JP2014049748A - Solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell and a solar cell module using a luscious white color on a light-receiving surface side thereof and having a high generation efficiency.SOLUTION: The solar cell includes a solar cell element and a diffusion layer formed on a light-receiving surface of the solar cell element through a clearance.

Description

  The present invention relates to a solar cell and a solar cell module.

Currently, efforts to curb CO ₂ emissions are being made on a global scale as a measure to prevent global warming. As a clean power generation device that replaces thermal power generation, solar cells and a plurality of such solar cells are electrically connected. Solar cell modules are attracting attention and are actively researched and developed.

  In recent years, solar cells and solar cell modules have been used by being mounted not only outdoors but also in various indoor items, and the design properties thereof may become a problem. There is also a desire to make the entire light receiving surface of the battery module clear white.

  As a technique for making the light-receiving surfaces of solar cells and solar cell modules white, there is a technique disclosed in Patent Document 1, for example.

Japanese Patent No. 3476251

  However, in Patent Document 1, for example, a diffusion layer is provided on the light receiving surface of the solar cell, and light is diffused by the diffusion layer, so that the light receiving surface of the solar cell can be made white, but an attempt is made to darken the white color. Then, the diffusion of light must be increased by that much, and the greater the diffusion of light, the less the light that enters the solar cell and the lower the power generation efficiency. That is, when white is expressed using only the diffusion layer, the white density and the power generation efficiency are in a trade-off relationship, and it is difficult to bring both of them to a desired level.

  The present invention is an invention made in view of such a current situation, and is a solar cell and a solar cell module that are expected as a measure for preventing global warming, and generates power while making its light-receiving surface side clean white. The main object is to provide a solar cell and a solar cell module with high efficiency.

  The invention for solving the above-described problems includes a solar cell element and a diffusion layer provided on the light receiving surface of the solar cell element via a gap.

  Another invention for solving the above problem is a solar cell module having two or more solar cell elements arranged at intervals, and a diffusion layer is formed on the light receiving surface of the solar cell module via a gap. It is provided.

  Moreover, in said invention, it is preferable to have a colored particle between the said solar cell element and a solar cell element, and the same colored layer as the said solar cell element exists.

  According to the solar cell and the solar cell module of the present invention, since the diffusion layer is provided on the light receiving surface via the gap, not only the light incident on the light receiving surface is diffused but also the diffusion layer. Light can also be refracted by the gap under the layer, and as a result, the whiteness of the light-receiving surface can be achieved by the synergistic effect of the diffusion layer and the gap without significantly reducing the amount of light incident on the solar cell. Can be increased.

It is a schematic sectional drawing of the solar cell concerning embodiment of this invention. It is sectional drawing of the solar cell module concerning the 1st Embodiment of this invention. It is sectional drawing of the solar cell module concerning the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the form demonstrated below, In the range which does not deviate from a technical thought, it can implement in various deformation | transformation. In the accompanying drawings, the vertical and horizontal scales may be exaggerated for the sake of explanation, and the actual scales may differ.

<Solar cell>
FIG. 1 is a schematic cross-sectional view of a solar cell according to an embodiment of the present invention.

  As shown in FIG. 1, the solar cell 10 according to the present embodiment includes a solar cell element 11 and a diffusion layer 13 provided on the light receiving surface of the solar cell element 11 with a gap 12 interposed therebetween. And As described above, by providing the gap 12 between the solar cell element 11 and the diffusion layer 13 instead of providing the diffusion layer 13 directly on the light receiving surface of the solar cell element 11, the light incident on the solar cell 10 is In addition to being diffused by the diffusion layer 13, it is also refracted and reflected at the interface between the gap 12 and the solar cell element 11, and the light-receiving surface side of the solar cell 10 due to the synergistic effect of the diffusion layer 13 and the gap 12. The whiteness of can be improved. The whiteness of the solar cell 10 according to this embodiment is reproduced only by the diffusion layer 13, that is, the diffusion layer 13 is formed directly on the light receiving surface of the solar cell element 11 without providing the gap layer 12. When reproducing the same whiteness as that of the solar cell 10 according to the embodiment, the degree of light diffusion by the diffusion layer must be increased, and as a result, the power generation efficiency is higher than that of the solar cell 10 according to the present embodiment. Will be reduced.

