JP2013004806A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module capable of efficiently converting the wavelength of light entering a solar cell to the long-wavelength side having high spectral sensitivity, and excellent in weather resistance.SOLUTION: A surface protection layer 7 serving as an outermost layer, a wavelength conversion layer 8, a sealing resin layer 6 are provided on the light-receiving surface of the solar cell, the surface protection layer 7 transmits light in a short wavelength region of 350 nm or shorter, the wavelength conversion layer 8 is provided directly under the surface protection layer 7 to absorb light in the short wavelength region of 350 nm or shorter, and has a wavelength conversion material having an emission wavelength in a longer wavelength region.

Description

  The present invention relates to a solar cell module, and more particularly to a solar cell module having a wavelength conversion layer that converts incident light into a wavelength region with high spectral sensitivity and emits light.

  In recent years, with the reduction of environmental burdens becoming a global issue, great expectations are placed on photovoltaic power generation as clean and renewable energy. Until now, the mainstream of solar cells is a crystalline silicon solar cell in which single crystal silicon or polycrystalline silicon crystals are manufactured and sliced and used as a plate-like semiconductor.

  The crystalline silicon solar cell module has a limited wavelength range in which photoelectric conversion can be performed, and there is a problem in that conversion efficiency does not increase because light in the ultraviolet region contained in sunlight cannot be photoelectrically converted. Therefore, a configuration is proposed in which a wavelength conversion substance such as a phosphor that converts light in the ultraviolet region into a wavelength that can be photoelectrically converted by the solar cell module is contained in the solar cell module.

  For example, Patent Document 1 discloses a wavelength converter that absorbs light in a wavelength range with a low photoelectric conversion efficiency in the photoelectric conversion layer and emits light in a wavelength range with a high photoelectric conversion efficiency on the light incident side of the photoelectric conversion layer. A solar cell in which this layer is provided in parallel with the photoelectric conversion layer is disclosed.

  In the solar cell described in Patent Document 1, for example, the wavelength converter layer is provided with a transparent adhesive layer between the photoelectric conversion layer and the transparent protective cover, and the wavelength converter fine particles are provided in the transparent adhesive layer. It is formed by dispersing and mixing powder.

  Similarly, Patent Document 2 discloses wavelength conversion for absorbing irradiated light and converting it into light having a wavelength longer than the wavelength of absorbed light in a solar battery module including a solar battery cell that converts light energy into electrical energy. A solar cell module having a layer is disclosed. In Patent Document 2, the wavelength conversion layer is formed by being applied to the cell light-receiving surface or is formed as a sealant that protects the solar battery cell.

  Patent Document 3 discloses a solar cell in which a material containing an oxide phosphor is disposed in a path until light reaches the solar cell element. Here, the oxide phosphor is capable of converting ultraviolet rays in a wavelength range of 200 to 400 nm into a wavelength range of 400 to 1000 nm.

JP 63-200576 A JP-A-7-202243 JP 2003-218379 A

  However, since a normal solar cell module uses glass as a surface protective layer, light in a short wavelength region of 350 nm or less is cut by the glass before reaching the wavelength conversion material.

  In addition, when a wavelength conversion layer is provided below the sealing resin layer, the ultraviolet absorbing material contained in the sealing resin due to the necessity of absorption of light in the short wavelength region by the sealing resin itself and prevention of deterioration. The conversion effect of the wavelength conversion layer was hindered by the absorption of light in the short wavelength region.

  This problem can be avoided by providing a film containing a wavelength conversion material on the front surface of the surface protective layer, but in this case, since the wavelength conversion layer is directly exposed to the outside world, the wavelength conversion material and the resin component forming the film are long-term. There is a problem that the weather resistance over the range is not satisfied.

  Then, an object of this invention is to provide the solar cell module which can convert efficiently the wavelength of the light which injects into a photovoltaic cell to the long wavelength side with high spectral sensitivity, and is excellent also in a weather resistance.

