JPWO2013065811A1 - Back surface protection sheet for solar cell module and solar cell module - Google Patents

Abstract

The back surface protection sheet for solar cell modules of the present invention is one or more selected from Fe, Co, Al, Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si and Cu. By having a black resin layer containing a black pigment made of a complex oxide containing a metal element, infrared rays incident on the solar cell module can be efficiently reflected.

Description

  The present invention relates to a back protective sheet for a solar cell module and a solar cell module in which a plurality of solar cell elements are enclosed.

  2. Description of the Related Art In recent years, a solar cell power generation system including a solar cell module has become widespread as one of power generation means using clean energy due to an increase in environmental awareness. The solar cell module has a plurality of plate-like solar cell elements arranged. These solar cell elements are sandwiched between ethylene-vinyl acetate copolymers called sealing materials, and a front plate such as glass is placed on the side where the sunlight strikes. However, the back surface protection sheet for solar cell modules (hereinafter abbreviated as back surface protection sheet) having weather resistance and moisture resistance is superimposed on the opposite side in this order. And it is integrally molded by a vacuum heating lamination method or the like.

  This back surface protection sheet for solar cell modules protects solar cell elements and sealing materials, protects solar cell elements from external mechanical shocks and pressures, and prevents moisture penetration. Various functions are required such as preventing deterioration.

  Under such circumstances, in the back surface protection sheet, the color on the light receiving surface side of the back surface protection sheet may be black in order not to impair the outdoor appearance when the solar cell module is installed. In this case, generally, carbon black, which has a high coloring power and is inexpensive, is used as a black pigment for the layer on the light receiving surface side. However, when carbon black is used, not only the visible light region but also the light in the infrared region is absorbed, so the temperature of the back surface protection sheet rises, and as a result, the entire solar cell module becomes high temperature. Generally, since the electrical conversion efficiency is likely to decrease as the temperature of the solar cell element increases, it is not desirable that the temperature of the entire solar cell module increases. That is, it is not preferable that the temperature of the back surface protection sheet rises. Also, in the case of a back surface protection sheet consisting only of a layer containing carbon black, the temperature of the back surface protection sheet further rises by absorbing the reflected light of sunlight from the ground or roof, so the back surface protection sheet A white resin layer was provided on the outermost layer in order to reflect the reflected light.

  For this reason, Patent Document 1 proposes a back surface protection sheet that does not reduce the electrical conversion efficiency even if the color of the light receiving surface side of the back surface protection sheet is black. Specifically, the layer in contact with the sealant layer of the back surface protective sheet is a layer containing a perylene black pigment that is less likely to absorb infrared rays than carbon black, and further has a reflectance of light having a wavelength of 700 to 1200 nm. It is a back surface protection sheet characterized by providing a layer of 60 to 100%. By doing so, the light having a wavelength of 700 to 1200 nm that is transmitted without being absorbed by the layer containing the perylene black pigment is reflected by the layer having a reflectance of 60 to 100% at the wavelength, thereby increasing the temperature. It is described that the effect of improving the electrical conversion efficiency is suppressed.

  However, when the back surface protective sheet having the above-described configuration is used, there is a problem that part of light in the infrared region having a wavelength of 700 nm or more is absorbed by the layer containing the perylene black pigment, resulting in an increase in temperature. Further, since the perylene black pigment is an organic pigment, when it is used in a solar cell module, the light resistance, heat resistance, chemical resistance and weather resistance are not sufficient.

JP 2011-155175 A

  The present invention has been made in view of the above-mentioned problems, does not impair the appearance with almost the same color as the solar cell element, and further reflects the infrared rays reaching the back surface protection sheet, so that the back surface protection sheet is heated to a high temperature. It aims at providing the back surface protection sheet which can prevent the fall of electrical conversion efficiency, and a solar cell module using the same.