  Below, each structure of the solar cell 10 is demonstrated.

(Solar cell element)
The solar cell element 11 in the solar cell 10 of the present embodiment is not particularly limited, and a conventionally known one can be appropriately selected and used. As such a solar cell element 11, for example, a single crystal silicone type solar cell element, a polycrystalline silicone type solar cell element, an amorphous silicone type solar cell element, a chemical solar cell element, a dye-sensitized solar cell element, Examples thereof include a quantum dot solar cell element and an organic thin film solar cell element.

  Among these solar cell elements, dye-sensitized solar cell elements are manufactured without the need for vacuum conditions in the manufacturing process and the advantage of high power generation efficiency at low illuminance such as indoor light such as fluorescent lamps and near windows. It can be particularly preferably used because of its low cost. In addition, since the dye-sensitized solar cell element is used indoors as described above, it is often required to have a design property and is also preferable in that the effect of the present invention can be exhibited.

(Void)
As described above, the air gap 12 in the solar cell 10 of the present embodiment prevents light that has passed through the diffusion layer 13 from directly entering the solar cell element 11, and allows the light that has passed through the diffusion layer 13 to pass through the solar cell element 11. It exists to be refracted or reflected again when it enters. Therefore, the gap is not particularly limited as long as it is capable of exhibiting the above-described effects.

  From such a viewpoint, it is not necessary to fill the gap 12 with a special gas, and it is sufficient that air exists.

  Further, the gap 12 does not have to be a continuous layer over the entire light receiving surface of the solar cell element 11. Therefore, as shown in FIG. 1, the spacer S is interposed between the light receiving surface of the solar cell element 11 and the diffusion layer 13. It may be formed by interposing a substance that functions as

  The thickness d of the air gap 12 is not particularly limited, and can be freely designed within the range where the above-described effects are exhibited. For example, the thickness is preferably about 1 nm to 1000 μm, and particularly preferably about 10 nm to 100 μm.

(Diffusion layer)
The diffusion layer 13 in the solar cell 10 of the present embodiment is not particularly limited as long as it can diffuse incident light and express whiteness. For example, various conventionally known diffusion layers can be used. It can be appropriately selected and used.

  More specifically, for example, the diffusion layer 13 can be formed by using a film made of a polyester resin, a polycarbonate resin, or a polyolefin resin and forming irregularities on the surface of the film. Thus, when using a film, although the thickness of the said film is suitably selected according to the use purpose, it can be set as about 30-300 micrometers. The surface irregularities can be formed, for example, by containing polymer or inorganic particles such as acrylic particles, polystyrene particles, silica particles, etc., and spherical, true spherical, and acicular particles are suitable. Can be used. For example, these particles may be mixed with a binder resin in a solvent, and the solution may be applied to the film surface. The average particle diameter of these particles is preferably 30 μm or less. If the average particle diameter exceeds 30 μm, the coarse resin particles are likely to fall off, which tends to cause loss of the resin particles, and the coating film appearance tends to be lacking in uniformity with a sense of foreign matter. The thickness of the portion containing these particles is not particularly limited, but is preferably about 1 to 15 μm, for example. The back surface of the film is preferably a back surface mainly composed of at least one kind of particles selected from spherical or true spherical acrylic particles, styrene particles, silicone, crosslinked polyacrylate, and polyurethane. The diameter of the particles used in this case is preferably in the range of 1 to 60 μm, and more preferably in the range of 5 to 20 μm. The thickness of the portion containing the particles on the back surface of the film is preferably in the range of 1 to 50 μm, for example. In addition, as a binder for fixing the particles on the back side of the film, polyester resin, acrylic resin, silicone acrylic resin, fluorine resin or fluorine-acrylic resin, or those obtained by adding a crosslinkable resin having a curing function to these resins, or polyurethane-based At least one or more resins selected from resins, curable resins such as epoxy resins, and the like can be used.

  By using the diffusion layer 13 as described above, since the particles are appropriately arranged on the back side thereof, the particles function as a spacer S between the light receiving surface of the solar cell element 11 and the diffusion layer 13. This is preferable because it is not necessary to install a special spacer S.

