Light condensation type photovoltaic generation apparatus

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an improvement of a concentrating photovoltaic power generation device that converts the light energy of condensed sunlight into electrical energy by a solar cell.

【0002】

[Conventional technology]

In general, a photovoltaic power generation device provided with a solar cell using a compound semiconductor takes the form of a condensing type photovoltaic power generation device in order to reduce costs and improve efficiency. A solar cell using a compound semiconductor has less decrease in conversion efficiency due to a temperature rise due to light collection than a solar cell using a silicon-based semiconductor, and can perform a high light collection operation of about 1000 times. Regarding a solar cell using such a compound semiconductor, development is underway for practical use of a multi-junction cell having a junction portion having a plurality of types of absorption wavelength bands having different center wavelengths in the thickness direction. Single junction cells with junctions with a single absorption wavelength band are limited to conversion efficiencies of 26-28%, while multijunction cells are expected to have conversion efficiencies in excess of 30%. As an example of a condensing photovoltaic power generation device equipped with a multi-junction cell, the length of the path through which the direct solar light incident perpendicularly to the atmosphere in the standard state is AM1 is equipped with a GaAs heteroface cell. Varian has reported a condensing photovoltaic power generation device that achieves an efficiency of 29.2% by condensing 205 times with a magnification of 1.5.

【0003】

As a configuration example of the concentrating photovoltaic power generation device, a case having one end open and a primary optical system fitted in the opening of the case are provided, and a lower surface of the semiconductor main body and a semiconductor main body adjacent thereto are provided. Concentrated photovoltaic power generation in which a plurality of solar cells in which both ends of a long metal leaf are fixed to the upper surface and connected in series are fixed to a seat plate (base plate) provided in a part of the case. The device is known. In the concentrating photovoltaic power generation device configured in this way, the solar cells are confined by emitting the sunlight condensing by the non-imaging Frenel lens, which is the primary optical system, onto the light receiving surface of the solar cell. The cell converts the light energy of sunlight into electrical energy and outputs power.

【0004】

As described above, there is a technique of using a liquid adhesive as a means for fixing the solar cell to the seat plate provided in the case, for example, as disclosed in US Pat. No. 4,711,972. Further, as disclosed in US Pat. No. 5,498,297, a technique has been devised in which a solar cell is fixed to a seat plate with a pressure-sensitive adhesive, sealed, and then pressed against the seat plate with a transparent tape to be fixed. There is.

【0005】

[Problems to be Solved by the Invention]

By the way, in the condensing type photovoltaic power generation device, since the solar cell is heated by condensing, the seat plate is provided with a heat radiating plate (heat sink), or the seat plate and the radiating plate are integrated. It is designed to dissipate heat efficiently. However, in the conventional concentrating photovoltaic power generation device, the thermal resistance between the solar cell and the seat plate is high and desired heat dissipation is not achieved, and as a result, even if the temperature difference between the seat plate and the solar cell is low. The temperature is about 15 ° C, which causes a problem that the conversion efficiency of the solar cell is reduced by about 10%.

【0006】

Further, as a means for wiring to a solar cell, a technique is known in which one end of a longitudinal copper foil is reflowed on the lower surface of a semiconductor main body and the other end of the copper foil is soldered to the upper surface of another solar cell. The copper foil is fixed at about 190 ° C. However, in the process of cooling the solar cell to which the copper foil is fixed to room temperature, the thermal expansion rate of the copper foil is the material of the solar cell. For example, because it is higher than silicon, germanium, gallium arsenic, etc., the shrinkage of the copper foil exceeds the shrinkage of the cell. Will occur. In order to prevent the occurrence of such warpage, it is easy to imagine a technique of reflowing copper foil on the upper surface and the lower surface of the solar cell to the same area and the same projection location to balance the warp, but the lower surface of the solar cell is good. It is preferable to reflow in as large an area as possible in order to obtain sufficient heat conduction and electrical conduction, and conversely, it is necessary to make the joint area as small as possible on the upper surface in order to prevent shade loss, and copper foil on the upper surface and lower surface. Is virtually impossible to reflow to the same area and the same projection location. Due to the remaining warp in the solar cell, (a) the focusing focal position shifts, (b) the outer shape that is the reference for accurate optical alignment collapses, and the focusing capture rate decreases, (c) residual distortion. As a result, dislocations inside the crystal increase, photocarriers disappear, and the rate of recombination increases, resulting in various obstacles such as a decrease in conversion efficiency.

