an epoxy topcoat agent, a phenol topcoat agent, and a (meth) acrylic top. Examples thereof include a coating agent, a polyvinyl acetate top coating agent, a polyolefin top coating agent such as polyethylene aly polypropylene, and a cellulose top coating agent. Among such topcoat agents, a polyester-based topcoat agent that has high adhesive strength with the reflective film 11 and contributes to surface protection of the reflective film 11, sealing of defects, and the like is particularly preferable.

  The coating amount (in terms of solid content) of the above-mentioned top coat agent is preferably 3 g / m 2 or more and 7 g / m 2 or less. If the coating amount of the top coat agent is smaller than 3 g / m 2, the effect of sealing and protecting the reflective film 11 may be reduced. On the other hand, even if the coating amount of the top coat agent exceeds 7 g / m 2 above, the sealing and protecting effect of the reflective film 11 does not increase so much, and the thickness of the protective sheet 5 increases.

  In addition, in the above-mentioned top coat agent, various additives such as a silane coupling agent for improving tight adhesion, an ultraviolet absorber for improving weather resistance and the like, an inorganic filler for improving heat resistance and the like Can be mixed as appropriate. The amount of the additive to be mixed is preferably 0.1% by weight or more and 10% by weight or less from the balance between the effect expression of the additive and the function inhibition of the topcoat agent. If the above-mentioned additive is less than 0.1% by weight, close adhesion, weather resistance and heat resistance cannot be sufficiently obtained, and if it is more than 10% by weight, the function of the topcoat agent is inhibited.

  When the reflective film 11 is used in the protective sheet 5, surface treatment may be performed on the surface of the structural layer 10, which is the deposition target surface of the reflective film 11, in order to improve the tight adhesion and the like. Examples of such surface treatment include (a) corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, and (b) primer. Examples of the coating treatment include undercoating, anchor coating, vapor deposition anchor coating, and the like. Among these surface treatments, corona discharge treatment and anchor coat treatment that improve the adhesive strength with the reflective layer 4 and contribute to the formation of a dense and uniform reflective film 11 are preferable.

  Examples of the anchor coating agent used in the above-described anchor coating treatment include a polyester anchor coating agent, a polyamide anchor coating agent, a polyurethane anchor coating agent, an epoxy anchor coating agent, a phenol anchor coating agent, and a (meth) acrylic anchor. Examples thereof include a coating agent, a polyvinyl acetate anchor coating agent, a polyolefin anchor coating agent such as polyethylene aly polypropylene, and a cellulose anchor coating agent. Among these anchor coating agents, polyester anchor coating agents that can further improve the adhesive strength of the reflective film 11 are particularly preferable.

  The coating amount (in terms of solid content) of the above-described anchor coating agent is preferably 1 g / m 2 or more and 3 g / m 2 or less. When the coating amount of the anchor coating agent is less than 1 g / m 2, the effect of improving the adhesion of the reflective film 11 is reduced. On the other hand, when the coating amount of the anchor coating agent is more than 3 g / m 2, the strength, durability, etc. of the protective sheet 5 may be lowered.

  In the above-mentioned anchor coating agent, various additives such as a silane coupling agent for improving tight adhesion, an anti-blocking agent for preventing blocking, and an ultraviolet absorber for improving weather resistance, etc. It can mix suitably.

  The permeable protective layer 12 is desirably excellent in heat resistance, moisture resistance, electrical characteristics (particularly, overall voltage resistance) and mechanical characteristics. Specific examples include a fluororesin film, a fluororesin coating film, and PET for electrical insulation.