<Solar cell module>
FIG. 2 is a cross-sectional view of the solar cell module according to the first embodiment of the present invention. In FIG. 2, the same components as those of the solar cell 10 shown in FIG.

  The solar cell module 100 according to this embodiment includes two or more solar cell elements 11, 11... Arranged at intervals, and a light-receiving surface side thermoplastic resin layer 30 that sandwiches these solar cells 11, 11. And the back surface side thermoplastic resin layer 31, the PET resin layer 33 disposed on the light receiving surface side thermoplastic resin layer 30, the back sheet 34 disposed on the back surface of the solar cell module 100, and the solar cell module 100. And a sealing material 35 disposed at the end of the light receiving surface, and the back sheet 34 and the sealing material 35 are heat-sealed, so that the whole is integrated.

  And in the solar cell module 100 which has the said structure, the diffusion layer 13 is arrange | positioned through the space | gap 12 on the PET resin layer 33. FIG.

  According to such a solar cell module 100, the entire light-receiving surface of the solar cell module 100 can be made white due to the synergistic effect of the diffusion layer 13 and the gap 12, as in the solar cell 10 described above.

(Solar cell elements, voids and diffusion layers)
About the space | gap 12 and the diffusion layer 13 in the solar cell module 100 concerning this embodiment, since it is the same as the solar cell element in the said "solar cell 10", a space | gap, and a diffusion layer, description here is abbreviate | omitted.

(Other configuration of solar cell module)
In the solar cell module 100 according to the first embodiment shown in FIG. 1, the solar cell element 11, the gap 12, and the diffusion layer 13, the light receiving surface side thermoplastic resin layer 30, the back surface side thermoplastic resin layer 31, Although it is comprised by the PET resin layer 33, the back sheet | seat 34, and the sealing material 35, these structures are an illustration to the last, The solar cell module of this invention is not limited to the said structure, Various The configuration can be adopted. Also, these materials are not limited to this, and can be selected from various materials.

  Therefore, for example, a glass substrate can be used instead of the PET resin layer, but the layer provided at the position of the PET resin layer 33 in the present embodiment, that is, the layer facing the diffusion layer 13 via the gap 12 is used. It is preferable to arrange a layer having a certain degree of hardness. In forming the solar cell module 100, as described above, the back sheet 34 and the sealing material 35 are heat-sealed and integrated as a whole. At this time, the diffusion layer 13 is pressed downward in the drawing. Therefore, when the layer provided at the position of the PET resin layer 33 is a soft material layer, the spacer S for forming the gap 12 is buried in the soft material layer, and as a result, the gap 12 disappears. This is because there is a fear.

  From this point of view, when a layer of another material is formed instead of the PET resin layer 33, it is preferable to form a layer of a material having a hardness equal to or higher than that of the PET resin.

  FIG. 3 is a cross-sectional view of a solar cell module according to the second embodiment of the present invention. In FIG. 3, the same components as those of the solar cell 10 according to the embodiment of the present invention shown in FIG. 1 and the solar cell module 100 according to the first embodiment shown in FIG.

  As shown in FIG. 3, the solar cell module 200 according to the second embodiment has the same configuration as the solar cell module 100 shown in FIG. 2, and further includes a back sheet 34 and a back surface side thermoplastic resin layer. It has the characteristic that it has a colored particle between 31 and the colored layer 20 of the same color as the solar cell element 11 exists.

  By providing the colored layer 20 at the position, the color of the colored layer 20 is between the solar cell elements 11, 11..., The back surface side thermoplastic resin 31, the light receiving surface side thermoplastic resin 30, and PET. The resin layer 33, the gap 12, and the diffusion layer 13 are permeated and visually recognized. In this case, since the color of the colored layer 20 and the solar cell element 11 is the same color, the entire light receiving surface of the solar cell module 200 can be made uniform white.

(Colored layer)
Although the colored layer 20 in the solar cell module 200 according to the present embodiment includes colored particles, the colored particles are not particularly limited, and are conventionally known depending on the desired color, that is, the color of the solar cell element 11. The various colored particles may be appropriately selected and used. Specifically, various dyes and various pigments can be used in combination as appropriate. Also, the shape of the colored particles is not particularly limited, and spherical, needle-like, and scale-like particles may be used, and the size may be about 1 nm to 100 μm.

