Solar heat collection system

Abstract

A solar heat collection system 1 comprises a plurality of solar heat collection members 10 installed on an installation object 5 constituting a building 2. Each solar heat collection member 10 has a hollow part 10a, a light-receiving surface 10b, a facing surface 10c, and a non-heat-insulating part 10d for performing convection heat transfer with ambient air. Each solar heat collection member 10 is installed on the installation object 5 in an installation orientation in which the facing surface 10c is inclined with respect to the installation object 5 so as to form a space together with the installation object 5. The plurality of solar heat collection members 10 are arranged with a prescribed installation interval L therebetween.

Description

Solar heat collection system

[0001] The present disclosure relates to solar thermal collection systems.

[0002] Patent Document 1 discloses a solar collector to be installed on the exterior wall of an apartment building. The solar collector has a heat insulating layer on the side opposite to the sunlight incident portion, and is installed parallel to the exterior wall.

[0003] Japanese Patent Application Laid-Open No. 2012-242016

[0004] In conventional solar collectors, the emphasis is on transferring radiant heat from sunlight to a heat medium. There is room for improvement in the amount of heat captured by the solar collector.

[0005] An object of the present disclosure is to improve the heat collection performance of a solar heat collection system.

[0006] One aspect of the present disclosure provides a solar heat collecting system comprising a plurality of solar heat collecting members installed on an installation object that constitutes a building, each of the solar heat collecting members having a hollow portion through which a heat medium flows, a light-receiving surface that receives sunlight, an opposing surface that faces the installation object on the opposite side of the light-receiving surface, and a non-insulated portion that performs convective heat transfer between the light-receiving surface and the opposing surface and the ambient air, and transferring radiant heat from the sunlight and convective heat from the ambient air to the heat medium, and the opposing surface is installed on the installation object in an installation position that forms a space between the opposing surface and the installation object, and the plurality of solar heat collecting members are arranged at predetermined installation intervals from each other.

[0007] As mentioned above, solar heat collecting members generally have an insulated structure to prevent convective heat transfer with the surrounding air. In contrast, with the above configuration, the solar heat collecting member actively has non-insulated parts that are expected to cause convective heat transfer with the surrounding air. As a result, each solar heat collecting member can transfer not only radiant heat from sunlight but also convective heat from the surrounding air to the heat medium, increasing the amount of heat gained by the solar heat collecting member.

[0008] In particular, the opposing surface forms a space between the object to be installed. Because the non-insulating portion is also provided on this opposing surface, the opposing surface can receive radiant heat from the object to be installed and can cause convective heat transfer between the opposing surface and the air in the space. In this way, the solar heat collecting member can collect heat from sources other than sunlight received on the light-receiving surface, and the amount of heat acquired increases.

[0009] The multiple solar heat collecting members are arranged at a predetermined interval from each other. Therefore, even if each solar heat collecting member is inclined with respect to the installation object, each solar heat collecting member is less likely to be in the shadow of an adjacent solar heat collecting member, and the light receiving surface is more likely to receive radiant heat from sunlight. Furthermore, sunlight can pass between two adjacent solar heat collecting members and irradiate the installation object. The installation object, the opposing surface, and the space between the installation objects are more likely to reach higher temperatures than solar heat collecting members through which a heat medium flows, making it easier to achieve heat input at the opposing surface as described above.

[0010] The solar heat collecting system may further include a heat storage material filled in a hollow portion provided in the installation object.

[0011] According to the above configuration, even during times when there is no or weak solar radiation, the opposing surface of the solar heat collecting member can collect the amount of heat stored in the heat storage material during times when there is strong solar radiation, thereby increasing the amount of heat acquired.

[0012] The solar heat collecting system may further include a cover member that is molded from a light-transmitting material and that covers the space between the opposing surface and the installation object.

[0013] According to the above-mentioned configuration, the space between the opposing surface and the installation object can be kept warm, and the amount of heat gained can be increased. Because the cover member is light-transmitting, it does not prevent sunlight from reaching the installation object.

[0014] The cover member may further cover a space on the light receiving surface side.

[0015] According to the above configuration, the cover member keeps the space on the light-receiving surface side warm. If the space on the light-receiving surface side becomes hotter than the light-receiving surface, the light-receiving surface can also receive convection heat from the space, increasing the amount of heat acquired.

[0016] Each of the solar heat collecting members may further include a recess on the light receiving surface. Also, each of the solar heat collecting members may further include a fin protruding from at least one of the light receiving surface and the opposing surface.

[0017] According to the above configuration, the surface area of ​​the solar heat collecting member increases, and the amount of heat acquired increases.

[0018] The solar heat collecting member may be made of an extruded aluminum alloy material.

[0019] According to the above configuration, a large solar heat collecting member with excellent thermal conductivity can be easily manufactured.

[0020] In the installation position, the light receiving surface of each of the solar heat collecting members may be perpendicular to the direction of solar radiation at a winter solar altitude.

[0021] According to the above-mentioned configuration, the light receiving surface can effectively receive sunlight even in winter when the sun's altitude is low, thereby optimizing the amount of heat gained throughout the year.

[0022] The inclination angle of the outer surface of the installation object with respect to the horizontal plane may be smaller than the complementary angle of the winter solar altitude, and the multiple solar heat collecting elements may be arranged at a predetermined installation interval from each other so that each element is not in the shadow of the adjacent solar heat collecting element at the winter solar altitude.

[0023] According to the above configuration, when the solar heat collecting members are installed on the roof of a building or the like, each solar heat collecting member will not be in the shadow of the adjacent solar heat collecting member throughout the year, and heat collection efficiency will be increased.

[0024] When the installation interval is L, the height of the light receiving surface is H, the inclination angle of the installation object is β, and the winter solar altitude is hw, the installation interval L may satisfy the following formula: L≧H / sin(β+hw).

[0025] According to the above configuration, when the inclination angle of the outer surface of the installation object with respect to the horizontal plane is relatively small, multiple solar heat collecting members can be arranged so that each solar heat collecting member does not fall into the shadow of an adjacent solar heat collecting member throughout the year.

[0026] The inclination angle of the outer surface of the installation object relative to the horizontal plane may be greater than the complementary angle of the winter solar altitude, and the multiple solar heat collecting elements may be arranged at a predetermined installation interval from each other so that each element is not in the shadow of the adjacent solar heat collecting element at the summer solar altitude.

[0027] According to the above configuration, when the solar heat collecting members are installed on the walls of a building or the like, each solar heat collecting member will not be in the shadow of the adjacent solar heat collecting member throughout the year, thereby increasing the heat collection efficiency.

[0028] When the inclination angle of the outer surface of the installation object relative to the horizontal plane is greater than the complementary angle of the winter solar altitude, the installation interval is L, the height of the light receiving surface is H, the inclination angle of the installation object is β, the winter solar altitude is hw, and the summer solar altitude is hs, the installation interval L may satisfy the following equation: L≧H{sin(β+hw)+cos(β+hw) / tan(hs+β)}.

[0029] According to the above configuration, when the inclination angle of the outer surface of the installation object with respect to the horizontal plane is relatively large, multiple solar heat collecting members can be arranged so that each solar heat collecting member does not fall into the shadow of the adjacent solar heat collecting rod throughout the year.

