US20100307480A1 - Non-tracking solar collectors - Google Patents
Non-tracking solar collectors Download PDFInfo
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- US20100307480A1 US20100307480A1 US12/375,490 US37549007A US2010307480A1 US 20100307480 A1 US20100307480 A1 US 20100307480A1 US 37549007 A US37549007 A US 37549007A US 2010307480 A1 US2010307480 A1 US 2010307480A1
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- prism
- solar collector
- collector according
- radiation
- tracking solar
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- 238000005253 cladding Methods 0.000 claims abstract description 26
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- 230000005611 electricity Effects 0.000 description 5
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- 229920002223 polystyrene Polymers 0.000 description 3
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- 238000010438 heat treatment Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
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- 230000020169 heat generation Effects 0.000 description 1
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Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
- H01L31/0543—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the refractive type, e.g. lenses
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
- F24S23/10—Prisms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
- F24S23/30—Arrangements for concentrating solar-rays for solar heat collectors with lenses
- F24S23/31—Arrangements for concentrating solar-rays for solar heat collectors with lenses having discontinuous faces, e.g. Fresnel lenses
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
- H01L31/0547—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B10/00—Integration of renewable energy sources in buildings
- Y02B10/10—Photovoltaic [PV]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B10/00—Integration of renewable energy sources in buildings
- Y02B10/20—Solar thermal
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/52—PV systems with concentrators
Definitions
- THIS invention relates to non-tracking solar collectors.
- the function of the solar collector is to concentrate the radiation onto relatively small photovoltaic (PV) cells, while in the case of heat generation, the function of the collector is generally to concentrate the radiation onto a conduit or container conveying or storing a fluid, such as a liquid or gas, the temperature of which is to be elevated.
- PV photovoltaic
- Concentrator systems that employ focussing lenses for primary concentration require either biaxial tracking, i.e. both N-S and E-W, or a secondary tracking system that varies the position of the lens or target in order to ensure that the collected radiation is focussed correctly on the target, i.e. PV cells or fluid conduit or container.
- the latter type of system frequently referred to as a 1.5 times tracking system, typically moves the assembly of lenses, associated reflectors and/or target either individually or in arrays. The apparatus required to achieve such movement can however be expensive and complicated.
- One example of a known solar collector uses an assembly of parallel wedges to reduce the angular dispersion of incident solar radiation. Radiation refracted by the wedges is then transported to the target by internal reflection in thin modules composed of wedge-shaped glass elements.
- a disadvantage of the system is however a relatively low concentration ratio of around 2:1.
- “Concentration ratio” refers to the ratio of the area of the solar aperture, i.e. the area on which the solar radiation is incident, to the area of the target onto which the radiation is concentrated. The low concentration ratio is indicative of a low level of efficiency.
- Another example described in U.S. Pat. No. 4,344,417, makes use of a narrow, wedge-shaped collector to receive incident radiation and reflect it internally to the target area. The concentration ratio is however again relatively low, indicating a low level of efficiency.
- JP 11305130 and JP 62266879 Further examples of prior art collectors are described in JP 11305130 and JP 62266879.
- the collector has wedge-shaped prisms and external reflectors arranged at a divergent angle with respect to one another in order to collect radiation over a larger solar aperture and to concentrate such radiation, by both internal reflection in the prisms and external reflection from the reflectors, onto a solar battery.
- N-S aligned, connected wedge-shaped prisms are again used to concentrate incident radiation by internal reflection.
- the prism assembly is used in conjunction with a conventional solar panel.
- a non-tracking solar collector comprising:
- the preferred refractor is a linear refractor, such as a linear Fresnel lens.
- the refractors can be spaced apart from one another by radiation-transmitting panels which are continuous with the refractors, and in this event the collector may be configured to form part of a roof or wall cladding structure, such as a corrugated expanse of roof or wall cladding in which the linear refractors are arranged at the crests of the corrugations and the radiation-transmitting panels at the valleys thereof.
- a roof or wall cladding structure such as a corrugated expanse of roof or wall cladding in which the linear refractors are arranged at the crests of the corrugations and the radiation-transmitting panels at the valleys thereof.
- the narrow edges of the prisms will extend in the pitch direction of an expanse of roof cladding.
- the narrow ends of the prisms extend E-W in a pitched roof cladding structure the ridge cap of which extends N-S.
- linear refractors and light-transmitting panels form a flat expanse of roof or wall cladding.
