JP2014225543A - Receiver for concentrated photovoltaic power generation module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver for a concentrated photovoltaic power generation module in which a stationary plate for supporting a homogenizer is never perforated and broken even when an irradiation position of the light condensed due to an inevitable accident is widely deviated from the center of the homogenizer.SOLUTION: A receiver 10 for a concentrated photovoltaic power generation module comprises: a substrate 12; a solar cell 14 fixed on the substrate 12 and for receiving sunlight; a homogenizer 16 mounted immediately above the solar cell 14 and for guiding the sunlight condensed by a light condensing device to the solar cell 14; a sealing material 18 for protecting the solar cell 16; a stationary plate 20 mounted on an upper surface of the homogenizer 16; and a fixture 22 for fixing the stationary plate 20 to the substrate 12. The stationary plate 20 is made of a material having thermal conductivity not less than 100 W/(m-K) and a melting point not less than 450°C.

Description

  The present invention relates to a receiver for a concentrating solar power generation module, and more specifically, a concentrating solar power generation that generates power by irradiating solar cells with high-energy sunlight condensed by a concentrating device. It relates to a receiver for a module.

  Photovoltaic power generation modules are broadly classified into a non-condensing type that directly irradiates solar cells with sunlight and a condensing type that irradiates solar cells with sunlight condensed using a condensing device. Among these, the concentrating solar power generation module can reduce the size of the solar battery cell, and therefore, even if an expensive cell with good conversion efficiency is used, the influence on the power production cost is small. Therefore, the concentrating solar power generation module has an advantage that it can efficiently produce inexpensive power.

  The concentrating solar power generation module includes a condensing lens (primary optical system: Primary Optic Element) for condensing sunlight. The light condensed by the condensing lens has a strong central portion and a weak peripheral portion. When such a light is directly applied to the solar battery cell, high power generation efficiency cannot be obtained. Therefore, the concentrating solar power generation module is usually provided with a columnar or frustum-shaped optical member (secondary optical system: Secondary Optic Element) called a homogenizer directly above the solar battery cell. The homogenizer is for uniformizing the energy of light by repeatedly totally reflecting high-energy sunlight condensed by the condenser lens on the side surface.

In the solar power generation module, the solar battery cell is fixed on a substrate, and a homogenizer is disposed directly above the solar battery cell. Furthermore, the circumference | surroundings of a photovoltaic cell and the lower part of a homogenizer are covered with the sealing material. A unit composed of such a substrate, a solar battery cell, and a homogenizer is called a “receiver”.
The homogenizer is simply placed directly above the solar cell. The sealing material is for preventing water from entering the solar battery cell, and has no function as an adhesive. Therefore, in order to prevent the position of the homogenizer from shifting even when external impact or vibration is applied, the homogenizer is usually fixed to the receiver using various fixing members.

For example, in Patent Document 1, four columns are erected around the solar cell, a light shielding plate having a through hole is placed on the column, and a homogenizer is inserted between the solar cell and the light shielding plate. A solar power generation device is disclosed.
This document describes that the sunlight that has passed through the through hole is guided to the homogenizer, and the intensity of the sunlight is equalized.

As described in Patent Document 1, if the upper end of the homogenizer is supported by a light-shielding plate (fixed plate) having a through hole, the position of the homogenizer becomes difficult to shift even when external impact or vibration is applied. Conventionally, stainless steel has been used for the light shielding plate.
However, in the concentrating solar power generation module, the irradiation position of the light condensed by force majeure may be greatly deviated from the center of the homogenizer. At this time, if the collected light is directly irradiated onto the light shielding plate, a hole may be formed in the light shielding plate due to the heat of sunlight. If left unattended, the shading plate will eventually be damaged and the homogenizer will fall off.

JP 2005-142373 A

  The problem to be solved by the present invention is that of a fixing plate (homogenizer support, light shielding plate) for supporting the homogenizer even when the irradiation position of the light condensed by force majeure is greatly deviated from the center of the homogenizer. An object of the present invention is to provide a receiver for a concentrating solar power generation module that does not cause perforation or breakage.

In order to solve the above problems, a receiver for a concentrating solar power generation module according to the present invention is summarized as having the following configuration.
(1) The receiver for the concentrating solar power generation module is:
A substrate,
A solar cell fixed on the substrate for receiving sunlight; and
A homogenizer that is placed directly above the solar cell and guides the sunlight collected by the light concentrator to the solar cell;
A sealing material for protecting the solar battery cell;
A fixing plate placed on the upper surface of the homogenizer;
A fixing jig for fixing the fixing plate to the substrate.
(2) The fixing plate is made of a material having a thermal conductivity of 100 W / (m · K) or more and a melting point of 450 ° C. or more.