[0030] According to the present disclosure, the heat collection performance of a solar heat collection system can be improved.

[0031] Schematic diagram of a building to which the solar heat collection system according to the embodiment is applied. Schematic diagram showing an example of the flow of the heat transfer medium in the solar heat collection system according to the embodiment. Perspective view of the solar heat collection member according to the first embodiment. Exploded perspective view of the solar heat collection member shown in FIG. 2A. Cross-sectional view of the solar heat collection member shown in FIG. 2A. Cross-sectional view of the solar heat collection member shown in FIG. 2A. Shows the installation posture of the solar heat collection member with respect to the installation object when the outer surface of the installation object is parallel to the horizontal plane. Shows the installation posture of the solar heat collection member with respect to the installation object when the inclination angle of the outer surface of the installation object with respect to the horizontal plane is smaller than the winter solar altitude. Shows the installation posture of the solar heat collection member with respect to the installation object when the inclination angle of the outer surface of the installation object with respect to the horizontal plane is equal to the winter solar altitude. Shows the installation posture of the solar heat collection member with respect to the installation object when the inclination angle of the outer surface of the installation object with respect to the horizontal plane is larger than the winter solar altitude. Shows the installation posture of the solar heat collection member with respect to the installation object when the outer surface of the installation object is perpendicular to the horizontal plane. Graph showing the time change of the solar altitude. Diagram showing the solar heat collection member according to the first embodiment. Diagram showing the solar heat collection member according to the second embodiment. Diagram showing the solar heat collection member according to the first modification of the first embodiment. Diagram showing the solar heat collection member according to the first modification of the second embodiment. Diagram showing the solar heat collection member according to the second modification of the first embodiment. Diagram showing the solar heat collection member according to the second modification of the second embodiment. Diagram showing the solar heat collection member according to the third modification of the first embodiment. Diagram showing the solar heat collection member according to the third modification of the second embodiment. Diagram showing the solar heat collection member according to the fourth modification of the first embodiment. Diagram showing the solar heat collection member according to the fourth modification of the second embodiment. Diagram showing the solar heat collection member according to the fifth modification of the first embodiment. Diagram showing the solar heat collection member according to the fifth modification of the second embodiment. Diagram showing the solar heat collection member according to the first embodiment. Diagram showing the solar heat collection member according to the first embodiment. Diagram showing a modification regarding the arrangement of the solar heat collection members according to the first embodiment. Diagram showing another modification regarding the arrangement of the solar heat collection members according to the first embodiment. Diagram showing another modification regarding the arrangement of the solar heat collection members according to the second embodiment. Diagram showing a modification regarding the shape of the solar heat collection member according to the embodiment. Diagram showing an example of the installation posture of the solar heat collection member shown in FIG. 14A. Diagram showing another modification regarding the shape of the solar heat collection member according to the embodiment.Fig. 15B is a diagram showing an example of the installation posture of the solar heat collecting member shown in Fig. 15A. Fig. 15C is a diagram showing yet another modified example regarding the shape of the solar heat collecting member according to the embodiment.

[0032] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0033] 1A , the solar heat collecting system 1 includes a plurality of solar heat collecting members 10 installed on an installation target 5 that constitutes a building 2. Hereinafter, the state in which the solar heat collecting members 10 are installed on the installation target 5 will be simply referred to as the "installed state."

[0034] The building 2 may be any structure with a roof 3 and walls 4, and may be a detached house, an apartment building, a building, or even an agricultural greenhouse. The roof 3 forms the upper part of the building 2. The roof 3 may be a flat roof or a sloped roof. The type of sloped roof is not particularly limited. The walls 4 extend vertically from the ground. The walls 4 may be inclined relative to the vertical direction.

[0035] Suitable examples of the installation object 5 include a roof 3 facing south, a horizontal roof 3, and a wall 4 facing south. The solar heat collecting member 10 may be installed on both the roof 3 and the wall 4 of one building 2, or on either the roof 3 or the wall 4 of one building 2.

[0036] The phrase "south-facing" for wall 4 does not necessarily include only cases in which wall 4 faces due south. Wall 4 may be slightly rotated around the vertical axis from a state in which it faces due south. For example, the orientation of wall 4 may be within a range between an orientation in which the outer surface of wall 4 faces southeast in a plan view (i.e., an orientation in which the outer surface extends from southwest to northeast in a plan view) and an orientation in which the outer surface of wall 4 faces southwest (i.e., an orientation in which the outer surface extends from southeast to northwest in a plan view). The same applies to the orientation of a sloped roof.

[0037] Referring to FIG. 1B , the solar heat collecting system 1 further includes a heat medium tank 21 , a heat medium circulation line 22 , and a pump 23 in addition to the solar heat collecting member 10 .

[0038] The solar heat collecting element 10 forms a flow path through which the liquid-phase heat medium M circulates. In this embodiment, the solar heat collecting element 10 is in the shape of a flat plate or panel, by way of example only. The heat medium tank 21 stores the heat medium M. The heat medium M is, for example, water, but may be a liquid other than water, such as an antifreeze solution containing ethylene glycol as a main component. The heat medium circulation line 22 includes an inflow line 22a that sends the heat medium M from the heat medium tank 21 to the solar heat collecting element 10, and an outflow line 22b that sends the heat medium M from the solar heat collecting element 10 to the heat medium tank 21. The pump 23 pressure-pumps the heat medium M along the heat medium circulation line 22.

[0039] In this embodiment, the heat medium tank 21 includes a supply tank 21a and a recovery tank 21b that is separate from the supply tank 21a. The inflow line 22a connects the supply tank 21a in parallel to the flow paths of the multiple solar heat collecting members 10. The outflow line 22b connects the recovery tank 21b in parallel to the flow paths in the multiple solar heat collecting members 10. Note that the flow paths of the multiple solar heat collecting members 10 may be connected in series.

[0040] The heat medium tank 21 has a thermal insulation structure, and can control the temperature of the heat medium M in the heat medium tank 21 to a required temperature regardless of the ambient temperature. The heat medium circulation line 22 is composed of piping members such as metal or resin pipes. The piping members may also have a thermal insulation structure.

[0041] The heat medium M is pressure-fed by the pump 23 from the supply tank 21a through the inflow line 22a to the solar heat collecting member 10. In the process of flowing through the flow path in the solar heat collecting member 10, the heat medium M is heated by the heat collected in the solar heat collecting member 10. When the heat medium M flows out of the solar heat collecting member 10, it is sent to the recovery tank 21b through the outflow line 22b. As a result, the hot water is stored in the recovery tank 21b.

[0042] The heat medium tank 21 may be a single unit, in which case the heat medium M is supplied to the solar heat collecting member 10 from the same tank and recovered to the same tank from the solar heat collecting member 10. A valve may be provided on the heat medium circulation line 22 to switch whether or not the heat medium M is allowed to flow or to adjust the flow rate.

[0043] With reference to FIGS. 2A to 2D, each solar heat collecting member 10 has a heat collecting member body 11 , a first header 12 , a second header 13 , an inlet 14 , and an outlet 15 .