【0007】

Further, as described above, the liquid adhesive used for fixing the solar cell to the seat plate provided in a part of the case has low adhesive strength and lacks reliability, and therefore squeezes out because it is liquid. Often occurred. In addition, the pressure-sensitive adhesive or transparent tape lacks stability after heat treatment, and has problems in long-term reliability and light resistance, especially in a wet and highly dew-condensed place such as Japan. Concentrated photovoltaic power generators, which are heated by condensed light during the day and cooled to the outside temperature at night, have a vigorous heat cycle, and can be used for a long time when bonded with liquid adhesive, pressure-sensitive adhesive, or transparent tape. This may cause adhesion, peeling of tape, or deterioration of insulation performance.

【0008】

The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide high conversion efficiency, long-term reliability and light resistance by efficiently dissipating heat from the solar cell. The purpose is to provide a concentrating solar power generation device.

【0009】

[First means to solve the problem]

In order to achieve the above object, the gist of the first invention is that both ends of a long metal foil are fixed to the lower surface of the semiconductor main body and the upper surface of the semiconductor main body different from the semiconductor main body. A concentrating photovoltaic power generator in which a plurality of solar cells connected in series are fixedly mounted on a seat plate, and the solar cells and the metal foil are made of carbon or glass fiber. , And is fixed to the seat plate via a heat radiating layer made of an epoxy resin in which a filler containing at least one of metal powders is dispersed.

【0010】

[Effect of the First Invention]

In this way, the temperature between the solar cell and the seat plate is formed because the heat radiating layer made of the epoxy resin in which the heat conductive filler is dispersed is formed between the solar cell and the seat plate. In addition to being able to suitably suppress the difference, the metal foil is fixed to the heat radiating layer, so that heat radiating from the metal foil can be effectively performed. Further, since the heat dissipation layer is made of an epoxy resin having a long-term track record for outdoor use such as outdoor building materials, it is excellent in durability and environmental stability. As described above, the heat dissipation of the solar cell is excellent. By efficiently performing the above, it is possible to provide a condensing type photovoltaic power generation device having high conversion efficiency, long-term reliability and light resistance.

【0011】

[Other Aspects of the First Invention]

Here, preferably, the metal foil covers the entire lower surface of the semiconductor main body. In this way, the semiconductor main body of the solar cell is preferably in contact with the heat radiating layer via the metal foil, so that more efficient heat radiating is performed.

【0012】

Further, preferably, the length of the metal foil in the width direction is equal to or greater than the length of the solar cell in the width direction. By doing so, the wide metal foil is fixed to the heat dissipation layer, so that more efficient heat dissipation can be performed from the metal foil, and the electrical resistance of the wiring by the metal foil can be easily reduced. it can. Further, by increasing the length of the metal foil in the width direction, it is possible to provide wiring having sufficiently low electrical resistance even with a thinner metal foil, so that the semiconductor body is warped due to heat shrinkage after reflow. Is unlikely to occur.

【0013】

Further, preferably, the seat plate is made of a metal containing aluminum as a main component, and the thickness of the seat plate is in the range of 2 to 5 (mm). In this way, it is not necessary to provide a heat radiating plate having a separate structure in order to efficiently dissipate heat from the seat plate made of an aluminum plate having a necessary and sufficient thickness. If the thickness of the aluminum plate is thinner than 2 (mm), heat dissipation is not sufficient, and if it is thicker than 5 (mm), the heat dissipation effect is saturated and concentrating photovoltaic power generation is performed. As the weight of the device itself increases, the power required for solar tracking increases.

【0014】

Further, preferably, the thermal conductivity λ (W / m · K) of the heat radiating layer, the thickness t (μm), and the collection of primary optical systems for condensing sunlight on the light receiving surface of the solar cell. The optical magnification c satisfies the following equation 1. In this way, the temperature difference between the solar cell and the seat plate can be suppressed to 10 ° C. or less. When the value of (ct) / λ is 500 or less, the heat dissipation effect is saturated and the dielectric strength is lowered, and when it is 20000 or more, the power generation performance of the solar cell is lowered.

【0015】

[Formula 1] 500 <(ct) / λ <20000 [0016]

Further, preferably, the portion of the heat radiating layer located directly below the metal foil has a lower electrical conductivity than the portion located below the semiconductor main body. In this way, the deterioration of the insulation of the metal foil due to the contact with the heat radiating layer is suitably suppressed, and efficient heat radiating is achieved from the semiconductor main body.

