WO2012008432A1 - Solar power generation module and light-concentrating solar power generation system - Google Patents

Abstract

In the present disclosures, heat from solar cells and the like arising when receiving light can be cooled by a cooling body (103) being provided in a manner so as to cover the entire back surface of a solar cell assembly (102) to which a plurality of solar cells (120) are rectangularly arranged. The cooling body (103) is an integral cast body having a coolant duct (123) inside, and so is robust with respect to heat shock in situations such as when suddenly hit by sunlight, and can reliably handle high temperatures resulting from a level of light concentration that is increased by around 800-2000 times.

Description

Solar power generation module and concentrating solar power generation system

The present invention relates to a solar power generation module and a concentrating solar power generation system.

A normal silicon solar battery cell can obtain a power generation efficiency of about 15% by applying non-condensing sunlight. On the other hand, III-V solar cells such as GaAs used for artificial satellites have high material costs but high conversion efficiency. A multi-junction cell structure has a conversion efficiency of 33%, and can also achieve a conversion efficiency of 40% or more by applying condensed sunlight. It is called concentrated solar power generation (CPV) and is attracting attention to generate high-efficiency power by applying concentrated sunlight to such high conversion efficiency solar cells.

As a concentrating device used in concentrating solar power generation, as illustrated in Japanese Patent Application Laid-Open No. 2000-227573, a dish type that always keeps facing the sun while tracking the sun. Mirrors are used. A plurality of mirror elements are formed in a dish shape, and a solar battery cell is fixed at the focal position.

However, in such a related technique, the temperature of the solar battery cell increases as the concentration degree increases, but the solar battery cell has an allowable upper limit temperature. Usually, the light concentration is about 500 times, but when it is to be increased to 800 times to 2000 times beyond that, the solar cells are brought to a temperature at which there is no problem even under such high light concentration conditions. There was no technology that could reliably cool. In other words, conventionally, there has been no cooling technology that can be simply cooled by air or water, and has a reliable cooling technique in which high temperature measures are taken due to high concentration.

In addition, since the light collecting device is a dish type, the light collecting degree is about 500 times, and there is a limit to the amount of power generated. That is, when the dish type is increased in size, the mirror surface is distorted by its own weight, which makes it difficult to increase the size, and the light collection degree of about 500 times is the limit. For this reason, if the light condensing degree is increased to about 800 to 2000 times, higher power generation efficiency can be obtained, but concentrating solar power generation for realizing it has not been proposed.

The present invention has been made by paying attention to the problems of the related technology, and a solar power generation module having a cooling technology in which a countermeasure against high temperature due to high concentration is applied, and a concentrating type capable of obtaining high concentration. It is an object to provide a solar power generation system.

According to the technical aspect of the present invention, a solar power generation module includes a solar battery cell assembly in which a plurality of solar battery cells, in which a part of the surface side is a light receiving element, are arranged in a rectangular shape, and the solar battery. A cooling body made of an integral casting having a refrigerant passage therein and covering the entire back surface of the cell assembly; provided on the surface side of the solar cell assembly; It is characterized by comprising one or a plurality of light collectors for concentrating light on the light receiving element of the battery cell.

According to the technical aspect of the present invention, the cooling body is provided so as to cover the entire back surface of the solar cell assembly in which a plurality of solar cells are juxtaposed in a rectangular shape. Heat can be cooled. The cooling body is an integral casting having a coolant passage therein. Because it is a cast body, it is also resistant to thermal shocks when it is suddenly exposed to sunlight.

However, the solar cells are rectangular with sides of about 20 to 30 mm, but the cooling body is the smallest size that can be practically produced with rectangles with sides of about 100 to 150 mm. It is also possible to produce a rectangle of about 1 m. Therefore, by setting the size of the plurality of solar battery cells and the size of the cooling body to substantially the same size, the solar battery cell can be efficiently cooled by the cooling body.

