JP6326393B2 - Solar panel cooling member - Google Patents

Description

  The present invention relates to a member for cooling a solar cell panel.

  It is known that the power generation efficiency of solar cells decreases as the temperature increases. For example, in a monocrystalline or polycrystalline solar cell, the power generation efficiency decreases by about 0.5% each time the surface temperature of the solar cell panel (module) increases by 1 ° C. (10% decrease at 20 ° C.). Therefore, in order to improve the power generation effect of the solar cell, a method of cooling the solar cell panel has been considered. For example, Patent Document 1 proposes an apparatus for cooling a panel surface by intermittently operating a rainwater storage tank and a pump for spraying this water.

JP 2010-34108 A

  As in Patent Document 1, when water is sprayed, it must be stored for water saving. When rainwater is stored, germs tend to propagate in the storage tank in summer and the transparency is lowered. Thus, intermittently sprinkling water with reduced transparency on the panel causes the surface of the panel to become polluted and also causes a decrease in power generation efficiency. Even when using tap water instead of rain water, the situation in which water must be stored in the storage tank remains the same, and water must be sprayed in a state of reduced transparency. Although transparency is improved compared to rainwater, there is a problem that tap water must be consumed.

  The panel surface must be cleaned in order to eliminate the decrease in power generation efficiency due to the contamination of the panel surface, but it must be cleaned regularly with detergents, etc., and maintenance costs are required for that purpose. In the case of (outdoors), there is a fear of contaminating the environment with detergents, and it will consume more water. And when the transparency of the water which stays on the panel surface falls, the irradiation amount of the sunlight which reaches | attains a panel will also fall and the power generation efficiency of a solar cell will fall.

  In addition, when water is sprayed on the solar cell panel, the infrared rays are cooled after absorbing heat once, so that they become a means for thermal cooling. In addition, a sufficient amount of water for heat dissipation cannot be secured for the heat generation of the solar battery cells, and a pump for supplying water from the rainwater storage tank to the header is necessary. There is also the problem of consuming some.

  The present invention has been made in view of such circumstances, and the object thereof is to improve the power generation efficiency of the solar cell by cooling the solar cell panel using a transparent liquid such as water, while An object of the present invention is to provide a solar cell panel cooling member capable of preventing a decrease in transparency.

  A cooling member for a solar cell panel according to the present invention has a liquid holding space into which a liquid can be injected, a main body configured to be able to seal the liquid holding space, and at least a hydroxy inside the main body. The main body has a back surface shaped to cover the light receiving surface of the solar cell panel by contact and a front side facing the sunlight side, and the liquid holding space is formed by the back surface and the front side. Both the back surface and the front side are made of transparent resin.

  According to the present invention, by injecting and holding a transparent liquid in the liquid holding space inside the main body, the solar cell panel can be cooled through contact of the main body with the solar cell panel. Since the contamination of the liquid injected by the antifouling agent disposed in the liquid holding space can be suppressed, the transparency of the held liquid can be ensured. Since the transparency of the retained liquid is ensured, even when the main body is brought into contact with the panel and placed on the sunlight incident side, the sunlight reaches the solar cell panel through the transparent front side, liquid, and back surface. It is possible to suppress a decrease in power generation efficiency due to a decrease in the transparency of the liquid.

It is a figure explaining the positional relationship of a solar cell panel and the member for cooling. It is a graph which shows the temperature characteristic of the band gap voltage of silicon. It is a graph explaining the spectral sensitivity of a single crystal silicon solar cell. It is a figure explaining the specific structure of the member for cooling concerning a basic structure. It is a figure which shows the structure at the time of changing the gradient of the north-south direction. It is a figure which shows the structure at the time of optimizing the incidence of sunlight in the east-west direction.

  First, a solar cell panel (module) will be described. An element that functions as a solar cell is referred to as a cell. A solar cell panel is formed by wiring and arranging a plurality of cells and packaging them with a protective sheet, tempered glass, a metal frame, or the like. As solar cell panels, those installed on the roof are generally used, but for example, many field solar cells that are installed directly on idle land are also installed.

  The member for cooling the solar cell panel according to the present embodiment can be used in any case. On the other hand, in this embodiment, since the solar cell panel is cooled by stacking directly on the solar cell panel, the solar cell panel is not affected even if a load is applied to the installation position like a field stand. It is considered that it is more preferable to use them.

  A solar cell panel receives sunlight by arranging it toward sunlight, and performs photovoltaic power generation by a photovoltaic effect. The cooling member of the solar cell panel according to the present embodiment is stacked on the light receiving surface side of the solar cell panel, and cools the solar cell panel by transmitting the temperature of the cooling member by contact.

