Solar energy collecting system

Abstract

To provide a solar energy collecting system composed of a reduced number of components, simplified in structure, and manufactured at a low cost.SOLUTION: A solar energy collecting system has a supporting frame 14 tiltably supporting a tilt part 20 in which a solar panel 12 is established and inclination angle change means 50. The inclination angle change means 50 has a main water tank 52, a ball tap supplying / stopping water to the main water tank 52, a cutoff valve cutting off or discharging water in the main water tank 52, a heat collection part made of heat insulation property / heat retaining property material, and an elastic member made of shape memory alloy. One end of the elastic member is connected to the cutoff valve within the main water tank 52, and while elastic force of the elastic member does not work in normal temperature, the elastic force work when the elastic member becomes equal to or higher than a predetermined temperature by sunlight shining in the heat collection part, so that the cutoff valve is opened, water is discharged from the main water tank 52, water is led into sub water tanks 62A and 62B, and the inclination angle of the tilt part 20 is changed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a solar energy collection system using solar panels (solar cells), and to a solar energy collection system equipped with a support frame that can automatically tilt the tilt angle of the solar panels (tilt angle relative to solar radiation) according to the angle of solar radiation. It also relates to a solar energy collection system equipped with a cooling mechanism for the solar panels. [Background technology]

[0002] Generally, solar power generation equipment and solar collectors are installed in a fixed position on roofs or on the ground, but the angle of inclination of the solar panels of the power generation equipment relative to the sun is set according to the local characteristics, such as the local climate and whether or not there is snowfall. For example, there are several ways to set the angle, such as determining the minimum or maximum annual power generation amount as a standard. For example, in Hokkaido, which is located near 45 degrees north latitude, the angle is set to a steeper angle of around 35 degrees to take into account the influence of snowfall, while in Okinawa, which is located near 27 degrees north latitude, the angle is set to around 18 degrees due to the high solar altitude. The angle also varies depending on the region. Furthermore, because the sun moves from east to west while changing altitude, the angle of sunlight varies depending on the time of day and season, and it is therefore preferable to adjust the tilt angle of the solar panel so that sunlight shines at a right angle on the panel surface, if possible, in order to improve power generation efficiency.

[0003] A known invention for responding to changes in the angle of solar radiation is disclosed in Japanese Patent Laid-Open Publication No. 2007-324387 (Patent Document 1), which relates to an automatic solar tracking device. The invention described in this publication uses a thermal deformation member (e.g., a spring made of a shape memory alloy) that expands and contracts due to solar heat, a reciprocating shaft connected to the thermal deformation member, a latch, gears, etc., as components, and changes the angle of elevation of the concentrating mirror by utilizing the contraction force of the thermal deformation member heated by sunlight. This is said to change the angle of elevation of the concentrating mirror to an optimal angle relative to sunlight without consuming power, thereby contributing to improved heat collection efficiency.

[0004] Furthermore, Japanese Patent Publication No. 6468575 (Patent Document 2) discloses an invention related to a power generation system including a mounting base for supporting solar panels. This invention includes a mounting base that is tiltably supported on a single support column and includes a first group of cables consisting of a first deployment cable and a winding cable, and a second group of cables consisting of two second deployment cables and one anchoring cable. These first and second groups of cables are made of wires or chains, and by winding up or unwinding these groups of cables, the mounting base can be tilted up or down relative to the support column, adjusting the angle of the solar panels to an appropriate angle relative to solar radiation. This invention allows a single worker to change the angle, and by concentrating the weight of the first and second groups of cables close to the bottom of the support column, it is said that this prevents the mounting base from shaking and suppresses vibrations caused by wind.

[0005] On the other hand, the amount of power generated by solar panels also depends on the temperature of the panel. It is known that a 1°C increase in panel surface temperature reduces power generation efficiency by approximately 0.4 percent. If the temperature of the panel surface reaches 70°C in the summer, for example, this will result in a drop in power generation of approximately 20%. For this reason, an invention is available, described in JP 2022-172631 A (Patent Document 3), which incorporates a mechanism for cooling the panel.