  The present inventors contain Fe, Co, Al, and one or more metal elements selected from Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si, and Cu. It has been found that a protective sheet for a solar cell module comprising a black resin layer containing a black pigment made of a complex oxide can prevent the solar cell module from becoming high temperature and can prevent a decrease in electrical conversion efficiency. The present invention has been completed.

That is, according to the present invention, (1) one or more metals selected from Fe, Co, Al, Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si, and Cu Provided is a back protective sheet for a solar cell module, comprising a black resin layer containing a black pigment made of a complex oxide containing an element.
The present invention also includes (2) a back surface protection sheet for solar cell modules according to (1), wherein the back surface protection sheet has a single-layer structure composed of the black resin layer; (3) adjacent to the black resin layer. The solar cell module back surface protective sheet according to (1), further including a reflective layer that reflects light having a wavelength of 700 to 2500 nm; and (4) the black resin layer and the reflective layer are coextruded. The back surface protection sheet for solar cell modules as described in said (3) laminated | stacked by the method is provided.
The present invention further provides (5) a solar cell module provided with a power generation element protected by the back surface protective sheet of any one of (1) to (4) above.

  The back surface protective sheet of the present invention has an extremely high average reflectance of light in the infrared region with a wavelength of 780 to 2500 nm as compared with conventionally used carbon black, and the back surface protective sheet does not have a high temperature and has an electric conversion efficiency. It has the effect that a fall can be prevented. Furthermore, the back surface protective sheet of the present invention is superior in hydrolysis resistance and has good weather resistance over a long period of time compared to the carbon black-containing back surface protective sheet.

It is a typical fragmentary sectional view of the solar cell module using the back surface protection sheet of one Embodiment of this invention. It is a typical fragmentary sectional view of the solar cell module using the back surface protection sheet of other embodiment of this invention. It is a figure which shows the measurement result of the reflectance of the back surface protection sheet of Example 1, Example 2, and Comparative Example 1. It is a figure which shows the measurement result of the reflectance of the back surface protection sheet of Example 3, Example 4, and Comparative Example 2. FIG.

  Hereinafter, the back surface protection sheet for solar cell modules and solar cell module of this invention are demonstrated in detail.

As schematically shown in FIG. 1, a solar cell module (1) constituting a solar cell includes a front plate (2) such as glass, a power generation element (including wiring and electrodes) (3), and this power generation element ( 3) a sealing material (4) for sealing, and a back surface protection sheet (5) for covering and protecting the sealing material (4) and then the power generating element (3). An ethylene-vinyl acetate copolymer resin (EVA) film as a sealing material (EVA) film, a power generation element, an EVA film, and a moisture-proof back surface protection sheet are stacked in this order on the glass (such as glass), and hot-pressed while degassing under reduced pressure. The EVA film is melted to seal the power generation element, and the sealing material is covered and protected with a back surface protection sheet to give durability and weather resistance to the power generation element and the solar cell module.

  The back surface protective sheet of the present invention contains Fe, Co, and Al, and further includes one or more metal elements selected from Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si, and Cu. A black resin layer containing a black pigment made of a complex oxide containing is provided. The black resin layer is a layer provided to reflect light in the infrared region with a wavelength of 780 to 2500 nm. The average reflectance in the infrared region with a wavelength of 780 to 2500 nm is 15% or more, and the light that has not been reflected is Permeates with little absorption. When this black resin layer is used as the reflection surface of the back surface protection sheet, the back surface protection sheet itself is difficult to absorb light in the infrared region with a wavelength of 780 to 2500 nm. Can prevent the entire solar cell module from becoming hot. As a result, it contributes to preventing a decrease in electrical conversion efficiency. In addition, by reflecting light in the infrared region having a wavelength of 780 to 2500 nm, it is possible to increase the electrical conversion efficiency by effectively using the light energy that was originally lost. Furthermore, the weather resistance of the solar cell module is increased.