[0044] The heat collecting member body 11 is made of an extruded aluminum alloy. As the aluminum alloy, 1000 series aluminum alloys having excellent thermal conductivity or 6000 series aluminum alloys having excellent thermal conductivity and strength are suitable.

[0045] The heat collecting member body 11 has a first main wall 11a, a second main wall 11b, and a pair of side walls 11c. The first main wall 11a, the second main wall 11b, and the pair of side walls 11c form a long, wide, and low rectangular tube, with both ends in the longitudinal direction open. This longitudinal direction is the extrusion direction.

[0046] The first main wall 11a is a rectangular flat plate. The long sides extend in the longitudinal direction of the heat collecting member body 11, the short sides extend in the width direction of the heat collecting member body 11, and the plate thickness direction corresponds to the thickness direction of the heat collecting member body 11. In the installed state, the dimension in the width direction of the heat collecting member body 11 is referred to as "height H" (see FIGS. 3A to 3D).

[0047] The pair of side walls 11c extend in the thickness direction from both side edges of the first main wall 11a. The second main wall 11b is a flat plate of the same shape as the first main wall 11a, is arranged parallel to the first main wall 11a, and completely overlaps the first main wall 11a when viewed in the thickness direction, connecting the ends of the pair of side walls 11c. These four walls define a wide, low-profile rectangular opening at both longitudinal ends.

[0048] The heat collecting member main body 11 has a plurality of partition walls 11d. The partition walls 11d extend between a pair of side walls 11c, parallel to the side walls 11c, and connect the inner surfaces of the first main wall 11a and the second main wall 11b. These partition walls 11d divide the space surrounded by the four walls into a plurality of hollow portions 10a arranged in the width direction. In the illustrated example, there are six partition walls 11d and one more hollow portion 10a, for a total of seven, but the number of hollow portions 10a can be changed as appropriate. Each hollow portion 10a has a rectangular cross section. By using extrusion molding, such a structure having a plurality of closed cross sections or a plurality of hollow portions 10a can be manufactured continuously and integrally.

[0049] Each hollow portion 10a is open at both ends in the longitudinal direction. The first header 12 closes the opening at one end of the hollow portion 10a. The second header 13 closes the opening at the other end of the hollow portion 10a. Both the first header 12 and the second header 13 close the openings of multiple hollow portions 10a together.

[0050] The first header 12 has a cover plate 12a, a peripheral wall 12b extending from the periphery of the cover plate 12a, and an internal space 12c surrounded by the cover plate 12a and the peripheral wall 12b. The internal space 12c is open on the side opposite the cover plate 12a. The internal space 12c has the same cross-sectional shape as the heat collecting member body 11 (rectangular in this embodiment). The first header 12 abuts against one end of the heat collecting member body 11 and is joined to the heat collecting member body 11 in a liquid-tight manner.

[0051] The second header 13 has a cover plate 13 a, a peripheral wall 13 b, and an internal space 13 c, similar to the first header 12, and is joined to the other end of the heat collecting member body 11 in a liquid-tight manner.

[0052] The inlet 14 and the outlet 15 are provided in the first header 12 or the second header 13. The inlet 14 is connected to an inlet line 22a, and the outlet 15 is connected to an outlet line 22b (see FIG. 1B ). The inlet 14 is cylindrical or nipple-shaped, and the inlet line 22a, which serves as a piping member, is attached to the inlet 14 in a liquid-tight manner. The same applies to the outlet 15 and the outlet line 22b. In this embodiment, a single inlet 14 is provided in the first header 12, and a single outlet 15 is provided in the second header 13. The inlet 14 and the outlet 15 penetrate the corresponding cover plates 12a, 13a.

[0053] The heat medium M flows into the internal space 12c of the first header 12 via the inlet 14, and is divided from the internal space 12c into each of the multiple hollow portions 10a. The heat medium M flows from each of the multiple hollow portions 10a to join together in the internal space 13c of the second header 13, and flows out from the internal space 13c via the outlet 15. In this way, a flow path from the inlet 14 to the outlet 15 is provided inside the solar heat collecting member 10. The heat medium M flows through the solar heat collecting member 10 in one direction, from one side to the other in the longitudinal direction.

[0054] 2A and 2D, the solar heat collecting member 10 has a light receiving surface 10b and an opposing surface 10c.

[0055] The light-receiving surface 10b is part of the outer surface of the solar heat collecting member 10 and receives sunlight. In this embodiment, the light-receiving surface 10b is mainly constituted by the outer surface of the first main wall 11a. Furthermore, the light-receiving surface 10b includes parts of the surfaces of the peripheral walls 12b, 13b that are continuous with the outer surface of the first main wall 11a. When radiant heat from sunlight is input to the light-receiving surface 10b, the solar heat collecting member 10 transfers the radiant heat to the heat medium M.

[0056] The facing surface 10c is part of the outer surface of the solar heat collecting member 10 and is the surface on the opposite side in the thickness direction to the light receiving surface 10b. The facing surface 10c faces the installation target 5 (see FIG. 1A). In this embodiment, the facing surface 10c is mainly constituted by the outer surface of the second main wall 11b. Furthermore, the facing surface 10c includes portions of the surfaces of the peripheral walls 12b, 13b that are continuous with the outer surface of the second main wall 11b.

[0057] The solar heat collecting member 10 actively has non-insulated portions 10d that are expected to allow convective heat transfer between the light-receiving surface 10b and the ambient air, and between the opposing surface 10c and the ambient air. When convective heat is input from the ambient air to the light-receiving surface 10b or the opposing surface 10c, the solar heat collecting member 10 transfers the convective heat to the heat medium M.

[0058] The heat medium M flows through the hollow portion 10a while filling the hollow portion 10a, i.e., while contacting the inner surface of the heat collecting member main body 11 that defines the hollow portion 10a. Radiant heat and convective heat are transferred to the heat medium M by solid-state heat transfer in the heat collecting member main body 11, thereby warming the heat medium M. Substantially the entire inner surfaces of the first main wall 11a, the second main wall 11b, the pair of side walls 11c, the first header 12, and the second header 13 are in contact with the heat medium M, and substantially the entire outer surfaces thereof are in contact with the ambient air. In this embodiment, no insulating material is provided on these inner surfaces or on these outer surfaces. As a result, substantially the entire first main wall 11a, the second main wall 11b, the pair of side walls 11c, the first header 12, and the second header 13 serve as the non-insulated portion 10d.

[0059] Since a non-insulated structure is adopted for the light-receiving surface 10b and the opposing surface 10c, the radiant heat from the sunlight collected by the light-receiving surface 10b can be used to heat the heat medium M, and the radiant heat from the installation object 5 collected by the opposing surface 10c can also be used to heat the heat medium M. In this embodiment, both the light-receiving surface 10b and the opposing surface 10c are colored approximately black. This makes the emissivity of the light-receiving surface 10b and the opposing surface 10c close to 1, improving the heat collection performance of the solar heat collecting member 10. The emissivity of an aluminum alloy is 10 -2 From 10 -1 Since this is an order of magnitude, the effect of coloring is significant when the heat collecting member body 11 is made of an aluminum alloy.