[0006] As described in paragraphs "0040" to "0044" of Patent Document 3, an outdoor unit of an air conditioner and a deflector are installed in the area below a mount that supports a solar panel, and the deflector installed on the housing of the outdoor unit blows the exhaust air from the outdoor unit outward from the space surrounded by the support columns of the solar panel mount. The blown-out air then attracts the air around the area below the solar panel, causing the air on the backside of the solar panel to flow, which is said to cool the solar panel. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-324387 [Patent Document 2] Patent No. 6468575 [Patent Document 3] Japanese Patent Publication No. 2022-172631 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0008] However, the solar automatic tracking device described in the aforementioned Patent Document 1 uses worm gears, shape memory alloy springs, latches, etc. as its drive mechanism, which leads to a complex structure, an increased number of parts, and the need for time-consuming maintenance and management. Furthermore, in the power generation system described in Patent Document 2, a mount including solar panels is supported by a single support, and the tilt angle is set by winding up the solar panels and mount with a group of cables such as wires. For this reason, there are issues that it is considered difficult to install a large number of solar panels in windy areas, and that the angle of the mount supporting the solar panels needs to be changed as needed depending on the season, etc., requiring manpower for maintenance. Furthermore, the solar panel mounting frame described in Patent Document 3 has limitations in that it can only be installed in limited locations, such as on the rooftop of a building where air conditioning equipment is present.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a solar energy collection system that can reduce the amount of manual maintenance required and does not require power that requires electricity, such as a motor. Another object of the present invention is to provide a solar energy collection system that can reduce the number of parts and has a simplified structure. [Means for solving the problem]

[0010] The invention of claim 1 is a solar energy collection system having a tilting section (20) on which a solar panel (12) is installed, a support stand (14) that supports the tilting section (20) so that the tilting section (20) can be tilted by a fulcrum, and a tilt angle changing means (50) that changes the tilt angle by tilting the tilting section (20) within a certain range in accordance with changes in the angle of solar radiation, wherein the tilt angle changing means (50) has a main water tank (52), a ball tap (54) that starts and stops the supply of water to the main water tank (52), a water stop valve (56) that stops or discharges water in the main water tank (52), a heat collecting section (58) made of a heat insulating and heat retaining material, and an elastic member (60) made of a shape memory alloy housed in the heat collecting section (58), and one of the elastic members (60) The end of the elastic member (60) is connected to the stop valve (56) in the main water tank (52) directly or via a cable (68), and the other end is fixed in the heat collecting section (58). At room temperature, the elastic member (60) does not exert any elastic force, but when sunlight shines into the heat collecting section (58) and the elastic member (60) reaches a predetermined temperature or higher, the elastic force is exerted to open the stop valve (56) in the main water tank (52), causing water to be discharged from the main water tank (52) and introduced into the sub-water tanks (62A, 62B) attached to the tilting section (20). The weight of the water in the sub-water tanks (62A, 62B) changes the center of gravity of the tilting section (20), thereby changing the tilt angle of the tilting section (20).

[0011] The invention described in claim 2 is characterized in that, in the above-mentioned claim 1, a vaporization promotion sheet (13) that promotes evaporation of water is attached to the back surface of the solar panel (12), and water is guided from a sub-water tank (62A, 62B) attached to the tilting portion (20) onto the vaporization promotion sheet (13), thereby cooling the solar panel (12) from the back surface.

[0012] The invention of claim 3 is characterized in that, in the above-mentioned claim 1 or 2, a tubular member (70) is arranged inside the heat collection section (58), a cord (68) connected to one end of the elastic member (60) is arranged inside the tubular member (70), and the other end of the elastic member (60) is attached to an upper position inside the heat collection section (58) so as to be suspended by a mesh member (74).

[0013] The invention of claim 4 is characterized in that, in any one of claims 1 to 3, water is supplied into the main water tank (52) by a ball tap (54) provided on the upper inside of the tank, and a water supply pipe (54B) for supplying water into the main water tank (52) is connected to the ball tap (54), and a water guide pipe (54C) for supplying water to the heat collection section (58) is connected to the ball tap (54).

[0014] The invention described in claim 5 is characterized in that, in any one of the above claims 1 to 4, the heat collecting part (58) has a double structure consisting of an outer tube (58A) and an inner tube (58B), and a ring-shaped part formed between the outer tube (58A) and the inner tube (58B) serves as a heat insulating layer, thereby improving the responsiveness of the elastic member (60) made of shape memory alloy installed inside the inner tube (58B) to a temperature rise due to solar radiation.

