JPS63254772A - Hybrid generator utilizing sunlight and heat - Google Patents

Abstract

PURPOSE:To make it possible to transduce solar energy into electric power at high efficiency, by constituting a generator with a condensing mirror and a generating part, facing a condensing mirror, and in which the heat receiving side of a thermoelectric element is closely attached to the non-light receiving surface of a solar cell through an electric insulating layer, and arranging the generating part in the vicinity of the focal position of the facing the condensing mirror. CONSTITUTION:A condensing mirror 1, which is also used as a heat radiating plate, tracks the sun and condenses sunlight 6. The light is inputted into a generating part 2. Part of the sunlight is transduced into electricity through a solar cell 4 in the generating part 2. The remaining sunlight is transduced into heat. The temperature of the solar cell 4 is increased. The temperature of the light receiving side of a thermoelectric element 5, which is closely attached to the solar cell 4 through an electric insulating layer 9, is increased. Meanwhile, the heat radiating side of the thermoelectric element 5 is closely attached to a condensing mirror 1', which is also used as a heat radiating plate, through an electric insulating layer 10. Therefore, a large temperature difference is yielded between the heat receiving side and the heat radiating side of the thermoelectric element. Electromotive force is generated between a P-type semiconductor 7 and an N-type semiconductor 8' owing to said temperature difference.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for converting solar energy into electric power,
In particular, the present invention relates to a power generation device suitable as a power source for an artificial satellite.

[Conventional technology]

Conventional power supplies for satellites have mainly used flat solar panels in which solar cells are arranged in a flat plate, but as satellites have become more powerful, solar panels with large surfaces have become necessary. . However, while increasing the area of solar cells is necessary to supply large amounts of power, it also increases air resistance, causing disturbances in the attitude and orbit of artificial satellites. It also causes an increase in the cost of launching into orbit. Therefore, efforts are being made to make solar panels smaller by increasing their power generation efficiency.

In the conventional device for the purpose of miniaturization mentioned above,
As described in Publication No. 3162, multiple solar cells are arranged on a paraboloid with the light-receiving surface inside, and a large number of thermoelectric elements (thermocouples) are arranged in series at the focal point of the paraboloid. By connecting the paraboloids and tracking the sun, the solar cells generate electricity, and the thermoelectric element converts sunlight reflected by the solar cells into electric power, increasing power generation efficiency.

Other conventional devices use gallium arsenide (G), which has high power generation efficiency.
aAs) Solar cells are used. Since GaAs solar cells are more than 10 times more expensive than commonly used silicon (Si) solar cells, cost reductions have been achieved by reducing the amount of GaAs solar cells used by using them together with a concentrator. Regarding this concentrating solar power generation device, please refer to the Proceedings of the 19th I.C.
E.C., August 19-24, 1984. Volume 1.

Pages 621 to 624 (Proceedings
of19th lECEC, August 1
9-24゜1984, Vol., pp621-624)
It is discussed in In the device of this document, a plurality of seed-shaped parabolic mirrors that also serve as heat sinks are arranged in parallel, and a strip-shaped solar cell is arranged on the non-light-receiving surface of the seed-shaped parabolic mirror. With this configuration, the sunlight reflected by the seed parabolic mirror is concentrated onto the strip-shaped solar cell arranged on the non-light receiving surface of the adjacent seed parabolic mirror.

It was generating electricity. The waste heat from the solar cells was transferred to the seed paraboloid by thermal conduction, and was radiated by radiation.

[Problem that the invention seeks to solve]

In the former of the above conventional techniques (Japanese Patent Application Laid-open No. 60-3162), the amount of sunlight that can be reflected by the solar cell and concentrated on the thermoelectric element is as small as 10% of the height of the sunlight that enters the solar cell. This is not taken into consideration, and the power generation efficiency of the thermoelectric element is 1.
There was a problem in that even if it was set to 0%, the power generation efficiency would only be improved by about 1%.

In addition, in the latter of the above-mentioned conventional technologies (IECEC: literature), no consideration is given to further utilizing the waste heat of the solar cells for power generation, and GaAs thick I'll! by condensing light! Although it is possible to reduce the amount of pond usage, there is a problem in that the power generation efficiency cannot exceed that of a GaAs solar cell. In addition, since a seed-shaped parabolic mirror is used, the condensing ratio (condensing magnification)
is as low as several dozen, and only the cooling of the solar cells is considered, so there is a problem that heat dissipation becomes difficult when the light concentration ratio is further increased.