As an example of a method for producing a protective sheet 5 as shown in FIG. 2, a gas barrier layer 8 is formed on a substrate 9 by vapor deposition or the like, and a metal plate is formed on the surface opposite to the surface on which the gas barrier layer 8 is formed. The structural layer 10 having the light reflecting concave / convex surface 13A is produced by a UV molding method using, and the reflective film 11 is formed thereon by vapor deposition or the like. Thereafter, there is a method in which the reflective film 11 and the transmissive protective layer 12 are bonded via the intermediate layer 7, and the gas barrier layer 8 and the outer layer 6 are bonded using the intermediate layer 7.
As described above, the protective sheet 5 of the present embodiment has the light-transmitting protective protective layer 12 having one surface as a light incident surface and the other surface as a light emission surface, and light emission. A reflective structure layer 13 having a reflection function of reflecting the light emitted from the light exit surface provided toward the surface toward the transparent protective layer 12, and a back surface side where the reflective structure layer 13 is located on the opposite side of the light exit surface And an outer layer 6 that protects the reflective structure layer 13.
Then, a light reflecting uneven surface 13A having light reflectivity is provided on at least one of the front surface and the back surface where the reflective structure layer 13 is located on the light emitting surface side.
The uneven surface for light reflection 13 </ b> A is configured by providing the reflective film 11 having light reflectivity on the uneven shape provided in the reflective structure layer 13.

  FIG. 3 is a side view showing an example of the configuration of the solar cell protective sheet according to the present embodiment. It has a layer structure in which the reflective film 11 is removed from the protective sheet 5 shown in FIG.

As described above, when the reflective film 11 is not present, it is desirable that the structural layer 10 itself is provided with reflectivity. Specifically, a method of using a material having reflectivity such as a metal material or a mixture of a filler, a pigment, or the like with the material forming the structural layer 10 may be used.
That is, in this example, the reflective structure layer 13 is composed of the structural layer 10 as a light reflective layer having light reflectivity, and the light reflecting uneven surface 13A is composed of the surface of the light reflective layer (structural layer 10). Has been.

  When a filler is mixed in the material forming the structural layer 10, it is desirable to use a material that can improve the heat resistance of the structural layer 10 and has a refractive index significantly different from that of the polymer composition. Thereby, light can be reflected. The inorganic material constituting the filler is not particularly limited, and an inorganic oxide is preferable. As the inorganic oxide, metal oxides such as silicon oxide and zinc sulfide can be used, but metal oxides such as titanium oxide and aluminum oxide are particularly desirable. Silicon oxide hollow particles can also be used. Of these, titanium oxide is preferable because of its high refractive index and easy dispersibility. The shape of the filler may be any particle shape such as a spherical shape, a needle shape, a plate shape, a scale shape, and a crushed shape, and is not particularly limited.

  The lower limit of the average particle diameter of the filler is preferably 0.1 μm, and the upper limit is preferably 30 μm. If the average particle diameter is smaller than 0.1 μm, light is not sufficiently reflected. Further, if the average particle size is larger than 30 μm, the moldability is poor.

  As a minimum of the compounding quantity with respect to 100 parts of polymer compositions of a filler, 30 parts is preferable in conversion of solid content. On the other hand, the upper limit of the amount of the filler described above is preferably 100 parts. This is because if the blending amount of the filler is less than 30 parts, light cannot be sufficiently reflected. On the contrary, if the blending amount exceeds the above range, the moldability is poor.

  As the above-mentioned filler, a material having an organic polymer fixed on its surface may be used. Thus, by using the filler fixed to the organic polymer, the dispersibility in the polymer composition and the affinity with the polymer composition can be improved. The organic polymer is not particularly limited with respect to its molecular weight, shape, composition, presence or absence of a functional group, and any organic polymer can be used. Moreover, about the shape of an organic polymer, the thing of arbitrary shapes, such as a linear form, a branched form, and a crosslinked structure, can be used.

  Specific resins constituting the above-mentioned organic polymer include, for example, (meth) acrylic resin, polystyrene, polyvinyl acetate, polyolefin such as polyethylene and polypropylene, polyester such as polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, and the like. And a resin partially modified with a functional group such as an amino group, an epoxy group, a hydroxyl group, or a carboxyl group. Among them, those having an organic polymer containing a (meth) acryl unit such as a (meth) acrylic resin, a (meth) acrylic-styrene resin, and a (meth) acrylic-polyester resin have a film forming ability. Is preferred. On the other hand, a resin having compatibility with the above-described polymer composition is preferable, and therefore, a resin having the same composition as the material forming the structural layer 3 is most preferable.