Furthermore, since it is composed of an integral cast body having a refrigerant passage inside, (a) (because the cross section of the refrigerant passage can be narrowed) as compared with a jacket structure (common as a cooling body). The flow rate of the refrigerant can be increased, and it can cope with a high heat load. (A) Since the turn part of the refrigerant passage can be reduced, the pressure loss of the refrigerant is reduced. (C) The turn part of the refrigerant passage Since no stagnation occurs, the growth of deposits inside the passage is suppressed and the cooling capacity is hardly lowered, and it is possible to cope with high temperatures due to the light collection degree increased to about 800 to 2000 times. In addition, since one or more light collectors that concentrate light on each light receiving element are provided, the light received by the photovoltaic power generation module can be used for power generation without waste, and the amount of power generation increases.

The perspective view which shows the concentrating solar power generation system which concerns on this embodiment. The top view which shows a concentrating solar power generation system. The side view which shows a concentrating solar power generation system. The perspective view which shows a heliostat. The disassembled perspective view which shows a heliostat. Schematic explanatory drawing which shows the support structure of the mirror of a heliostat. The figure which shows the attachment state of an electric power generation area. The figure which shows the condensing spot which hits a power generation area. The perspective view which shows a photovoltaic power generation module. The figure which shows the structure of a solar power generation module. The perspective view which shows a condensing body. Sectional drawing which shows the condensing state of a solar power generation module. The back view which shows a cooling body. FIG. 14 is a cross-sectional view of the cooling body taken along line SA-SA in FIG.

1 to 14 are views showing a preferred embodiment of the present invention. In this embodiment, a small pilot plant class concentrating solar power generation will be described as an example. The direction of east, west, south, and north will be explained using an example of the mid-latitude region of the northern hemisphere as in Japan.

The tower 1 has a height of 10 m, and a slope 1a facing diagonally downward is formed on the north side of the top. A power generation area 3 is provided on the slope 1 a of the tower 1. In the power generation area 3, solar power generation modules 101 described later are juxtaposed in a rectangular shape with 9 pieces (3 rows and 3 columns) without a gap.

On the north side of the tower 1, as shown in FIG. 2, a total of 34 units arranged in a plurality of layers in an arc shape in a sector area E having an angle θ (azimuth angle of 30 degrees) centered on the tower 1. Heliostat 5 is installed.

This heliostat 5 is of a multi-mirror type in which the reflection function is distributed to four mirrors 2 as mirror elements. On the base 6 of each heliostat 5, a bar 7 is erected on the tower 1 side, and a sensor 8 is fixed to the upper end thereof. A support column 9 is provided on the opposite side of the base 6 from the bar 7, and a first drive unit 10 is provided on the upper end thereof. The first drive unit 10 is provided with a first shaft 11 that is parallel to the rotation axis of the earth and has a predetermined angle with respect to the ground. The first shaft 11 can be rotated by the first driving unit 10 in the ascending direction A (see FIG. 6) related to the diurnal motion around the axis.

A U-shaped frame 12 is fixed to the tip of the first shaft 11. A second shaft 13 passes through the flanges on both sides of the frame 12 in a direction perpendicular to the first shaft 11. The second shaft 13 is a metal pipe, and both sides protrude to the outside of the flange. Between the frame 12 and the second shaft 13, there is provided a second drive unit 14 that rotates the second shaft 13 in the declination direction B (see FIG. 6) related to seasonal motion.

Another support pipe 15 penetrates in the orthogonal direction at both ends of the second shaft 13 protruding outward from the frame 12. The second shaft 13 and the support pipe 15 form an H shape, and the mirrors 2 are respectively attached to both ends of the support pipe 15 at the four corners by metal fittings 16. The mirror 2 is circular with a diameter of 50 cm, and the surface thereof is a concave spherical surface having a focal length corresponding to the distance to the power generation area 3 of the tower 1.

A sensor mirror 18 is attached to the second shaft 13 inside the frame 12 via a pair of brackets 17. The sensor mirror 18 is a horizontally long rectangle and has a flat surface.

The sunlight L reflected by the sensor mirror 18 is received by the sensor 8. The sensor 8 is located between the sensor mirror 18 and the power generation area 3, and the power generation area 3 exists on the extended line connecting the sensor mirror 18 and the sensor 8. Therefore, when the rotation of the mirror 2 in the longitude and declination direction A and declination direction B is controlled so that the sunlight L reflected by the sensor mirror 18 is always received by the sensor 8, the sunlight L is reflected by the sensor 8. You will definitely head to the previous power generation area 3. The four mirrors 2 are angled in advance so that the light path of the sunlight L reflected by the sensor mirror 18 is a representative optical axis, and is completely overlapped as one condensing spot P at the focal length position on the optical axis. Has been adjusted.