[0060] 3A to 3E show the installation postures of the solar heat collecting member 10 according to the tilt angle β of the outer surface of the installation object 5 relative to the horizontal plane. The winter solar altitude hw and summer solar altitude hs in each figure will be described later with reference to FIG.

[0061] For ease of explanation, it is assumed below that building 2 is located in the mid-latitude zone of the Northern Hemisphere, for example, in the latitude zone between the Tropic of Cancer and the Arctic Circle. In other words, it is assumed that the sun is in the south at noon throughout the year and that no midnight sun or polar night occurs. The solar altitude at noon on the winter solstice (hereinafter referred to as "noon altitude") is greater than 0°, and the noon altitude on the summer solstice is less than 90°.

[0062] 3A to 3E, the solar heat collecting member 10 is installed on the installation object 5 in an installation posture in which the longitudinal direction is oriented in the horizontal east-west direction (orthogonal to the plane of the paper in FIGS. 3A to 3E) and the width direction is oriented in a direction intersecting the vertical direction (longitudinal direction in FIGS. 3A to 3E) and the horizontal north-south direction (horizontal direction in FIGS. 3A to 3E).

[0063] One of the pair of long side edges of the solar heat collecting member 10 extends in the east-west direction on the south and lower side (hereinafter, this long side edge may be referred to as the "south side edge"), and the other extends in the east-west direction on the north and upper side (hereinafter, this long side edge may be referred to as the "north side edge").

[0064] The width direction is oriented in the north-south direction, tilting relative to the vertical, with the upward direction being more northerly. The thickness direction is perpendicular to both the longitudinal direction and the width direction. The thickness direction (i.e., the normal direction to the light-receiving surface 10b) is oriented in the north-south direction, tilting relative to the vertical, with the downward direction being more northerly.

[0065] The light receiving surface 10b is perpendicular to the direction of sunlight at the winter solar altitude hw, and the normal direction of the light receiving surface 10b is parallel to the direction of sunlight at the winter solar altitude hw. The opposing surface 10c forms a space between itself and the installation object 5.

[0066] 3C , when the tilt angle β is equal to the complementary angle of the winter solar altitude hw, the light receiving surface 10b is parallel to the outer surface of the installation target 5. In order to form a space between the opposing surface 10c and the installation target 5, the solar heat collecting member 10 is installed on the installation target 5 via the support structure 29 in a state where it is floating above the outer surface of the installation target 5 by a float amount F.

[0067] As shown in Figures 3A, 3B, 3D, and 3E, when the inclination angle β is different from the complementary angle of the winter solar altitude hw, the light receiving surface 10b is inclined at an inclination angle α relative to the outer surface of the installation object 5 so as to be perpendicular to the direction of solar radiation at the winter solar altitude hw.

[0068] 3A and 3B , when the inclination angle β is smaller than the complementary angle of the winter solar altitude hw, the southern edge is closer to the installation target 5 in the vertical direction than the northern edge. The light receiving surface 10b is inclined at an inclination angle α with respect to the outer surface of the installation target 5, moving away from the installation target 5 upward as it moves from south to north. This forms a space between the facing surface 10c and the installation target 5, widening as it moves north and upward. The solar heat collecting member 10 is installed on the installation target 5 via a support structure (not shown) with the southern edge in contact with or close to the installation target 5, while the northern edge is floating above the installation target 5. Even when the southern edge is in contact with the installation target 5, a space can be secured.

[0069] 3D and 3E , when the inclination angle β is greater than the complementary angle of the winter solar altitude hw, the northern edge is closer to the installation target 5 in the vertical direction than the southern edge, as opposed to the above. The light receiving surface 10b is inclined at an inclination angle α with respect to the outer surface of the installation target 5, moving further south from the installation target 5 as it goes from top to bottom. This inclination forms a space between the opposing surface 10c and the installation target 5, widening toward the south and downward. The solar heat collecting member 10 is installed on the installation target 5 via a support structure (not shown) with the northern edge in contact with or close to the installation target 5, while the southern edge is floating above the installation target 5. Even when the northern edge is installed on the installation target 5, a space can be secured.

[0070] Next, the shadow length Ls will be described.

[0071] 3C, when the tilt angle β is equal to the complement angle of the winter solar altitude hw, a shadow is formed directly behind the opposing surface 10c in winter, while in summer the shadow slides south and downward. Because the light-receiving surface 10b is parallel to the outer surface of the installation target 5, the shadow length Ls is equal to the height H regardless of the season.

[0072] Next, as shown in Figure 3B, when the tilt angle β is smaller than the complementary angle of the winter solar altitude hw and the northern edge is raised above the installation target 5, the shadow extends northward and upward regardless of the season. In winter when the solar altitude is low, the shadow becomes longer.

[0073] Point A is the southern edge, point B is the northern edge, and point C is the tip of the shadow. The length of side AC corresponds to the winter shadow length Ls. The length of side AB corresponds to the height H, angle ABC is a right angle, and angle BAC corresponds to the tilt angle α. Then, shadow length Ls is expressed by the following equation (1). Note that the sum of tilt angle α, tilt angle β, and winter solar altitude hw is 90° (α = 90° - (β + hw)).

[0074]

[0075] 3A shows the case where the tilt angle β is 0°. In this case, from equation (1), the shadow length Ls is expressed by the following simplified equation (2).

[0076]

[0077] Next, as shown in Figure 3D, when the tilt angle β is larger than the complementary angle of the winter solar altitude hw and the southern edge is raised above the installation target 5, the shadow extends southward and downward regardless of the season. In the summer when the solar altitude is high, the shadow becomes longer.

[0078] Point A is the northern edge, point B is the southern edge, point C is the tip of the shadow, and point D is the intersection of a perpendicular line drawn from point B to the surface of the installation target object 5 and said surface. The length of side AC is equal to the sum of the lengths of sides AD and DC, and corresponds to the summer shadow length Ls. The length of side AB corresponds to the height H, and angle CAB corresponds to the tilt angle α. The sum of the value obtained by subtracting tilt angle α from tilt angle β and the winter solar altitude hw is 90° (β - α + hw = 90°).

[0079] The lengths of the sides AD and BD are expressed by the following equations (3) and (4), respectively.

[0080]

[0081] The length of side DC is expressed by the following equation (5): where ∠BCD is the supplementary angle of the sum of the tilt angle β and the summer solar altitude hs (180° - (hs + β)).

[0082]

[0083] From equation (4), equation (5) can be transformed into the following equation (6).

[0084]

[0085] From equations (3) and (6), the shadow length Ls is expressed by the following equation (7).

[0086]

[0087] 3E shows the case where the tilt angle β is 90°. In this case, from equation (7), the shadow length Ls is expressed by the following simplified equation (8).