  The cooling member is made of a material that is transparent as a whole so that sunlight can be transmitted through the cooling member even after being stacked on the light receiving surface side of the solar cell panel, and sunlight can be received by the light receiving surface. Specifically, it is a transparent resin, and it is particularly preferable to use a transparent acrylic resin. The cooling member is filled with a transparent liquid. The transparent liquid is mainly water, but it may be an aqueous solution mixed with salt or granulated sugar for the purpose of lowering the freezing point because of its outdoor use.

  As described above, the basic skeleton of the present embodiment is to cool the solar cell panel while allowing it to pass through the sunlight while being transparent. The cooling member according to the present embodiment forms a water tank on the surface of the solar cell panel, and by making the water depth of this water tank several centimeters or more, infrared rays are absorbed by the surface of the water tank, and the heat generation of visible light is deep in the water tank. It cools by absorbing heat through the glass surface of the surface of the solar cell panel. The configuration of the cooling member for this purpose will be described with reference to the drawings.

  Note that “transparent” only needs to be transparent enough to allow light to pass through and see beyond, and includes the concept of translucency. Even if there is some turbidity and 100% of visible light is not transmitted, it is sufficient that light passes through and reaches the solar cell to the extent that power generation by the solar cell is possible, but it is desirable that the transparency be as high as possible. Needless to say.

(Basic configuration)
FIG. 1 is a diagram illustrating the positional relationship between a solar cell panel and a cooling member. First, the support member 10 is installed, and the solar cell panel 20 is disposed thereon. The support member 10 is a member for imparting an angle to the grounding of the solar cell panel 20, and a member having an angle of θ1 with respect to the ground surface is used when viewed from the side section. The higher side (right) of the support member 10 is the north side, and the apex side (left) forming the angle θ1 is the south side. As a general configuration, θ1 = 30 degrees. However, there are cases where θ1 = 20 degrees to 40 degrees, which is slightly larger or smaller than 30 degrees according to the region.

  By arranging in the north-south manner in this way, the solar cell panel 20 is arranged so as to face the south side, not directly above. The angle θ1 is preferably 30 degrees, but may be any numerical value in the vicinity thereof. For example, the range is from 25 degrees to 35 degrees, but in order to receive more sunlight in the summer, the range may be from 15 degrees to 35 degrees. Since sunlight is irradiated not from right above but from the south side, by tilting in this way, the amount of irradiation can be increased and the power generation efficiency of the solar cell can be improved.

  The cooling member 30 is further stacked on the support member 10 on which the solar cell panels 20 are further stacked. When stacking the cooling member 30 on the solar cell panel 20, it may be possible to fix the position by some fixing member. On the other hand, when the cooling member 30 is installed, a method of spreading or coating water on the solar cell panel 20 and stacking the cooling member 30 thereon is also conceivable. Thus, without using a special fixing member, the cooling member 30 is brought into close contact with the solar cell panel 20 and the temperature of the cooling member 30 is easily transmitted to the solar cell panel 20, in other words. It becomes easy to transmit the temperature of the solar cell panel 20 to the cooling member 30.

  The cooling member 30 is provided with a liquid holding space 31 inside. The cooling member 30 is an internal space that holds the liquid in the liquid holding space 31, thereby forming a container or a water tank. The side facing the sunlight is the front side 32, and the surface in contact with the solar cell panel 20 is the back side 33. The front side 32 and the back surface 33 are part of a wall that partitions the liquid holding space 31 from the outside. A wall that partitions the cooling member 30 is formed by the front side 32 and the back side 33 and the side wall. The front side 32 and the back surface 33 both have a constant thickness between the inner wall and the outer wall, and the inner wall surface is formed in parallel to the outer wall surface. The thickness does not always have to be constant, and there may be a portion where the thickness varies locally for manufacturing convenience.

  The back surface 33 is a flat surface. Since the light receiving surface of the solar cell panel 20 is a flat surface, the back surface 33 and the light receiving surface are in contact with each other by making them flat. Of course, it does not have to be a completely flat surface, and unevenness may occur in part. In this case as well, the surface is formed as a whole. However, in order to efficiently transmit the temperature and realize the above-described water bonding, a flat surface is preferable.

  A front side 32 is disposed on the opposite side of the back surface 33. The front side 32 may be a flat surface like the back surface 33. However, unlike the back surface 33, the front side 32 is not necessarily a portion to be stacked with other members. It is also possible. First, in the basic configuration, the front side 32 will be described by taking a flat surface like the back side 33 as an example.

  The liquid holding space 31 provided inside the cooling member 30 is sandwiched between the front side 32 and the back side 33. The liquid holding space 31 is hollow at the initial stage. Thereafter, a transparent liquid (particularly water) is allowed to flow into the interior, thereby filling the interior of the liquid holding space 31 with the transparent liquid. As a result, the solar cell panel 20 is cooled, and the relationship between the temperature of the solar cell panel 20 and the power generation efficiency will be described.

