JPWO2015102100A1 - Optical element, optical element manufacturing method, and concentrating solar power generation apparatus - Google Patents

Abstract

An optical element capable of reducing the occurrence of a change in the lens shape of the light condensing function pattern even in an environment with a temperature change after bonding the glass substrate and the sheet-like molded body having the light condensing function pattern, and A concentrating solar power generation device is provided. An optical element (4) comprising a glass substrate (5) and a sheet-like molded body (6) having a Fresnel lens pattern (6a) made of a thermoplastic resin bonded on the glass substrate (5), When a light beam having a diameter of 5 mmφ is incident on the sheet-shaped molded body (6) perpendicularly to the sheet-shaped molded body (6) from a position outside the center of the concentric circle of the sheet-shaped molded body (6) by 70% or more of the radius. The maximum value for α when the temperature is changed between 25 ° C. and 55 ° C., where α is the size of the range from the maximum luminance to 1/10 of the luminance at the position where the central light intersects the center line. Is αA and the minimum value is αB, the value of αB / αA is 0.70 or more.

Description

  The present invention relates to an optical element, a method for manufacturing the optical element, and a concentrating solar power generation apparatus.

  In recent years, the use of natural energy has attracted attention, and one of them is solar power generation that converts solar energy into electric power using a solar cell. As such solar power generation, in order to increase power generation efficiency (photoelectric conversion efficiency) and obtain large power, sunlight is collected on each solar cell element on the front side of a plurality of solar cell elements arranged on the same plane. A concentrating solar power generation apparatus having a configuration in which an optical element (condensing lens) for causing light to be emitted is known (see, for example, Patent Document 1).

  The concentrating solar power generation device can reduce the size of an expensive solar cell element by concentrating sunlight with an optical element (condensing lens) and receiving the light to the solar cell element. Cost can be reduced. For this reason, the concentrating solar power generation apparatus is spreading as a power supply application in a vast area where the sunshine duration is long and the condensing surface can be installed even when the condensing surface is enlarged.

JP 2006-343435 A

  In the concentrating solar power generation device of Patent Document 1, environmental resistance is considered on the surface on the sunlight incident surface side of the sheet-like optical element (condensing lens) made of acrylic resin (PMMA resin). A transparent glass substrate is bonded.

  By the way, when pasting and bonding a condensing lens sheet having a light condensing function pattern made of an acrylic thermoplastic resin that has both transparency and light resistance and a glass substrate, adhesion of silicone resin or the like is conventionally required. Agents are used.

  However, when the temperature at which the glass substrate and the thermoplastic resin are bonded becomes high, the glass substrate is made of a thermoplastic resin due to the difference between the linear expansion coefficient of the glass substrate and the linear expansion coefficient of the thermoplastic resin when the temperature is returned to room temperature after bonding. Since the lens shape of the condensing lens formed on the optical member is distorted, the optical characteristics differ from the design values, and further, when the manufactured optical element is placed in an environment with a temperature change, it is collected. A change occurs in the lens shape of the optical lens.

  As described above, when the lens shape of the condensing lens formed on the optical member made of the thermoplastic resin is changed, the light cannot be efficiently collected on the solar cell element, and the power generation efficiency is lowered.

  Therefore, the present invention provides a lens shape of the light condensing function pattern even in an environment where the temperature changes after the glass substrate and the thermoplastic resin (condensing lens sheet having the light condensing function pattern) are bonded and bonded together. It is an object of the present invention to provide an optical element, a method for manufacturing the optical element, and a concentrating solar power generation device that can reduce the occurrence of a change in power consumption and suppress a decrease in power generation efficiency.

  In order to achieve the above object, an optical element according to the present invention is a block polymerization composition comprising a glass substrate, a concentric light condensing function pattern on one surface, and the other surface adhered to the glass substrate. An optical element comprising a condensing lens sheet made of an acrylic thermoplastic resin having the condensing lens sheet, the condensing lens from a position outside of 70% or more of its radius with respect to the concentric center of the condensing lens sheet When a light beam having a diameter of 5 mmφ is incident perpendicularly to the sheet, α is the size of the range in which the brightness at the center of the beam crosses the center line and becomes 1/10 of the maximum brightness. When the temperature is changed between 25 ° C. and 55 ° C., the value of αB / αA is 0.7 or more when the maximum value for α is αA and the minimum value is αB.