[0015] The invention of claim 6 is characterized in that, in any one of claims 1 to 4, the heat collecting section (80) is formed by a cylindrical member (82) in which a plurality of convex lenses (84A, 84B, 84C) corresponding to the solar radiation angle of sunlight are arranged, and the focal positions of the plurality of convex lenses (84A, 84B, 84C) coincide with an elastic member (86) made of a shape memory alloy that is installed inside the cylindrical member (82), and the inclination angles of the plurality of convex lenses are different from each other.

[0016] According to the present invention, it is possible to set the light-collecting section at an orientation and tilt angle that provides high light-collecting efficiency with respect to sunlight, thereby enabling effective use of solar energy. Furthermore, the number of components can be reduced, and no power is required to collect sunlight, contributing to the effective use of energy resources. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an overall perspective view showing a first embodiment of a solar energy collection system according to the present invention; [Figure 2] FIG. 2 is a perspective view of the solar energy collecting system of the first embodiment as viewed from the rear side. [Figure 3] FIG. 2 is a side view of the solar energy collection system according to the first embodiment. [Figure 4] FIG. 10 is a general perspective view showing the solar energy collecting system of the first embodiment when the tilting portion on the support frame is tilted. [Figure 5] FIG. 10 is a perspective view of the solar energy collecting system of the first embodiment when the tilting portion is tilted, as viewed from the rear side. [Figure 6] FIG. 6 is a side view of the solar energy collecting system of the first embodiment, as viewed from the side in the state shown in FIGS. 4 and 5. [Figure 7] FIG. 10 is a partially cutaway schematic perspective view of the internal structure of a main water tank, which is a main part of the tilt angle changing means in the solar energy collecting system of the first embodiment. [Figure 8] FIG. 10 is a schematic side view of the internal structure of the main water tank, which is a main part of the tilt angle changing means in the solar energy collecting system of the first embodiment. [Figure 9] FIG. 10 is an explanatory diagram showing the structure of a heat collecting section which is a main part of a second embodiment of a solar energy collecting system according to the present invention. [Figure 10] FIG. 10 is an explanatory view showing the operation of the heat collecting portion, which is a main part of the second embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a solar energy collection system according to the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 is an overall oblique view of the solar energy collection system of the first embodiment, Figure 2 is an oblique view of the solar energy collection system of the first embodiment viewed from the back side, Figure 3 is a side view of the solar energy collection system of the first embodiment, Figure 4 is an overall oblique view showing the solar energy collection system of the first embodiment when the support frame is tilted, Figure 5 is an oblique view of the solar energy collection system of the first embodiment when the support frame is tilted viewed from the back side, and Figure 6 is a side view of the state of Figures 4 and 5 viewed from the side.

[0019] 1 to 3, the solar energy collection system 10 of the first embodiment is configured to include a support frame 14 on which solar panels 12 are installed, a fixed frame 15 on which the solar panels 12 are also installed, and an inclination angle changing means 50 for changing the inclination angle of the frame. In this example, a total of nine solar panels 12 are installed, but the two lower solar panels 12, 12 are fixed to the roof surface 17 of the building by the fixed frame 15, with their inclination angles kept constant. On the other hand, the six solar panels 12 installed above are tiltable within a certain range by tilt angle changing means 50, which will be described later, and are capable of tracking the angle of sunlight irradiation.

[0020] 2 and 3, the support frame 14 and the fixed frame 15 in the first embodiment are formed using, for example, square pipes, and the support frame 14 includes a fixed part 16 to be installed on the roof surface, rising parts 18A and 18B, a tilting part 20, etc. Of these, the fixed part 16 is installed on the roof surface, and the rising parts 18A and 18B are attached to stand upward from the fixed part 16. At the upper end of the rising portion 18, a tilting shaft portion 22 is attached which supports the tilting portion 20 relative to the support base 14 so that it can tilt. The tilting portion 20 of the support base 14 can tilt within a certain range like a seesaw, with these tilting shaft portions 22 as fulcrums.