FIG. 2 is a graph showing the temperature characteristics of the band gap voltage of silicon. First, the band gap voltage V _G of silicon can be approximated by the following equation using the absolute temperature T on the surface of the solar cell panel 20.
V _G = −2.67 × 10 ⁻⁴ · T +1.2 (1)
The relationship between the band gap voltage V _G and the absolute temperature is shown in the graph of FIG. At 300 K close to room temperature, the band gap voltage V _G is 1.12 eV.

The solar cell is made of a junction of a p-type semiconductor and an n-type semiconductor, and the output voltage V _OP of the solar cell is the difference between the Fermi levels of the pn junction of the battery, so that
_{V OP = (Ec-Ev)} - k · T · In (Nc · Nv / N D · N A) (2)
It becomes.

Where N _D : donor concentration, N _A : acceptor concentration, Nc: effective state density for electrons in the conductor, Nv: effective state density for holes in the valence band, Ec: conduction band, Ev: valence band is there.

Since Ec-Ev in the equation (2) corresponds to the band gap voltage V _G ,
_{V OP = V G - k ·} T · In (Nc · Nv / N D · N A) (3)
And α = k · In (Nc · Nv / N _D · N _A )
V _OP = −2.67 × 10 ⁻⁴ · T +1.2 −α · T (4)
It becomes.

V _OP is the temperature at which the semiconductor is in the intrinsic region (Fermi level is (Ec−Ev) / 2), and the output is 0 v. Therefore, from this equation (4) at 600 K,
Since α = 2.27 × 10 ⁻³ ,
V _OP = 1.2−20 × 10 ⁻⁴ · T (5)

Therefore, V _OP decreases in proportion to the temperature, and power decreases by the square thereof. That is, the power generation efficiency due to solar radiation of the solar cell decreases as the temperature increases, and conversely, if the temperature can be decreased, the power generation efficiency can be improved.

  For the reasons described above, the present embodiment improves the power generation efficiency by cooling the solar cell panel 20, but there are two aspects to cooling the solar cell panel 20. There are two major factors that cause the solar panel 20 to rise in temperature due to solar radiation. (1) Heat generation due to absorption of infrared rays longer than 0.83 μm (2) Heat generation due to Joule heat due to extra energy for power generation by light energy having a relatively short wavelength with energy greater than 1.5 ev in visible light.

  Thus, since the temperature rise on the solar panel 20 is deeply related to the wavelength of the irradiated light, this relationship will be described with reference to FIG.

  FIG. 3 is a graph illustrating the spectral sensitivity of a single crystal silicon solar cell. With reference to FIG. 3, a heat generation phenomenon and a cooling mechanism for each wavelength of light will be described. The spectrum of sunlight includes photons of various wavelengths, 380 nm to 780 nm is in the visible light range, and if it exceeds 830 nm, it becomes an infrared region.

  (1) First, the infrared region will be described. Since the basic unit cell of the solar cell panel is made of silicon, the surface color is indigo, so it absorbs infrared rays well. This causes heat generation due to infrared absorption. Among these infrared regions, there are spectral bands that are easily absorbed by water in the 0.95 μm, 1.2 μm, 1.4 μm, and 1.9 μm bands. In this wavelength range, the spectral energy is attenuated by being absorbed by moisture in the atmosphere.

  In the present embodiment, as shown in FIG. 1, the cooling member 30 is disposed before the sunlight enters the solar cell panel 20, so that the sunlight first removes the water in the cooling member 30. It passes through and reaches the solar cell panel 20. In this process, the light in the spectral band is absorbed while passing through water. By utilizing the property of being easily absorbed by water in this manner, the temperature band of the solar cell panel 20 is considerably increased by absorbing most of the spectrum band longer than 1.2 μm in the infrared region before reaching the solar cell panel 20. Can be suppressed.

  Further, sunlight enters from a small incident angle in the sunrise time zone and the sunset time zone. Since sunlight with a small incident angle passes through the atmosphere for a long time, only light with a long wavelength, such as infrared light, reaches the earth's surface so that light with a short wavelength is scattered by the atmosphere, resulting in sunrise and sunset. . That is, at this time, the light received by the solar panel 20 is only heat that generates only heat and has low power generation efficiency.

  In the present embodiment, since sunlight passes through the water in the cooling member 30 and reaches the solar cell panel 20, light having a small angle is totally reflected when entering the water. Specifically, sunlight is totally reflected with respect to the water in the cooling member 30 for an incident angle of less than 45 degrees. On the other hand, since sunlight with an incident angle of less than 45 degrees is light that generates only heat and has low power generation efficiency, such as infrared light, the temperature rises until a time period in which the angle of sunlight exceeds 45 degrees. Can hinder. In particular, it is possible to shift to photovoltaic power generation while maintaining a state in which the water temperature is lowered at night.