  In the method for producing an optical element according to the present invention, an acrylic thermoplastic resin having a block polymerization composition is molded into a condensing lens sheet having a concentric light condensing function pattern on one surface, and the molded The other surface of the condensing lens sheet opposite to the condensing function pattern is subjected to an activation treatment, and a silane coupling agent is used as a cross-linking agent and bonded to the glass substrate.

  A concentrating solar power generation apparatus according to the present invention includes an optical element that condenses sunlight, and a concentrating solar element that includes a solar cell element that receives and photoelectrically converts sunlight collected by the optical element. In the photovoltaic device, the optical element is an optical element according to any one of claims 1 to 6.

  According to the optical element of the present invention, even when the temperature is changed to 25 ° C. and 55 ° C., the shape change of the light condensing function pattern (for example, Fresnel lens pattern) of the condensing lens sheet can be reduced. It is possible to reduce the spread of a condensed image of sunlight (hereinafter referred to as a “condensing spot”) condensed by the light condensing function pattern, protruding from the solar cell element, and reducing power generation efficiency.

  Moreover, according to the concentrating solar power generation device according to the present embodiment, the light collected by this optical element is converted into a solar cell even in a natural environment where the temperature change is, for example, 25 ° C. to 55 ° C. Since light can be received stably and satisfactorily in the light receiving region of the element, high power generation efficiency can be stably maintained. Furthermore, according to the concentrating solar power generation device according to the present embodiment, the condensing spot of the light collected by this optical element even in a natural environment where the temperature change is 25 ° C. to 55 ° C., for example. Can be received stably and satisfactorily in the light receiving region of the solar cell element, so that the size of the expensive solar cell element can be reduced and the cost of the apparatus can be greatly reduced.

The figure which showed schematic structure of the concentrating solar power generation device provided with the optical element which concerns on embodiment of this invention. The top view which showed the outline | summary seen from the sunlight incident side of the concentrating solar power generation device which concerns on embodiment of this invention. The figure which showed each adhesion surface of a glass substrate and a sheet-like molded object. The figure which showed the state by which each adhesive surface of the glass substrate and the sheet-like molded object was adhere | attached. The figure for demonstrating the measurement of the change rate of (alpha) when changing temperature from 25 degreeC to 55 degreeC with respect to the optical element which concerns on this embodiment. The figure which shows the state which entered the laser beam in the position away from the center of the optical element. Sectional drawing which shows schematic structure of the concentrating solar power generation device which provided the ultraviolet-ray absorption layer in the optical element surface. Sectional drawing which shows schematic structure of the concentrating solar power generation device which provided the antifouling coating layer in the optical element surface. Sectional drawing which shows schematic structure of the concentrating solar power generation device which provided the antireflection coating layer in the optical element surface. The figure which shows the measurement result of the magnitude | size of a focal spot when changing temperature from 25 degreeC to 55 degreeC with respect to the optical element of a present Example and a comparative example.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a diagram schematically illustrating a schematic configuration of a concentrating solar power generation apparatus including an optical element according to an embodiment of the present invention.

<Overall configuration of concentrating solar power generation system>
As shown in FIG. 1, a concentrating solar power generation device 1 according to this embodiment includes a solar cell element (solar cell) 2 that photoelectrically converts received sunlight, and the solar cell element 2. A solar cell substrate 3 and an optical element 4 that is arranged so as to face the front side (sunlight incident side) of the solar cell element 2 and condense sunlight are provided as main constituent members. In FIG. 1, L <b> 1 indicates sunlight incident on the optical element 4, and L <b> 2 indicates sunlight condensed by the optical element 4.