As for content of Fe in the said black pigment, 10-90 mol% is preferable with respect to all the metal elements in a black pigment. As for content of Co in the said black pigment, 1.0-70 mol% is preferable with respect to all the metal elements in a black pigment. Moreover, as for content of Al in the said black pigment, 1.0-70 mol% is preferable with respect to all the metal elements in a black pigment. When the contents of Fe, Co and Al of the black pigment are in the above ranges, the lightness (L ^* ) is 30 or less, and a black pigment with high blackness is obtained. For the same reason, the content of Fe in the black pigment is more preferably 10 to 80 mol%, more preferably 10 to 50 mol%, and more preferably 10 to 50 mol% with respect to all metal elements in the black pigment. Is more preferably from 3.0 to 60 mol%, still more preferably from 5.0 to 50 mol%, based on the total metal elements in the black pigment, and the content of Al is the total metal elements in the black pigment More preferably, it is 3.0-68 mol%, More preferably, it is 5-65 mol%. The content of one or more metal elements selected from Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si and Cu is 2 to 80 mol%.

The total amount of Fe, Co, and Al in the black pigment is preferably 20 to 98 mol%, more preferably 30 to 95 mol%, and even more in terms of a molar ratio to all metal elements in the black pigment. Preferably it is 40-95 mol%. When the total content of Fe, Co and Al of the black pigment having infrared reflectivity according to the present invention is within the above range, the lightness (L ^* ) is 30 or less, and the black pigment has high blackness.

  The average particle diameter of the black pigment is preferably 0.02 to 5.0 μm. When the average particle diameter of the black pigment is 5.0 μm or less, high coloring power is obtained, and when the average particle diameter is 0.02 μm or more, dispersibility in the resin is enhanced. From the same viewpoint, the more preferable average particle diameter of the black pigment is 0.025 to 3.0 μm. The black pigment can be produced by a known method. For example, by a solid phase method in which various raw materials are mixed and fired, or a wet method in which alkali is added to an aqueous solution containing the metal salt to form various hydroxide precipitates, which are then washed, dried, and fired. A black pigment can be obtained.

  It is preferable that the solar pigment has a solar reflectance of 16% or more from the viewpoint of the effect of suppressing the temperature increase due to sunlight of the back protective sheet produced using the black pigment.

  It is preferable that content of the said black pigment is 0.5-30 weight part in 100 weight part of black resin layers. When the content of the black pigment is 0.5% by weight or more, the blackness of the black resin layer is enhanced and light in the infrared region can be sufficiently reflected. Moreover, when the content of the black pigment is 30 parts by weight or less, the obtained back surface protection sheet is excellent in strength and extrudability. From the same viewpoint, the black pigment content is more preferably 1 to 20% by weight.

  The resin used for the black resin layer of the present invention is, for example, a polyester resin selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycyclohexanedimethanol-terephthalate (PCT), polycarbonate-based resin It can be selected from resin or acrylic resin. Other polyolefin resins, polyamide resins, polyarylate resins, and the like can be appropriately selected in consideration of heat resistance, strength, electrical insulation, and the like. Among them, PBT is excellent in hydrolysis resistance and film forming property in addition to heat resistance, strength, and electrical insulation.