[0088]

[0089] FIG. 3A illustrates an example where the installation object 5 is a flat roof, which is a type of roof 3. FIGS. 3B to 3D illustrate an example where the installation object 5 is a sloped roof, which is a type of roof 3. When the installation object 5 is a sloped roof, the inclination angle β is the so-called roof slope. FIG. 3E illustrates an example where the installation object 5 is a wall 4. FIGS. 3C and 3D may also include cases where the installation object 5 is a sloped wall 4. In either case, the multiple solar heat collecting elements 10 are arranged at a predetermined installation interval L so that each solar heat collecting element 10 is not in the shadow of an adjacent solar heat collecting element 10. The installation interval L is equal to or slightly longer than the length of the shadow of the solar heat collecting element 10 that may be formed on the outer surface of the installation object 5 (hereinafter, shadow length Ls).

[0090] When the tilt angle β is smaller than the complementary angle of the winter solar altitude hw as in Fig. 3B, the installation interval L satisfies the following equation (9) from equation (1): In particular, when the tilt angle β is 0 degrees as in Fig. 3A, the installation interval L satisfies the following equation (10) from equation (2):

[0091]

[0092] When the tilt angle β is greater than the complementary angle of the winter solar altitude hw as in Fig. 3D, the installation interval L satisfies the following equation (11) from equation (7): In particular, when the tilt angle β is 90 degrees as in Fig. 3E, the installation interval L satisfies the following equation (12) from equation (8):

[0093]

[0094] Figure 4 shows the daily change in solar altitude at around 36 degrees north latitude. The dashed line indicates the summer solstice, the dashed line indicates the winter solstice, and the solid line indicates the equinox, i.e., the day of the equinox (vernal or autumnal equinox). The noon altitude on the summer solstice is calculated by subtracting the latitude from 90 degrees and adding the Earth's axial tilt (i.e., adding the solar declination on that day); in this example, it is 77.4 degrees. The noon altitude on the winter solstice is calculated by subtracting the latitude from 90 degrees and adding the Earth's axial tilt (i.e., adding the solar declination on that day); in this example, it is 30.6 degrees.

[0095] The winter solar altitude hw is a representative value of the solar altitude in winter at the location of the building 2. For example, the winter solar altitude hw may be the altitude at noon on the day of the winter solstice.

[0096] Alternatively, the winter solar altitude hw may be set within a range between the solar altitude at noon on the winter solstice and the solar altitude k hours before (or k hours after) the noon time on the winter solstice. The value k may be set appropriately based on the available daylight hours (the period from sunrise to sunset) on the winter solstice, which is determined according to the latitude of the location of the building 2. As a mere example, k may be set to 70 to 90 percent of the period from sunrise to noon, and does not necessarily have to be an integer. In this example, at a latitude of 36 degrees north, the period from sunrise to noon is approximately 5 hours, so k may be set to 4, for example.

[0097] As described above, when the winter solar altitude hw is set to be less than the noon altitude on the winter solstice, the winter solar altitude hw may be the arithmetic mean of two values: the noon altitude on the winter solstice and the solar altitude k hours before (or k hours after) the noon time on the winter solstice.

[0098] The winter solar altitude hw may be the median of the solar altitude from k hours before the noon on the winter solstice to k hours after the noon. While the solar altitude is essentially an analog quantity, calculating the median requires multiple samples. The multiple samples may be time-series data acquired discretely at predetermined intervals (e.g., one minute) during the period from k hours before the noon on the winter solstice to k hours after the noon.

[0099] The same applies to the summer solar altitude hs. The summer solar altitude hs is a representative value of the solar altitude in summer at the location of the building 2. For example, the summer solar altitude hs may be the altitude at noon on the summer solstice. Alternatively, the summer solar altitude hs may be set within a range between the altitude at noon on the summer solstice and the solar altitude k hours before (or k hours after) the noon on the summer solstice. The value k here may be the same as or different from the value k used to determine the winter solar altitude hw.

[0100] The summer solar altitude hs may be the arithmetic mean of the solar altitude at noon on the day of the summer solstice and the solar altitude k hours before (or k hours after) the noon time. The summer solar altitude hs may also be the median of the solar altitude within the period from k hours before the noon time on the day of the summer solstice to k hours after the noon time. The median can be calculated from the time series data as described above.

[0101] (First embodiment) Next, a solar heat collecting system 1 according to a first embodiment will be described with reference to Fig. 5A. In the first embodiment, a plurality of solar heat collecting members 10 are installed on a roof 3 as an installation object 5. The number of solar heat collecting members 10 is not particularly limited. As described above, as a mere example, the roof 3 faces due south, and the eaves extend without inclining in the east-west direction.

[0102] The multiple solar heat collecting members 10 are installed at different installation positions on the roof 3 in the north-south direction and the vertical direction, but are installed in the same installation orientation relative to the roof 3. The multiple solar heat collecting members 10 are lined up in the north-south direction of the roof 3, and are arranged at a predetermined installation interval L between each other.

[0103] The installation interval L is the distance between the same positions of two adjacent solar heat collecting members 10, and is the distance along the extension direction of the outer surface of the roof 3. In Figure 5A, just as an example, the distance between the southern edges of two adjacent solar heat collecting members 10 is shown as the installation interval L.

[0104] 3B, the tilt angle β (roof slope) of the roof 3 is greater than 0 degrees and less than the complementary angle of the winter solar altitude hw. Therefore, the installation interval L is equal to or slightly longer than the shadow length Ls calculated according to the above formula (1), and satisfies the above formula (9).

[0105] During seasons or time periods when the light-receiving surface 10b of the heat collecting member is not perpendicular to the set winter solar altitude hw, sunlight passes between adjacent solar heat collecting members 10 and is irradiated onto the roof 3. The roof 3 receives radiant heat from the sunlight. This heats the roof 3, and radiant heat Q2 is emitted from the roof 3. The space between the opposing surface 10c and the roof 3 is also heated. The temperature of this space tends to become higher than that of the solar heat collecting member 10 through which the heat medium M flows, and as a result, convective heat Q3 is input from the air within the space to the opposing surface 10c that defines the space. The non-insulated portion 10d is also provided on the opposing surface 10c and the second main wall 11b of the heat collecting member main body 11 that forms it, and convective heat transfer on the opposing surface 10c is not hindered by any insulating material.

[0106] The roof 3 has a plurality of hollow portions 5a arranged along the extension direction of the roof 3. The solar thermal collecting system 1 has a heat storage material 26 filled in each of the plurality of hollow portions 5a. The heat storage material 26 is a phase change material (latent heat storage material) such as paraffin, fatty acid, or hydrated salt, and is capable of undergoing a phase transition between solid and liquid phases in the application environment of the solar thermal collecting system 1. During the day, when the roof 3 is irradiated, the heat storage material 26 is heated and becomes liquid. When melting, it absorbs latent heat. At night or on suddenly cloudy days, the heat storage material 26 cools and becomes solid. When solidifying, it releases latent heat Q4. The released latent heat Q4 is transferred to the roof 3 by solid heat transfer and can be released from the roof 3 to the space between the opposing surface 10c and the roof 3 in the form of radiant heat Q2 and convective heat Q3.