  The optical element 4 includes a transparent glass substrate 5 provided on the sunlight incident side, and a light-transmitting thermoplastic layer bonded to the surface of the glass substrate 5 on the emission side (opposite the solar cell element 2). It is comprised with the sheet-like molded object 6 which consists of a united composition.

  A Fresnel lens pattern 6 a that condenses incident sunlight on the light receiving region of the solar cell element 2 is concentrically formed on the surface of the sheet-like molded body 6 opposite to the glass substrate 5 (side facing the solar cell element 2). It is formed in a shape. Thus, the sheet-like molded body 6 on which the Fresnel lens pattern 6a is formed functions as a condenser lens.

  As shown in FIG. 2, the concentrating solar power generation device 1 has a plurality of solar cell elements 2 mounted on a solar cell substrate 3 (see FIG. 1) at regular intervals, and receives light from each solar cell element 2. A plurality of optical elements 4 are integrally provided on the same plane so as to face the regions.

  Each solar cell element 2 and each optical element 4 are accurately positioned and arranged, and the side surface periphery between the solar cell substrate 3 and the optical element 4 is between the solar cell substrate 3 and the optical element 4. It is sealed so that moisture (moisture), dust and the like do not enter the space between them. Note that the number and size of the solar cell elements 2 and the optical elements 4 that are opposed to each other are arbitrarily set depending on the size, installation location, and the like of the concentrating solar power generation device 1.

<Details of sheet-like molded body 6>
The sheet-like molded body 6 in the present embodiment is excellent in transparency, weather resistance, flexibility, and the like, and is composed of a thermoplastic heavy resin containing the following acrylic block copolymer (A) and acrylic resin (B). It is formed using a coalescence composition.

In the thermoplastic polymer composition described above, the acrylic block copolymer (A) is a heavy polymer mainly composed of methacrylic ester units at both ends of the polymer block (a1) composed mainly of acrylate units. An acrylic block copolymer having at least one structure in the molecule to which the combined block (a2) is bonded, and having a weight average molecular weight of 10,000 to 100,000;
Content of the acrylic block copolymer (A1) and the polymer block (a2) in which the content of the polymer block (a2) is 40% by mass or more and 80% by mass or less. An acrylic block copolymer (A2) having an amount of 10% by mass or more and less than 40% by mass;
The acrylic resin (B) is mainly composed of methacrylate units;
The mass ratio [(A) / (B)] of the acrylic block copolymer (A) and the acrylic resin (B) is 97/3 to 10/90.

  In the acrylic block copolymer (A), the polymer block (a2) mainly composed of methacrylic ester units was bonded to both terminals of the polymer block (a1) mainly composed of acrylate units. It is an acrylic block copolymer having at least one structure in the molecule, that is, a structure of (a2)-(a1)-(a2) (in the structure, “-” indicates a chemical bond).

  The acrylic resin (B) is an acrylic resin mainly composed of methacrylic acid ester units. From the viewpoint of improving the transparency, molding processability, etc. of the sheet-like molded article comprising the thermoplastic polymer composition, it is a methacrylic acid ester homopolymer or a copolymer mainly composed of a methacrylic acid ester unit. Is preferred.

  The details of the thermoplastic polymer composition in the present embodiment are described in International Publication No. 2010/055798. And the sheet-like molded object (molded object before a Fresnel lens pattern is formed in the surface) which consists of this thermoplastic polymer composition can be manufactured by the well-known T-die method, an inflation method, etc., for example.

  Moreover, as a method of forming the Fresnel lens pattern 6a on the surface of the sheet-like molded body 6 made of this thermoplastic polymer composition, for example, a well-known press molding method, injection molding method, 2P (using ultraviolet curable resin) Photo Polymerization) molding method.

  Next, a method for bonding the glass substrate 5 and the sheet-like molded body 6 in the method for manufacturing the optical element 4 according to the present embodiment will be described.

  As shown in FIG. 3A, before bonding the glass substrate 5 and the sheet-like molded body 6, the surface 6 a is irradiated with plasma (active energy) on the bonding surface 6 a of the sheet-like molded body 6 with the glass substrate 5. (Plasma treatment).