  Note that the sensitivity peak of the solar cell panel 20 is in the vicinity of 0.9 μm to 1.0 μm, which is slightly shorter than 1.1 μm, which is a wavelength that can exceed the silicon band gap 1.1 ev shown in FIG. 2. In the wavelength range of the optical spectrum, particularly in the case of single crystal silicon, the wavelength contributing to power generation is only 0.4 μm to 1.1 μm, and light having a wavelength longer than 1.2 μm does not contribute to power generation. By absorbing light in this wavelength region with water, it is possible to block only the heat generating element with almost no reduction in power generation efficiency. In addition, since even longer wavelengths than the infrared region do not contribute to power generation, the generation of heat can be similarly prevented for light in a wavelength band that is absorbed when passing through water.

(2) Next, the optical spectrum in the visible light region will be described. Since the relatively short spectrum of the visible light wavelength has energy exceeding the silicon band energy gap of 1.1 ev, surplus energy after power generation becomes Joule heat and causes a temperature rise. Of the energy given by light, the band energy gap of 1.1 ev is used for solar power generation, but the remaining energy is not used for power generation, and the solar cell panel 20 is heated as surplus energy. This temperature increase causes the operating voltage (V _OP ) described with reference to FIG. 2 to decrease, resulting in an extreme decrease in power generation output.

  On the other hand, as described with reference to FIG. 1, the temperature of water stored in the cooling member 30 is transmitted to the solar cell panel 20 by bringing the cooling member 30 into contact with the solar cell panel 20. Cool down.

Summary,
1) Light energy in the infrared region longer than 1.2 μm is attenuated before reaching the solar cell panel 20. Therefore, light in a wavelength region that causes a temperature rise among infrared rays does not reach the solar cell panel 20 so much, so that a temperature rise due to light in the infrared region can be suppressed.

2) With respect to light having an energy of 1.5 ev or more, particularly light in the visible light region with a shorter wavelength, the extra energy Joule heat generated by power generation is generated in the liquid (water) held in the liquid holding space 31. The surface of the solar cell panel 20 is cooled. In particular, direct cooling of the surface of the solar cell panel 20 with water having a thickness of several centimeters or more can be expected from the value of the thermal conductivity. Since the thermal conductivity of silicon is 168 W / m · k and has a thermal conductivity similar to that of metal, the speed of transmission to the glass surface of the solar panel is high. The thermal conductivity of glass is 0.8 W / m · k. Compared with 0.022 W / m · k for air and 0.59 W / m · k for water, water is about 27 times that for air. Therefore, a cooling effect can be expected. Also, due to the temperature drop at night, the panel can be effectively cooled during the next day's solar radiation by cooling the water.
From the above two aspects, the solar cell panel 20 is cooled in the present embodiment. Next, a specific configuration of the cooling member 30 will be described.

  FIG. 4 is a diagram illustrating a specific configuration of the cooling member according to the basic configuration. As described with reference to FIG. 1, the configuration of the cooling member 30 includes the front side 32 and the back side 33, thereby forming the liquid holding space 31 therein. The back surface 33 is disposed on the solar cell panel 20. Since the cooling member 30 has a three-dimensional structure, it further includes side portions 34A, 34B, 36A, and 36B as side walls.

  As shown in FIG. 4, when the front side 32 is arranged on the upper side and the rear surface 33 is arranged on the lower side, the side part 34A is on the west side (left side in the figure), the side part 34B is on the east side (right side in the figure), and the side part 36A is on the north side. The middle upper) and the side portion 36B are arranged on the south side (lower in the figure). That is, in addition to the front side 32 and the back surface 33, the liquid holding space 31 is formed inside by forming a rectangular parallelepiped by surrounding the six sides of the side portions 34A, 34B, 36A, and 36B.

  The back surface 33 has a shape that covers the light receiving surface of the solar cell panel by contact. For this reason, the back surface 33 is designed to be the same size as or slightly larger than the glass surface of the solar cell panel 20. Accordingly, the front side 32 also has a size that matches the back surface 33, and the size of the cooling member 30 is also determined according to the size of the front side 32 and the back surface 33. By setting it as such a magnitude | size, all the light which reaches | attains the solar cell panel 20 passes the member 30 for cooling and the liquid inside.

  Since sunlight is basically transmitted through the front side 32 and the back side 33, transparent resin is used only for the front side 32 and the back side 33, and for the side portions 34A, 34B, 36A, 36B, other relatively Inexpensive materials such as firewood may be used. In addition, about the side parts 34A and 34B, in order to transmit the light from east and west, you may use transparent resin. As shown in FIG. 1, the solar cell panel 20 and the cooling member 30 are structured such that the structure upper part 36B tilted to the south side is arranged at a low position, and the side part 36A is arranged on the north side. The need for transparency is relatively low. Therefore, other relatively inexpensive materials such as bags may be used only for the side portions 36A and 36B, but a transparent resin may be used for all members in contact with the liquid holding space 31.