[0107] As described above, the solar heat collecting system 1 according to this embodiment includes a plurality of solar heat collecting members 10 installed on the installation object 5 that constitutes the building 2. Each solar heat collecting member 10 has a hollow portion 10a through which the heat medium M flows, a light-receiving surface 10b that receives sunlight, an opposing surface 10c that faces the installation object 5 on the opposite side of the light-receiving surface 10b, and a non-insulated portion 10d that allows convective heat transfer between the light-receiving surface 10b and the opposing surface 10c and the ambient air. Therefore, each solar heat collecting member 10 can transfer not only radiant heat Q1 from sunlight but also convective heat Q3 from the ambient air to the heat medium M. This increases the amount of heat captured by the solar heat collecting member 10.

[0108] Each solar heat collecting member 10 is installed on the installation object 5 in an installation position in which the light receiving surface 10b is perpendicular to the direction of solar radiation at the winter solar altitude hw and the facing surface 10c forms a space between it and the installation object 5. Because the non-insulating portion 10d is also provided on such facing surface 10c, the facing surface 10c can input radiant heat Q2 from the installation object 5 and can cause convective heat transfer between it and the air in the space. Therefore, the amount of heat acquired increases.

[0109] The multiple solar heat collecting members 10 are arranged at a predetermined installation interval L so that each solar heat collecting member 10 is not in the shadow of an adjacent solar heat collecting member 10. Therefore, even if each solar heat collecting member 10 is tilted with respect to the installation object 5, the light-receiving surface 10b can receive a maximum amount of radiant heat Q1 from sunlight.

[0110] Second Embodiment Next, a second embodiment will be described with reference to Figure 5B, focusing on the differences from the first embodiment. In the second embodiment, a plurality of solar heat collecting members 10 are installed on a wall 4. As mentioned above, by way of example only, the outer surface of the wall 4 faces due south and extends vertically.

[0111] The plurality of solar heat collecting members 10 are installed at different installation positions in the vertical direction on the wall 4. The plurality of solar heat collecting members 10 are arranged at predetermined installation intervals L from each other.

[0112] The installation interval L is the distance between the same positions of two adjacent solar heat collecting members 10, and is the distance along the extension direction (vertical direction) of the outer surface of the wall 4. In Fig. 5B, just as an example, the distance between the northern edges of two adjacent solar heat collecting members 10 is shown as the installation interval L.

[0113] In this embodiment, as in FIG. 3E, the outer surface of the wall 4 is perpendicular to the horizontal plane (β=90°). Therefore, the installation interval L is equal to or slightly longer than the shadow length Ls calculated according to the above formula (8), and satisfies the above formula (12).

[0114] In seasons or time periods when the light-receiving surface 10b of the heat collecting member is not perpendicular to the set winter solar altitude hw, sunlight passes between adjacent solar heat collecting members 10 and is irradiated onto the wall 4. The wall 4 receives radiant heat from the sunlight. This heats the wall 4, and radiant heat Q2 is emitted from the wall 4. The space between the opposing surface 10c and the wall 4 is also heated. The temperature of this space tends to become higher than that of the solar heat collecting member 10 through which the heat medium M flows, and therefore convective heat Q3 is input from the air within the space to the opposing surface 10c that defines the space. The non-insulated portion 10d is also provided on the opposing surface 10c and the second main wall 11b of the heat collecting member main body 11 that forms it, and convective heat transfer on the opposing surface 10c is not hindered by any insulating material.

[0115] The wall 4 also has a plurality of hollow portions 5a, each of which is filled with a heat storage material 26. During the day, the wall 4 is irradiated, and the heat storage material 26 is heated to a liquid phase. When melted, it absorbs latent heat. At night or on suddenly cloudy days, the heat storage material 26 is cooled to a solid phase. When solidified, it releases latent heat Q4. The released latent heat Q4 is transferred to the wall 4 by solid heat transfer and can be released from the wall 4 to the space between the opposing surface 10c and the wall 4 in the form of radiant heat Q2 and convective heat Q3.

[0116] The solar heat collecting system 1 according to this embodiment also increases the amount of heat acquired, similarly to the above-described embodiments.

[0117] (First Modification) Next, a first modification of each of the first and second embodiments will be described with reference to FIGS. 6A and 6B.

[0118] 6A and 6B , the solar heat collecting system 1 according to the first modified example includes a cover member 27 that covers the space between the opposing surface 10c and the installation target object 5. The cover member 27 is formed from a light-transmitting material and has a plate shape.

[0119] 6A , when the tilt angle β is smaller than the complementary angle of the winter solar altitude hw, the cover member 27 extends from the northern edge of a certain solar heat collecting member 10 substantially parallel to the direction of solar radiation at the winter solar altitude hw. In this example, the cover member 27 reaches the southern edge of the adjacent solar heat collecting member 10 on the north side. The space between the facing surface 10c and the roof 3 is closed on the north side by the cover member 27.

[0120] 6B , when the tilt angle β is greater than the complementary angle of the winter solar altitude hw, the cover member 27 extends from the southern edge of a certain solar heat collecting member 10 substantially parallel to the direction of solar radiation at the summer solar altitude hs. In this example, the cover member 27 reaches the northern edge of the adjacent solar heat collecting member 10 on the lower side. The space between the facing surface 10c and the wall 4 is closed on the lower side by the cover member 27.

[0121] According to the first modified example, the cover member 27 is optically transparent and does not prevent sunlight from being irradiated onto the installation object 5. The installation object 5 can receive radiant heat from sunlight. The cover member 27 closes the space between the opposing surface 10c and the installation object 5, thereby maintaining heat. The solar heat collecting member 10 can acquire greater radiant heat Q2 and convective heat Q3.

[0122] The cover member 27 does not necessarily have to reach the edge of the adjacent solar heat collecting member 10. Even if the cover member 27 terminates midway, it is possible to keep the space between the opposing surface 10c and the installation object 5 warm, thereby increasing the amount of heat acquired.

[0123] (Second Modification) Next, a second modification of each of the first and second embodiments will be described with reference to FIGS. 7A and 7B.

[0124] 7A and 7B , the solar heat collecting system 1 according to the second modified example also includes a plate-shaped cover member 27 made of a light-transmitting material. The cover member 27 covers the space between the opposing surface 10c and the installation target 5, and also covers the space on the light-receiving surface 10b side. The cover member 27 extends parallel to the outer surface of the installation target 5, and is supported by the edges of the multiple solar heat collecting members 10.

[0125] 7A , when the tilt angle β is smaller than the complementary angle of the winter solar altitude hw, the northern edge of the solar heat collecting member 10 is spaced upward from the installation target 5. The cover member 27 is supported by the northern edges of the multiple solar heat collecting members 10, and extends above the installation target 5 and parallel to the installation target 5. The multiple solar heat collecting members 10 are arranged between the installation target 5 and the cover member 27. Both the space on the opposing surface 10c side and the space on the light-receiving surface 10b side are covered by the cover member 27.

[0126] 7B , when the tilt angle β is larger than the complementary angle of the winter solar altitude hw, the southern edge of the solar heat collecting member 10 is spaced south from the installation target 5. The cover member 27 is supported by the southern edges of the multiple solar heat collecting members 10, and extends parallel to the installation target 5 on the south side of the installation target 5. The multiple solar heat collecting members 10 are arranged between the installation target 5 and the cover member 27. Both the space on the opposing surface 10c side and the space on the light-receiving surface 10b side are covered by the cover member 27.