- each reflector structure may include a pair of convergent reflector panels arranged to reflect radiation which is transmitted by the radiation-transmitting panels onto the prisms for collection and concentration by the prisms.
- the preferred embodiments of the invention include a radiation transmitting secondary solar concentrator at the wider end of each prism.
- This concentrator may have side walls, typically planar or concave, which converge towards one another to a width less than that of the wider end of the prism.
- the secondary solar concentrator should be made of a material with a higher refractive index than the material of which the prism is made and the prism and secondary solar concentrator should meet one another at a curved interface where a convex surface of the secondary solar concentrator mates with a concave surface of the prism.
- FIG. 1 diagrammatically illustrates a pitched roof cladding structure incorporating a solar collector according to this invention
- FIG. 2 shows a diagrammatic cross-sectional detail of a portion of the solar collector forming part of the roof cladding structure seen in FIG. 1 ;
- FIG. 3 illustrates the use of a secondary solar radiation concentrator.
- FIG. 1 shows a roof cladding structure 10 comprising pitched sections 12 and 14 aligned in an E-W direction with the ridge cap 16 of the roof structure extending in a N-S direction, i.e. into the plane of the paper in FIG. 1 .
- the roof cladding structure has a corrugated profile, with arcuate crests, peaks or high points 18 alternating with arcuate valleys, troughs or low points 20 .
- the cladding structure incorporates a solar collector or concentrator in which the crests 18 of the corrugations are provided by arcuate strips 22 designed as linear refractors, for example as linear Fresnel refractors.
- the refractors may be made of a suitable radiation refracting material such as glass, acrylic or polystyrene and are treated with ultraviolet (UV) filter material in view of their exposure to solar radiation.
- the valleys 20 of the corrugations are provided by radiation-transmitting strips or panels 24 made of a clear acrylic or other suitable material, treated with UV filter material if necessary.
- each linear refractor 22 Located beneath each linear refractor 22 is a prism 26 made of, for instance, glass, acrylic or polystyrene.
- the individual prisms 26 are elongate both vertically and in the pitch direction of the roof cladding structure 10 , i.e. in the E-W direction.
- Each prism has major, planar side surfaces 28 and 30 which converge at an acute angle 32 , in this case about 3°, to one another towards a relatively narrow end 34 of the prism.
- the opposite end 36 of the prism is relatively wide and has mounted to it a heat transmitting coupler 38 in heat transmitting contact with a pipe 40 conveying a fluid, such as water or a gas, which is to be heated by concentrated solar radiation.
- the narrow ends 34 of the prisms point to and are attached to the underside of the linear refractors 22 . Although the narrow ends are shown as sharp edges, they may in practice be slightly truncated.
- the prisms are arranged with their narrow edges 34 extending E-W, i.e in the pitch direction and the linear refractors are designed to refract solar radiation incident thereon onto the major side surfaces 28 and 30 of the prisms.
- reflector structures 42 each composed of upwardly inclined pairs of reflectors 44 .
- these reflectors may be of polished aluminium or they may be of steel with external surfaces carrying reflective films.
- the reflectors are connected to the wider ends 36 of the prisms and their upper ends are joined to one another and to the valleys 20 of the corrugations by connecting strips 46 .
- the reflectors 44 are inclined at a latitude angle 48 .
- FIG. 2 Preferred dimensions for the solar collector components are shown in FIG. 2 .
- the numeral 50 designates exemplary, parallel solar rays which are incident on each of the linear refractors at mid-day i.e. 12h00 and an overhead latitude angle. Such rays are refracted by the linear refractors onto the side surfaces 28 and 30 of the associated prism 26 .
- the refracted rays are incident on the side surfaces 28 and 30 at angles 52 of about 20°. This is within the acceptance range for the prism, so the radiation enters the prism rather than being externally reflected off a surface 28 or 30 .
- the surfaces 28 and 30 may be treated with a non-reflective coating to increase the acceptance range if necessary.
- Radiation which enters the prisms undergoes normal refraction at the air/prism material interface and thereafter undergoes total internal reflection within the prisms for eventual concentration on the pipes 40 in order to heat the fluid conveyed in the pipes.
- the numeral 54 indicates solar rays which are incident on the roof cladding structure but which do not fall on the refractors 22 . These may for instance be solar rays at around 08h00 and 16h00 during the day with the sun at an overhead latitude angle. Such rays pass through the intermediate panels 24 and are incident on the reflector panels 44 which reflect the rays onto the surfaces 28 and 30 . These rays also enter the prisms and are internally reflected therein for eventual concentration on the pipes 40 . Thus the reflector structures provide a means for collecting radiation which would otherwise be lost and for directing it into the prisms for eventual concentration.