  In FIG. 4, the cooling member 30 is shown as having a liquid holding space 31 formed by hollowing out the inside, but the front side 32, the back side 33, and the side parts 34 </ b> A, 34 </ b> B, 36 </ b> A, 36 </ b> B are joined. Can be formed. Alternatively, the front side 32, the back surface 33, and the side portions 34A and 34B can be formed by bending one material, and another material can be bonded to the side portions 36A and 36B.

  A transparent acrylic resin is used as the transparent resin. Acrylic resin (English acrylic resin) is a polymer of acrylic acid ester or methacrylic acid ester, and is a highly transparent amorphous synthetic resin. The transparent acrylic resin is referred to as methacrylic resin, polymethyl methacrylate, polymethyl methacrylate or the like. Among them, for example, a transparent solid material made of polymethyl methacrylate resin (PMMA), which is also called acrylic glass, can be used. Further, as another material of the transparent resin, for example, polycarbonate (PC) can be considered.

By configuring as described above, the cooling member 30 can be realized as having the following properties.
(1) High light transmittance (2) No deterioration even under direct sunlight (3) Able to withstand temperatures from -40 degrees to 80 degrees (4) Water resistance (5) Strength

  An injection port 40 is provided in the side portion 36A. The injection port 40 is a seal, plug, or lid provided on a part of the side portion 36A. When the injection port 40 is opened, it becomes a hole penetrating between the outside of the cooling member 30 and the liquid holding space 31. When the opening is made, a transparent liquid such as water is poured into the liquid holding space 31 from the outside. After the injection, the injection port 40 is sealed or sealed with a seal, a stopper or a lid. Since the liquid is held inside, it is sealed or sealed so that the liquid does not leak from the inside. Through this process, a transparent liquid is held in the liquid holding space 31.

In the liquid holding space 31, antifouling agents 50A, 50B, 50C, and 50D are provided. Hereinafter, the anti-fouling agent 50 will be collectively referred to. In the drawing, four antifouling agents 50 are shown as being provided, but the number is not limited, and may be one or two, and conversely, a large number may be arranged. Antifouling agent 50 contains at least hydroxyapatite (HAp), and further contains silver (Ag) and titanium oxide (TiO ₂ ). In other words, a composite powder of a ceramic material is used for the antifouling agent 50.

Hydroxyapatite (HAp) has the property of adsorbing bacteria and viruses and not releasing them. Titanium oxide (TiO ₂ ) has the property of degrading proteins such as viruses, bacteria, and odors. Silver (Ag) functions as an electrode and has the property of promoting the reaction rate. Therefore, the pollution inhibitor 50 may be a combination of hydroxyapatite (HAp) and titanium oxide (TiO ₂ ).

  The antifouling agent 50 can suppress the growth of various bacteria. Among them, soil fungi are particularly important. In the present embodiment, in order to maintain the transparency of the liquid in the liquid holding space 31, it is sufficient if only bacteria that lower the transparency can be suppressed. Among them, it is soil fungi that particularly lowers transparency, and the growth of the soil fungi is suppressed by the pollution control agent 50. As a result, the transparency of the liquid in the liquid holding space 31 is maintained.

  In particular, when tap water is used as the liquid in the liquid holding space 31, if bacteria are removed and the oxygen dissolved in the water is reduced, germs are likely to propagate. When cooling with accumulated water, if this sterilization measure is not successful, the panel surface will turn red and the transparency will drop. As a result, power generation is reduced.

As a countermeasure, when trying to take measures by putting chemicals such as “sodium chloride” in water, the following conditions must be satisfied.
(1) Transparency does not drop (2) It must be bactericidal against all germs affecting transparency (3) Environmentally friendly (4) Economically viable

  As a countermeasure for this, sodium chloride capable of maintaining transparency to some extent can be considered, but the sterilizing power is not sufficient. Further, as an example of the bacterium, a bacterium called “highly halophilic bacterium” is likely to be generated as a soil bacterium. When this fungus propagates, the surface turns red. By using the above-described antifouling agent 50, it is possible to suppress the growth of soil bacteria.

  Although the specific material was shown about the pollution control agent 50, more specifically, "NIPON" of Try Company Co., Ltd. using the earth plus (registered trademark) technology can be used. Since this product is used for sterilization of drinking water, it is also conceivable to prevent liquid contamination by using the same material used for sterilization of drinking water as the antifouling agent 50.