PBT refers to at least one polyester having butylene terephthalate as a main repeating unit. Specifically, 1,4-butanediol as a glycol component and terephthalic acid or a lower alcohol ester thereof as a dicarboxylic acid component. Polyester obtained by polycondensation, but 20 mol% or less of these components are other raw materials, for example, a part of 1,4-butanediol as a glycol component is ethylene glycol, propylene glycol, triethylene glycol, etc. Further, it may be a copolyester obtained by replacing terephthalic acid, which is a dicarboxylic acid component, or a part of its lower alcohol ester with isophthalic acid, orthophthalic acid or the like. The melting point of PBT is generally 200 to 230 ° C., but in the present invention, a melting point of 215 to 230 ° C. is preferably used. In addition, the intrinsic viscosity is preferably about 0.6 to 1.5 from the viewpoint of extrudability.
In addition, the solar cell module is required to stably convert solar energy into electric energy over a long period of time, and the back surface protection sheet for the solar cell module of the present invention has its characteristics over a long period of time. It is required not to greatly reduce. The PBT suitable for the present invention contains an ester bond, causes hydrolysis due to moisture, lowers the molecular weight, and may deteriorate physical properties when used over a long period of time. Accordingly, the PBT used in the present invention preferably has a small number of terminal carboxyl groups in order to prevent hydrolysis under high temperature and high humidity. Specifically, PBT having a carboxyl group equivalent of 40 meq / kg or less, more preferably 30 meq / kg or less is preferable.
The black resin layer has a carbodiimide-based compound to suppress hydrolysis within a range that does not greatly change its properties, and phenolic, phosphorus-based, sulfur-based, etc. to prevent thermal degradation during melt processing into a sheet. Antioxidants, UV absorbers and light stabilizers, lubricants, anti-blocking agents, antistatic agents, anti-fogging agents, fillers, plasticizers, colorants and other additives to prevent deterioration due to ultraviolet rays contained in sunlight Can be added as needed.

  The back surface protective sheet of the present invention may have a single layer structure including only the black resin layer containing the black pigment, or may have a multilayer structure in which other layers are laminated on at least one surface of the black resin layer. In the case of a single-layer structure, the back surface protection sheet does not reach a high temperature by reaching the back surface protection sheet and reflecting infrared rays and transmitting most of the light that has not been reflected without deteriorating the appearance of the solar cell. In addition, a decrease in electrical conversion efficiency can be prevented.

In the case of a multilayer structure, it is preferable to have a reflective layer that reflects light having a wavelength of 700 to 2500 nm on one adjacent surface of the black resin layer. When the back surface protective sheet has the reflective layer, the light transmitted through the black resin layer can be reflected by the reflective layer. As a result, by reflecting the light in the infrared region, it is possible to increase the electrical conversion efficiency by effectively using the light energy that was originally lost.
Furthermore, the back surface protective sheet of the present invention may have a gas barrier layer such as an inorganic oxide vapor-deposited layer or an aluminum layer and other layers conventionally used in order to impart gas barrier properties. . In this case, the back surface protective sheet can have, for example, a structure in which a gas barrier layer is stacked on a black resin layer, or a structure in which a reflective layer and a gas barrier layer are stacked in this order on a black resin layer. In the case of a multilayer structure, the black resin layer must be structured so as to form one surface of both surfaces of the back surface protection sheet. However, this is not the case when a transparent layer is provided on the surface of the black resin layer.

The reflective layer that reflects light having a wavelength of 700 to 2500 nm is not particularly limited, and examples thereof include a white resin layer. The white pigment used for coloring the white resin layer is not particularly limited, and examples thereof include titanium dioxide, zinc oxide, and aluminum oxide. Among these, titanium dioxide is most preferably used because of its fine particle size, excellent coloring power and dispersibility, and excellent light resistance, heat resistance and chemical resistance. The reflective layer preferably reflects light having a wavelength of 700 to 2500 nm by 50% or more, particularly 60% or more.
The average particle diameter of the white pigment is preferably 0.01 to 5.0 μm, more preferably 0.1 to 1.0 μm, from the viewpoint of colorability. Moreover, it is preferable that content of a white pigment is 5-30 weight part in 100 weight part of white resin layers. When the content of the white pigment is 5 parts by weight or more, the light transmitted through the black resin layer can be sufficiently reflected by the white resin layer. Moreover, when the content of the white pigment is 30 parts by weight or less, the obtained back surface protective sheet has excellent strength and extrusion moldability. For the same reason, the content of the white pigment is more preferably 10 to 25 parts by weight in 100 parts by weight of the white resin layer.

  The resin used for the white resin layer of the present invention can be the same resin as the black resin layer. Moreover, the additive can use the same thing as a black resin layer.