  In addition, before the glass substrate 5 and the sheet-shaped molded body 6 are bonded, a process of applying a silane coupling agent to the bonding surface 5a of the glass substrate 5 with the sheet-shaped molded body 6 is performed.

  Then, as shown in FIG. 3B, the adhesive surfaces 5a and 6b of the glass substrate 5 and the sheet-like molded body 6 that have been subjected to such a process, for example, are well-known by vacuum bonding (thermocompression bonding) or vacuum laminating. Is bonded in a temperature range of 20 to 50 ° C.

  In this way, by irradiating plasma (activation energy) on the adhesion surface of the resin molded body (sheet-shaped molded body 6) containing an acrylate ester, the surface of the adhesion surface is activated, and OH groups and COOH groups are generated. In the increased state, the silane coupling agent is bonded to the OH group or the COOH group firmly by passing the silane coupling agent between the glass substrate 5 and the adhesive surfaces 5a and 6b of the sheet-like molded body 6.

  The optical element 4 obtained by the bonding method in the present embodiment has an appropriate temperature range of 20 to 50 ° C. (temperature that is neither low nor high temperature) between the glass substrate 5 and the bonding surfaces 5a and 6b of the sheet-like molded body 6. In this case, the warp of the entire optical element 4 after bonding is suppressed, and distortion of the lens shape of the Fresnel lens pattern 6a is suppressed.

  In addition, when the temperature at the time of bonding is high, the entire optical element 4 warps so as to be convex toward the glass plate 5 side, and when the temperature at the time of bonding is low, the entire optical element 4 moves toward the sheet-like molded body 6 side. Warps to be convex.

  Then, as shown in FIGS. 4A and 4B, a planar light receiving sensor (two-dimensional sensor) 10 is disposed at the focal position of the Fresnel lens pattern 6a with respect to the optical element 4 obtained by the bonding method described above. A spot diameter of 5 mmφ perpendicular to the optical element 4 at a position where the concentric center M of the condensing lens of the optical element 4 (Fresnel lens pattern 6a of the sheet-like molded body 6) is 70% or more of the lens radius. Laser beam L (wavelength: 532 nm) is incident. Note that the optical element 4 shown in FIGS. 4A and 4B has a size of 200 mm square.

  Then, the maximum luminance with respect to the point where the light at the center of the beam at the focal position (light receiving sensor 10) of the condensing lens of the optical element 4 (Fresnel lens pattern 6a of the sheet-like molded body 6) intersects the center M of the concentric circle. The value of αB / αA when the maximum value is αA and the minimum value is αB when the temperature is changed to 25 ° C and 55 ° C, where α is the size of the brightness range of 1/10 to Was 0.7 or more.

  In addition, the size α of the range in which the luminance is 1/10 from the maximum luminance is expressed as a focal spot on the light receiving sensor 10 of the laser light L incident on the optical element 4.

  As described above, even when the manufactured optical element 4 is changed in temperature to 25 ° C. and 55 ° C., the shape change of the Fresnel lens pattern 6a is small, and as a result, the rate of change of α is small.

  Therefore, according to the concentrating solar power generation device 1 according to the present embodiment, the light collected by the optical element 4 can be collected even in a natural environment where the temperature change is, for example, 25 ° C. to 55 ° C. Since the light receiving region of the solar cell element 2 can receive light stably and satisfactorily, high power generation efficiency can be stably maintained without lowering power generation efficiency, resulting in reduction in power generation cost. it can.

  Moreover, you may comprise so that an ultraviolet absorber may be included in the above-mentioned sheet-like molded object 6 or / and the glass substrate 5. FIG. Furthermore, as shown in FIG. 5A, an ultraviolet absorber may be applied to the surface of the glass substrate 5 on the sunlight incident side to form the ultraviolet absorbing layer 7. With these configurations, ultraviolet rays of sunlight incident on the optical element 4 are absorbed, so that coloring of the sheet-like molded body 6 and changes in physical properties due to ultraviolet rays can be suppressed, and good power generation efficiency can be maintained over a long period of time. .