  With this single capsule, about 5 liters of water can be sterilized and stored in the cooling member 30. Since the water used for the cooling member 30 is several tens of liters per panel, an appropriate number is used in consideration of the place where it can be installed. Since the cooling member 30 is disposed at an inclination, the temperature of the liquid surface due to solar radiation causes the water to warm up and rise upward, causing convection to rise in the cooling member 30. The warmed water is sterilized by the capsule attached on top, and the chilled water goes down, so the low-temperature water is sterilized on the lower side. In this way, a large amount of water can be sterilized with a small number of capsules. Further, the efficiency is further increased by making the upper and lower mounting positions zigzag. In addition, an arrangement that allows efficient circulation may be employed as appropriate.

  As described above, the contamination prevention agent 50 is disposed in the liquid holding space 31 in this embodiment to prevent the contamination. However, it is important that the cooling member 30 is sealed here. If it is not sealed, for example, when rainwater is used in an open state, bacteria enter from the outside without restriction, so there is a limit even if it is suppressed by the antifouling agent 50, and it is considered that the adsorption state will eventually be saturated. . However, in this embodiment, since the cooling member 30 is hermetically sealed, it is conceivable that bacteria may enter in the initial stage, but the contamination is suppressed while the liquid circulates internally. Once the bacteria have been adsorbed, no further bacteria will flow in from the outside, so the bacteria will not increase and the liquid will remain transparent.

(Configuration on implementation)
Heretofore, the basic configuration of the cooling member 30 according to the present embodiment has been described. Since the cooling member 30 itself according to the basic configuration has been described as having no inclination, as shown in FIG. 1, when the solar cell panel 20 is inclined by the support member 10, the cooling member 30 is provided. The front side 32 and the back side 33 are inclined parallel to the solar cell panel 20. On the other hand, in the configuration on mounting described here, the gradient in the north-south direction is changed.

  FIG. 5 is a diagram illustrating a configuration when the gradient in the north-south direction is changed. Each part of the cooling member 30 shown in FIG. 5 is the same as that shown in FIG. That is, in addition to the front side 32 and the back surface 33, the liquid holding space 31 is formed inside by forming a rectangular parallelepiped by surrounding the six sides of the side portions 34A, 34B, 36A, and 36B. An injection port 40 is provided in the side portion 36A. A transparent liquid such as water is injected into the liquid holding space 31 from the outside through the injection port 40. In the liquid holding space 31, antifouling agents 50A, 50B, 50C, and 50D are provided.

  On the other hand, unlike FIG. 4, in FIG. 5, the side part 36A is made low, and conversely, the side part 36B is made high. As a result, the side portions 34A and 34B are trapezoidal in which the side portion 36A side is short and the side portion 36B side is high. When the back surface 33 is placed on a flat surface, the front side 32 becomes a surface that forms an inclination that descends from the side portion 36B toward the side portion 36A. That is, the thickness between the cooling member 30 and the back surface 33 of the liquid holding space 31 and the front side 32 increases as the side portion 36A moves from the end on the side where the side portion 36A is located to the other end side where the side portion 36B is located. .

  The solar cell panel 20 is tilted by the support member 10 so that the tilt angle θ1 is 30 degrees. The altitude (elevation angle) of the sun changes from morning to evening even during the day, but the altitude changes depending on the season even in the highest time zone around noon. At the time of the summer solstice, the sun is directly above and becomes an elevation angle of 0 degrees (90 degrees with respect to the ground surface), and at the time of the winter solstice, the sun is at the lowest position and the elevation angle is 60 degrees (with respect to the ground surface). 30 degrees in angle). In the middle of the spring equinox and autumn equinox, the elevation angle is 30 degrees (60 degrees with respect to the ground surface). Therefore, the support member is generally configured so that sunlight at this time is incident at a right angle. 10 is arranged such that the inclination angle θ1 is 30 degrees.

  In the cooling member 30 of the present embodiment, an inclination of θ2 = 15 degrees is further provided. Thus, when the side portion 36A is disposed on the south side and the side portion 36B is disposed on the north side, the inclination angle provided with respect to the front side 32 is θ1 + θ2 = 45 degrees. This inclination angle is an angle at which sunlight of the day just between spring equinox or autumn equine and winter solstice is incident from directly above the front side 32. Therefore, it corresponds to the average incident angle of the sun from autumn to winter solstice to spring equinox.

  Of course, in this case, since appropriate sunlight cannot be incident in the summer, the positions of the side part 36A and the side part 36B are interchanged between north and south. That is, the side part 36A is arranged on the north side, and the side part 36B is arranged on the south side. By arranging in this way, θ1−θ2 = 15 degrees. This inclination angle is an angle at which sunlight on the day just between spring or autumn and the summer solstice is incident from directly above the front side 32. Therefore, it corresponds to the average incident angle of sunlight between spring equinox, summer solstice and autumn equinox.

  As described above, by providing the cooling member 30 with the inclination angle θ2 in addition to the basic configuration shown in FIG. 4, the inclination angle θ1 is merely corresponding to the average sun angle for one year. On the other hand, the incident angle of the sun can be made to correspond to summer and winter only by changing the positional relationship of the cooling member 30 in summer and winter.