  In order to solve the above-described problems, the solar cell module according to the present invention is provided with a surface protective layer, a wavelength conversion layer, and a sealing resin layer that are outermost layers on the light receiving surface of the solar cell, and the surface protection described above. The layer transmits light in a short wavelength region of 350 nm or less, and the wavelength conversion layer is provided immediately below the surface protective layer, absorbs light in a short wavelength region of 350 nm or less, and emits light in a longer wavelength region. It has a wavelength conversion material having a wavelength.

  According to the present invention, the surface protective layer that is the outermost layer transmits light in a short wavelength region, so that the excitation band of the wavelength conversion layer can be covered over the entire range, and a higher wavelength conversion effect can be obtained. Photoelectric conversion efficiency by the solar battery cell can be improved. Moreover, since the surface protective layer is the outermost layer, the wavelength conversion layer is not exposed to the outside, and the weather resistance is excellent.

It is a disassembled perspective view which shows the solar cell module to which this invention was applied. It is sectional drawing which shows the string of a photovoltaic cell. It is a top view which shows the back surface electrode and connection part of a photovoltaic cell. It is a disassembled perspective view which shows the module structure (alpha) based on an Example. It is a disassembled perspective view which shows the module structure (beta) based on an Example.

  Hereinafter, a solar cell module to which the present invention is applied and a method for manufacturing a solar cell will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Hereinafter, although a crystalline silicon solar cell will be described as an example, the present invention can be used for various solar cells such as a thin film silicon solar cell, a so-called compound thin film solar cell, an organic type, and a quantum dot type.

[Solar cell module]
The solar cell module 1 to which the present invention is applied has a string 4 in which a plurality of solar cells 2 are connected in series by a tab wire 3 serving as an interconnector, as shown in FIGS. A matrix 5 in which a plurality of 4 are arranged is provided. In the solar cell module 1, the matrix 5 is sandwiched between resin sheets 6 of a sealing adhesive, the surface protective layer 7 and the wavelength conversion layer 8 provided on the light receiving surface side, and the back sheet 9 provided on the back surface side. It is formed by laminating together.

  That is, the solar cell module 1 is laminated | stacked in order of the surface protective layer 7, the wavelength conversion layer 8, the sealing resin sheet 6, the photovoltaic cell 2, the sealing resin sheet 6, and the back sheet 9 in an order from the light-receiving surface side. Note that the solar cell module 1 is appropriately attached with a metal frame such as aluminum around it.

  As the sealing adhesive constituting the sealing resin sheet 6, for example, a translucent sealing resin such as polyethylene-polyvinyl acetate copolymer (EVA) is used. The sealing resin preferably has a light transmittance of 80% or more at a wavelength of 200 nm to 800 nm. Further, as the back sheet 8, a laminated body in which glass or aluminum foil is sandwiched between resin films is used.

  Each solar battery cell 2 of the solar battery module has a photoelectric conversion layer 11. The photoelectric conversion layer 11 is a crystalline silicon solar cell using a single crystal silicon photoelectric conversion element or a polycrystalline photoelectric conversion element.

  The photoelectric conversion layer 11 is provided with a finger electrode 12 that collects electricity generated inside and a bus bar electrode 13 that collects electricity of the finger electrode 12 on the light receiving surface side. The bus bar electrode 13 and the finger electrode 12 are formed by, for example, applying an Ag paste on the surface serving as the light receiving surface of the solar battery cell 2 by screen printing or the like and then baking it. In addition, the finger electrode 12 is formed with a plurality of lines having a width of about 50 to 200 μm, for example, approximately in parallel at a predetermined interval, for example, every 2 mm, over the entire light receiving surface. The bus bar electrodes 13 are formed so as to be substantially orthogonal to the finger electrodes 12, and a plurality of bus bar electrodes 13 are formed according to the area of the solar battery cell 2.