An object of the present invention is to eliminate the problems of the prior art described above and to provide a power generation device for converting solar energy into electric power with high efficiency.

[Means for solving problems]

The above object is achieved by configuring one power generation device as follows. That is, the heat-receiving side (high-temperature junction side) of the thermoelectric element is brought into close contact with the non-light-receiving surface of the solar cell through an electrically insulating layer, and the heat-radiating side (low-temperature junction side) of the thermoelectric element is used to discharge electricity through the electrically insulating layer. The power generation section is configured by bringing it into close contact with a condensing mirror that also serves as a plate. This power generation section is arranged near the focal point of the condensing mirror on which the power generation section is disposed or an adjacent condensing mirror.

The light-receiving side of the condensing mirror that also serves as a heat sink has a mirror surface, the non-light-receiving side is blackened, and a narrow heat pipe is disposed on the non-light-receiving side.

[Effect]

The solar/thermal hybrid power generation device of the present invention configured as described above operates as follows.

A condensing mirror that also serves as a heat sink tracks the sun and collects sunlight.
The collected light is made to enter the solar cell light-receiving surface of the power generation section. This allows the light receiving area of the power generation section to be reduced, thereby reducing costs.

The large pII battery in the power generation section converts a portion of the incident light into electricity and the remaining light into heat, which increases the temperature of the solar cell. As a result, a temperature difference occurs between the solar cells and the collector mirror that also serves as a heat sink, and as a result, the heat generated by the solar cells flows through the thermoelectric element to the collector mirror that also serves as a heat sink, and is radiated into space. Heat is dissipated. At this time, an electromotive force is generated in the thermoelectric element due to the temperature difference between the heat receiving side and the heat dissipating side of the thermoelectric element, and the thermoelectric element converts the heat into electric power. As a result, sunlight is converted into electricity by solar cells as in conventional technology, and at the same time, most of the waste heat from solar cells, which had not been used in the past, can be used to generate electricity using thermoelectric elements. The power generation efficiency can be greatly improved.

The blackening treatment on the non-light-receiving surface of the condenser mirror, which also serves as a heat sink, increases the heat dissipation ability by radiation, and the heat pipe placed on the non-light-receiving surface increases the heat dissipation ability by increasing the fin efficiency. Even if the condensing ratio is increased, the temperature of the condensing mirror, which also serves as a heat sink, can be kept low. Therefore, the temperature difference between the thermoelectric elements can be increased without increasing the temperature of the solar cell more than necessary, so the amount of power generated by the thermoelectric elements can be further increased.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a plan view of the solar/thermal hybrid power generation device of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. In FIG. 1 and FIG. 2, a plurality of heat dissipating plate-cum-condensing mirrors 1 are arranged, and the focal position of each condensing mirror 1 is adjacent to the condensing mirror 1'.
Each condenser mirror is arranged so as to be on the non-light-receiving surface (back surface) of the light-receiving surface. The non-light-receiving surface of each condenser mirror is blackened to enhance its ability to dissipate heat through radiation. The holding frame 3 holds the relative positions of the respective condensing mirrors. A power generation section 2 is arranged at the focal point position and together with the condensing mirror 1 constitutes a power generation unit. This power generation section 2 is composed of a large battery 4 and a thermoelectric element 5.

The structure of the power generation section 2 is shown in FIG. In FIG. 3, the power generation section 2 is constructed by bringing the heat receiving side (high temperature junction side) of a thermoelectric element 5 into close contact with the non-light receiving surface of the solar cell 4 via an electrically insulating layer 9. It is closely attached to a condensing mirror for heat radiation via a layer 10.

The thermoelectric element 5 includes P-type semiconductors 7 and 7' and n-type semiconductors 8 and 8'.
It is structured more like this.

) In this embodiment, the output of the solar cell 4 is the (+) side electrode 1.
1 and the (-) side electrode 12, and the (+) side electrode 11 is connected to the heat radiation side of the P-type semiconductor 7 constituting the thermoelectric element 5, and then connected to the common electrode 11'. .