  5B, the antifouling coating layer 8 may be formed by applying an antifouling coating agent to the surface of the glass substrate 5 on the sunlight incident side. By applying antifouling treatment in this way and suppressing adhesion of sand, dust, etc. to the surface of the glass substrate 5 on the sunlight incident side, a decrease in light transmittance can be suppressed, and thereby good power generation efficiency over a long period of time. Can be maintained.

  Further, as shown in FIG. 5C, an antireflection coating layer 9 may be formed by applying an antireflection coating agent to the surface of the glass substrate 5 on the sunlight incident side. By performing the antireflection treatment in this way, the sunlight transmittance can be further improved, and the power generation efficiency can be further increased.

  Next, in order to evaluate the rate of change of α when the temperature is changed from 25 ° C. to 55 ° C. of the optical element 4 according to the present embodiment described above, it is compared with Example 1 of the present invention shown below. Optical elements having the configurations of Comparative Examples 1 to 3 were prepared.

<Example 1>
In Example 1, the linear expansion coefficient is 6.6 × 10 ⁻⁵ / ° C., the tensile elastic modulus in the MD direction (length direction) is 300 MPa, and the tensile elastic modulus in the TD direction (width direction) is 200 MPa. Adhesiveness to a sheet-like molded article having a thickness of 400 μm made of a mixture of a block copolymer of methyl acrylate (MMA) and butyl acrylate (BA) and a methacrylic resin (corresponding to the above thermoplastic polymer composition). The following plasma treatment was performed in order to increase the temperature. A Fresnel lens pattern is formed on one surface of the sheet-like molded body.

  A silane coupling agent (trade name: KBM-903) manufactured by Shin-Etsu Chemical Co., Ltd. was applied to the surface of the glass substrate facing the sheet-like molded product with a thickness of about 40 nm. Then, a 200 mm square optical element having a structure in which a sheet-like molded body was bonded to a transparent glass substrate having a thickness of 2 mm by vacuum compression bonding (thermocompression bonding) while applying a temperature of 25 ° C. was produced.

  The plasma treatment on the sheet-like molded body was performed as follows.

Using an atmospheric pressure plasma apparatus (APG-500 type) manufactured by Kasuga Electric Co., Ltd., irradiation was performed under the conditions of a supply air flow rate of 190 NL / min, a rated output power of 450 to 500 W, and an irradiation distance of 10 mm. The area irradiated with the atmospheric plasma was about 3 cm ² , and the head was moved under the condition that the plasma was irradiated to the same place for about 1 second, and the entire sheet-like molded body was irradiated with the plasma.

  Then, as shown in FIG. 4A, a planar light receiving sensor is disposed at the focal position of the Fresnel lens pattern with respect to the manufactured optical element, and the condenser lens ( The maximum brightness at the point where laser light (wavelength 532 nm, spot diameter 5 mmφ) is incident at a position 117.4 mm from the center of the concentric circle of the Fresnel lens pattern of the sheet-like molded body) and the light at the beam center intersects the center of the concentric circle. The maximum value of the range in which the luminance is 1/10 to 1 was measured to be 3.78 mm.

  Then, by changing the temperature from 25 ° C. to 55 ° C., similarly, laser light (wavelength 532 nm, spot) at a position 117.4 mm from the concentric center of the condensing lens of the optical element (Fresnel lens pattern of the sheet-like molded product). The maximum value of the size within a range from the maximum luminance to 1/10 of the luminance at the point where the light at the center of the beam intersects the center of the concentric circle was measured and found to be 2.78 mm.

  Therefore, when the temperature is changed from 25 ° C. to 55 ° C., the value of αB / αA is 0.74 when the maximum value for α is αA and the minimum value is αB, and the lens shape of the Fresnel lens pattern 6a The change was small.