[0021] 4 to 6 are diagrams showing tilting section 20 in a tilted state, and as shown in these figures, tilting section 20 can be moved by angle change means 50 from a deep angle (first tilt angle) to a shallow angle (second tilt angle) with respect to the horizontal direction. In other words, when the sun's altitude rises during the day, the light-receiving surface of solar panel 12 can be tilted to a position close to perpendicular to the direction of sunlight irradiation, thereby improving the power generation efficiency of solar panel 12.

[0022] 3 and 6, buffer members 24A, 24A... are attached to the upper end of the rising portion 18B, and buffer members 24B, 24B... are also attached to the lower part of the fixed portion 16. When the tilting portion 20 tilts in the direction of arrow X from the state shown in FIG. 3 and stops at a shallower tilt angle as shown in FIG. 6, the buffer members 24A, 24A... come into contact with and support the lower surface of the upper end of the tilting portion 20, thereby absorbing impact.

[0023] On the other hand, the buffer members 24B are in contact with the lower end of the tilting part 20 when the tilting part 20 is at the first angle θ1, which is the normal tilt position. In other words, the buffer members 24A and 24B have the function of absorbing the shock when the tilting part 20 tilts from the first angle θ1 and stops at the second angle, or when the tilting part 20 moves in the opposite direction, thereby protecting the solar panel 12. In the first embodiment, the buffer members 24A, 24B are made of an elastic rubber material. Of course, other materials can be used as long as they can absorb impacts. For example, a damper that generates rotational resistance in the tilting shaft 22 can be used to gradually tilt the shaft, or a hydraulic damper can be used instead of the rubber buffer members 24A, 24B. The tilting range of the tilting portion 20 can also be adjusted by changing the position and height of the buffer member 24A.

[0024] Next, the configuration of the tilt angle changing means 50 for changing the tilt angle of the tilting portion 20 of the support base 14 will be described. 7 is a schematic perspective view, partly cut away, showing the structure of the main water tank 52, which is a main part of the tilt angle changing means 50. FIG. As shown in Figures 7 and 8, the inclination angle change means 50 comprises a main water tank 52, a ball tap 54 for supplying or stopping water to the main water tank 52, a water stop valve 56 made of rubber or the like for stopping or discharging the water in the main water tank 52, a heat collection section 58 made of insulating and heat-retaining material, and a helical spring (elastic member) 60 made of a shape memory alloy housed in the heat collection section 58.

[0025] As shown in Figure 3, the main water tank 52 is mounted on a stand on the roof surface 17 of the building. A branch 62, which communicates with the water stop valve 56, is provided at the bottom of the main water tank 52, and water supply pipes 64A and 64B are connected to this branch 62. Of these, water supply pipe 64A is connected to a sub-water tank 62A installed on the upper side of the tilting section 20, and water supply pipe 64B is connected to a sub-water tank 62B installed on the lower side of the tilting section 20, so that water can be supplied from the main water tank 52 to each water tank 62A and 62B. The water supply pipes 64A and 64B are preferably made of a flexible material, that is, a product that can follow the changes in angle of the tilting section 20. For example, a cloth hose is conceivable.

[0026] As shown in Figure 7, a ball tap 54 is disposed within the main water tank 52. This ball tap 54 includes a float 54A, a main water tank water supply pipe 54B, and a heat collection section water conveying pipe 54C. The float 54A moves up and down depending on the water level within the main water tank 52, and the ball tap 54 adjusts the amount of water supplied to the main water tank 52. In other words, when the main water tank 52 is filled with water at a certain level, the float 54A is positioned at the top and stops the supply of water from the water supply pipe (not shown) installed at the top of the main water tank 52, the main water tank water supply pipe 54B, and the heat collection section water conveying pipe 54C. The float 54A is made of a floating ball made of resin, copper, stainless steel, or the like, and the water stop valve 56 is made of rubber.

[0027] As shown in Figures 7 and 8, the heat collection section 58 is installed on one side of the main water tank 52 so as to be exposed to sunlight, such as on the south side, and this heat collection section 58 has an outer tube 58A and an inner tube 58B made of a transparent material such as glass or acrylic glass. The ring-shaped portion surrounded by outer cylinder 58A and inner cylinder 58B is a heat insulating layer made of vacuum or inert gas, and the main body of heat collecting portion 58 is a Dewar vessel to minimize the heat released from heat collecting portion 58. In the first embodiment, heat collecting portion 58 is a Dewar vessel with a double structure having inner cylinder 58A and outer cylinder 58B, but it is also possible to use a single structure with thermal insulation.