  As a material for forming the structural layer 10 described above, a polyol having a cycloalkyl group is preferable. By introducing a cycloalkyl group into the polyol as the polymer composition, the hydrophobicity of the polymer composition, such as water repellency and water resistance, is increased, and the structure layer 10 is resistant to bending and dimensional stability under high temperature and high humidity conditions. Sex etc. are improved. In addition, the basic properties of the coating layer such as weather resistance, hardness, feeling of holding, and solvent resistance of the structural layer 10 are improved. Furthermore, the affinity with the filler having the organic polymer fixed on the surface and the dispersibility of the filler are further improved.

  Moreover, it is good to contain isocyanate as a hardening | curing agent in a polymer composition. Thus, by containing an isocyanate hardening | curing agent in a polymer composition, it becomes a much stronger crosslinked structure and the film physical property of the structure layer 10 further improves. As this isocyanate, the same substance as the above-mentioned polyfunctional isocyanate compound is used. Of these, aliphatic isocyanates that prevent yellowing of the coating are preferred.

  The filler may contain an organic polymer inside. Thereby, moderate softness and toughness can be imparted to the inorganic material that is the core of the filler.

  An organic polymer containing an alkoxy group may be used as the organic polymer, and the content is not particularly limited, but is preferably 0.01 mmol or more and 50 mmol or less per 1 g of filler. The alkoxy group can improve the affinity with the polymer composition and the dispersibility in the polymer composition.

  The above-described alkoxy group represents an RO group bonded to a metal element that forms a fine particle skeleton. R is an alkyl group which may be substituted, and the RO groups in the fine particles may be the same or different. Specific examples of R include methyl, ethyl, n-propyl, isopropyl, n-butyl and the like. The same metal alkoxy group as the metal constituting the filler is preferably used. When the filler is colloidal silica, it is preferable to use an alkoxy group having silicon as a metal.

  The content of the organic polymer in the filler to which the organic polymer is fixed is not particularly limited, but is preferably 0.5% by mass or more and 50% by mass or less based on the filler.

FIG. 4 is a side view showing an example of the configuration of the solar cell protective sheet according to the present embodiment. It has a layer structure in which the base material 9 and the gas barrier layer 8 are removed from the protective sheet 5 shown in FIG.
The form shown in FIG. 4 may not be used depending on the usage environment of the solar cell module. In particular, when high barrier properties are required, some ingenuity is required such as separately coating a material having a barrier strengthening effect. Moreover, since the structure shown in FIG. 4 uses few members, the material cost reduction effect is acquired.

  FIG. 5 is a side view showing an example of the configuration of the solar cell protective sheet according to the present embodiment. The outer layer 6, the gas barrier layer 8, the base material 9, the structural layer 10, the reflective film 11, and the transmissive protective layer 12 are laminated.

  As an example of a method for producing the protective sheet 5 as shown in FIG. 5, a gas barrier layer 8 is formed on a substrate 9 by vapor deposition or the like, and a metal plate is formed on the surface opposite to the surface on which the gas barrier layer 8 is formed. The structural layer 10 having the light reflecting concave / convex surface 13A is produced by a UV molding method using, and the reflective film 11 is formed thereon by vapor deposition or the like. Then, the method of coating the transparent protective layer 12 on the reflective film 11 and the outer layer 6 on the gas barrier layer 8 is mentioned.