When a low thermal conductivity material (for example, stainless steel) is used as a fixing plate for fixing the homogenizer, when the sunlight is directly applied to the fixing plate by force majeure, holes are easily formed or damaged.
On the other hand, when a high thermal conductivity material (for example, Al, Cu) is used as the fixed plate, heat is easily dissipated even if sunlight is directly irradiated to the fixed plate by force majeure. Therefore, the fixing plate can be prevented from being punched or damaged.

It is the top view (upper figure) and front view (lower figure) of the receiver for concentrating solar power generation modules which concern on one embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described in detail.
[1. Concentrator photovoltaic module receiver]
FIG. 1 shows a plan view (upper view) and a front view (lower view) of a receiver for a concentrating solar power generation module (hereinafter also simply referred to as “receiver”) according to an embodiment of the present invention. In FIG. 1, the receiver 10 includes a substrate 12, a solar battery cell 14, a homogenizer (secondary optical system) 16, a sealing material 18, a fixing plate 20, and a fixing jig 22.

[1.1. substrate]
The board | substrate 12 is for fixing the photovoltaic cell 14 to the surface. The material of the substrate 12 is not particularly limited, and various materials can be used. Examples of the material of the substrate 12 include aluminum and copper.

[1.2. Solar cell]
The solar battery cell 14 is a cell for receiving the irradiated light and converting it into electric power. In the present invention, the structure of the solar battery cell 14 and the material constituting it are not particularly limited, and cells composed of various structures and materials can be used.
The solar battery cell 14 generally has a structure in which a back electrode, a semiconductor layer having a photovoltaic effect, and an upper electrode are laminated in this order. An antireflection film may be formed on the surface of the semiconductor layer. As the semiconductor layer, for example, crystalline silicon, a III-V group compound semiconductor represented by InGaP / InGaAs / Ge, and the like are known.

  In the present embodiment, the solar battery cell 14 is fixed to the surface of the substrate 12. In addition to the solar battery cells 14, various components necessary for power generation by the solar battery cells 14 are provided on the substrate 12. Although not shown in FIG. 1, an insulating layer and a plate are formed in this order on the substrate 12, and solar cells 14 are fixed on the plate via lead electrodes.

[1.3. Homogenizer]
[1.3.1. Homogenizer shape]
The homogenizer (secondary optical system) 16 is for guiding the sunlight collected by a light collecting device (not shown) to the solar battery cell 14. The homogenizer 16 is also for making the light energy uniform by repeatedly totally reflecting the guided light on the side surface. The homogenizer 16 is erected at a position directly above the solar battery cell 14 so that its lower end surface faces the solar battery cell 14.

  In the present invention, the homogenizer 16 has a frustum shape in which the cross-sectional area on the light collecting device side (the upper side in the drawing in FIG. 1) is larger than the cross-sectional area on the solar cell 14 side. The shape of the cross section of the homogenizer 16 is not particularly limited, and may be any of a circle, an ellipse, and a polygon. The angle of the side surface of the homogenizer 16 (or the apex angle when the homogenizer 16 is assumed to be a cone) is not particularly limited, and various angles can be selected according to the purpose.

In the example shown in FIG. 1, the homogenizer 16 includes a frustum-shaped main body 16a and a plate-shaped ridge 16b provided integrally with the upper end (on the light collecting device side) of the main body 16a. The area of the ridge 16b is larger than the area of the upper end (condenser side) of the main body 16a. Although the hook 16b is not necessarily required, it is easy to fix the homogenizer 16 to the substrate 12 by providing it.
In the example shown in FIG. 1, the planar shape of the flange 16 b is a square, but the planar shape is not limited to this.

  In the concentrating solar power generation module, since the sunlight is bent by the condensing device, it is necessary to always direct the solar battery cell 14 accurately in the direction of the sun. Therefore, the concentrating solar power generation module generally includes a tracking device for directing the solar cells 14 toward the sun. However, when the shape of the homogenizer 16 is a columnar shape, the conversion efficiency is remarkably reduced when a tracking shift occurs. On the other hand, when the shape of the homogenizer 16 is a frustum shape, there is an advantage that the conversion efficiency is not greatly reduced even if a slight tracking shift occurs.

[1.3.2. Homogenizer materials]
The homogenizer 16 is made of a material having high light transmittance. As a material of the homogenizer 16, for example,
(A) Sodium-containing glass such as borosilicate glass and silicate glass,
(B) aluminosilicate glass, soda calibarium glass,
and so on. In particular, sodium-containing glass is suitable as a material for the homogenizer 16 because it is inexpensive and easy to process.