  When the back surface protection sheet of this invention is a single layer of a black resin layer, it is preferable that it is 30-400 micrometers from a viewpoint of film forming property or intensity | strength. Moreover, when the back surface protection sheet of this invention is a multilayer, it is preferable that the thickness of each layer is 5-300 micrometers from a viewpoint of film forming property or intensity | strength. Furthermore, it is preferable that the whole thickness of the back surface protection sheet of this invention is 30-600 micrometers from a viewpoint of film forming property or intensity | strength.

  The method for producing such a back surface protective sheet is not particularly limited, and can be carried out by a conventionally performed method. For example, in the case of a single-layer back surface protection sheet consisting only of the black resin layer, the master batch of the resin and the pigment is supplied to an extruder equipped with a flat die, and the sheet extruded from the flat die of the extruder is pinched. It is obtained by picking it up between rolls. Moreover, in the case of the back surface protection sheet of a multilayer structure, it is obtained by co-extrusion from a multilayer flat die using a plurality of extruders. Furthermore, when laminating a gas barrier layer on the back surface protection sheet, it can be laminated by a known method such as a dry lamination method or an extrusion lamination method. When laminating by a dry laminating method, it is preferable to use a polyurethane adhesive or an epoxy adhesive.

  The back surface protection sheet thus obtained is applied to a solar cell module in which a plurality of solar cell elements (either single-sided light incident type or double-sided light incident type may be used) are encapsulated. An application example of the back surface protective sheet of the present invention is shown in FIG. In the figure, the same reference numerals as those in FIG. 1 denote the same components. In this example, the back surface protective sheet (5) is composed of a black resin layer (51) and a reflective layer (52). The front plate (2), the power generating element (3), the sealing material (4), and the back protective sheet (5) are arranged in this order so that the black resin layer (51) of the back protective sheet (5) is on the power generating element side. A solar cell module is configured by integrating them.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The characteristics were evaluated by the following method.

(1) Measurement of content of metal element in black pigment The content of metal element in the black pigment was determined by using a “fluorescent X-ray analyzer 3063M type” (manufactured by Rigaku Corporation) and JIS.
Measured according to K 0119 "General X-ray fluorescence analysis rules".

(2) Measurement of average particle diameter of black pigment The average particle diameter of the black pigment was measured by an air permeation method (Fischer method).

(3) Hue ^{(L *} value) of the measurement black pigment hue ^{(L *} value) of the black pigment is kneaded and sample 0.5g and castor oil 0.5ml Hoover muller to form a paste, the paste 4.5 g of clear lacquer was added, kneaded and paint-coated, and an application piece (coating thickness: about 30 μm) applied on cast-coated paper using a 150 μm (6 mil) applicator was prepared. The coating piece is measured using a “color / color difference meter CR-300” (manufactured by Konica Minolta Sensing Co., Ltd.).
The color index (L ^* value) is shown in accordance with Z 8729.

(4) Measurement of reflectivity Using a spectrophotometer (U-3500, manufactured by Hitachi, Ltd.), the surface side of the black resin layer is irradiated with light having a wavelength of 300 to 2500 nm, and the reflectivity of each back surface protection sheet is measured. did.

(5) Calculation of solar reflectance of black pigment The solar reflectance of the black pigment is the reflection at a wavelength of 300 to 2500 nm using the above spectrophotometer for the coating film piece prepared for measuring the above hue. Measure the rate (%), JIS
The solar reflectance was calculated according to R 3106.

(6) Temperature change measurement The back surface temperature of each back surface protection sheet was measured by irradiating infrared rays (lamp output 250 W, distance between the lamp and each back surface protection sheet 300 mm) for 60 minutes.

(7) Surface temperature measurement of the back surface protection sheet in the solar cell module The solar cell module is installed outdoors on a sunny day, and the surface temperature of each back surface protection sheet is measured using a contact thermometer immediately after installation and every hour. It was measured.