[0028] Furthermore, a heat absorption layer capable of selectively absorbing infrared rays from sunlight is formed on the inner surface of the inner tube 58B, improving the thermal response of the elastic member made of shape memory alloy to the temperature rise when sunlight is incident on the heat collection section 58. In addition, the heat collection section 58 includes a helical spring 60, a cable 68, a tubular member 70, a spherical member 72, a mesh member 74, etc., which are elastic members made of shape memory alloy, and the helical spring (elastic member) 60 is positioned at an upper position of the heat collection section 58, and one end (lower end) of the helical spring 60 is connected to the upper end of the cable 68.

[0029] Meanwhile, the cable 68 is housed in a tubular member 70 within the heat collecting section 58, and its lower end is routed in a substantially horizontal direction below the heat collecting section 58 and connected to the water stop valve 56, thereby enabling the water stop valve 56 to be opened and closed by the tension generated by the helical spring (elastic member) 60 and the cable 68. The tubular member 70 may be an outer cable or the like that can house a linear wire (cable).

[0030] One end (lower end) 60A of the helical spring (elastic member) 60 is located above the tubular member 70 within the heat collection section 58 and is exposed and not covered by the tubular member 70, while the other end (upper end) 60B of the helical spring 60 is suspended by the mesh section 74 and installed within the heat collection section 58. The helical spring 60 is in an extended state at room temperature and does not exert any elastic force. However, when sunlight shines into the heat collection section 58, the interior of the heat collection section 58 becomes hot, and the temperature of the helical spring 60 rises accordingly. This causes the shape memory alloy to cause the helical spring 60 to contract into a coil, and this elastic force acts on the cable 68. Because the helical spring 60 is connected to the cable 68, tension acts via the cable 68 in the X direction, which opens the water stop valve 56. This allows the water stored in the main water tank 52 to be guided to the branching portion 62, and then the water is sent from the water guide pipes 64A and 64B to the sub-water tanks 62A and 62B.

[0031] A cooling water absorbing film 13 made of a water-absorbing nonwoven fabric or the like, which acts as an evaporation promotion sheet, is attached to the back of the solar panel 12 installed on the tilting section 20. Water from the sub-water tanks 62A, 62B is gradually introduced to moisten the cooling water absorbing film 13, and the heat of vaporization generated by the evaporation of that water cools the solar panel 12 from the back side. This makes it possible to suppress the temperature rise of the solar panel 12 even when the temperature rises during the day and the solar panel is exposed to direct sunlight on a sunny day, preventing a decrease in power generation efficiency.

[0032] In addition, a water inlet 59 is formed at the upper end of the heat collection section 58, and below the water inlet 59, a spherical member 72 that expands or contracts due to heat is positioned so as to be sandwiched between the spherical member 72 and the lower mesh section 74, and this spherical member 72 makes it possible to close or open the inside of the heat collection section 58. Alternatively, a water-absorbent resin having water absorption properties can be used for the spherical members 72. In other words, a material that has the property of absorbing water and expanding, and also shrinking and reducing in volume when dried, such as a sphere formed from a composite of polymer materials, can be used.

[0033] For this reason, when spherical member 72 expands, it blocks water inlet port 59, and on the other hand, when water is not supplied from water inlet port 59, spherical member 72 dries out and contracts, reducing its volume. For this reason, water supplied from heat collection unit water-conducting pipe 54C described above is guided through water inlet port 59 and mesh portion 74 into heat collection unit 58, and this water introduced into heat collection unit 58 has the function of directly cooling helical spring 60 and returning it to room temperature. In the first embodiment, a spherical member 72 is used as the member that performs the blocking operation, but the shape is not necessarily limited to a polymeric material or a spherical shape, and the material and shape are not important as long as it is a material that absorbs or releases moisture or whose volume changes with temperature changes.

[0034] The operation and function of the solar energy collecting system of the first embodiment configured as above are as follows. During times when the sun's altitude is low, such as from sunrise to early morning, tilting section 20 receives sunlight at a tilt angle θ1 relative to the horizontal, as shown in Figures 1 to 3. Also, as shown in Figure 8, main water tank 52 is normally filled with water up to water level W, which is adjusted by ball tap 54.