Various films may be formed on the surface of the homogenizer 16 as necessary.
For example, an antireflection film may be formed on the upper end surface (light incident surface) of the homogenizer 16. As an antireflection film, for example,
(A) a TiO ₂ / Al ₂ O ₃ antireflection film having a multilayer structure of alumina and titania,
(B) an antireflection film comprising a magnesium fluoride layer or a calcium fluoride layer;
and so on.

Further, a protective film for preventing moisture from entering may be interposed at the interface between the homogenizer 16 and the solar battery cell 14.
For the protective film, it is preferable to use a material having high translucency and high heat resistance. Examples of the material for the protective film include a gel-like silicone resin and an acrylic resin film.

[1.4. Encapsulant]
[1.4.1. Sealant Material]
The sealing material 18 covers the exposed portion of the solar battery cell 14 and protects the solar battery cell 14. In the example shown in FIG. 1, the sealing material 18 further covers the lower side surface of the homogenizer 16.

When the lower side surface of the homogenizer 16 is covered with the sealing material 18, it is necessary to prevent water from entering the solar battery cell 14 due to deterioration of the sealing material 18 for a long period of time. Therefore, it is necessary to use a material having high heat resistance and weather resistance for the sealing material 18.
As a material of the sealing material 18, for example,
(A) Silicon resin with fine glass,
(B) Self-adhesion filled with a white and opaque inorganic material powder (for example, calcium carbonate, titanium oxide, high purity alumina, high purity magnesium oxide, beryllium oxide, aluminum nitride, etc.) having high thermal conductivity and light reflectivity RTV rubber,
(C) A material obtained by further adding 10% by weight or more of a fluorinated silicon resin to the material of (b),
(D) epoxy resin,
and so on.

[1.4.2. Refractive index and height of encapsulant]
Various materials described above are known as materials that can prevent water from entering the solar battery cell 14 and have heat resistance and / or weather resistance. There is a correlation between the weather resistance and the refractive index of the above-described materials, and generally, the higher the weather resistance, the higher the refractive index tends to be. That is, a material that satisfies both the low refractive index and the high weather resistance and can be used as the sealing material 18 of the solar battery cell 14 is not known.

  In FIG. 1, the receiver 10 is covered with a sealing material 18 having a height H at the lower side surface of the homogenizer 16. Here, “the height of the sealing material 18” refers to the distance from the lower end surface of the homogenizer 16 to the upper end of the sealing material 18.

  In the case where the lower side surface of the homogenizer 16 is covered with the sealing material 18, the refractive index of the sealing material 18 decreases, and the difference in the refractive index between the sealing material 18 and the homogenizer 16 increases. Light tends to be totally reflected at the lower part. However, since the low refractive index material generally has low heat resistance and / or weather resistance, it tends to deteriorate even when the amount of leaked light is relatively small.

  On the other hand, a high refractive index material generally has high heat resistance and / or weather resistance. However, the higher the refractive index of the sealing material 18 and / or the higher the height H of the sealing material 18, the less the light is totally reflected at the lower part of the homogenizer 16. As a result, part of the light leaks into the sealing material 18. Since the high refractive index material has high heat resistance and / or weather resistance, it does not easily deteriorate even if light leakage occurs, but the light leakage causes a decrease in conversion efficiency.

  On the other hand, when the solar cell 14 is covered with the sealing material 18 so that the sealing material 18 does not cover the lower side surface of the homogenizer 16 more than necessary (in other words, the height H of the sealing material 18 is zero). The light leakage from the side surface of the lower part of the homogenizer 16 can be suppressed as it gets closer to. Further, since the deterioration of the sealing material 18 due to light leakage is suppressed, a low-cost low refractive index material can be used for the sealing material 18.

[1.5. Fixed plate]
[1.5.1. Fixing plate shape]
The fixing plate 20 is for fixing the homogenizer 16 to the substrate 12 and is placed on the upper surface of the homogenizer 16. The shape of the fixing plate 20 is not particularly limited as long as it can reliably fix the homogenizer 16.

  In the example shown in FIG. 1, the fixed plate 20 has a square planar shape. Further, through-holes 20a, 20a,... For inserting the tips of the fixing members 22, 22,.

  A through hole 20 b is provided in the center of the fixed plate 20. The through-hole 20b only needs to have an area that can guide light to the main body 16a of the homogenizer 16 and is smaller than the area of the flange 16b. The reason why the area of the through hole 20b is made smaller than the area of the flange 16b is to press the homogenizer 16 against the upper surface of the solar battery cell 14 by the fixing plate 20. In the example shown in FIG. 1, the through hole 20b has a square planar shape.