  Of course, the angle of the solar panel 20 does not change, but it is possible to prevent variation in the passing distance in the cooling member 30. Further, since the liquid holding space 31 is filled with the liquid, it is refracted when sunlight enters the cooling member 30 and can enter the solar panel 20 at an appropriate angle. By providing the inclination angle θ2 as shown in FIG. 5, the angle of the incident surface can be adjusted appropriately.

  As described above, by setting the inclination angle given by the cooling member 30 to θ1 + θ2, the liquid in the liquid holding space 31 has many wavelengths with wavelengths particularly longer than 1.2 μm that cause a temperature rise in particular in the infrared rays of sunlight. Absorb. Then, the water depth is adjusted so that infrared rays shorter than 1.1 μm reach the panel surface to some extent. As a result, the temperature rise on the surface of the solar cell panel 20 can be reduced, and excess energy Joule heat generated by power generation by light in a shorter visible light region can be cooled by the liquid.

(Other configuration on implementation)
As above, the cooling member 30 according to the present embodiment has been described with respect to the configuration in which the inclination in the north-south direction is changed with reference to FIG. On the other hand, here, a configuration for optimizing the incidence of sunlight in the east-west direction will be described with reference to FIG. FIG. 6 shows that the slope in the north-south direction is not provided for easy illustration based on the configuration in FIG. 4, but a configuration in which the slope is provided in the north-south direction may be combined with the configuration in FIG. 5. Rather, in addition to the configuration of FIG. 6, it is desirable to add an inclination in the north-south direction as shown in FIG. 5 in terms of optimizing the incidence of sunlight in both directions.

  FIG. 6 is a diagram illustrating a configuration when the incidence of sunlight is optimized in the east-west direction. As a difference from FIGS. 4 and 5, a raised portion 51 and a raised portion 52 are provided so as to face each other outside the front side 32. In FIG. 6, the cooling member 30 is arranged so that the front is south and the north is facing the back, so that the raised portion 51 is arranged on the east side and the raised portion 52 is arranged on the west side.

  Further, by providing the bulging portion 51 and the bulging portion 52 at both ends in the east-west direction so as to extend from north to south, the central portion, that is, the portion extending from north to south at the inside becomes a shape recessed downward toward the liquid holding space 31. That is, the belt-like region 53 is formed in a belt-like shape at a position recessed inside the ridge 51 and the bulge 52 in the east-west direction, which is the central portion of the front side 32 in the east-west direction. And the inclined surface 54 is formed with respect to the center strip | belt-shaped area | region 53, the protruding part 51, and the protruding part 52, respectively.

  The raised portion 51 and the raised portion 52 are thicker than the belt-like region 53 in the thickness up to the back surface 33. This thickness gradually decreases along the inclined surface 54 as it goes to the center, and becomes the thinnest in the band-like region 53. The belt-like region 53 is formed in parallel with the back surface 33 as a plane. Accordingly, the thickness of the back surface 33 is uniform over the entire belt-like region 53, but may be an appropriate thickness according to the convenience of design.

  Further, when combined with the configuration of FIG. 5, the thickness between the cooling member 30 and the back surface 33 of the liquid holding space 31 and the front side 32 extends from the end on the side where the side portion 36 </ b> A is present along the longitudinal direction of the band-shaped region 53. The side portion 36B becomes larger as it goes to the other end side.

  And the side part 61 is provided in the both ends of the north-south direction of the protruding part 51, the protruding part 52, and the strip | belt-shaped area | region 53. As shown in FIG. The side portion 61 corresponds to the side portions 36A and 36B in FIGS. In addition, injection ports 60 </ b> A and 60 </ b> B are provided in the upper portion of the side portion 61. Although omitted in FIG. 6, the side portions 61 are also provided on the north side corresponding to the side portion 36 </ b> B. A transparent liquid (water) is injected from the inlets 60A and 60B and sealed. This is the same configuration as the injection port 40 according to the basic configuration described with reference to FIG.

  As shown in the side portion 61, the angle formed by the belt-like region 53 and the inclined surface 54 is θ3. The inclined surface 54 is the same for both the raised portion 51 and the raised portion 52. However, different inclination angles may be provided for the inclined surfaces 54 of the raised portion 51 and the raised portion 52. Since the necessity to block sunlight from the west side is smaller than the necessity to block sunlight from the east side, for example, the inclination angle of the raised portion 52 may be reduced.

  The inclination angle θ3 is limited to 45 degrees, which is the maximum angle at which sunlight is directly incident on the belt-like region 53. If the angle exceeds 45 degrees, light having high power generation efficiency must pass through the raised portions 51 and the raised portions 52, and the power generation efficiency is lowered as a whole. The lower limit is assumed to be 15 degrees. This is because if it is too small, there is no point in providing the raised portion 51 and the raised portion 52.