  The photoelectric conversion layer 11 is provided with a back electrode 14 made of aluminum or silver on the back side opposite to the light receiving surface. As shown in FIGS. 2 and 3, the back electrode 13 is formed of an electrode made of, for example, aluminum or silver on the back surface of the solar battery cell 2 by screen printing, sputtering, or the like. The back electrode 14 has a tab wire connecting portion 15 to which the tab wire 3 is connected via a conductive adhesive film 17 described later.

  In the solar battery cell 2, the tab bar 3 connects each bus bar electrode 13 formed on the surface and the back electrode 14 of the adjacent solar battery cell 2 so that the strings connected in series are electrically connected. 4 is configured. The tab wire 3 is connected to the bus bar electrode 13 and the back electrode 14 by a conductive adhesive film 17.

[Tab line]
As shown in FIG. 2, the tab line 3 is a long conductive substrate that electrically connects each of the adjacent solar cells 2X, 2Y, and 2Z. The tab wire 3 is substantially the same as the conductive adhesive film 17 by, for example, slitting a copper foil or aluminum foil rolled to a thickness of 50 to 300 μm, or rolling a thin metal wire such as copper or aluminum into a flat plate shape. A flat wire with a width of 1 to 3 mm is obtained. The tab wire 3 is formed by applying gold plating, silver plating, tin plating, solder plating or the like to the flat wire as necessary.

  In the solar cell module 1, the solar cells 2 are electrically connected to each other by the tab wire 3 to form the strings 4. In addition, the solar cell module 1 is provided with a terminal box (not shown) that supplies power collected by the tab wire 3 to the outside by electrically connecting an external output line to the back surface side of the solar cell 2. Yes.

[Wavelength conversion layer]
The wavelength conversion layer 8 absorbs light in the short wavelength region of sunlight incident through the surface protective layer 7, converts the light into a long wavelength region light having high spectral sensitivity, and emits light, whereby the solar cell module 1. It improves power generation efficiency.

  The wavelength conversion layer 8 is configured as a wavelength conversion film by dissolving or dispersing a phosphor substance in a transparent resin and molding the film into a film. The phosphor material performs wavelength conversion on incident light, absorbs light in a short wavelength region with low photoelectric conversion efficiency in the photoelectric conversion layer, and emits light in a long wavelength region with high photoelectric conversion efficiency. .

  In the solar cell having the photoelectric conversion layer 11 made of single crystal silicon or polycrystalline silicon, although there are some differences, the absorption is small for light with a wavelength of 500 nm or less, and for light with a wavelength of 400 nm or less, Absorption is very small.

  Therefore, when the photoelectric conversion layer 11 is used, the phosphor material of the wavelength conversion layer 8 absorbs light in a short wavelength region of 400 nm or less, more preferably 350 nm or less, and has a longer emission wavelength. A conversion material is used.

As such a phosphor substance, an inorganic compound doped with europium or manganese as the emission center can be used. For example, BaMgAl ₁₀ O ₁₇ : Eu (BAM) exhibiting blue emission is characterized by an excitation band of 200 nm to 430 nm and a fluorescence peak of 400 nm to 550 nm, and an internal quantum efficiency of about 90%. Further, BaMgAl ₁₀ O ₁₇ : Eu, Mn (BAM, Mn) exhibiting green light emission has an absorption peak of 200 nm to 400 nm and a fluorescence peak of 480 nm to 570 nm, and has an internal quantum efficiency of about 85%. .

  Transparent resin for dispersing the phosphor material is, for example, silicone resin, epoxy resin, urethane resin, polyvinyl butyral, polystyrene / polyethylene / polybutylene / polystyrene block copolymer (SEBS), polyethylene-polyvinyl acetate random copolymer (EVA). Can be used.