On the other hand, the (-) side electrode 12 is connected to the heat radiation side of the n-type semiconductor 8' and then connected to the common electrode 12'. That is, in this embodiment, the outputs of the solar cell 4 and the thermoelectric element 5 that constitute the power generation section 2 are connected in parallel.

FIG. 4 shows voltage-current characteristics (V-■ characteristics) and output characteristics when the solar cell 4 and the thermoelectric element 5 are used alone and when they are connected in parallel. In the figure, a solid line 20 is the VI characteristic of the thermoelectric element 5, a broken line 22 is the output characteristic, and the thermoelectric element 5 takes its maximum output Po at a voltage V2 around 1/2 of the open voltage vO. On the other hand, regarding the solar cell, the solid line 21 is its VI characteristic, and the broken line 23 is its output characteristic, and its maximum output Ps is taken at voltage Vx'. Therefore, in this embodiment, the characteristics of the solar cell 4 and the thermoelectric element are combined so that the voltage v2 and the voltage Vz' substantially match under operating conditions.

Therefore, as shown by the broken line 24, when the lines are connected in parallel, the maximum amount Pi (=Po+Pt) is obtained at the voltage V2 (:V2').

The power generation units 2 are connected in series or in parallel depending on the required voltage and current, as shown in FIG.

The operation of this embodiment will be explained below.

A condensing mirror 1 that also serves as a heat sink tracks the sun, collects sunlight 6, and makes the collected sunlight enter a power generation section 2. A portion of this incident sunlight is converted into electricity by the solar cell 4 of the power generation unit 2. The remaining sunlight that has not been converted into electricity is converted into heat, raising the temperature of the solar cell 4. Therefore, the temperature on the heat receiving side of the thermoelectric element 5, which is in close contact with the solar cell 4 via the electrical insulating layer 9, increases. On the other hand, thermoelectric element 5
Since the heat dissipation side of the discharge element 5 is in close contact with the condensing mirror 1' which also serves as a heat dissipation plate via the electrical insulating layer 10, a large temperature difference occurs between the heat receiving side and the heat dissipation side of the discharge element 5.

This temperature difference generates an electromotive force between the P-type semiconductor 7 and the N-type semiconductor 8' of the thermoelectric element 5, converting heat into electricity.

The solar cell 4 and the thermoelectric element 5 are connected in parallel, and the power generation unit 2 outputs an output P2 that is the sum of their respective maximum outputs Po and Pi. Since the power generation section 2 is further connected in series and parallel, it is possible to extract the necessary voltage and current.

Note that the material of the condenser mirror 1 is aluminum (Al1).
Materials that are lightweight and have high thermal conductivity are suitable. As a solar cell, power generation efficiency is high ≦ and 150-250℃
Gallium arsenide (GaAs) solar cells that can be used at high temperatures are suitable.

Furthermore, as a thermoelectric element, B1-Te, Pb-Te, Ge
Thermoelectric elements such as -3i and Fe-5i can be used.

In this example, the non-light-receiving surface of A is treated with blackening as a condensing mirror.
By using a Q mirror, a GaAs solar cell as a solar cell, and a Fe-8i thermoelectric element as a thermoelectric element,
While the power generation efficiency of conventional concentrating GaAs solar cells is approximately 15%, the power generation efficiency is approximately 2% without increasing costs.
0% can be achieved.

In addition, in this embodiment, the solar cell and thermoelectric element in the power generation section are connected in parallel, so even if a failure such as disconnection occurs in either one, the other becomes a bypass circuit, providing redundancy. This has the effect of being highly reliable. Furthermore, since the number of reflections by the condensing mirror is only one, there is also the effect that there is little reduction in the utilization rate of sunlight due to reflection loss.

Another embodiment of the heat sink and collector mirror of the solar/thermal hybrid power generation device of the present invention is shown in FIG.

In FIG. 6, a power generation section 15 is arranged on the non-light receiving surface of the condensing mirror 14 which also serves as a heat dissipation plate, and a plurality of heat pipes 16 are arranged radially. This condensing mirror 14 is arranged in the same manner as in FIG. In this embodiment, the heat pipe 16
distributes the heat from the power generation unit 15 to each part of the condensing mirror 14,
To increase the fin efficiency of the condenser mirror 14. Therefore, condenser mirror 1
Since the heat dissipation capacity of 4 is increased, even if the light concentration ratio is further increased, the temperature difference between the thermoelectric cables can be increased without increasing the temperature of the solar cells in the power generation unit 15, so the amount of power generation can be further increased. becomes.