【0017】

[Second means to solve the problem]

In order to achieve the above object, the gist of the second invention is to fix both ends of a long metal foil to the lower surface of the semiconductor main body and the upper surface of the semiconductor main body different from the semiconductor main body. This is a method for manufacturing a concentrating photovoltaic power generation device in which a plurality of solar cells are connected in series and the plurality of solar cells are fixedly fixed on a seat plate, and (a) the condensing type. The method for manufacturing a photovoltaic power generation device includes a resin layer forming step of forming a resin layer made of an epoxy resin in which a filler containing at least one of carbon, glass fiber, and metal powder is dispersed on the seat plate. b) The seat plate is placed on a flat heating plate, the plurality of solar cells connected in series on the resin layer are installed, and the plurality of solar cells are placed above the plurality of solar cells via a thermoplastic synthetic resin sheet. This includes a laminating step of fixing the plurality of solar cells on the seat plate by heating the seat plate while pressing the elastic body.

【0018】

[Effect of the Second Invention]

In this way, the resin layer made of an epoxy resin in which a heat conductive filler is dispersed between the solar cell and the seat plate is cured to form a heat radiating layer having suitable heat conductivity. Therefore, the temperature difference between the solar cell and the seat plate can be suitably suppressed. Further, in the laminating step, when the plurality of solar cells are fixed on the seat plate by heating the seat plate while pressing the elastic body from above the solar cell via the thermoplastic synthetic resin sheet. In addition, the warpage of the solar cell caused by the reflow is corrected, and damage and deterioration of the solar cell at the assembly stage can be prevented. That is, it is possible to provide a method for manufacturing a concentrating photovoltaic power generation device having high conversion efficiency, long-term reliability and light resistance by efficiently dissipating heat from the solar cell.

【0019】

[Other Aspects of the Second Invention]

Further, preferably, the resin layer is 100 (N / m) between the resin layer and the solar cell attached to the surface thereof.²) It has adhesiveness that causes the above tensile strength. In this way, even if the seat plate is deformed due to non-uniform heating of the seat plate (the central portion warms first and the temperature rise in the peripheral portion is delayed) in the laminating process, the position of the solar cell is displaced. It can be prevented and the alignment of the optical system can be maintained with high accuracy.

【0020】

[Example]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the dimensional ratios and the like of each part are not always drawn accurately with respect to the drawings used in the following description.

【0021】

FIG. 1 is a perspective view of a solar tracking device 12 in which the concentrating photovoltaic power generation device 10 according to an embodiment of the present invention is used. The solar tracking device 12 shown in FIG. 1 enables the concentrating photovoltaic power generation device 10 according to the embodiment of the present invention and the condensing photovoltaic power generation device 10 to be rotatable around the vertical axis and the horizontal axis. A vertical axis that supports and rotationally drives the concentrating photovoltaic device 10 around the vertical axis and the horizontal axis so that the concentrating photovoltaic device 10 is maintained in a posture facing the sun. It has a drive device 14 and a horizontal axis drive device 16, and is designed to track the position of the sun so that it can always face the sun. The vertical axis drive device 14 is fixed to a vertical axis 18 that can rotate around the vertical axis that protrudes upward, and the vertical axis 18 that rotatably supports the concentrating photovoltaic power generation device 10 around the horizontal axis. It is equipped with a U-shaped arm 20 for doing so. The horizontal shaft drive device 16 is provided at one end of the U-shaped arm 20, and is directly or indirectly connected to the horizontal shaft 22 supporting the photovoltaic power generation device 10 via a simple speed reducer. It has an output shaft that does not.

【0022】

2A and 2B are views showing the configuration of the concentrating photovoltaic power generation device 10 of the present embodiment, in which FIG. 2A is a plan view and FIG. is there. As shown in this figure, the concentrating photovoltaic power generation device 10 is fitted into, for example, a case 24 having one end surface formed of a plastic material or the like and an opening of the case 24 in order to function as a primary optical system. The attached non-imaging Fresnel lens 26 and a seat plate 28 formed at the bottom of the case 24, for example, formed of a metal containing aluminum as a main component (referred to as an aluminum alloy in the following description) or the like. A solar cell 30 installed via a heat radiation layer 34 on the bottom surface of the case 24, that is, a seat plate 28, which is the condensing position of the Fresnel lens 26, and a tubular reflector 32 functioning as a secondary optical system are provided. ing.