  FIG. 6 shows the concentric circle center of the condensing lens (Fresnel lens pattern of the sheet-like molded body) of the optical element when the temperature is 25 ° C. and 55 ° C. in Example 1 and Comparative Examples 1 to 3 below. A laser beam (wavelength of 532 nm, spot diameter of 5 mmφ) is incident at a position of 117.4 mm, and the size of the range in which the light at the center of the beam intersects with the center of the concentric circle is 1/10 of the maximum luminance ( (Shape and position) are schematically shown. Note that the measurement range in Example 1 and Comparative Examples 1 to 3 shown in FIG. 6 is 10 mm on a side, and corresponds to the size of the light receiving surface of the light receiving sensor (see FIG. 4A).

<Comparative example 1>
In Comparative Example 1, a 200 mm square optical element having a structure in which a sheet-like molded body was bonded to a transparent glass substrate having a thickness of 2 mm while applying a temperature of 180 ° C. by vacuum pressure bonding (thermocompression bonding) was produced. Other than that, the glass substrate and sheet-like molded object which performed the process similar to Example 1 were used.

  Then, a planar light receiving sensor (see FIG. 4A) is arranged at the focal position of the Fresnel lens pattern with respect to the manufactured optical element, and the condensing lens (sheet-like molding) of the optical element in an environment of a temperature of 25 degrees. Laser light (wavelength 532 nm, spot diameter 5 mmφ) is incident at a position 117.4 mm from the center of the concentric circle of the Fresnel lens pattern of the body), and the beam intensity at the point where the light at the center of the beam intersects the center of the concentric circle is It was 6.7 mm when the maximum value of the magnitude | size of the range used as the brightness | luminance of 10 was measured.

  Then, by changing the temperature from 25 ° C. to 55 ° C., similarly, laser light (wavelength 532 nm, spot) at a position 117.4 mm from the concentric center of the condensing lens of the optical element (Fresnel lens pattern of the sheet-like molded product). The maximum value of the size within the range from the maximum luminance to 1/10 of the luminance at the point where the light at the center of the beam intersects the center of the concentric circle was measured and found to be 4.4 mm.

  Therefore, when the temperature is changed from 25 ° C. to 55 ° C., the value of αB / αA is 0.65 when the maximum value is αA and the minimum value is αB, and the lens of the Fresnel lens pattern 6a. The shape change was large.

<Comparative example 2>
In Comparative Example 2, a silicone resin (trade name: KE-106) manufactured by Shin-Etsu Chemical Co., Ltd. was used as a sheet-like molded body, and cured and formed while forming a Fresnel lens shape on a glass substrate at 25 ° C. An optical element having a 200 mm square size having the above-described configuration was produced.

  Then, a planar light receiving sensor (see FIG. 4A) is disposed at the focal position of the Fresnel lens pattern for the manufactured optical element, and the condensing lens (sheet-shaped molding) of the optical element is performed in an environment at a temperature of 25 ° C. Laser light (wavelength 532 nm, spot diameter 5 mmφ) is incident at a position 117.4 mm from the center of the concentric circle of the Fresnel lens pattern of the body), and the beam intensity at the point where the light at the center of the beam intersects the center of the concentric circle is It was 2.5 mm when the maximum value of the magnitude | size of the range used as the brightness | luminance of 10 was measured.

  Then, by changing the temperature from 25 ° C. to 55 ° C., similarly, laser light (wavelength 532 nm, spot) at a position 117.4 mm from the concentric center of the condensing lens of the optical element (Fresnel lens pattern of the sheet-like molded product). The maximum value of the size within the range from the maximum luminance to 1/10 the luminance at the point where the light at the center of the beam intersects the center of the concentric circle was measured and found to be 9.7 mm.

  Therefore, when the temperature is changed from 25 ° C. to 55 ° C., the value of αB / αA is 0.26 with αA being the maximum value and αB being the minimum value, and the lens of the Fresnel lens pattern 6a. The shape change was large.

<Comparative Example 3>
In Comparative Example 3, a silicone resin (trade name: KE-106) manufactured by Shin-Etsu Chemical Co., Ltd. was used as a sheet-like molded body, and cured and formed while forming a Fresnel lens shape on a glass substrate at 55 ° C. An optical element having a 200 mm square size having the above-described configuration was produced.