Thus, the layer formed on the light-reflective uneven surface 13A is formed on the reflective film 11 by coating or the like, and the formed surface is substantially smooth, and the protective sheet 5 is When viewed from a cross section, the uppermost surface and the lowermost surface (in this example, the surface opposite to the side where the transparent protective layer 12 faces the reflective structure layer 13 and the surface opposite to the side where the outer layer 6 faces the reflective structure layer 13) ) Is generally parallel.
When the layer formed on the uneven surface for light reflection 13A is not smooth, it is easy to be scratched by friction during transportation and assembly, and the re-condensing efficiency is reduced due to a decrease in transmittance due to the scratch. there's a possibility that. In addition, there is a high possibility that air bubbles will be involved during assembly, due to phenomena such as refraction, scattering, reflection, etc. due to the occurrence of peeling starting from the air bubbles involved and the difference in refractive index between the bubbles and the material in contact with the air bubbles. There is a possibility that the re-condensing efficiency is lowered. In addition, there is a high possibility that fine dust such as dust is involved during transportation and peeling or the like occurs.
Further, when the uppermost surface and the lowermost surface when the protective sheet 5 is viewed from the cross section are not substantially parallel, the possibility of entrainment of bubbles during assembly is increased, and the occurrence of peeling starting from the entrained bubbles or There is a possibility that the re-condensing efficiency is lowered due to a phenomenon such as refraction, scattering, reflection, etc. due to a difference in refractive index between the bubble and the material in contact with the bubble. Further, when the protective sheet 5 is stored in a laminated state, the load of pressure is locally increased, and the smoothness of the protective sheet 5 may not be maintained.
As a specific numerical value relating to the smoothness, the surface roughness Ra is desirably 20 μm or less, and more desirably 5 μm or less. When Ra exceeds 5 μm, dust or the like is likely to adhere, and when Ra exceeds 20 μm, scratches due to friction or the like are likely to occur.

FIGS. 6A and 6B are perspective views showing an example of the light reflecting uneven surface 13A according to the present embodiment. The light reflecting uneven surface 13A is provided on one surface of the structural layer 10 and has a function of dimming the light beam 1. Depending on the type and installation location of the solar cell, examples of effective shapes include a pyramid type as shown in FIG. 6A and a V-groove type as shown in FIG. 6B. Moreover, it is sunlight which becomes a light source of a solar cell mainly. Since the sun is approximated to a light source located at infinity from the solar cell module, sunlight enters the solar cell as parallel light on a rooftop, a roof or the like where the solar cell is installed. However, it is not all parallel light, but there is also scattered light that is reflected by the surrounding objects, but most of the light is incident as parallel light. A prism shape having a flat surface is effective for dimming parallel light.
In addition, the V-groove type and the pyramid type have an advantage that they are easy to manufacture as compared with spherical and aspherical shapes such as microlenses.

FIG. 7 is a side view showing an apex angle of an example of the light reflecting uneven surface 13A according to the present embodiment. The apex angle θ of the light reflecting uneven surface 13A indicates an angle between lines L1 and L2 that are parallel to two opposing side surfaces forming the light reflecting uneven surface 13A.
In other words, the shape of the light reflecting uneven surface 13A is composed of a plurality of convex portions and a plurality of concave portions, and the apex angle θ of the convex portions is included in the range of 120 ° to 135 °.
[Example]

  Next, examples of the present invention will be described. In this example, the configuration shown in FIG. 4 was used, and the recondensing efficiency was measured for two types of protective sheets in which the apex angles of the light reflecting uneven surface 13A were α and Β (α <Β). .

  FIG. 8 shows a schematic diagram of the measurement method. Assuming noon sunlight as a light source, parallel light having an incident angle of about 0 degrees was adopted as a measurement light source. Further, the power meter 16 was used for the measurement of the refocusing efficiency. Assuming the configuration of the solar cell, the protective sheet 5, the power meter 16, and the blue plate glass 15 were laminated in this order. Moreover, in order to match | combine a refractive index between each layer, it immersed in glycerin 17. FIG.

  In the embodiment of the present invention, the reflective structure layer 13 was produced by using an ultraviolet curable acrylic resin with a PET film as a molding substrate, and aluminum was deposited as the reflective film 11. A PET film was used for the permeable protective layer 12 and the outer layer 6.

  FIG. 9 shows the measurement results of the manufactured sample with light incident from the surface where the relief is formed and the opposite surface. For comparison, measurement was performed on black paper assumed to have no reflection and white PET assumed to cause scattering reflection.