  In addition, as the photoelectric conversion layer, any of the known photoelectric conversion layers can be applied to the solar battery cell 2 in addition to the above-described one using single crystal silicon and the one using polycrystalline silicon. Since the photovoltaic cell 2 has a unique band gap depending on the photoelectric conversion layer, the spectral sensitivity is different. Therefore, a phosphor material in which the wavelength range of the emission spectrum includes the wavelength range of the spectral sensitivity of the solar battery cell 2 to be used is selected.

[Surface protective layer]
Moreover, as the surface protective layer 7, for example, a translucent material such as transparent glass or translucent plastic is used. Since the surface protective layer 7 needs to allow light in the short wavelength region to be incident on the wavelength conversion layer 8, a material that transmits light in the short wavelength region, preferably 350 nm or less, without absorbing it is used.

  As such a surface protective layer 7, a quartz glass plate is preferably used. Quartz glass has the advantage that the wavelength of the excitation band of the inorganic phosphor can be widely used because there is almost no absorption of 200 nm to 330 nm that occurs in ordinary glass.

[effect]
In the solar cell module 1, a surface protective layer 7 made of a quartz glass plate or the like is laminated as an outermost layer, and a wavelength conversion layer 8 is provided immediately below the surface protective layer 7. The wavelength conversion layer 8 is provided directly below the surface protective layer 7 and is provided on the light receiving surface of the solar battery cell 2 sealed with the sealing resin sheet 6.

  Since the surface protective layer 7 which is the outermost layer transmits light in a short wavelength region, preferably 350 nm or less, the excitation band of the wavelength conversion layer 8 can be covered over the entire range, and a higher wavelength conversion effect can be obtained. Obtained and the photoelectric conversion efficiency by a photovoltaic cell can be improved. Further, since the surface protective layer 7 is the outermost layer, the wavelength conversion layer 8 is not exposed to the outside, and the weather resistance is excellent.

  The wavelength conversion layer 8 is provided immediately below the surface protective layer 8 so that light in a short wavelength region is incident before being absorbed by a resin such as EVA constituting the sealing resin sheet 6 or an additive in the resin. , Can emit light in a long wavelength region efficiently. In addition, the wavelength conversion layer 8 is provided on the light receiving surface of the solar battery cell 2 sealed with the sealing resin sheet 6, thereby allowing light in a long wavelength region with high spectral sensitivity to be received on the light receiving surface of the solar battery cell 2. It can be made incident.

Next, examples of the present invention will be described. First, the wavelength conversion film 20 was created. The wavelength conversion film 20 was prepared by dissolving a polystyrene / polyethylene / polybutylene / polystyrene block copolymer (SEBS) in toluene to prepare a 25 wt% solution. A dispersion in which BaMgAl ₁₀ O ₁₇ : Eu (BAM), which is a fluorescent material, was added to this solution was prepared. Next, a film was formed on a 38 μm peeled PET (Poly Ethylene Terephthalate) using a bar coater and dried at 115 ° C. to obtain a 60 μm wavelength conversion film. Hereinafter, a wavelength conversion film using BAM as the phosphor is referred to as a wavelength conversion film A.

Further, the wavelength conversion film B using BaMgAl ₁₀ O ₁₇ : Eu, Mn (BAM, Mn) is converted into the wavelength conversion film C using an organic fluorescent dye (LUMOGEN F VIOLET 570: manufactured by BASF) by the same production method. Got. A SEBS film that does not contain a fluorescent substance or an organic fluorescent dye is referred to as film D.

  In Example 1, quartz glass was used as the translucent surface protection member 21, and the wavelength conversion film A described above was used as the wavelength conversion film 20. The quartz glass having a thickness of 1.0 mm (manufactured by Shin-Etsu Quartz Co., Ltd .: SUPRASIL-P248) was used. Moreover, as shown in FIG. 4, the surface protection member 21 (quartz glass plate), the wavelength conversion film 20 (wavelength conversion film A), the sealing resin (EVA resin) 22, the solar battery cell 23, in order from the light receiving surface side. The sealing resin (EVA resin) 22 and the back surface protection member 24 were piled up, and the solar cell module laminated at 160 degreeC using the vacuum laminator was created. Hereinafter, such a module structure is referred to as a structure α. In the wavelength conversion film A according to Example 1, the phosphor (BAM) concentration was 0.5 wt% with respect to the resin. Moreover, the film thickness of this wavelength conversion film A is 60 micrometers.