Inside the sensor 8 is provided a light detection element that detects a neutral position of the sunlight L in the left-right direction (red meridian direction) and the up-down direction (declination direction). A signal is output to the second drive unit 14. The first drive unit 10 and the second drive unit 14 are feedback-controlled so that the sunlight L reflected by the sensor mirror 18 is always received by the sensor 8 (toward the direction of the sensor 8), The first shaft 11 and the second shaft 13 are rotated in the ecliptic direction A and the declination direction B by the equator method, and the four sunlights L reflected by the four mirrors 2 are reflected on the surface of the power generation area 3. A single focused spot P is applied (see FIG. 8).

The shape of the focused spot P depends on the surface shape accuracy of the mirror 2, the size of the focused spot P depends on the focal length, and the position of the focused spot P depends on the position of the sensor 8. Therefore, the sunlight L can be applied almost uniformly to the power generation area 3 by adjusting the positions of the plurality of condensing spots P present on the power generation area 3.

At this time, since each mirror 2 is small, the surface shape accuracy at the time of manufacture is maintained as it is, and a condensing spot P with less distortion can be formed. The condensing spot P having a shape with less distortion is advantageous when calculating the intensity and range of the sunlight L falling on the power generation area 3, and adjustment for uniformly applying the sunlight L to the power generation area 3 is easy.

In addition, the mirror 2 of the heliostat 5 is easy to track the sun because of the equatorial method that rotates in a diurnal motion around the first axis 11 and a seasonal motion around the second axis 13. That is, the movement of the mirror 2 in one day is governed exclusively by the diurnal movement, and the seasonal movement is very slight. Therefore, for example, when the sun S is hidden by a cloud during the tracking of the sun S by the sensor 8, the state is detected from a numerical value such as an illuminometer, and the real-time control by the sensor 8 is used to detect the normal sun. Switch to clock control that reproduces constant speed rotation according to movement. Then, since the mirror 2 is rotated in the same manner as that controlled by the sensor 8, the sunlight L reflected by the sensor mirror 18 is always detected by the sensor 8 when the cloud S disappears and the sun S appears again. In this case, the control by the sensor 8 is restored, and the real-time tracking control by the sensor 8 can be continued from there.

Furthermore, the control by the sensor 8 detects the optical path position of the sunlight L actually reflected by the sensor mirror 18 in real time, so that it becomes a so-called secondary side control (outgoing side control), and an external factor applied to the heliostat 5 ( Wind pressure, backlash, etc.) can be controlled, and the condensed spot P of sunlight L reflected by the heliostat 5 and hitting the power generation area 3 is completely stopped and does not move. Therefore, the intensity of the sunlight L adjusted to be uniform in advance in the power generation area 3 does not vary, and the variation in the power generation output can be reduced.

As described above, the power generation area 3 includes nine (three rows and three columns) solar power generation modules 101. The solar power generation module 101 includes a solar cell assembly 102, a cooling body 103, and a light collector 104. In the solar cell assembly 102, 36 solar cells 120 each having a light receiving element 119 on the surface are juxtaposed in a 6-row 6-column rectangular shape without any gap. The solar battery cell 120 is a square, and the center light receiving element 119 is also a small square. The part other than the light receiving element 119 of the solar battery cell 120 is an electrode for extracting electric power generated by the light receiving element 119. Each solar battery cell 120 is connected in series. Therefore, the voltage obtained in the entire photovoltaic power generation module 101 is obtained by multiplying the generated voltage of the solar battery cell 120 by the number juxtaposed.

Since the generated voltage of the germanium / gallium-based three-layer junction solar cell is 2.7V, the generated voltage of the solar power generation module 101 is 97.2V. Since the operating voltage of an electric device is generally 100 V, 200 V, or 400 V, a desired voltage can be obtained by arbitrarily combining two or four sets of solar power generation modules 101 in series. But it is not essential to connect all the photovoltaic cells 120 juxtaposed to the photovoltaic power generation module 101 in series, and the number to be connected in series can be arbitrarily determined.