  Fixing claws 24, 24... Are provided on the lower surface of the fixing plate 20 and around the through hole 20b. The fixing claws 24, 24... Are for fixing the flange 16 b to the fixing plate 20. Although the fixing claws 24, 24... Are not necessarily required, if the hooks 16b are fixed by the fixing claws 24, 24..., The lateral displacement of the homogenizer 16 due to external force or vibration can be reliably prevented. The fixed claws 24, 24... Can be formed by welding, bending, or the like.

[1.5.2. Fixing plate material]
In the present invention, the fixing plate 20 is made of a material having a thermal conductivity of 100 W / (m · K) or more and a melting point of 450 ° C. or more. This point is different from the conventional one. When a material having a high thermal conductivity and a high melting point is used as the material of the fixing plate 20, even if sunlight is irradiated to the fixing plate 20 by force majeure, the fixing plate 20 can be prevented from being perforated.

As a material satisfying such conditions, for example,
(1) Al (thermal conductivity: 230 W / (m · K), melting point: 660 ° C.), Cu (thermal conductivity: 400 W / (m · K), melting point: 1085 ° C.),
(2) Al alloys such as A1100, A1050 (pure Al series), A2012 (Al-Cu-Mg series), A5052 (Al-Mg series), A6063 (Al-Mg-Si series),
(3) Cu alloys such as brass (Cu—Zn), bronze (Cu—Sn), and white copper (Cu—Ni) are available.

[1.6. fixing jig]
The fixing jigs 22, 22... Are for fixing the fixing plate 20 to the substrate 12. The shape, number, installation position, etc. of the fixing jigs 22, 22... Are not particularly limited as long as the homogenizer 16 can be reliably fixed by the fixing plate 20 and the substrate 12.

  In the example shown in FIG. 1, the fixing jigs 22, 22... Projections 22a, 22a,... Are provided at the tips of the fixing jigs 22, 22,. The protrusions 22a, 22a ... are inserted into the through holes 20a, 20a ... of the fixing plate 20, respectively. The protrusions 22a, 22a... And the fixing plate 20 are fixed by an adhesive, a nut (not shown), or the like.

[2. Action]
When a low thermal conductivity material (for example, stainless steel) is used as a fixing plate for fixing the homogenizer, when the sunlight is directly applied to the fixing plate by force majeure, holes are easily formed or damaged.
On the other hand, when a high thermal conductivity material (for example, Al, Cu) is used as the fixed plate, heat is easily dissipated even if sunlight is directly irradiated to the fixed plate by force majeure. Therefore, the fixing plate can be prevented from being punched or damaged.

(Example 1, Comparative Example 1)
[1. Production of receiver]
A receiver 10 having the structure shown in FIG. 1 was produced. For the fixing plate 20, aluminum (Example 1) or stainless steel (Comparative Example 1) was used.

[2. Test method]
The fixed plate 20 was intentionally irradiated with the light condensed by the condenser lens. During irradiation, the temperature of the back surface of the fixed plate 20 was measured.

[3. result]
In the case of a receiver using a stainless steel fixing plate 20, a hole was opened in the fixing plate 20 in about 5 seconds after the start of irradiation. Therefore, the back surface temperature could not be measured.
On the other hand, in the case of the receiver using the aluminum fixed plate 20, the back surface temperature was about 150 ° C. Further, even after 30 minutes from the start of irradiation, no holes were generated in the fixing plate 20.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.

  The receiver for a concentrating solar power generation module according to the present invention can be used as a power generation device for supplying power to a factory or a house.

DESCRIPTION OF SYMBOLS 10 Concentrator photovoltaic module receiver 12 Substrate 14 Solar cell 16 Homogenizer (secondary optical system)
18 Sealing material 20 Fixing plate 22 Fixing jig

Claims (2)

A receiver for a concentrating solar power generation module having the following configuration.
(1) The receiver for the concentrating solar power generation module is:
A substrate,
A solar cell fixed on the substrate for receiving sunlight; and
A homogenizer that is placed directly above the solar cell and guides the sunlight collected by the light concentrator to the solar cell;
A sealing material for protecting the solar battery cell;
A fixing plate placed on the upper surface of the homogenizer;
A fixing jig for fixing the fixing plate to the substrate.
(2) The fixing plate is made of a material having a thermal conductivity of 100 W / (m · K) or more and a melting point of 450 ° C. or more.   The receiver for a concentrating solar power generation module according to claim 1, wherein the fixing plate is made of Al, Cu, an Al alloy, or a Cu alloy.

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