  Example 2 is the same as Example 1 except that the wavelength conversion film B is used. In the wavelength conversion film B, the concentration of the phosphor (BAM, Mn) was 0.5 wt% with respect to the resin. Moreover, the film thickness of this wavelength conversion film B is 60 micrometers.

  Example 3 is the same as Example 1 except that the concentration of the phosphor (BAM) in the wavelength conversion film A is 0.1 wt% with respect to the resin.

  Example 4 is the same as Example 1 except that the concentration of the phosphor (BAM) in the wavelength conversion film A is 1.0 wt% with respect to the resin.

  In Example 5, quartz glass was used as the translucent surface protection member 21, and the wavelength conversion film A described above was used as the wavelength conversion film 20. Further, as shown in FIG. 5, in order from the light receiving surface side, a surface protection member 21 (quartz glass plate), a sealing resin (EVA resin) 22, a wavelength conversion film 20 (wavelength conversion film A), a solar battery cell 23, The sealing resin (EVA resin) 22 and the back surface protection member 24 were piled up, and the solar cell module laminated at 160 degreeC using the vacuum laminator was created. Hereinafter, such a module structure is referred to as a structure β. That is, Example 5 is the same as Example 1 except for the module structure.

  In Example 6, the wavelength conversion film C was used. The concentration of the organic fluorescent dye is 0.5 wt% with respect to the resin. Moreover, the film thickness of this wavelength conversion film is 60 micrometers. The module structure is the structure α as in the first embodiment.

  In Comparative Example 1, a soda glass plate was used as the translucent surface protection member 21, and a wavelength conversion film D (SEBS film) not containing a phosphor material was used as the wavelength conversion film 20. The soda glass having a thickness of 1.0 mm (manufactured by Central Glass Co., Ltd .: soda lime glass) was used. Furthermore, as shown in FIG. 5, the structure β, that is, the surface protection member 21 (soda glass), the sealing resin (EVA resin) 22, the wavelength conversion film 20, the solar battery cell 23, the sealing resin (EVA resin) 22, The back surface protection member 24 was piled up and the solar cell module laminated at 160 degreeC using the vacuum laminator was created. The SEBS film has a film thickness of 60 μm.

  Comparative Example 2 has the same configuration as Comparative Example 1 except that the wavelength conversion film A is used as the wavelength conversion film 20. In the wavelength conversion film A according to Comparative Example 2, the concentration of the phosphor (BAM) was 0.5 wt% with respect to the resin. Moreover, the film thickness of this wavelength conversion film A is 60 micrometers.

  Comparative Example 3 has the same configuration as Comparative Example 1 except that the same wavelength conversion film as in Example 6 was used.

About the solar cell modules according to these examples and comparative examples, each solar cell module and solar cells are irradiated with simulated solar light with an irradiation intensity of 100 mW / cm ² formed by a solar simulator (manufactured by Wacom Denso Co., Ltd.). The current-voltage characteristics were measured using a commercially available IV tester, and the short circuit current value Isc was calculated. Pseudo sunlight is formed by passing xenon lamp light through an AM filter (AM1.5) by the solar simulator.

  The experimental results are shown in Table 1. In the table, ΔIsc (A) is a current value obtained by subtracting the solar cell Isc (A) from the module Isc (A), that is, a component other than the solar cell such as a wavelength conversion film or a translucent surface protection member. This is an increased current value. Moreover, in the table | surface, an increase part shows how much the electric current value increased in each Example and the comparative example on the basis of the comparative example 1 which inserted the SEBS film which does not use a wavelength conversion material.