FIG. 7 shows still another embodiment of the heat sink and collector mirror of the solar/thermal hybrid power generation device of the present invention. In the figure, a sawtooth-shaped reflective surface 18 is provided on the light receiving surface of a heat dissipating plate/collecting mirror 17. This increases the effective curvature of the condenser mirror 17. Therefore, there is an effect that the condensing mirror 17 can be made thinner.

FIG. 8 is a sectional view of a power generating unit portion showing another embodiment of the present invention. In the figure, sunlight is reflected by a heat dissipating plate/concentrating mirror 31, further reflected by a sub-concentrating mirror 33, and concentrated on a power generation section 32 that is in close contact with the condensing mirror 31. With this configuration, it is possible to collect light and generate electricity with a single power generation unit, and the optical system can be easily adjusted.

FIG. 9 is a power generation section and a wiring diagram between the power generation sections showing another embodiment of the present invention. As shown in the figure, in this embodiment, the solar cell 41 and thermoelectric element 42 of one power generation section 43 are connected in series. At this time, in FIG. 4, the characteristics of the solar cell 41 and the thermoelectric element 42 are combined so that the current Iz' which provides the maximum power of the solar cell and the current I2 which provides the maximum power of the thermoelectric element almost match. Thereby, the sum of the voltage v2 of the thermoelectric element and the voltage VZ' of the solar cell can be extracted from the power generation section 43 at the same time as obtaining the maximum output Pz.

Therefore, there is an effect that high voltage can be extracted even if the number of power generation units connected in series is small.

FIG. 10 shows an external view of an element showing another embodiment of the present invention. In the figure, a power generation section 52 is provided at the upper part of the back surface of a Fresnel type condenser mirror 51, which is made of a lightweight thin plate such as an aluminum plate with sawtooth grooves formed on the surface. Sunlight reflected by the Fresnel condensing mirror 51 is focused on the power generation section 52. The lower end of the Fresnel condenser mirror 51 is connected to a frame 54 by a hinge 53 containing a spring and a stopper (not shown). Thereby, the Fresnel condenser mirror 51 can be opened to a predetermined position as shown in FIG. 10 during power generation, and folded as shown in FIG. 11 during transportation. In addition,
Hole 55 provided at the bottom of the Fresnel condenser mirror 51 in FIG.
is for storing the power generation section 52 when folded as shown in FIG.

In this embodiment, since the device is foldable, the device can be folded during transportation, thereby facilitating transportation.

Other embodiments of the present invention are shown in FIGS. 10, 13, and 14. Figure 12 is a plan view of the solar/thermal hybrid power generation device of the present invention, Figure 13 is an external view of the power generation unit in Figure 12, and Figure 14 is a folded view of the power generation unit in Figure 13. It is an external view at the time.

In FIG. 12, a Fresnel type condenser mirror 61, a power generation section 62
, a power generation unit 64 composed of a heat dissipation plate 63 is arranged in a plane to form a power generation panel 65. 13th
In the power generation unit shown in the figure, a power generation section 62 composed of a solar cell and a thermoelectric element is connected to the upper part of a heat sink 63 via a support 66 made of a heat conductive material such as a heat pipe. At its lower end, it is connected to a Fresnel type condenser mirror 61 by a hinge 67 containing a spring and a stopper (not shown). The Fresnel type condenser mirror 61 has a lens 668 located at a position approximately equal to the distance from the hinge 67 to the power generation section 62.
is provided. With the heat sink 63 in an open state as shown in FIG.

The power generation unit 62 is arranged so as to substantially coincide with the focal position of the Fresnel condenser mirror.

With this configuration, as shown in FIG. 14, there is an effect that transportation can be facilitated by folding the container. Furthermore, in this embodiment, since the heat dissipation plate and the condensing mirror are provided separately, the condensing mirror is not deformed by thermal strain, and there is an effect that the light can be condensed with high precision.