(8) Output characteristics of solar cell module In accordance with JIS C 8192, the output of one crystalline solar cell was measured, and then a module was produced using the cell, and the output was measured again.
Formula: [Change rate of maximum output (%)] = [(Maximum output in module) / (Maximum output in cell)] × 100
Based on the above, the change rate of the maximum output was obtained.

(9) Tensile strength measurement According to JIS K 7127 (1989) (test piece: No. 4 type test piece, tensile speed: 50 mm / min), 1000 hours in an atmosphere before exposure and in an atmosphere of room temperature 85 ° C. and humidity 85%. The tensile strength after exposure for 2000 hours and 3000 hours was measured.

[Example 1]
Using a film forming apparatus equipped with a flat die and using a polybutylene terephthalate resin (hereinafter referred to as PBT), a black pigment composed of the composite oxide 1 shown in Table 1 with respect to 100 parts by weight of PBT (HR manufactured by Toda Kogyo Co., Ltd.) -B (A)) The mixture added with 8 parts by weight was extruded from a flat die, and the molten sheet was sandwiched between a rubber roll and a metal roll having a surface set temperature of 25 ° C. A single-layer back protection sheet was obtained. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 2.

[Example 2]
A single-layer back protective sheet was obtained in the same manner as in Example 1 except that the black pigment of the black resin layer was a black pigment composed of the composite oxide 2 shown in Table 1 (HR-GB manufactured by Toda Kogyo Co., Ltd.). It was. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 2.

[Comparative Example 1]
A black back layer protective sheet was obtained in the same manner as in Example 1 except that the black pigment of the black resin layer was carbon black and 1 part by weight was added to 100 parts by weight of PBT. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 2.

  As is clear from the above results, from the back protective sheet consisting only of the black resin layer containing the carbon black of Comparative Example 1, from only the black resin layer containing the black pigment consisting of the specific composite oxide of Examples 1 and 2. Since the back surface protection sheet that reflects a large amount of light in the infrared region transmits a large part of the light that has not been reflected, the back surface protection sheet does not stay in the back surface protection sheet, so that the back surface protection sheet has a high temperature. In addition, by suppressing the temperature rise of the solar cell module, it is possible to prevent a decrease in electrical conversion efficiency as a result.

[Example 3]
Using a film forming apparatus equipped with a flat die, all the layers were made of PBT, and the black resin layer was made of a black pigment made of the composite oxide 1 shown in Table 1 with respect to 100 parts by weight of PBT (HR-B made by Toda Kogyo Co., Ltd. A)) 8 parts by weight of the mixture was added, and the white resin layer was made of a mixture of 8.5 parts by weight of titanium oxide with respect to 100 parts by weight of PBT. The thickness ratio of each was black resin layer: white resin layer = By extruding from a flat die so as to be 1: 5, and sandwiching the melted sheet between a rubber roll and a metal roll having a surface setting temperature of 25 ° C., a two-layer back protective sheet having a thickness of 300 μm is formed. Obtained. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 3.

[Example 4]
A two-layer back protection sheet was obtained in the same manner as in Example 3 except that the black pigment of the black resin layer was a black pigment composed of the composite oxide 2 shown in Table 1 (HR-GB manufactured by Toda Kogyo Co., Ltd.). It was. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 3.

[Comparative Example 2]
A two-layer back protection sheet was obtained in the same manner as in Example 3 except that the black pigment of the black resin layer was carbon black and 1 part by weight was added to 100 parts by weight of PBT. The obtained back surface protective sheet was evaluated by the method described above, and the results are shown in Table 3.

  As is clear from the above results, in the case of the back surface protection sheet in which the white resin layer is provided on the adjacent surface of the black resin layer, compared to the back surface protection sheet using the carbon black of Comparative Example 2, Examples 3 and 4 The back surface protection sheet having a black resin layer containing a black pigment made of a specific composite oxide reflects a large amount of light in the infrared region while transmitting most of the light that has not been reflected. Is not kept in the back surface protection sheet, the back surface protection sheet does not become high temperature, suppresses the temperature rise of the solar cell module, and reflects the light energy that was originally lost, resulting in electrical conversion A decrease in efficiency can be prevented.