[0127] According to the second modification, similarly to the first modification, the installation object 5 can receive radiant heat from sunlight, and the opposing surface 10c can acquire greater amounts of radiant heat Q2 and convective heat Q3. Furthermore, the space on the light-receiving surface 10b side is closed off by the cover member 27, thereby maintaining heat. The light-receiving surface 10b can also receive convective heat Q5 from the space, further increasing the amount of heat acquired.

[0128] (Third Modification) Next, a third modification of each of the first and second embodiments will be described with reference to FIGS. 8A and 8B.

[0129] As shown in Figures 8A and 8B, the light receiving surface 10b and the opposing surface 10c of the solar heat collecting member 10 do not necessarily have to be flat. In the illustrated third modified example, the light receiving surface 10b has multiple recesses 16. Each recess 16 is provided in one-to-one correspondence with a hollow portion 10a. One of the four surfaces defining the hollow portion 10a is curved, which slightly reduces the cross-sectional area of ​​the hollow portion 10a but increases the surface area of ​​the hollow portion 10a. The surface area of ​​the light receiving surface 10b is also increased compared to when the light receiving surface 10b is flat. Furthermore, the projected area of ​​the solar heat collecting member 10 onto the light receiving surface 10b can be maintained even if the solar altitude changes from the set winter solar altitude hw.

[0130] According to the third variant, by increasing the surface area of ​​the hollow portion 10a and the light receiving surface 10b and maintaining the projection area of ​​sunlight, more radiant heat Q1 from sunlight can be input, and the efficiency of heat transfer from the heat collecting member main body 11 to the heat medium M is improved.

[0131] (Fourth Modification) Next, a fourth modification of each of the first and second embodiments will be described with reference to FIGS. 9A and 9B.

[0132] The solar heat collecting member 10 may have fins 17 protruding from at least one of the light-receiving surface and the opposing surface. In a fourth modified example shown in Figures 9A and 9B, a plurality of fins 17 protrude from the opposing surface 10c. As just one example, the plurality of fins 17 are aligned in the width direction of the solar heat collecting member 10, and each fin 17 protrudes from the opposing surface 10c perpendicular to the opposing surface 10c and extends in the longitudinal direction of the solar heat collecting member 10.

[0133] According to the fourth modified example, the surface area of ​​the solar heat collecting member 10 increases on the opposing surface 10c side. Therefore, the solar heat collecting member 10 can acquire larger radiant heat Q2 and convective heat Q3 on the opposing surface 10c side.

[0134] (Fifth Modification) Next, a fifth modification of each of the first and second embodiments will be described with reference to FIGS. 10A and 10B.

[0135] 10A and 10B , in the fifth modified example, a plurality of fins 17 protrude from both the opposing surface 10 c and the light-receiving surface 10 b. The arrangement, protruding direction, and extending direction of the fins 17 are the same as those in the fourth modified example. Furthermore, as in the second modified example, the space on the light-receiving surface 10 b side is covered by a cover member 27 together with the space on the opposing surface 10 c side.

[0136] According to the fifth modified example, the surface area of ​​the solar heat collecting member 10 is increased on the light-receiving surface 10b side. Therefore, the solar heat collecting member 10 can acquire a larger amount of radiant heat Q1 on the light-receiving surface 10b side. Because the space on the light-receiving surface 10b side is covered, convection heat Q5 can also be acquired. Combined with the increased surface area on the light-receiving surface 10b side, the heat collection performance on the light-receiving surface 10b side is improved.

[0137] (Other Modifications) Although the embodiments and their modifications have been described above, the above configurations can be modified as appropriate within the scope of the present disclosure. For example, any feature described in the above embodiments or modifications may be combined with other modifications.

[0138] In the above embodiment and its modified examples, the solar heat collecting member 10 is formed in a panel shape, as shown not only in Figure 1A but also in Figures 11A and 11B. Furthermore, in the installation position of the solar heat collecting member 10, the longitudinal direction of the solar heat collecting member 10 extends horizontally, in other words, in a direction perpendicular to the extension direction of the surface of the installation object 5 (the slope direction of the roof outer surface in the case of a roof 3, and the extension direction of the wall outer surface in the case of a wall 4). This configuration is one example and can be modified as appropriate.

[0139] Regarding the installation posture, for example, as shown in Fig. 12 , in the installation posture of the solar heat collecting member 10, the longitudinal direction of the solar heat collecting member 10 may be inclined with respect to the horizontal direction or with respect to the extension direction of the surface of the installation target 5. Fig. 12 shows a case where the inclination of the surface of the installation target 5 with respect to the horizontal plane S is relatively gentle. Although not shown, the solar heat collecting member 10 can also be disposed at an incline, as in Fig. 12 , when the inclination of the surface of the installation target 5 with respect to the horizontal plane S is relatively steep, or when the surface of the installation target 5 is perpendicular to the horizontal plane S.

[0140] 13A and 13B , in the installation posture of the solar heat collecting member 10, the longitudinal direction of the solar heat collecting member 10 may extend parallel to the extension direction of the surface of the installation target 5. Fig. 13A shows a case where the inclination of the surface of the installation target 5 with respect to the horizontal plane S is relatively gentle. Fig. 13B shows a case where the inclination of the surface of the installation target 5 with respect to the horizontal plane S is relatively steep.

[0141] Regarding the shape or structure of the solar heat collecting member 10, for example, the solar heat collecting member 10 may be a rectangular tube as shown in Figures 14A and 14B, a cylindrical shape as shown in Figures 15A and 15B, or a semi-cylindrical shape as shown in Figure 16. The solar heat collecting member 10 may be made of an aluminum alloy, as in the above embodiment. In that case, the light receiving surface 10b is colored black (see the cross-hatched area in each figure), thereby improving the emissivity.

[0142] Both Figures 14B and 15B show cases where the longitudinal direction of the solar heat collecting member 10 extends parallel to the extension direction of the surface of the installation target 5. The solar heat collecting member 10 shown in Figure 16 may be arranged in the same manner as in Figures 14B and 15B. Although detailed illustration is omitted, each of the solar heat collecting members 10 shown in Figures 14A, 14B, and 16 may be horizontal as shown in Figures 11A and 11B, or may be inclined as shown in Figures 12A and 12B.

[0143] The surface of the installation target 5 does not necessarily have to face due south. If the surface of the installation target 5 faces a direction other than due south, the solar heat collecting member 10 may have a partially curved surface so that the solar heat collecting member faces due south.

[0144] The location of the building 2 is not limited to the low latitudes of the Northern Hemisphere, but may be in the Southern Hemisphere, a latitude lower than the Tropic of Capricorn, or the Polar Circle. In this case, the installation posture and installation interval L are appropriately changed according to the solar altitude or the daylight hours.

[0145] This application claims priority from Japanese Patent Application No. 2024-017459, filed February 7, 2024. Japanese Patent Application No. 2024-017459 is incorporated herein by reference.