[0035] As the solar altitude gradually increases and the ambient temperature rises, sunlight passes through the outer tube 58A and inner tube 58B shown in Figures 7 and 8 and enters the light collecting unit 58, warming the inside of the heat collecting unit 58 and causing the temperature of the helical spring (elastic member) 60 made of a shape memory alloy located inside it to rise. In this case, the helical spring 60 acts as a shape memory alloy, causing its overall length to shrink, i.e., its shape to become more densely coiled. This change in the helical spring 60 generates tension in the cord 68, and the tension of the helical spring 60 is then transmitted via the cord 68 to open the water stop valve 56. That is, when sunlight enters the inside of the heat collecting unit 58, the temperature rises due to its insulating properties, and the helical spring 60 made of a shape memory alloy arranged inside returns to its original coil shape, generating an elastic biasing force in the contracting direction, i.e., upward in Figure 8. As a result, the cable 68 is pulled in the Y direction, opening the water stop valve 56.

[0036] When the water stop valve 56 is opened, the water stored in the main water tank 52 passes through the branching section 62 and is sent from the water supply pipes 64A, 64B to the sub-water tanks 62A, 62B. When the sub-water tanks 62A, 62B are filled with water to a certain extent, the center of gravity of the tilting section 20 on which the solar panel 12 is installed becomes higher. As a result, the tilting section 20 rotates around the tilting shaft 22 as a fulcrum from the state shown in FIG. 3 to the state shown in FIG. 6, rotating from the first tilting angle θ1 to a position nearly parallel to the roof surface (second tilting angle), becoming shallower. This allows the solar panel 12 installed on the support frame 14 by the tilting section 20 to receive sunlight at an angle nearly perpendicular to the sunlight.

[0037] The water in the sub-water tanks 62A, 62B is gradually introduced to the cooling water absorbing film 13 attached to the back surface of the solar panel 12 by a permeable member or hose (not shown), moistening the cooling water absorbing film 13, and the heat of vaporization generated by the evaporation of the water cools the solar panel 12 from the back surface side. Therefore, even if the air temperature rises during the day, the temperature rise of the solar panel 12 is suppressed, and a decrease in power generation efficiency due to a temperature rise on the panel surface can be prevented.

[0038] Subsequently, when the water in main water tank 52 is completely drained and empty, float 54A of ball tap 54 also descends, allowing water to be supplied to main water tank 52 through main water tank water supply pipe 54B. At the same time, water is also supplied from heat collector water supply pipe 54C into light collector 58. At this time, spherical member 72 that was blocking water inlet 59 is above the normal water level line W, and therefore dries and shrinks due to no contact with water, reducing its volume, allowing the supplied water to be introduced into light collector 58 through water inlet 59.

[0039] Alternatively, if the spherical member 72 is made of a material that can expand and contract due to heat, the spherical member 72 will be exposed to the introduced water and cooled, causing its volume to contract, allowing water to be introduced into the light collecting section 58 through the water inlet 59. Then, the helical spring 60 in the light collecting section 58 is cooled by the water introduced into the light collecting section 58 and enters a stretched state in which no elastic biasing force is generated, and as a result, the tension generated in the cable 68 is also released. This causes the water stop valve 56 to move from an open position to a position that closes the tank, allowing water to be stored in the main water tank 52. When water is supplied to the main water tank 52, the ball tap 54 stops the water supply when the water level in the main water tank 52 reaches line W and the float 54A rises.

[0040] Meanwhile, as described above, the water in the sub-water tanks 62A, 62B gradually seeps out so as to wet the cooling water absorption membrane 13 attached to the back surface of the solar panel 12. The tilting angle can be adjusted by optimizing the amount of water seeping out or the position of the tilting axle 22, i.e., the position of the fulcrum. That is, since the position of the center of gravity of the tilting unit 20 changes depending on the amount of water in the sub-water tanks 62A, 62B and the position of the tilting axle 22, the temperature at which the tilting unit 20 starts to tilt can be set by optimizing the amount or position of these values. Note that when all the water in the sub-water tanks 62A, 62B is drained, the tilting angle returns to θ1 shown in FIG. 3. The temperature and other conditions at which the tilting angle starts to return to θ1 can similarly be set by optimizing the amount of water seeping out of the sub-water tanks 62A, 62B and the position of the fulcrum (position of the tilting axle 22).