【0023】

In the concentrating photovoltaic power generation device 10 configured as described above, the sunlight condensing by the Fresnel lens 26 passes through the tubular reflector 32 as shown by the two-point chain line in FIG. 2 (b). When the light is emitted to the light receiving surface 40 of the solar cell 30, the power generated from the solar cell 30 is output. In this condensing type photovoltaic power generation device 10, since the non-imaging Fresnel lens 26 is used, the solar cell 30 is collected by the Fresnel lens 26 as long as it is within a predetermined angle range with respect to the direction toward the sun. The light intensity can be kept constant.

【0024】

FIG. 3 is a structural diagram illustrating the structure of the solar cell 30. As shown in this figure, the solar cell 30 used in this embodiment has a multi-junction structure in which a plurality of types of pn junctions having different absorption wavelength bands are laminated, and is a p-type Ge substrate 44. The bottom junction layer 46, in which a pn junction is formed by making the upper part n-type by impurity diffusion, and n of about 0.1 μm.⁺-GaAs layer and n⁺-The buffer layer 48, which is sequentially composed of (In) GaAs layers and laminated on the Ge substrate, and n⁺⁺-InGaP layer and p⁺⁺-The first tunnel layer 50, which is sequentially composed of AlGaAs layers and laminated on the buffer layer 48, and p.⁺-InGaP layer, p- (In) GaAs layer, n⁺-(In) GaAs layer, n⁺-Intermediate junction layer 52, in which a pn junction is formed by being sequentially composed of AlInP layers, and n⁺⁺-InGaAs layer and p⁺⁺-The second tunnel layer 54, which is sequentially composed of AlGaAs layers and laminated on the intermediate junction layer 52, and the p-AlInP layer, p-InGaP layer, and n.⁺-InGaP layer, n⁺-It has an upper junction layer 56 in which a pn junction is formed by being sequentially composed of AlInP layers. Further, a lower electrode, that is, a metal foil 58, is fixed to the lower surface of the solar cell 30, and an upper electrode 42 is fixed to the upper surface except for the light receiving surface 40. N of the upper electrode 42 and the upper bonding layer 56⁺-With the AlInP layer, for example, n⁺A contact layer 60 made of-(In) GaAs is provided, and n of the upper bonding layer 56.⁺-An antireflection film 62 is provided on the exposed surface of the AlInP layer. The substances shown in [] in FIG. 3 are impurities diffused or ion-implanted in order to set the semiconductor type.

【0025】

The pn junctions provided in the bottom junction layer 46, the intermediate junction layer 52, and the upper junction layer 56 are electrically connected in series and have absorption wavelength bands having different center wavelengths. For example, blue light having a wavelength of 300 to 600 (nm) is bonded to the upper bonding layer 56, yellow light having a wavelength of 600 to 1000 (nm) is bonded to the middle bonding layer 52, and red light having a wavelength of 1000 to 1800 (nm) is bonded to the bottom. By absorbing each of the layers 46, high conversion efficiency can be obtained by setting the absorption wavelength band in the wavelength band of sunlight as a wide range.

【0026】

FIG. 4 is an enlarged view showing the vicinity of the solar cell 30 in the concentrating photovoltaic power generation device 10 of the present embodiment, (a) is a plan view, and (b) is a front view. As shown in this figure, in the condensing type photovoltaic power generation device 10 of the present embodiment, the length is extended to the lower surface of the semiconductor main body and the upper electrode 42 provided on the upper surface of the semiconductor main body different from the semiconductor main body. A plurality of solar cells connected in series by fixing both ends of the shaped metal foil 58 to each other, for enhancing a filler containing at least one of carbon, glass fiber, and metal powder, that is, thermal conductivity. It is configured to be fixed on the seat plate 28 via a heat radiating layer 34 made of an epoxy resin in which a filler is dispersed. The heat dissipation layer 34 of this embodiment has a thickness of about 100 (μm), a thermal conductivity of about 5.0 (W / m · K), and about 1 × 10.¹⁵It is equipped with a volume resistance of (Ω · cm), efficiently dissipates heat from the solar cell 30 heated by the condensing operation, and attaches the solar cell 30 and the metal leaf 58 to the seat plate 28. It has an effect as an adhesive layer for fixing, and further has an effect as an insulating layer for electrically insulating between the solar cell 30 and the metal foil 58 and the seat plate 28.