- the numeral 56 indicates solar rays which are incident on the linear refractors at mid-day and emanate from the sun at a limit solstice latitude angle of 23.5°. It will be noted that such rays pass, parallel to the adjacent reflector panel 44 , to the wider end of the prism where acceptance and internal reflection concentrates them on the pipes 40 .
- the numeral 58 indicates solar rays, emanating from a 20° latitude angle, which are incident at mid-day on the roof cladding structure. Rays 58 which pass through the panels 24 are directly incident on the wider ends of the prisms, which accept them for internal reflection and concentration.
- the solar collector effectively forms an integral part of the actual roof cladding structure and there is no requirement, as with conventional solar collectors, to mount a separate collector externally on a roof or other supporting structure.
- the concentrated solar radiation is used to heat up a fluid conveyed in a pipe. It will however be understood that the apparatus could equally well be used for electricity generation, in which case the radiation could be concentrated on PV cells located at the wider ends of the prisms. The random internal reflection of the radiation also ensures that there is an equal distribution of radiation on the PV cells.
- roof cladding structure in the illustrated embodiment has a corrugated profile it is also envisaged that embodiments in which alternating linear refractors and intermediate, radiation-transmitting panels are arranged in a flat configuration would also operate efficiently. In such a configuration the refractors and intermediate panels would be flat and would, in combination, form a flat expanse of roof or wall cladding. Further embodiments are also envisaged in which the reflectors 44 are offset for use as wall cladding structures.
- FIG. 3 illustrates a modified version of the apparatus.
- a secondary solar radiation concentrator is indicated by the reference numeral 70 .
- the concentrator extends for the full length of the prism 26 and is of a solid or liquid material having a higher refractive index than the material of which the prism is made.
- the prism is made of an acrylic having a refractive index of less than 1.5 and the secondary concentrator 70 of polystyrol or glass having a refractive index of more than 1.5.
- the secondary concentrator is placed at the wider, lower end of the prism 26 and is intimately connected to the prism at an upwardly convex interface defined by a convex surface 72 of the secondary concentrator and a concave surface 74 of the prism.
- the secondary concentrator 70 has planar side surfaces 76 and 78 and a planar lower surface 80 to which the coupler 38 is intimately attached. As before the coupler 38 is in intimate contact with the pipe 40 .
- the numeral 82 indicates a solar ray which enters the prism 26 through the side surface 30 , is refracted at the prism/air interface, travels through the lower part of the prism to the convex interface between the prism and the solar concentrator 70 where it is refracted into the secondary concentrator, and is thereafter reflected internally off the side surface 76 of the secondary concentrator and onto the coupler 38 . It will be understood that other solar rays that have been internally reflected in the prism will likewise be refracted into the secondary concentrator 70 for subsequent passage directly or through internal reflection onto the coupler.
- inwardly facing mirrors 84 may be placed against the surfaces 76 and 78 or these surfaces may themselves be mirrored.
- the side surfaces of the secondary concentrator may be concave as indicated diagrammatically by the numeral 86 , or convex.
- the convex interface defined by the surfaces 72 and 74 is preferred to a planar, horizontal interface because it will tend to refract radiation in the appropriate direction for subsequent reflection onto the coupler 38 .
- a secondary concentrator having a convex interface as illustrated may be referred to as a secondary convex concentrator (SCC).
Abstract
The invention concerns a non-tracking solar collector which includes laterally spaced, radiation-transmitting prisms (26) which are wedge-shaped in cross-section. Each prism (26) has major side surfaces (28, 30) converging at an acute angle (32) to a relatively narrow end (34) of the prism (26), and an opposite, relatively wide end (36). For each prism (26) there is a refractor (22), typically a linear refractor such as a linear Fresnel lens, arranged over the prism (26) to refract solar radiation incident thereon onto the major side surfaces (28, 30) of the prism (26), as the sun moves relative to the earth, at angles allowing such radiation to enter the prism (26) and be internally reflected towards a target (38) at the relatively wide (36) end of the prism (26). The refractors (22) are spaced laterally apart from one another, possibly by intermediate, radiation transmitting panels (24) which are continuous with the refractors (22). In the preferred construction, the refractors (22) and intermediate panels (24) form an integral part of a roof or wall cladding structure.
Description
- THIS invention relates to non-tracking solar collectors.