  Actually, it is desirable to make the inclination angle θ3 smaller than 45 degrees, and about 40 degrees is a practical maximum value. As the inclination angle θ3 is increased, the sunlight blocking effect becomes higher. Therefore, considering the balance with the incident angle of the light to be blocked, the inclination angle θ3 is set within a range of 20 degrees to 30 degrees. It is preferable.

  Next, the relationship between the incident angle of sunlight in the east-west direction and the raised portions 51 and the raised portions 52 will be described. In the sunrise time zone and sunset time zone, sunlight enters from a small incident angle. At this time, the light received by the solar panel 20 only generates heat and has only low power generation efficiency.

  Light having a low angle reaches the raised portion 51 and the raised portion 52 before the band-like region 53. The light having a low angle reaches the solar panel 20 through the liquid held in the liquid holding space 31 via the raised portion 51 and the raised portion 52. Therefore, since sunlight passes a long distance in the liquid holding space 31, infrared light is mainly absorbed by the liquid (water) held in the liquid holding space 31 and hardly reaches the solar panel 20.

  As described above, the critical condition for sunlight to pass through the raised portion 51 and the raised portion 52 is that the incident angle of sunlight exceeds the inclination angle θ <b> 3 of the inclined surface 54. When the angle is sufficiently large, the light incident on the belt-like region 53 does not pass through the ridge 51 and the ridge 52, and the light reaching the ridge 51 and the ridge 52 is also raised by the increase in the incident angle. The distance across the part 51 and the raised part 52 is shortened. Further, considering that mainly the infrared light is absorbed by the liquid, the amount of sunlight blocked by the raised portions 51 and the raised portions 52 is limited. As a result, the calorific value can be suppressed without reducing the power generation efficiency.

  Further, as shown in FIG. 6, a cavity 62 may be provided at a position where the liquid holding space 31 is located. The cavity 62 penetrates from the surface of the side part 61 on the south side to the surface of the side part 61 on the north side. In other words, the liquid holding space 31 is divided by the cavity 62, and the upper part of the cavity 62 becomes the first space and the lower part becomes the second space. The first space and the second space are connected at the east and west ends. The first space including the front side 32 and the second space including the back surface 33 are divided, and a cavity 62 that is a gap into which liquid is not injected is provided between the first space and the second space.

  In the configuration example according to FIG. 6, as a result of providing the bulging portion 51 and the bulging portion 52, the liquid holding space 31 and the area occupied by the liquid as a whole become too large, and sunlight has to pass through the liquid more than necessary. In order to subtract the area of the liquid that needs to pass through as a whole, a cavity 62 is provided. As a result, the light shielding panel 20 can be appropriately reached with respect to light having a large angle while exhibiting the above-described blocking effect on light having a small angle.

  The present invention is not limited to the embodiment described above. That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.

DESCRIPTION OF SYMBOLS 10 ... Support member, 20 ... Solar cell panel, 30 ... Cooling member, 31 ... Liquid holding space, 32 ... Front side, 33 ... Back surface, 34A, 34B, 36A, 36B ... Side part, 40 ... Inlet, 50 ... Pollution Inhibitor, 51 ... raised portion, 52 ... raised portion, 53 ... band-like region, 54 ... inclined surface

Claims (7)

A main body configured to have a liquid holding space capable of injecting liquid therein and capable of sealing the liquid holding space;
Provided with an antifouling agent containing at least hydroxyapatite inside the main body,
The main body has a back surface shaped to cover the light receiving surface of the solar cell panel by contact and a front side facing the sunlight side, the liquid holding space is sandwiched between the back surface and the front side, and the back surface and the front side Made of transparent resin,
A member for cooling solar cell panels.   The cooling member according to claim 1, wherein the antifouling agent contains silver and titanium oxide in addition to the hydroxyapatite. The front side of the main body is
Ridges provided to face each other on the outside,
A band-shaped region formed in a band shape at a recessed position inside the raised portion;
The cooling member according to claim 1, comprising:   The belt-like region is continuously inclined from the belt-like region to the outside of the belt-like region, and the angle of the slope is in the range of 45 to 15 degrees with respect to the back surface or the surface formed by the belt-like region. The cooling member according to claim 3, wherein the cooling member is inside.   3. The cooling member according to claim 1, wherein a thickness between the back surface and the front side of the main body portion increases from a predetermined end side toward the other end side.   The thickness between the said back surface of the said main-body part and the said front side becomes large as it goes to the other end side from the predetermined end side along the longitudinal direction of the said strip | belt-shaped area | region. The cooling member as described. The liquid holding space is divided into a first space including the front side and a second space including the back surface, and a gap in which the liquid is not injected is provided between the first space and the second space.
The cooling member according to claim 3, 4 or 6.