The solar power generation module 101 is provided with a light collector 104 on the surface side of the solar battery cell 120. This condensing body 104 is formed by integrally forming prisms made of substantially square pyramid glass 121 in the same height and in the same direction in six rows. Since the light collector 104 is an integrally molded product, attachment to the solar battery cell 120 is facilitated as compared to a case where individual prisms are assembled. Further, since it is integrally molded, there is no joint surface with adjacent prisms, so there is no possibility of rainwater entering from the joint surface or damage to the joint surface.

The surface on the light entrance side of the light collecting body 104 as an integral body is approximately the same size as the solar cell assembly 102. Each surface serving as an exit of light has the same size as the light receiving element 119 of the solar battery cell 120 and is disposed close to the light receiving element 119. The condensing body 104 has a small cross-sectional area, so that the sunlight L incident from the front side is condensed six times while being reflected by the inner surface, and is emitted from the end surface on the back side. That is, the total area on the outlet side is 1/6 of the area on the inlet side. Since the end face on the exit side of the light collector 104 has a shape and size corresponding to the light receiving element 119 of the solar battery cell 120, the sunlight L incident on the inner side of the light collector 104 is in a rectangular range that matches the light receiving element 19. The light is condensed and dispersed and strikes the light receiving element 119.

A transparent glass member 122 is provided on the further front side (light entrance side) of the light collector 104. The sunlight L condensed on the glass member 122 is incident and reflected and refracted inside, whereby the intensity of the incident sunlight L can be made uniform within the shape range of the glass member 122. Moreover, since it is made of transparent glass, the ultraviolet region of sunlight L can be absorbed when passing through the inside. Since ultraviolet rays are in a wavelength region that causes the light receiving element 119 to deteriorate, the light receiving element 119 is protected. In addition, since it is made of the same transparent glass when passing through the light collector 104, ultraviolet rays are similarly absorbed.

The area of power generation area 3 in which nine photovoltaic power generation modules 101 having such a structure are combined (3 rows and 3 columns) is 0.16 square meters. In addition, since each of the 34 heliostats 5 has four circular mirrors 2 each having a diameter of 50 cm, the total number of mirrors 2 is 136, and the total reflection area of the mirrors 2 is about 27 square meters. All of the sunlight L reflected by the group of mirrors 2 enters the range of the power generation area 3. By collecting all the sunlight L within the area of the power generation area 3, the light collection degree is about 170 times. The sunlight L collected about 170 times is further condensed 6 times by the above-described light collector 104. Therefore, the concentration of sunlight L that passes through the condenser 104 and enters the light receiving element 119 of the solar battery cell 120 is about 1000 times. When the sunlight L about 1000 times is incident, the power generation efficiency of the power generation element 19 is increased to 40% or more.

When the concentration of sunlight L is about 1000 times, the solar battery cell 120 is strongly heated. For this purpose, the cooling body 103 is provided in close contact with the back surface of the solar battery cell assembly 102 to lower the temperature of the solar battery cell 120. The cooling body 103 is made of copper metal having a high thermal conductivity, and is an integral casting in which two systems of refrigerant passages 123 are formed. At both ends of the refrigerant passage 123, an inlet 124 and an outlet 125 are formed on the back side of the cooling body 103, respectively, and a circulation pipe 126 is connected to the refrigerant 124 so that water W as a refrigerant can be circulated.

Accordingly, the heated solar battery cell 120 is deprived of heat by the cooling body 103, and the heat transmitted to the cooling body 103 is sequentially taken out by the water W, so that the temperature of the solar battery cell 120 is maintained at 100 ° C. or lower. . Since the cooling body 103 is made of copper having good thermal conductivity and the fluid is water W having a large specific heat, the thermal resistance is small and a sufficient temperature difference can be secured at all times, and the heat received by the solar battery cell 120 is reliably transferred to the heat. And can be recovered by heat transport. Furthermore, since it is an integral cast body, it is possible to cope with a high heat load by increasing the flow rate of the water W, and the pressure loss of the water W is reduced by reducing the turn part 127. Since the growth of deposits is suppressed, the cooling capacity is hardly lowered.