【0027】

The seat plate 28 is made of, for example, a plate-shaped aluminum alloy such as A5203P specified in JIS-H4000, and preferably has a thickness in the range of 2 to 5 (mm). Aluminum alloy is preferably used as a material for the seat plate 28 because it is hard to oxidize, is lightweight, and has excellent thermal conductivity as compared with other metals. Further, the metal foil 58 is, for example, a copper foil having a thickness of about 0.1 (mm), and as shown in FIG. 4A, has a sufficient length in the width direction, that is, a length in the width direction of the solar cell 30. It is formed to have substantially the same length and covers the entire lower surface of the semiconductor main body. Further, the heat dissipation layer 34 has a thermal conductivity of λ (W / m · K), a thickness of t (μm), and a focusing magnification of the primary optical system, that is, a non-imaging Fresnel lens 26, which is c. Occasionally, it is preferable that the equation 1 is satisfied. In concentrating photovoltaic power generation, the output current increases in proportion to the condensing magnification, so it is required to suppress the electrical resistance of the wiring as low as possible. In the concentrating photovoltaic power generation device 10 of the present embodiment, as shown in FIG. 2, wiring by a metal foil 58 having a sufficient length in the width direction to leave a sufficient surplus area on the seat plate 28. In addition to having a lower electrical resistance than ordinary metal wire, the wide metal foil 58 has the advantage that it can be expected to have a heat dissipation effect by being fixed to the heat dissipation layer 34. is there. Further, when the metal foil 58 covers the entire lower surface of the semiconductor main body, it comes into good contact with the heat radiating layer 34 and suitable heat conduction is performed.

【0028】

Further, in the heat radiating layer 34 of this embodiment, two types of regions having different electric conductivitys are provided. That is, in the heat radiating layer 34, there is a first region located directly below the metal foil 58 and a second region located below the semiconductor main body. In the first region, the electric conductivity is suppressed to be low as described above by reducing the content of the filler as compared with the second region. Forming the metal foil 58 with a sufficient length in the width direction as described above has the effect of suppressing the electrical resistance of the metal foil 58 itself to be low, but has a large contact area with the heat radiating layer 34. This may cause a decrease in insulation. By reducing the content of the filler in the first region located directly below the metal leaf 58 as described above, the thermal conductivity as well as the electrical conductivity is reduced, but the heat radiation via the metal leaf 58 is a semiconductor. Since it is smaller than the heat radiated from the main body, the characteristics of the concentrating photovoltaic power generation device 10 are improved by preferably suppressing the deterioration of the insulation of the metal foil 58.

【0029】

FIG. 5 shows a process diagram illustrating a process of fixing the main part of the manufacturing method of the concentrating photovoltaic power generation device 10, that is, the solar cell 30 to the seat plate 28 via the heat radiating layer 34, and a schematic front view thereof. Is shown in Fig. 6. In this embodiment, first, in the lower surface soldering step P1, the metal foil 58 is fixed by reflow to the lower surface of the semiconductor main body provided with the upper electrode 42 on the upper surface. FIG. 6 (1) shows a state in which the metal foil 58 is fixed to the entire lower surface of the semiconductor main body through the lower surface soldering step P1.

【0030】

In the upper surface soldering step P2 following the lower surface soldering step P1, the other end of the metal leaf 58 fixed to the lower surface of the solar cell 30 is fixed to the upper electrode 42 of another adjacent solar cell 30. To do. FIG. 6 (2) shows a state in which a plurality of solar cells 30 are connected in series through the top surface soldering step P2. Here, preferably, the solar cell 30 is placed on a flat heating plate with the side to which the metal foil 58 is fixed facing down, and the heating plate brings the solar cell 30 to about 180 ° C. In the heated state, the metal foil 58 is momentarily heated to the upper electrode 42 by a pulse heater to be fixed to the upper electrode 42. The melting points of the upper electrode 42 and the metal leaf 58 are about 190 ° C. In this way, the metal leaf 58 is heated instantaneously, so that shrinkage due to cooling does not occur, and as a result, warpage is unlikely to occur. , Does not cause defects such as cracks in the semiconductor body. Further, the height of the metal foil 58 fixed on the upper electrode 42 becomes uniform.