[0041] According to the first embodiment, the tilt angle of the solar panel 12 can be set to an angle with high light collection efficiency without consuming energy such as electricity, contributing to the effective use of solar energy. In addition, the solar panel can be cooled during the daytime when the panel body becomes hot, improving power generation efficiency, and the simplified structure for this has the advantage of being inexpensive.

[0042] Next, a second embodiment of the solar energy collecting system according to the present invention will be described. In the second embodiment, only the structure of the heat collecting unit is different from that of the first embodiment, and other parts are the same, so the structure of the heat collecting unit will be described. 9 is an explanatory side view showing the heat collecting section 80 in the second embodiment. This figure shows the main part of the heat collecting section 80 attached to the main water tank 50, and other parts are omitted from the illustration.

[0043] The heat collecting section 80 shown in the figure differs from the heat collecting section 58 of the first embodiment in that it is configured by arranging three convex lenses 84A, 84B, and 84C in a cylindrical member 82. Of these convex lenses, convex lens 84A is attached to cylindrical member 82 so that it has an inclination angle β1, convex lens 84B has an inclination angle β2, and convex lens 84C has an inclination angle β3. The refractive index of each of convex lenses 84A, 84B, and 84C is set so that its focal position is on wire 86 provided inside cylindrical member 82. Therefore, sunlight incident through each of convex lenses 84A, 84B, and 84C is focused on wire 86 due to the light-concentrating effect of each lens, which causes the temperature of wire 86 to rise rapidly. Furthermore, since each of the convex lenses 84A, 84B, and 84C is installed in the cylindrical member 82 at a different angle, it is possible to accommodate changes in the angle of the sunlight when the altitude of the sun changes with time or season.

[0044] The cylindrical member 82 is made of a transparent material with thermal insulation properties, and like the heat collecting section 58 in the first embodiment, a wire 86, which is an elastic member made of a shape memory alloy, is installed inside it with one end attached to the mesh member 74. The wire 86 is straight at room temperature, but when heated to a predetermined temperature or higher, it deforms into a coil shape and generates a tensile force. The lower end of the wire 86 is connected to the cable 68, and like the first embodiment described above, the cable 68 can open and close the water stop valve 56.

[0045] That is, in the second embodiment, the light collecting action is performed by three convex lenses 84A, 84B, and 84C provided in the cylindrical member 82. This makes it possible to simplify the structure of the cylindrical member 82, and also makes it possible to change the tilt angle of the tilting section 20 in the same manner as in the first embodiment by utilizing the elastic force of the wire 86 made of shape memory alloy. As a result, the structure of the heat collecting section 80 can be simplified, and costs can be reduced. In the second embodiment, three convex lenses 84A, 84B, and 84C are provided in the cylindrical member 82, but it is of course possible to increase or decrease the number. Furthermore, by processing a part of the transparent cylindrical member 82 into a convex shape, and using this convex part to concentrate sunlight and align the focus with the wire 86 serving as the elastic member, it is similarly possible to instantly heat the wire 86 and cause it to contract into a coil.

[0046] FIG. 10 is an explanatory diagram showing the operation of the second embodiment when sunlight is incident on the heat collecting unit 80. FIG. 10(a) shows the case where sunlight is incident almost perpendicularly to the upper convex lens 84A when the angle of the upper convex lens 84A is β1. As shown in FIG. 10(a), sunlight incident on the convex lens 84A heats the shape-memory alloy wire 86 due to its focusing effect. This heating causes the wire 86 to coil around the focal point L1-L1 of the convex lens 84A, pulling the cable 68 upward. This opens the water stop valve 56 connected to the cable 68, allowing water in the main water tank 52 to be guided to the sub-water tanks 62A and 62B. Subsequently, the tilting unit 20 on which the solar panels 12 are installed can be tilted, and each solar panel 12 can be cooled from its back surface, similar to the operation in the first embodiment.