- There exist numerous devices designed to concentrate solar radiation for the purpose of generating electricity or heat. In the case of electricity generation, the function of the solar collector is to concentrate the radiation onto relatively small photovoltaic (PV) cells, while in the case of heat generation, the function of the collector is generally to concentrate the radiation onto a conduit or container conveying or storing a fluid, such as a liquid or gas, the temperature of which is to be elevated.
- In the known devices it is recognised that for efficient collection and concentration of the solar energy it is necessary for the device to track the sun as the position of the sun relative to the earth changes during the year and/or as the position of the sun relative to the earth changes during the day. A single-axis system aligned N-S (north-south) should track the sun E-W (east-west) during the day, while a single axis system aligned E-W should track the sun N-S during the year.
- Concentrator systems that employ focussing lenses for primary concentration require either biaxial tracking, i.e. both N-S and E-W, or a secondary tracking system that varies the position of the lens or target in order to ensure that the collected radiation is focussed correctly on the target, i.e. PV cells or fluid conduit or container. The latter type of system, frequently referred to as a 1.5 times tracking system, typically moves the assembly of lenses, associated reflectors and/or target either individually or in arrays. The apparatus required to achieve such movement can however be expensive and complicated.
- Where electricity is to be generated with the use of PV cells an added disadvantage of systems which employ a focussing lens is the fact that dirt particles on the lens create shadows which result in uneven distribution of radiation on the PV cells. Apart from the fact that this reduces the efficiency of the PV cells, it can also cause permanent damage to the cells. Dirt particles on the reflectors of a reflector-type concentrating system can also be problematical.
- One example of a known solar collector, described in U.S. Pat. No. 4,282,862, uses an assembly of parallel wedges to reduce the angular dispersion of incident solar radiation. Radiation refracted by the wedges is then transported to the target by internal reflection in thin modules composed of wedge-shaped glass elements. A disadvantage of the system is however a relatively low concentration ratio of around 2:1. “Concentration ratio” refers to the ratio of the area of the solar aperture, i.e. the area on which the solar radiation is incident, to the area of the target onto which the radiation is concentrated. The low concentration ratio is indicative of a low level of efficiency. Another example, described in U.S. Pat. No. 4,344,417, makes use of a narrow, wedge-shaped collector to receive incident radiation and reflect it internally to the target area. The concentration ratio is however again relatively low, indicating a low level of efficiency.
- Further examples of prior art collectors are described in JP 11305130 and JP 62266879. In the former case, the collector has wedge-shaped prisms and external reflectors arranged at a divergent angle with respect to one another in order to collect radiation over a larger solar aperture and to concentrate such radiation, by both internal reflection in the prisms and external reflection from the reflectors, onto a solar battery. In the latter case N-S aligned, connected wedge-shaped prisms are again used to concentrate incident radiation by internal reflection. The prism assembly is used in conjunction with a conventional solar panel.
- An additional disadvantage of each of the known systems described above is the necessity for a tracking system to enable the system to track the sun.
- Yet another disadvantage is the fact that each of these systems provides an independent collector which must be mounted externally on a roof or other supporting structure where it will be appropriately exposed to solar radiation.
- It is an objective of the present invention to provide an efficient solar collector which does not require any independent tracking system.
- According to the present invention there is provided a non-tracking solar collector comprising:
-
- a plurality of laterally spaced, radiation-transmitting prisms which are wedge-shaped in cross-section and which have major side surfaces converging at an acute angle to a relatively narrow end of the prism, each prism having an opposite, relatively wide end; and
- for each prism, a refractor arranged over the prism to refract solar radiation incident thereon onto the major side surfaces of the prism, as the sun moves relative to the earth, at angles allowing such radiation to enter the prism and be internally reflected therein towards a target at or adjacent the relatively wide end of the prism, the refractors being spaced laterally apart from one another.
- The preferred refractor is a linear refractor, such as a linear Fresnel lens.
- The refractors can be spaced apart from one another by radiation-transmitting panels which are continuous with the refractors, and in this event the collector may be configured to form part of a roof or wall cladding structure, such as a corrugated expanse of roof or wall cladding in which the linear refractors are arranged at the crests of the corrugations and the radiation-transmitting panels at the valleys thereof.
- Typically the narrow edges of the prisms will extend in the pitch direction of an expanse of roof cladding. In one preferred configuration, the narrow ends of the prisms extend E-W in a pitched roof cladding structure the ridge cap of which extends N-S.