  Moreover, the colored layer 20 may contain arbitrary components in addition to the colored particles. For example, components necessary for forming the colored layer 20 such as a resin as a binder, a solvent, and a dispersant can be arbitrarily blended.

  The thickness of the colored layer 20 is not particularly limited, and is appropriately designed in consideration of the portion where the colored layer 20 is formed, the overall configuration of the solar cell module 200, and the color expected of the colored layer 20. can do. For example, when forming as a solid layer on the back sheet | seat 34 like this embodiment, it can be set as about 100 nm-10 micrometers.

  The method for forming the colored layer 20 is not particularly limited. For example, it may be formed by preparing ink containing colored particles and applying it on the back sheet 34 by various application methods, or by printing on the back sheet 34 by various printing methods.

The color of the colored layer 20 is the same color as the solar cell element 11. Here, the color of the solar cell element 11 means the color of the photoelectric conversion layer constituting the solar cell element 11. Further, the same color means that it is difficult to distinguish between the solar cell element 11 and the solar cell element 11 and the solar cell element 11 when the solar cell module 200 is observed from the light receiving surface side. More specifically, it means that the color difference ΔE calculated by the following equation is less than 3. The following L ^* , a ^* , and b ^* are values measured with a color difference meter CR-5 (manufactured by Konica Minolta).
ΔE = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2
Delta] E: The color difference [Delta] L ^*: difference between the photoelectric conversion layer of the L ^* a colored layer of the solar cell L ^* .DELTA.a ^*: difference between a ^* of the photoelectric conversion layer of a ^* and the coloring layer of the solar cell [Delta] b ^*: solar cell Difference between b ^* of the photoelectric conversion layer and b ^* of the colored layer L ^* , a ^* , and b ^* : L ^* a ^* recommended by the International Commission on Illumination (CIE) in 1976 and defined in JIS Z8729 b ^* Color system value

  In the solar cell module 200 according to the second and second embodiments, the colored layer 20 is formed as a solid layer between the back sheet 34 and the back surface side thermoplastic resin layer 31, but is not limited thereto. For example, (1) The colored layer 20 may be formed only between the back sheet 34 and the back surface side thermoplastic resin layer 31 and between the solar cell element 11 and the solar cell element. 2) By including colored particles in the back surface side thermoplastic resin layer 31, the back surface side thermoplastic resin layer 31 may function as a colored layer, and (3) the light receiving surface side thermoplastic resin layer 30. The colored layer 20 may be formed only between the solar cell element 11 and the solar cell element between the PET resin layer 33 and the PET resin layer 33.

Example 1
The solar cell module of Example 1 of the present invention was created in the following manner.

(Creation of solar cell elements and solar cell modules)
On a Ti foil (Takeuchi Metal Foil Industry Co., Ltd.) having a thickness of 50 μm as an electrode base material, 0.5% ethyl cellulose (STD-100: Nisshin Kasei Kogyo Co., Ltd.) in titanium oxide particles (P25: Nippon Aerosil Co., Ltd.) in ethanol (Company) was applied and dried. Subsequently, it roll-pressed at the speed of 1 m / min with the pressure of 0.5 t / cm using the roll small press machine, Then, it baked at 500 degreeC for 30 minutes, and obtained the layer for porous layer formation with a film thickness of 5 micrometers. .

  Next, a dye sensitizer solution in which 0.3 mM of N719 dye (Dyesol) was dissolved in acetonitrile / t-butanol = 1/1 solution was prepared, and the porous layer forming layer was added to the dye sensitizer solution. After being soaked for 20 hours, an oxide semiconductor electrode substrate having a size of 10 cm × 4 cm (deposition position: 9.5 cm × 4 cm) was produced.

Subsequently, 6 mol / l hexyl methylimidazolium (Toyama Pharmaceutical), 0.6 mol / l I ₂ (Merck Co., Ltd.), and 0.45 mol / l n-methyl benzimidazol (Aldrich) were used. An electrolytic solution dissolved in the same company was prepared. Next, a resin solution in which 0.5% ethyl cellulose (STD-100: Nisshin Kasei) was dissolved in ethanol at 10 wt% was prepared, and the resin electrolyte solution was mixed at the above electrolyte solution: resin solution = 1: 6 (weight ratio). Was made. This was applied to the oxide semiconductor electrode substrate with a Miya bar and heated at 120 ° C. for 10 minutes.