  When the measurement results of the black paper and white PET and the sample of this example were compared, it was confirmed that the sample of this example had high refocusing performance. For samples with apex angle α, the re-condensing performance is higher when light is incident from the relief surface, and for samples with apex angle 再, the light is incident again from the opposite surface. It was confirmed that the light collecting performance was high.

  In addition, when comparing the re-condensing performance of the sample with the apex angle α and the sample with the apex angle Β, the re-condensing performance of the apex angle α is generally better, but since α <Β, the sample with the apex angle α It was confirmed that the advantageous apex angle changes depending on the arrangement of the cells because of the larger range of collision with the cell wall.

It is a side view which shows an example of a structure of the solar cell module which concerns on this Embodiment. It is a side view which shows an example of a structure of the solar cell protection sheet which concerns on this Embodiment. It is a side view which shows an example of a structure of the solar cell protection sheet which concerns on this Embodiment. It is a side view which shows an example of a structure of the solar cell protection sheet which concerns on this Embodiment. It is a side view which shows an example of a structure of the solar cell protection sheet which concerns on this Embodiment. It is a perspective view which shows an example of the uneven surface 13A for light reflection which concerns on this Embodiment. It is explanatory drawing which shows apex angle (theta) in the uneven surface 13A for light reflection which concerns on this Embodiment. It is a side view which shows the implementation structure of evaluation of the solar cell protection sheet which concerns on this Embodiment. It is a figure which shows the measurement result of the re-condensing efficiency of the solar cell protection sheet which concerns on this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Outside light, 2 ... Front plate, 3 ... Filler, 4 ... Solar cell, 5 ... Protective sheet, 6 ... Outer layer, 7 ... Intermediate layer, 8 ... Gas barrier layer, 9 ... ... base material, 10 ... structural layer, 11 ... reflective film, 12 ... transparent protective layer, 13 ... reflective structural layer, 13A ... uneven surface for light reflection, 14 ... light source, 15 ... blue plate glass , 16 ... Power meter, 17 ... Glycerin.

Claims (11)

A light-transmitting protective layer having one surface as a light incident surface and the other surface as a light exit surface;
A reflective structure layer provided on the light exit surface side and having a reflection function of reflecting light emitted from the light exit surface toward the transparent protective layer;
The reflective structure layer is provided on the back surface side opposite to the light emitting surface and has an outer layer for protecting the reflective structure layer;
An uneven surface for light reflection having light reflectivity is provided on at least one of the front surface and the back surface where the reflective structure layer is located on the light emitting surface side,
A solar cell protective sheet characterized by that. ^2. The solar cell protective sheet according to claim 1, further comprising a barrier layer having a water vapor permeability in the range of 0 to 0.5 g / m ² between the transmissive protective layer and the reflective structure layer. . ^2. The solar cell protective sheet according to claim 1, further comprising a barrier layer having a water vapor permeability in a range of 0 to 0.5 g / m ² between the reflective structure layer and the outer layer.   4. The solar cell protective sheet according to claim 1, wherein the uneven surface for light reflection has a V-shaped groove, a polygonal pyramid shape, or a reverse type thereof. 5.   The shape of the uneven surface for light reflection is constituted by a plurality of convex portions and a plurality of concave portions, and the apex angle of the convex portions is included in a range of 120 ° to 135 °. Solar cell protective sheet.   The uneven surface for light reflection is configured by providing a reflective film having light reflectivity on an uneven shape provided in the reflective structure layer. A solar cell protective sheet according to 1.   6. The reflection structure layer is formed of a light reflection layer having light reflectivity, and the light reflection uneven surface is formed of a surface of the light reflection layer. A solar cell protective sheet according to 1.   The solar cell protective sheet according to claim 6, wherein the reflective film is a metal.   The solar cell protective sheet according to claim 8, wherein an antioxidant layer is formed on the reflective film.   The solar cell protective sheet according to claim 6, wherein the reflective film contains at least one kind of diffusion filler mixed material.   A solar cell module using the solar cell protective sheet according to claim 1.

Images