- In an alternative arrangement the linear refractors and light-transmitting panels form a flat expanse of roof or wall cladding.
- The narrow ends of the prisms can be adjacent to or in contact with the linear refractors, and there may be reflector structures between the prisms. In this case each reflector structure may include a pair of convergent reflector panels arranged to reflect radiation which is transmitted by the radiation-transmitting panels onto the prisms for collection and concentration by the prisms.
- The preferred embodiments of the invention include a radiation transmitting secondary solar concentrator at the wider end of each prism. This concentrator may have side walls, typically planar or concave, which converge towards one another to a width less than that of the wider end of the prism.
- The secondary solar concentrator should be made of a material with a higher refractive index than the material of which the prism is made and the prism and secondary solar concentrator should meet one another at a curved interface where a convex surface of the secondary solar concentrator mates with a concave surface of the prism.
- In electricity generating applications, there may be a PV cell at the wider end of each prism or at the end of the secondary solar concentrator.
- In heating applications, there may be a pipe conveying a fluid which is to be heated at the wider end of the prism or at the end of the secondary solar concentrator.
- The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
-
FIG. 1 diagrammatically illustrates a pitched roof cladding structure incorporating a solar collector according to this invention; -
FIG. 2 shows a diagrammatic cross-sectional detail of a portion of the solar collector forming part of the roof cladding structure seen inFIG. 1 ; and -
FIG. 3 illustrates the use of a secondary solar radiation concentrator. -
FIG. 1 shows a roof cladding structure 10 comprisingpitched sections ridge cap 16 of the roof structure extending in a N-S direction, i.e. into the plane of the paper inFIG. 1 . - As shown in the diagrammatic cross-section of
FIG. 2 , the roof cladding structure has a corrugated profile, with arcuate crests, peaks orhigh points 18 alternating with arcuate valleys, troughs or low points 20. The cladding structure incorporates a solar collector or concentrator in which thecrests 18 of the corrugations are provided byarcuate strips 22 designed as linear refractors, for example as linear Fresnel refractors. The refractors may be made of a suitable radiation refracting material such as glass, acrylic or polystyrene and are treated with ultraviolet (UV) filter material in view of their exposure to solar radiation. The valleys 20 of the corrugations are provided by radiation-transmitting strips orpanels 24 made of a clear acrylic or other suitable material, treated with UV filter material if necessary. - Located beneath each
linear refractor 22 is aprism 26 made of, for instance, glass, acrylic or polystyrene. Theindividual prisms 26 are elongate both vertically and in the pitch direction of the roof cladding structure 10, i.e. in the E-W direction. Each prism has major,planar side surfaces acute angle 32, in this case about 3°, to one another towards a relativelynarrow end 34 of the prism. Theopposite end 36 of the prism is relatively wide and has mounted to it aheat transmitting coupler 38 in heat transmitting contact with apipe 40 conveying a fluid, such as water or a gas, which is to be heated by concentrated solar radiation. - The
narrow ends 34 of the prisms point to and are attached to the underside of thelinear refractors 22. Although the narrow ends are shown as sharp edges, they may in practice be slightly truncated. The prisms are arranged with theirnarrow edges 34 extending E-W, i.e in the pitch direction and the linear refractors are designed to refract solar radiation incident thereon onto themajor side surfaces - Located between
adjacent prisms 26 arereflector structures 42 each composed of upwardly inclined pairs ofreflectors 44. By way of example, these reflectors may be of polished aluminium or they may be of steel with external surfaces carrying reflective films. At their lower ends the reflectors are connected to the wider ends 36 of the prisms and their upper ends are joined to one another and to the valleys 20 of the corrugations by connecting strips 46. In the preferred arrangement, thereflectors 44 are inclined at a latitude angle 48. - Preferred dimensions for the solar collector components are shown in
FIG. 2 . - During each day the sun moves in an E-W direction relative to the earth and to the illustrated roof cladding structure. During each year, the sun moves in a N-S direction relative to the earth and to the illustrated roof cladding structure, between limit solstice positions at latitude angles of 23.5° north and 23.5° south. The numeral 50 designates exemplary, parallel solar rays which are incident on each of the linear refractors at mid-day i.e. 12h00 and an overhead latitude angle. Such rays are refracted by the linear refractors onto the side surfaces 28 and 30 of the associated
prism 26. With the prism having a refractive index of the order of 1.4 to 1.5, eg acrylic or glass, the refracted rays are incident on the side surfaces 28 and 30 atangles 52 of about 20°. This is within the acceptance range for the prism, so the radiation enters the prism rather than being externally reflected off asurface surfaces - Radiation which enters the prisms undergoes normal refraction at the air/prism material interface and thereafter undergoes total internal reflection within the prisms for eventual concentration on the
pipes 40 in order to heat the fluid conveyed in the pipes. - The numeral 54 indicates solar rays which are incident on the roof cladding structure but which do not fall on the
refractors 22. These may for instance be solar rays at around 08h00 and 16h00 during the day with the sun at an overhead latitude angle. Such rays pass through theintermediate panels 24 and are incident on thereflector panels 44 which reflect the rays onto thesurfaces pipes 40. Thus the reflector structures provide a means for collecting radiation which would otherwise be lost and for directing it into the prisms for eventual concentration. - The numeral 56 indicates solar rays which are incident on the linear refractors at mid-day and emanate from the sun at a limit solstice latitude angle of 23.5°. It will be noted that such rays pass, parallel to the
adjacent reflector panel 44, to the wider end of the prism where acceptance and internal reflection concentrates them on thepipes 40. - The numeral 58 indicates solar rays, emanating from a 20° latitude angle, which are incident at mid-day on the roof cladding structure.