【0031】

Further, in the resin layer forming step P3, a resin layer 34p made of an epoxy resin in which a filler containing at least one of carbon, glass fiber, and metal powder is dispersed is formed on the seat plate 28. FIG. 6 (3) shows how the resin layer 34p is formed on the seat plate 28 through the resin layer forming step P3. The resin layer 34p is made of, for example, a resin sheet made of an epoxy resin in which the filler is dispersed is placed on the seat plate 28, or is made of an epoxy resin in which the filler is dispersed by using a roller, screen printing, or the like. Since the resin layer is formed by printing on the seat plate 28, the productivity is high and the thickness of the joint is constant. Further, by doing so, it is possible to easily form the heat radiating layer 34 provided with the regions 1 and 2 having different electrical conductivity as described above. Further, preferably, the resin layer 34p is 100 (N / m) between the resin layer 34p and the solar cell 30 attached to the surface thereof.²) It has adhesiveness that causes the above tensile strength. In this way, even if the seat plate is deformed due to non-uniform heating of the seat plate 28 (the central portion warms first and the temperature rise in the peripheral portion is delayed) in the subsequent laminating step P4, the solar cell 30 Positional deviation can be prevented, and the alignment of the optical system can be maintained with high accuracy.

【0032】

In the laminating step P4 following the steps P1 to P3, the seat plate 28 is placed on a flat heating plate, the plurality of solar cells 30 are installed on the resin layer 34p, and the plurality of solar cells 30 are installed. The plurality of solar cells 30 are fixed onto the seat plate 28 by heating the seat plate 28 while pressing the elastic body 38 from above the thermoplastic synthetic resin sheet 36. FIG. 6 (4) shows how the laminating step P4 is applied. Here, the heating plate is preferably provided with a cooling device in order to enable forced cooling in the cooling step P5 described later. Further, preferably, the thermoplastic synthetic resin sheet 36 is, for example, a PET (polyethylene terephthalate) film having a thickness of 100 (μm), and the thermoplastic synthetic resin sheet 36 is placed on the upper surface of the solar cell 30. Later, while pressing the elastic body 38, for example, silicon rubber or the like from above, in the direction indicated by the one-point chain line arrow in FIG. 6 (4), that is, in the direction perpendicular to the light receiving surface 40 of the solar cell 30, the seat plate 28 is pressed. Heat at about 150 ° C for about 10 minutes. By heating while pressing the elastic body 38 through the thermoplastic synthetic resin sheet 36 in this way, the thermoplastic synthetic resin sheet 36 is fluidized and is between the elastic body 38 and the elastic body 38 as shown in FIG. 6 (4). Fills and forms a fluidized bed to absorb lateral shear stress. Further, by pressing the elastic body 38, the warp generated in the solar cell 30 in the lower surface soldering step P1 can be corrected.

【0033】

In the cooling step P5 following the laminating step P4, the heating plate is forcibly cooled, and when the temperature of the solar cell 30 is lowered to about 50 ° C., the pressing by the elastic body 38 is released. Such forced cooling reduces the time required for manufacturing. In this way, the resin layer 34p was cured to form the heat dissipation layer 34, and as shown in FIG. 6 (5), the solar cell 30 and the metal foil 58 dispersed the heat conductive filler. It is fixed to the seat plate 28 via a heat radiating layer 34 made of epoxy resin.

【0034】

As described above, the seat plate 28 to which the plurality of solar cell 30s are fixed is subsequently fixed to a predetermined position of the case 24 after the secondary optical system, for example, the tubular reflector 32 is attached. FIG. 7 is a perspective view showing the tubular reflector 32 used in this embodiment. As shown in this figure, the tubular reflector 32 is a tubular hexahedron having two openings, an upper opening 32a forming a light receiving portion and a lower opening 32b forming a light emitting portion, and the seat is formed from one side of the lower opening 32b. The fixing allowance 32c for fixing to the plate 28 is extended. The inner wall surface of the tubular reflector 32 is a mirror surface having a reflectance of about 95%.

【0035】

FIG. 8 shows the vicinity of the solar cell 30 in the concentrating photovoltaic power generation device 10 in which the tubular reflector 32 is fixedly formed, cut along a plane substantially perpendicular to the light receiving surface 40 of the solar cell 30. It is a sectional view. The tubular reflector 32 is fixed to the seat plate 28 by a fixing allowance 32c (not shown), and a part of the sunlight collected by the non-imaging Frenel lens 26, which is the primary optical system, is reflected in the tubular shape. The chromatic aberration caused by the primary optical system is corrected by being reflected by the inner wall surface of the mirror 32 and irradiating the light receiving surface 40 of the solar cell 30. Further, even if the tracking of the solar tracking device 12 is slightly deviated, the focused sunlight can be irradiated to the light receiving surface 40 of the solar cell 30, so that the condensed sunlight is irradiated. There is an advantage that deterioration of wiring etc. does not occur due to this.