[0047] 10(b) is an explanatory diagram showing a case where sunlight enters the heat collecting unit 80 through the lower convex lens 84C, and the lower part is shown extended because the sunlight entering the convex lens 84C causes the cable 68 to coil and contract. In this case as well, the wire 86 becomes coiled near the focus L2-L2 of the convex lens 84C, and by pulling the cable 68 upward, the water stop valve 56 is opened, and the tilting unit 20 is tilted by the same action as in the case of FIG. 10(a). According to the second embodiment described above, the cylindrical member 82 used in the heat collecting portion 80 does not need to have a double structure, which has the advantage of being inexpensive. [Industrial Applicability]

[0048] As described above, the present invention requires a small number of components, does not require power, and can tilt the solar panel to an optimal angle in response to sunlight that changes with the seasons and time of day, thereby contributing to a significant improvement in light collection efficiency. The present invention can be used in the renewable energy field. [Explanation of symbols]

[0049] 10. Solar Energy Collection System 12. Solar Panels 13 Cooling water absorption film (evaporation promotion sheet) 14 Support stand 15 16 Fixed part 18A 18B Standing part 20 Tilt part 22 Tilt axis 24A 24B Buffer material 50 Means for changing tilt angle 52 Main water tank 54 Ball Tap 54A Float 54B Main water tank water supply pipe 54C Heat collector water supply pipe 56 Water stop valve 58 Heat collection section 59 Water inlet 58A outer cylinder 58B Inner cylinder 60 helical spring (made of shape memory alloy) 62 Branch 64A 64B Water pipe 68 Cable 70 Tubular member 72 Closure member 74 Reticulum 80 Heat collection section 82 Cylindrical member 84A 84B 84C Convex lens 86 Wire rod

Claims

1. A solar energy collection system comprising: a support stand having a tilting section on which a solar panel is installed, the support stand supporting the tilting section so that the tilting section can be tilted by a fulcrum; and a tilt angle changing means for changing the tilt angle by tilting the tilting section within a certain range in accordance with changes in the angle of solar radiation, The tilt angle changing means is The device comprises a main water tank, a ball tap for supplying and stopping water to the main water tank, a water stop valve for stopping or discharging the water in the main water tank, a heat collecting part made of a heat insulating and heat retaining material, and an elastic member made of a shape memory alloy housed in the heat collecting part, One end of the elastic member is connected to a water stop valve in the main water tank directly or via a cable, and the other end is fixed to the heat collecting unit, At room temperature, the elastic member does not exert an elastic force. When sunlight shines into the heat collecting section and the elastic member reaches a predetermined temperature or higher, an elastic force is applied to open the water stop valve in the main water tank, thereby discharging water from the main water tank and introducing water into the sub-water tank attached to the tilting section, A solar energy collection system characterized in that the tilt angle of the tilting section is changed by changing the center of gravity position of the tilting section due to the weight of the water in the sub-water tank.

2. The solar energy collection system described in claim 1, characterized in that an evaporation promotion sheet that promotes evaporation of water is attached to the back surface of the solar panel, and the solar panel is cooled from the back surface by guiding water from a sub-water tank attached to the tilting section onto the evaporation promotion sheet.

3. 3. The solar energy collection system according to claim 1, wherein a tubular member is disposed inside the heat collection unit, a cord connected to one end of the elastic member is disposed inside the tubular member, and the other end of the elastic member is attached to an upper position within the heat collection unit so as to be suspended by a mesh member.

4. A solar energy collection system as described in any one of claims 1 to 3, characterized in that water is supplied into the main water tank by a ball tap provided on the inside upper part of the tank, and that the ball tap is connected to a water supply pipe that supplies water into the main water tank and to a water conveyance pipe that supplies water to the heat collection section.

5. A solar energy collection system as described in any one of claims 1 to 4, characterized in that the heat collection section has a double structure consisting of an outer tube and an inner tube, and the ring-shaped portion formed between the outer tube and the inner tube serves as an insulating layer, thereby improving the responsiveness of the elastic member made of shape memory alloy installed inside the inner tube to temperature increases due to solar radiation.

6. 5. The solar energy collection system according to claim 1, wherein the heat collecting section is formed by a cylindrical member in which a plurality of convex lenses corresponding to the solar radiation angles of the sunlight are arranged, and the focal positions of each of the plurality of convex lenses coincide with an elastic member made of a shape memory alloy installed inside the cylindrical member, and the inclination angles of the plurality of convex lenses are installed so that they are each different.

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