  Next, a 10 cm × 4 cm counter electrode was produced by depositing pt on the ITO film of the PEN substrate on which ITO of 30Ω / sq was deposited to a transmittance of 80%.

  Then, the oxide semiconductor electrode substrate with an electrolyte produced above and the counter electrode were bonded in a state of being shifted 5 mm above and below, and the electrode of one element and the counter electrode of the other element were connected with a metal tape.

  Next, on the light-receiving surface side, a light-receiving surface side thermoplastic resin layer (11 cm × 10 cm (High Milan 400 μm: manufactured by Mitsui DuPont Chemicals)), a PET resin layer (10 cm × 9 cm (Lumirror T60: manufactured by Toray)) and a diffusion layer (10 cm × 9cm (D123: manufactured by Tsujiden)), and the outer peripheral part (non-power generation part) of the element is installed so as to be covered with a sealing material having a barrier property (aluminum laminated zip: ASONE) that can be thermally laminated, and a back sheet ( 12 cm × 11 cm (aluminum lami zip: as one)) and heat laminated at 120 degrees to create a solar cell module of Example 1. In addition, a convex portion is formed on the surface side of the diffusion layer in contact with the PET resin layer. In addition, since the diffusion layer was thermally laminated only at the outer peripheral portion of the element, there was a gap between the diffusion layer and the PET resin layer.

(Measurement of Example 1)
When the battery performance of the solar cell module of Example 1 and the whiteness of the light receiving surface were measured, it was as follows.
-Photoelectric conversion efficiency: 2.0%
・ Output characteristics: Open voltage 1.5V
・ Whiteness: 56.5%

(Example 2)
A solar cell module of Example 2 was created under the same conditions as in Example 1 except that a black colored layer was provided on the inner side of the back sheet in Example 1.

(Measurement of Example 2)
When the battery performance of the solar cell module of Example 2 and the whiteness of the light receiving surface were measured, it was as follows.
-Photoelectric conversion efficiency: 2.1%
・ Output characteristics: Open voltage 1.5V
・ Whiteness: 56.0%

(Comparative Example 1)
Except for placing the thermoplastic resin layer on the PET resin layer in Example 1 and thermally laminating the entire surface so as to fill the space between the diffusion layer and the PET resin layer with the thermoplastic resin layer, all the same as in Example 1 above. A solar cell module of Comparative Example 1 was created under the same conditions. In the solar cell module of Comparative Example 1, no voids existed under the diffusion layer.

(Measurement of Comparative Example 1)
It was as follows when the battery performance of the solar cell module of the comparative example 1 and the whiteness of the light-receiving surface were measured.
-Photoelectric conversion efficiency: 2.5%
・ Output characteristics: Open circuit voltage 1.6V
・ Whiteness: 18.26%

(Evaluation)
From the measurement results of the solar cell modules of Examples 1 and 2 and Comparative Example 1, the solar cell modules of Examples 1 and 2 of the present invention have the same battery performance as the solar cell module of Comparative Example 1. I understood. On the other hand, since the solar cell modules of Examples 1 and 2 of the present invention have not only the diffusion layer but also a gap below the solar cell module, compared with the solar cell module of Comparative Example 1 having only the diffusion layer, Whiteness increased. Furthermore, since the solar cell module of Example 2 had a colored layer, the surface white color was uniform compared to the solar cell module of Example 1.

DESCRIPTION OF SYMBOLS 10 ... Solar cell 11 ... Solar cell element 12 ... Space | gap 13 ... Diffusion layer 20 ... Colored layer 30 ... Light-receiving surface side thermoplastic resin layer 31 ... Back surface side thermoplastic resin layer 33 ... PET resin layer 34 ... Back sheet 35 ... Sealing Material 100, 200 ... Solar cell module

Claims (1)

A solar cell element;
A diffusion layer provided on the light receiving surface of the solar cell element via a gap,
The diffusion layer has irregularities on its surface,
The convex portion of the unevenness of the diffusion layer is in direct contact with the light receiving surface of the solar cell element, so that the convex portion functions as a spacer, and the concave portion of the unevenness is the gap. Solar cell featuring.

Images