〔Effect of the invention〕

According to the present invention, sunlight is efficiently converted into electricity by solar cells as in the conventional technology, and at the same time, most of the waste heat of solar cells, which has not been used in the past, is efficiently converted into electricity by thermoelectric elements. Since it is possible to generate electricity, conventional concentrating G
Compared to the power generation efficiency of the aAs solar cell, which has a power generation efficiency of about 15%, this method has the effect of achieving a power generation efficiency of about 20% without increasing costs. Furthermore, since solar cells and thermoelectric elements are used, reliability can be improved by increasing redundancy and output voltage can be increased.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a solar/thermal hybrid power generation device showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG.
FIG. 3 is a structural diagram showing details of the power generation section in FIG. 2, and FIG. 4 is an explanatory diagram showing the characteristics of the power generation section. Figures 5 and 9 are wiring diagrams showing the method of electrical connection within and between the power generation units, Figure 6 is a plan view of the back side of the condenser fi showing an example for increasing heat dissipation capacity, and Figure 7 is the FIG. 8 is a cross-sectional view of a condensing mirror showing an embodiment for making the light mirror thinner; FIG. 8 is a cross-sectional view of a power generation unit section showing another embodiment of the present invention; FIG.
The figure is an external view of a power generation unit showing another embodiment of the present invention.
FIG. 11 is a sectional view when the power generation unit of FIG. 10 is folded, and FIG. 12 is a plan view showing another embodiment of the present invention.
FIG. 13 is an external view of the power generating unit shown in FIG. 12, and FIG. 14 is an external view of the power generating unit shown in FIG. 13 when it is folded. 1.14.31... Heat sink and condensing mirror, 2.15°32
．． 43,52,62...Power generation section, 4...Solar cell,
5...Thermoelectric element, 7...P-type semiconductor,...n-type semiconductor. 16... Heat vibe, 18... Serrated reflective surface, 3
3...Sub-condensing mirror, 51.61...Fresnel type condensing mirror. 53.67...Hinge. Mine Z's broom 3 no ge + z, (-) -I Shigiko [-Yuuzei [-5m 60th Mocha 70 11. Power generation! P 30th 0pm 110th 547L/-* 55 6$IZ Otsu 21 Generator 140

Claims (1)

[Scope of Claims] 1. At least one or more condensing mirrors, and a power generation section corresponding to the condensing mirrors in which the heat receiving side of a thermoelectric element is brought into close contact with the non-light receiving surface of a solar cell via an electrical insulating layer. 1. A solar/thermal hybrid power generation device comprising: the power generation unit disposed near the focal point of the corresponding condensing mirror. 2. In the apparatus according to claim 1, a plurality of the above-mentioned condensing mirrors are arranged, and the focal position of each of the above-mentioned condensing mirrors is made to coincide with the non-light-receiving surface of the adjacent condensing mirror, and the above-mentioned focal position A solar/thermal hybrid power generation device characterized in that the above-mentioned power generation section is arranged in. 3. The device according to claim 1, wherein the solar cell voltage for obtaining the maximum output of the solar cell is approximately equal to 1/2 of the open voltage of the thermoelectric element, and the output of the solar cell is and the output of the thermoelectric element described above are connected in parallel. 4. The device according to claim 1, wherein the solar cell current for obtaining the maximum output of the solar cell and the thermoelectric element current for obtaining the maximum output of the thermoelectric element are made to approximately match, and A solar/thermal hybrid power generation device characterized in that the output of the thermoelectric element and the output of the thermoelectric element are connected in series. 5. The apparatus according to claim 1, wherein the condenser mirror is a flat Fresnel condenser mirror, and a heat sink is provided at the end or frame of the Fresnel condenser mirror via a hinge, A solar/thermal hybrid power generation device characterized in that the power generation section is provided on the heat sink, and the heat sink is foldable. 6. A solar/thermal hybrid power generation device according to claim 2, characterized in that a heat pipe is disposed on the non-light receiving surface of the condensing mirror. 7. In the device according to claim 2, the condenser mirror is a flat Fresnel condenser mirror, and a part of the Fresnel condenser mirror is provided with a hinge and connected to the frame, A solar/thermal hybrid power generation device characterized in that the Fresnel type condenser mirror described above is foldable.