  A tempered glass having a thickness of 3 mm, an EVA sheet, one crystalline solar battery cell, an EVA sheet, and the protective sheet for solar battery prepared in Example 3 and Comparative Example 2 were superposed in this order, and a vacuum laminator was attached. By using and hot-pressing, EVA and each member were adhered, and the solar cell module was obtained. At this time, the protective sheets for solar cells of Example 3 and Comparative Example 2 were arranged so that the black resin layer was in contact with the EVA sheet. Further, as a bonding method, a vacuum laminator was used, and after vacuuming at 140 ° C. for 5 minutes, pressure was applied for 10 minutes to perform a bonding process. The surface temperature measurement and output characteristics of the obtained solar cell module were evaluated by the method described above, and the results are shown in Table 4.

  As is clear from the above results, in the case of the back surface protective sheet of Example 3, the temperature increase of the solar cell module can be suppressed more than that of the back surface protective sheet using the carbon black of Comparative Example 2. Moreover, the change rate of each maximum output at the time of using the back surface protection sheet of Example 3 and the comparative property 2 is 99.92% and 97.79%, and in the case of the back surface protection sheet of Example 3, it is a comparison. The output improvement of 2.13% was confirmed from the back surface protection sheet using the carbon black of Example 2.

[Example 5]
The black resin layer was the same as in Example 3 except that 16 parts by weight of a black pigment (HR-B (A) manufactured by Toda Kogyo Co., Ltd.) made of the composite oxide 1 shown in Table 1 was added to 100 parts by weight of PBT. A two-layer back protective sheet was obtained. The tensile strength of the obtained back surface protective sheet and the back surface protective sheet of Comparative Example 2 was evaluated by the method described above. The results are shown in Table 5.

As is clear from the above results, in the case of the back protective sheet of Example 5, the tensile strength after the exposure test was superior to the back protective sheet using the carbon black of Comparative Example 2. That is, the back surface protection sheet of Example 5 using a black pigment made of a specific composite oxide is superior in hydrolysis resistance to the back surface protection sheet using carbon black.
In addition, the tension test was done about the back surface protection sheet of Example 5 provided with the black resin layer which contains more black pigments which consist of specific complex oxide than Example 3 as a representative example of a back surface protection sheet.

The back surface protection sheet of the present invention has a black resin layer containing a specific black pigment, thereby reflecting light in the infrared region of a wavelength of 780 to 2500 nm without absorbing light, compared with carbon black conventionally used. Therefore, it is possible to prevent a decrease in electrical conversion efficiency without increasing the temperature of the back protective sheet. Furthermore, by reflecting the light in the infrared region, it is possible to increase the electrical conversion efficiency by effectively utilizing the light energy that was originally lost.

1: Solar cell module 2: Front plate 3: Power generation element 4: Sealing material 5: Back surface protection sheet 51: Black resin layer 52: White resin layer (reflection layer)

Claims (5)

  Black made of a composite oxide containing Fe, Co, Al, and one or more metal elements selected from Li, Mg, Ca, Sr, Ba, Ti, Mn, Zn, Sn, Zr, Si, and Cu The back surface protection sheet for solar cell modules provided with the black resin layer containing a pigment.   The back surface protection sheet according to claim 1, wherein the back surface protection sheet has a single layer structure composed of the black resin layer.   The back surface protection sheet according to claim 1, further comprising a reflective layer provided adjacent to the black resin layer and reflecting light having a wavelength of 700 to 2500 nm.   The back surface protective sheet for use according to claim 3, wherein the black resin layer and the reflective layer are laminated by a coextrusion method.   The solar cell module provided with the electric power generation element protected by the back surface protection sheet in any one of Claims 1-4.

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