  As shown in Table 1, in Examples 1 to 6 using a quartz glass plate as the translucent surface protective layer 21, ΔIsc (A) is higher than those of Comparative Examples 1 to 3 using soda glass. It is increasing more. This is because the transmittance of a general soda glass suddenly decreases at 350 nm or less, while quartz glass has a high transmittance up to about 170 nm. Therefore, in Examples 1-6 using the quartz glass plate which has the high transmittance | permeability in an ultraviolet region, it turns out that the excitation band of fluorescent substance can be covered in the whole range, and a higher wavelength conversion effect is acquired.

  When comparing the solar cell module into which the SEBS film not using the wavelength conversion agent according to Comparative Example 1 is inserted and the module into which the wavelength conversion film according to Examples 1 to 6 is inserted, all the modules into which the wavelength conversion film is inserted ΔIsc increases. This is considered to be the effect of converting light in a short wavelength region having a low spectral sensitivity of a solar cell into light having a long wavelength having a high spectral sensitivity by wavelength conversion using a phosphor.

  The first embodiment of the module structure α is compared with the fifth embodiment of the module structure β. The solar cell module with the module structure α showed ΔIsc (A) = 0.695, and the solar cell module with the module structure β showed ΔIsc (A) = 0.679. The module structure α shows a higher effect because it is not affected by the sealing resin or the ultraviolet absorber contained therein, and thus the wavelength conversion effect is increased.

  In Example 1, Example 3 and Example 4 having the same module structure α, comparison of the concentration of the BAM phosphor showed that 0.5 wt% was the most effective (ΔIsc (A) = 0. 695). At 0.1 wt% (ΔIsc (A) = 0.682), the concentration is thin, so the wavelength conversion effect is considered to be weak. At 1 wt% (ΔIsc (A) = 0.585), the concentration is too high. It is considered that the characteristics do not improve so much because the transmittance is reduced due to light scattering by the phosphor particles. Therefore, the effect of the wavelength conversion on the improvement of ΔIsc is greatly influenced by the concentration, and the highest effect was exhibited at 0.5 wt% in the concentration range tested this time.

  When Example 1 is compared with Comparative Example 1, in Example 1, solar cell characteristics are improved by inserting a wavelength conversion film having an optimally controlled concentration in a module structure α using a quartz glass plate. I understood that I could do it.

DESCRIPTION OF SYMBOLS 1 Solar cell module, 2 Solar cell, 3 Tab wire, 4 Strings, 5 matrix, 6 sheet | seat, 7 Surface protective layer, 8 Wavelength conversion layer, 9 Back sheet | seat, 11 Photoelectric conversion layer, 12 Finger electrode, 13 Busbar electrode, 14 Back electrode, 15 Tab wire connection part, 17 Conductive adhesive film

Claims (6)

On the light-receiving surface of the solar battery cell, a surface protective layer, a wavelength conversion layer, and a sealing resin layer that are the outermost layers are provided,
The surface protective layer transmits light in a short wavelength region of 350 nm or less,
The said wavelength conversion layer is a solar cell module which has a wavelength conversion material which is provided immediately under the said surface protective layer, and absorbs the light of a short wavelength range of 350 nm or less, and has a longer wavelength range emission wavelength.   The solar cell module according to claim 1, wherein the surface protective layer is made of quartz glass.   The solar cell module according to claim 2, wherein a surface protective layer, a wavelength conversion layer, a sealing resin layer, and a solar cell are provided in order from the light receiving surface of the solar cell.   The solar cell module according to claim 3, wherein the wavelength conversion layer is a film containing a phosphor that is the wavelength conversion material.   The solar cell module according to claim 4, wherein the phosphor is made of an inorganic compound to which a light emitting element is added.   The solar cell module according to claim 4, wherein the concentration of the phosphor is 0.5 wt%.

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