  Then, a planar light receiving sensor (see FIG. 4A) is disposed at the focal position of the Fresnel lens pattern for the manufactured optical element, and the condensing lens (sheet-shaped molding) of the optical element is performed in an environment at a temperature of 25 ° C. Laser light (wavelength 532 nm, spot diameter 5 mmφ) is incident at a position 117.4 mm from the center of the concentric circle of the Fresnel lens pattern of the body), and the beam intensity at the point where the light at the center of the beam intersects the center of the concentric circle is It was 9.1 mm when the maximum value of the magnitude | size of the range used as the brightness | luminance of 10 was measured.

  Then, by changing the temperature from 25 ° C. to 55 ° C., similarly, laser light (wavelength 532 nm, spot) at a position 117.4 mm from the concentric center of the condensing lens of the optical element (Fresnel lens pattern of the sheet-like molded product). The maximum value of the size within the range from the maximum luminance to 1/10 of the luminance at the point where the light at the center of the beam intersects the center of the concentric circle was measured and found to be 3.9 mm.

  Therefore, when the temperature is changed from 25 ° C. to 55 ° C., the value of αB / αA is 0.44 when the maximum value is αA and the minimum value is αB, and the lens of the Fresnel lens pattern 6a. The shape change was large.

Cross-reference of related applications

  This application claims the priority based on Japanese Patent Application No. 2014-000582 for which it applied to the Japan Patent Office on January 6, 2014, The indications of all are fully incorporated by reference in this specification.

DESCRIPTION OF SYMBOLS 1 Concentration type solar power generation device 2 Solar cell element 3 Solar cell substrate 4 Optical element 5 Glass substrate 5a Adhesive surface 6 Sheet-like molded object (condensing lens sheet)
6a Fresnel lens pattern 6b Adhesive surface 10 Light receiving sensor

Claims (9)

An optical element comprising a glass substrate and a condensing lens sheet made of a thermoplastic resin having a concentric light condensing function pattern on one surface and the other surface adhered on the glass substrate,
When a light beam having a diameter of 5 mmφ is incident on the condensing lens sheet perpendicularly with respect to the concentric center of the condensing lens sheet from a position outside the radius of 70% or more,
If the size of the range in which the light at the center of the beam is perpendicular to the main plane of the condenser lens and intersects with the center line passing through the center of the lens and the luminance is 1/10 of the maximum luminance is α, the temperature is An optical element, wherein the value of αB / αA is 0.70 or more when the maximum value is αA and the minimum value is αB when α is changed to 25 ° C and 55 ° C.   The optical element according to claim 1, wherein the light condensing function pattern is a Fresnel lens pattern.   The optical element according to claim 1 or 2, wherein the condensing lens sheet contains an ultraviolet absorber.   The optical element according to any one of claims 1 to 3, wherein an ultraviolet absorbing layer is formed on a surface of the glass substrate opposite to a surface to which the condenser lens sheet is bonded.   5. The optical element according to claim 1, wherein a surface of the glass substrate opposite to a surface to which the condenser lens sheet is bonded is subjected to an antifouling treatment.   The optical element according to any one of claims 1 to 5, wherein an antireflection treatment is performed on a surface of the glass substrate opposite to a surface to which the condenser lens sheet is bonded. Acrylic thermoplastic resin having a block polymerization composition is molded into a condensing lens sheet having a concentric light condensing function pattern on one side,
The other surface of the molded condensing lens sheet opposite to the light condensing function pattern is subjected to an active treatment, and a silane coupling agent is used as a cross-linking agent to be bonded to the glass substrate. A method for manufacturing an optical element.   The method for manufacturing an optical element according to claim 7, wherein a temperature when the condensing lens sheet is bonded to the glass substrate is in a range of 20 ° C. to 50 ° C. 8. In a concentrating solar power generation apparatus including an optical element that condenses sunlight and a solar cell element that receives and photoelectrically converts sunlight collected by the optical element,
The said optical element is an optical element as described in any one of Claims 1 thru | or 6, The concentrating solar power generation device characterized by the above-mentioned.

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