【0036】

In order to verify the effect of the present invention, when the condensing type solar power generation device 10 of the present embodiment produced by going through the above steps P1 to P5 was tried for actual solar power generation, the condensing type was 500 times. The temperature difference between the solar cell 30 and the seat plate 28 when the Fresnel lens 26 is used is about 8.5 ° C. In the concentrating photovoltaic power generation device 10 of this embodiment, the heat radiation of the solar cell 30 is efficient. It was confirmed that it was done in a targeted manner.

【0037】

As described above, according to the present embodiment, since the heat radiating layer 34 made of the epoxy resin in which the heat conductive filler is dispersed is formed between the solar cell 30 and the seat plate 28, the solar cell In addition to being able to suitably suppress the temperature difference between the 30 and the seat plate 28, the metal foil 58 is fixed to the heat radiating layer 34, so that the heat radiating from the metal foil 58 is also effectively performed. Further, since the heat radiating layer 34 is made of an epoxy resin having a long-term track record for outdoor use such as outdoor building materials, it is excellent in durability and environmental stability. As described above, the solar cell 30 It is possible to provide a concentrating photovoltaic power generation device 10 having high conversion efficiency, long-term reliability and light resistance due to efficient heat dissipation.

【0038】

Further, since the metal foil 58 of the present embodiment preferably covers the entire lower surface of the semiconductor main body, the semiconductor main body of the solar cell 30 is preferably connected to the heat radiating layer 34 via the metal foil 58. More efficient heat dissipation is achieved due to contact.

【0039】

Further, since the length of the metal leaf 58 in the present embodiment in the width direction is preferably equal to or greater than the length in the width direction of the solar cell 30, the wide metal leaf 58 is fixed to the heat radiation layer. As a result, in addition to more efficient heat dissipation from the metal leaf 58, the electrical resistance of the wiring by the metal leaf 58 can be easily reduced. Further, by increasing the length of the metal foil 58 in the width direction, it is possible to provide wiring having sufficiently low electrical resistance even with a thinner metal foil 58, so that the semiconductor main body due to heat shrinkage after reflowing can be provided. Warp is unlikely to occur.

【0040】

Further, the seat plate 28 of this embodiment is preferably made of a metal containing aluminum as a main component, and the thickness of the seat plate is in the range of 2 to 5 (mm), so that it is necessary and sufficient. Since efficient heat dissipation is performed from the seat plate 28 made of a thick aluminum plate, it is not necessary to provide a heat radiation plate having a separate structure.

【0041】

Further, in this embodiment, preferably, sunlight is focused on the thermal conductivity λ (W / m · K) of the heat radiation layer 34, the thickness t (μm), and the light receiving surface 40 of the solar cell 30. The focusing magnification c of the primary optical system, that is, the non-imaging Fresnel lens 26, satisfies the above equation 1. In this way, the temperature difference between the solar cell and the seat plate can be suppressed to 10 ° C. or less.

【0042】

Further, preferably, in the heat radiating layer 34 of the present embodiment, the portion located directly below the metal foil 58 has a lower electrical conductivity than the portion located below the semiconductor main body. In addition to preferably suppressing deterioration of the insulation of the metal foil 58 due to contact with the heat radiating layer 34, efficient heat dissipation is achieved from the semiconductor main body.

【0043】

Further, in the laminating step P4 of the present embodiment, the plurality of solar cells are heated by heating the seat plate 28 while pressing the elastic body 38 from above the solar cell 30 via the thermoplastic synthetic resin sheet 36. Since 30 is fixed on the seat plate 28, the warp of the solar cell 30 caused by the reflow of the lower surface soldering step P1 is corrected, and damage and deterioration of the solar cell 30 at the assembly stage can be prevented. ..

【0044】

Further, the resin layer 34p of this embodiment is preferably 100 (N / m) between the resin layer 34p and the solar cell 30 adhering to the surface thereof.²) Since it has adhesiveness that causes the above tensile strength, even if the seat plate 28 is deformed due to non-uniform heating of the seat plate 28 in the laminating step P4, the position of the solar cell 30 is prevented from being displaced. And the alignment of the optical system can be maintained with high accuracy.