[0146] The present disclosure may include the following aspects. (Aspect 1) A solar heat collecting system comprising a plurality of solar heat collecting members installed on an installation object that constitutes a building, each of the solar heat collecting members having: a hollow portion through which a heat medium flows, a light-receiving surface that receives sunlight, a facing surface that faces the installation object on the opposite side from the light-receiving surface, and a non-insulated portion that allows convective heat transfer between the light-receiving surface and the facing surface and the ambient air, and transferring radiant heat from the sunlight and convective heat from the ambient air to the heat medium; the facing surface is installed on the installation object in an installation position that forms a space between it and the installation object; and the plurality of solar heat collecting members are arranged at predetermined installation intervals from one another. (Aspect 2) The solar heat collecting system according to Aspect 1, further comprising: a heat storage material filled in a hollow portion provided in the installation object. (Aspect 3) The solar heat collecting system according to Aspect 1 or 2, further comprising: a cover member molded from a light-transmitting material that covers the space between the facing surface and the installation object. (Aspect 4) The solar heat collecting system according to Aspect 3, wherein the cover member further covers a space on the light-receiving surface side. (Aspect 5) The solar heat collecting system according to any of Aspects 1 to 4, wherein each of the solar heat collecting members further has a recess on the light-receiving surface. (Aspect 6) The solar heat collecting system according to any of Aspects 1 to 5, wherein each of the solar heat collecting members further has a fin protruding from at least one of the light-receiving surface and the opposing surface. (Aspect 7) The solar heat collecting system according to any of Aspects 1 to 6, wherein the solar heat collecting member is made of an extruded aluminum alloy. (Aspect 8) The solar heat collecting system according to any of Aspects 1 to 7, wherein, in the installed position, the light-receiving surface of each of the solar heat collecting members is perpendicular to the direction of solar radiation at a winter solar altitude. (Aspect 9) A solar heat collecting system according to any one of Aspects 1 to 8, wherein the tilt angle of the outer surface of the installation object with respect to the horizontal plane is smaller than the complementary angle of the winter solar altitude, and the plurality of solar heat collecting elements are arranged at predetermined intervals from each other so that each solar heat collecting element is not in the shadow of an adjacent solar heat collecting element at the winter solar altitude.(Aspect 10) The solar heat collecting system according to Aspect 9, wherein the installation interval L satisfies the following formula: L≧H / sin(β+hw), where L is the installation interval, H is the height of the light receiving surface, β is the tilt angle of the installation object, and hw is the winter solar altitude. (Aspect 11) The solar heat collecting system according to any of Aspects 1 to 8, wherein the tilt angle of the outer surface of the installation object with respect to the horizontal plane is greater than the complement angle of the winter solar altitude, and the multiple solar heat collecting members are arranged at predetermined installation intervals from each other so that each is not in the shadow of an adjacent solar heat collecting member at the summer solar altitude. (Aspect 12) When the installation interval is L, the height of the light receiving surface is H, the inclination angle of the installation object is β, the winter solar altitude is hw, and the summer solar altitude is hs, the installation interval L satisfies the following formula: L≧H{sin(β+hw)+cos(β+hw) / tan(hs+β)}. The solar heat collecting system according to aspect 11.

[0147] DESCRIPTION OF SYMBOLS 1 Solar heat collecting system 2 Building 3 Roof 4 Wall 5 Installation object 5a Hollow portion 10 Solar heat collecting member 10a Hollow portion 10b Light receiving surface 10c Opposing surface 10d Non-insulated portion 11 Heat collecting member body 11a First main wall 11b Second main wall 11c Side wall 11d Partition wall 12 First header 12a Cover plate 12b Peripheral wall 12c Internal space 13 Second header 13a Cover plate 13b Peripheral wall 13c Internal space 14 Inlet 15 Outlet 16 Recess 17 Fin 21 Heat medium tank 21a Supply tank 21b Recovery tank 22 Heat medium circulation line 22a Inlet line 22b Outlet line 23 Pump 26 Heat storage material 27 Cover member 29 Support structure M Heat medium H Height L Installation interval Ls Shadow length Q1 Radiant heat Q2 Radiant heat Q3 Convective heat Q4 Latent heat Q5 Convective heat h Solar altitude hs Summer solar altitude hw Winter solar altitude S Horizontal plane α Inclination angle β Inclination angle

Claims

1. A solar heat collecting system comprising a plurality of solar heat collecting members installed on an installation object that constitutes a building, each of the solar heat collecting members having a hollow section through which a heat medium flows, a light-receiving surface that receives sunlight, an opposing surface that faces the installation object on the opposite side of the light-receiving surface, and a non-insulated section that performs convective heat transfer between the light-receiving surface and the opposing surface and the ambient air, and transferring radiant heat from the sunlight and convective heat from the ambient air to the heat medium, the opposing surface being installed on the installation object in an installation position that forms a space between it and the installation object, and the plurality of solar heat collecting members being arranged at predetermined installation intervals from each other.

2. The solar heat collecting system according to claim 1, further comprising a heat storage material filled in a hollow portion provided in the installation object.

3. The solar heat collecting system according to claim 1, further comprising a cover member molded from a light-transmitting material and covering the space between the opposing surface and the installation object.

4. The solar heat collecting system according to claim 3, wherein the cover member further covers the space on the light receiving surface side.

5. A solar heat collecting system according to any one of claims 1 to 4, wherein each of the solar heat collecting members further has a recess in the light receiving surface.

6. A solar heat collecting system according to any one of claims 1 to 4, wherein each of the solar heat collecting members further has a fin protruding from at least one of the light receiving surface and the opposing surface.

7. A solar heat collecting system according to any one of claims 1 to 4, wherein the solar heat collecting member is made of an extruded aluminum alloy material.

8. A solar heat collecting system according to any one of claims 1 to 4, wherein, in the installation position, the light receiving surface of each of the solar heat collecting members is perpendicular to the direction of solar radiation at the winter solar altitude.

9. A solar heat collecting system as described in any one of claims 1 to 4, wherein the inclination angle of the outer surface of the installation object with respect to the horizontal plane is smaller than the complementary angle of the winter solar altitude, and the multiple solar heat collecting elements are arranged at predetermined intervals from each other so that each element is not in the shadow of an adjacent solar heat collecting element at the winter solar altitude.

10. The solar heat collecting system of claim 9, wherein the installation interval L satisfies the following formula: L≧H / sin(β+hw), where L is the installation interval, H is the height of the light receiving surface, β is the inclination angle of the installation object, and hw is the winter solar altitude.

11. A solar heat collecting system as described in any one of claims 1 to 4, wherein the inclination angle of the outer surface of the installation object with respect to the horizontal plane is greater than the complementary angle of the winter solar altitude, and the multiple solar heat collecting elements are arranged at predetermined intervals from each other so that each element is not in the shadow of an adjacent solar heat collecting element at the summer solar altitude.

12. The solar heat collecting system according to claim 11, wherein the installation interval L satisfies the following formula: L≧H{sin(β+hw)+cos(β+hw) / tan(hs+β)}, where L is the installation interval, H is the height of the light receiving surface, β is the inclination angle of the installation object, hw is the winter solar altitude, and hs is the summer solar altitude.

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