Further, since the refrigerant passage 123 is two independent passages, even if one passage is clogged or the cooling body 103 is partially burned, the cooling function may be lost completely. Is low. Furthermore, the water W flowing to the cooling body 103 can be cut off and the flow rate can be controlled autonomously. Therefore, even if a problem such as damage to the solar battery cell 120 or trouble in the refrigerant passage 123 (clogging, water leakage, etc.) occurs in the photovoltaic power generation module 101, the water W can be shut off or the flow rate can be controlled independently of the others. The power generation can be continued by the photovoltaic power generation module 101 in which no malfunction occurs. In addition, since the water W that has passed through the cooling body 103 is heated, the heat can be effectively used for other purposes.

As described above, according to the present embodiment, the solar power generation module 101 having the light collecting function and the cooling function is condensed so that the sunlight L reflected by the heliostat 5 installed on the ground is superimposed. For this reason, the light collection efficiency of the solar battery cell 120 can be significantly increased and highly efficient power generation can be achieved. More specifically, the following effects can also be pointed out.

Since the light receiving element of the solar battery cell is a compound crystal multijunction cell structure, power generation efficiency is high. Since the cooling body is made of copper or a copper alloy, the thermal conductivity is high and the cooling capacity can be increased.

Since the refrigerant passages provided in the cooling body are two or more independent passages, even if one passage is clogged or the cooling body is partially burned out, the cooling function is completely lost. The risk of being broken is low. It is also possible to generate electricity by stopping the circulation of the refrigerant in only one system.

Furthermore, the light collecting body is integrally formed in a state in which substantially square pyramid prisms having a narrow cross section on the light exit side are arranged side by side in a rectangular shape. Therefore, it becomes easier to attach to the solar battery cell as compared to a prism in a disjoint state. Further, since it is integrally molded, there is no joint surface with adjacent prisms, so there is no possibility of rainwater entering from the joint surface or damage to the joint surface.

Since the glass member is provided on the surface side of the light collector, the intensity of sunlight condensed by the glass member can be made uniform, and ultraviolet rays that cause deterioration of the solar battery cell can be absorbed.

A power generation area where one or more photovoltaic power generation modules are installed is provided at a predetermined height position of the tower, and the sunlight reflected by a plurality of heliostats installed on the ground is condensed so as to overlap. The degree of light collection with respect to the solar cells can be increased by the number of mirrors in the stat and the number of heliostats themselves.

Since the cooling body can autonomously shut off the refrigerant or control the flow rate, even if a problem such as damage to the solar battery cell or trouble in the water channel (refrigerant passage) (clogging, water leakage, etc.) occurs in the solar power generation module, Since only the refrigerant flowing through the cooling body of the module in which the problem has occurred can be shut off or the flow rate can be controlled, power generation can be continued by the photovoltaic power generation module in which no other problem has occurred.

Since the condensing degree of the entire system is increased by 800 times or more, the conversion efficiency of the solar battery cell is increased and the power generation amount can be improved.

Since the Heliostat is a multi-mirror type in which the reflection function is distributed to multiple mirror elements, each mirror element is smaller than when reflected by a single large mirror, so the surface shape accuracy is maintained and distortion is achieved. It is possible to form a light condensing spot with less. A condensing spot having a shape with less distortion is advantageous in calculating the intensity and range of sunlight falling on the solar cell. When the shape of the focused spot is irregularly distorted, it becomes very difficult to calculate the intensity and range of sunlight that strikes the solar cells.

The mirror element of the heliostat is an equatorial method that rotates with a diurnal motion around the first axis and a seasonal motion around the second axis, making it easy to track the sun. Also, the sunlight actually reflected by the sensor mirror is received by the sensor and the movement of the mirror element is controlled, so it becomes so-called secondary side control (outside control), and external factors (wind pressure, backlash, etc.) added to the heliostat ), And the condensed spot of sunlight reflected by the heliostat and hitting the solar cell completely stops and does not move. Therefore, the intensity of sunlight adjusted to be uniform in advance in the solar battery cell does not fluctuate, and the fluctuation in the power generation output of the solar battery cell can be reduced.