【0045】

Although a preferred embodiment of the present invention has been described in detail with reference to the drawings, the present invention is not limited to this, and is also carried out in still another embodiment.

【0046】

For example, FIG. 9 is an enlarged view showing the vicinity of the solar cell 30 in the concentrating photovoltaic power generation device according to another embodiment of the present invention, (a) is a plan view, and (b) is a front view. It is a figure. In the above-described embodiment, as shown in FIG. 4, the length of the metal foil 58 in the width direction is formed to be substantially the same as the length of the solar cell 30 in the width direction. The present invention is not limited to this, and as shown in FIG. 9, even if the metal foil 70 has a length in the width direction longer than the length in the width direction of the solar cell 30. Good. In this way, in addition to being able to further reduce the electrical resistance of the wiring due to the metal leaf 70, more efficient heat dissipation from the metal leaf 70 can be expected. The present invention is also suitably used for a concentrating photovoltaic power generation device provided with a metal foil having a length in the width direction longer than the length in the width direction of the solar cell 30.

【0047】

Further, FIG. 10 is an enlarged view showing the vicinity of the solar cell 30 in the concentrating photovoltaic power generation device according to still another embodiment of the present invention, (a) is a plan view, and (b) is a plan view. It is a front view. As shown in FIG. 4, the above-described embodiment was a point-condensing type concentrating photovoltaic power generation device 10, but the present invention is not limited to this, and a line as shown in FIG. 10 is used. It is also suitably applied to a condensing type condensing type photovoltaic power generation device. Further, although the upper electrode 42 is not fixed to the upper surface of the solar cell 30 of FIG. 10, the metal foil 80 may also serve as the upper electrode as shown in this figure.

【0048】

Further, in the above-described embodiment, since the seat plate 28 has a function as a heat radiating plate, a separate heat radiating device is not installed in the vicinity of the seat plate 28, but for example, it is simple on the back surface of the seat plate 28. A heat radiating device may be provided.

【0049】

Further, in the above-described embodiment, the multi-junction solar cell 30 was used, but the present invention is also suitably used for a condensing photovoltaic power generation device using a single-junction solar cell. Is.

【0050】

Although not illustrated one by one, the present invention is used with various modifications without departing from the spirit of the present invention.

[Simple explanation of drawings]

[Figure 1]

It is a perspective view of the solar tracking apparatus which uses the condensing type photovoltaic power generation apparatus of this Example.

[Figure 2]

It is a figure which shows the structure of the condensing type photovoltaic power generation apparatus of this Example, (a) is a plan view, (b) is a schematic cross-sectional view shown cut by the alternate long and short dash line of (a).

[Fig. 3]

It is a structural drawing explaining the structure of the solar cell used in the condensing type photovoltaic power generation apparatus of this Example.

[Fig. 4]

It is an enlarged view which shows the vicinity of the solar cell in the condensing type photovoltaic power generation apparatus of this Example, (a) is a plan view, (b) is a front view.

[Fig. 5]

It is a process drawing explaining the main part of the manufacturing method of the condensing type photovoltaic power generation apparatus of this Example.

[Fig. 6]

It is a schematic front view explaining the main part of the manufacturing method of the condensing type photovoltaic power generation apparatus of this Example.

[Fig. 7]

It is a perspective view which shows the tubular reflector used in the condensing type photovoltaic power generation apparatus of this Example.

[Fig. 8]

FIG. 5 is a cross-sectional view showing the vicinity of a solar cell in a concentrating photovoltaic power generation device in which the tubular reflector is fixed, cut along a plane substantially perpendicular to the light receiving surface of the solar cell.

[Fig. 9]

It is an enlarged view which shows the vicinity of the solar cell in the condensing type photovoltaic power generation apparatus of another Example of this invention, (a) is a plan view, (b) is a front view.

[Fig. 10]

It is an enlarged view which shows the vicinity of the solar cell in the condensing type photovoltaic power generation apparatus of still another Example of this invention, (a) is a plan view, (b) is a front view.

[Explanation of symbols]

10: Concentrating solar power generation device 26: Non-imaging Fresnel lens (primary optical system) 28: Seat plate 30: Solar cell 34: Heat dissipation layer 34p: Resin layer 36: Thermoplastic resin sheet 38: Elastic body 40: Light receiving surface 58, 70, 80: Metal leaf P3: Resin layer forming process P4: Laminating process