In addition, although the example which provides the solar power generation module 101 in the tower 1 was shown in the above embodiment, it is not limited to this. For example, you may install in the tracker type solar tracking mechanism which does not use the heliostat 5. FIG. When the photovoltaic power generation module 101 is installed in this tracker type solar tracking mechanism, the degree of light collection is increased by a Fresnel lens or the like. Moreover, you may install the solar power generation module 101 in the focus position of a dish type mirror.

In addition, although the multi-mirror type in which the reflection function of the heliostat 5 is distributed to the plurality of mirrors 2 has been taken as an example, if the size is such that the surface shape accuracy can be maintained, or the surface shape accuracy can be maintained. If measures are taken, it is possible to implement with one large mirror.

Furthermore, when the multi-mirror type is used, the number of mirrors 2 is not limited to four, and can be five or more.

Furthermore, the condensing body 104 may be a tapered metal tube whose inner surface is a mirror surface.

Although copper is taken as an example of the material of the cooling body 103, other metal having good thermal conductivity may be used, and the fluid circulating there may be a liquid other than water or a gas such as air.

Further, the number of solar cells constituting the solar cell assembly, the number of integrally formed prisms constituting the light collector, and the number of light collectors constituting the solar power generation module are not limited to the exemplified numbers. .

Furthermore, although the light collectors have the same size as that of the solar cell assembly or the cooling body, it is possible to arrange smaller light collectors.

(US designation)
This international patent application is based on US designation 119 (a) regarding Japanese Patent Application No. 2010-157949 (filed on July 12, 2010) filed on July 12, 2010 with respect to designation in the United States. Incorporate the interests of the rights and cite the disclosure.

Claims (11)

A plurality of solar cells in which a part of the surface side is a light receiving element, and a solar cell assembly in which the cells are arranged in a rectangular shape,
A cooling body that is provided so as to cover the entire back surface of the solar cell assembly, and is constituted by an integral casting having a refrigerant passage inside;
One or more light collectors that are provided on the surface side of the solar cell assembly and concentrate light on the light receiving element of each of the solar cells;
A photovoltaic power generation module comprising: The photovoltaic module according to claim 1, wherein the light receiving element of the solar battery cell has a compound crystal multijunction cell structure. 3. The solar power generation module according to claim 1, wherein the cooling body is made of copper or a copper alloy. The solar power generation module according to any one of claims 1 to 3, wherein the refrigerant passages are two or more independent passages. 5. The light collecting body according to claim 1, wherein the condensing body is integrally formed in a state in which substantially quadrangular pyramid prisms having a narrow cross section on the light exit side are arranged side by side in a rectangular shape. The photovoltaic power generation module according to item. The photovoltaic power generation module according to any one of claims 1 to 5, wherein a glass member that equalizes the intensity of sunlight and absorbs ultraviolet rays is provided on the light entrance side of the light collector. . A power generation area in which one or more photovoltaic power generation modules according to any one of claims 1 to 6 are installed at a predetermined height position of the tower;
One or more heliostats that reflect sunlight toward the light receiving surface of the power generation area;
A concentrating solar power generation system comprising: The concentrating solar power generation system according to claim 7, wherein the cooling body can autonomously block or control a flow rate of the refrigerant. The concentrating solar power generation system according to any one of claims 7 and 8, wherein the condensing degree of the entire system is 800 times or more. 10. The concentrating solar power generation system according to any one of claims 7 to 9, wherein the heliostat is a multi-mirror type in which a reflecting function is dispersed in a plurality of mirror elements. The heliostat has a first axis that is parallel to the rotation axis of the earth and that is rotatable about the axis about the diurnal motion of the sun and that is freely rotatable in the meridian direction, and a U-shape that is fixed to the tip of the first axis. A frame and a second axis that passes through the frame in a direction perpendicular to the first axis and is rotatable about the axis in the declination direction related to the seasonal motion of the sun,
Supporting a plurality of mirror elements on both outer sides of the frame in the second axis, supporting one sensor mirror on the inner side of the frame in the second axis,
A sensor that receives sunlight reflected by the sensor mirror is fixed on a straight line connecting the sensor mirror and the power generation area, so that the sunlight reflected by the sensor mirror is always received by the sensor. The concentrating solar power generation system according to claim 10, further comprising a drive unit that controls rotation of the first axis and the second axis.

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