Rays 58 which pass through thepanels 24 are directly incident on the wider ends of the prisms, which accept them for internal reflection and concentration. - From the above it will be understood that irrespective of the time of day or time of the year the illustrated combination of linear refractors, intermediate light-transmitting panels and reflector structures ensures that a substantial portion of all available radiation which is incident on the roof cladding structure is directed to the prisms at appropriate angles for acceptance by the prisms, whereafter the prisms act, through internal reflection of the radiation, to concentrate the radiation onto the
pipes 40. Thus efficient solar heating of the pipe contents is achieved without the need for any independent tracking system to move the concentrating components in order to track the sun as its position relative to the earth changes. - It will furthermore be understood that the solar collector effectively forms an integral part of the actual roof cladding structure and there is no requirement, as with conventional solar collectors, to mount a separate collector externally on a roof or other supporting structure.
- In the embodiment described above, the concentrated solar radiation is used to heat up a fluid conveyed in a pipe. It will however be understood that the apparatus could equally well be used for electricity generation, in which case the radiation could be concentrated on PV cells located at the wider ends of the prisms. The random internal reflection of the radiation also ensures that there is an equal distribution of radiation on the PV cells.
- It is envisaged that relatively high concentration ratios of the order of 8:1 can be achieved with the solar collector described above and illustrated in the drawings.
- Although the roof cladding structure in the illustrated embodiment has a corrugated profile it is also envisaged that embodiments in which alternating linear refractors and intermediate, radiation-transmitting panels are arranged in a flat configuration would also operate efficiently. In such a configuration the refractors and intermediate panels would be flat and would, in combination, form a flat expanse of roof or wall cladding. Further embodiments are also envisaged in which the
reflectors 44 are offset for use as wall cladding structures. -
FIG. 3 illustrates a modified version of the apparatus. In this version a secondary solar radiation concentrator is indicated by the reference numeral 70. The concentrator extends for the full length of theprism 26 and is of a solid or liquid material having a higher refractive index than the material of which the prism is made. In one example, the prism is made of an acrylic having a refractive index of less than 1.5 and the secondary concentrator 70 of polystyrol or glass having a refractive index of more than 1.5. The secondary concentrator is placed at the wider, lower end of theprism 26 and is intimately connected to the prism at an upwardly convex interface defined by aconvex surface 72 of the secondary concentrator and aconcave surface 74 of the prism. The secondary concentrator 70 has planar side surfaces 76 and 78 and a planar lower surface 80 to which thecoupler 38 is intimately attached. As before thecoupler 38 is in intimate contact with thepipe 40. - The numeral 82 indicates a solar ray which enters the
prism 26 through theside surface 30, is refracted at the prism/air interface, travels through the lower part of the prism to the convex interface between the prism and the solar concentrator 70 where it is refracted into the secondary concentrator, and is thereafter reflected internally off theside surface 76 of the secondary concentrator and onto thecoupler 38. It will be understood that other solar rays that have been internally reflected in the prism will likewise be refracted into the secondary concentrator 70 for subsequent passage directly or through internal reflection onto the coupler. - To ensure that all rays which enter the secondary concentrator 70 are reflected onto the
coupler 38, inwardly facing mirrors 84 (only one shown) may be placed against thesurfaces - Instead of side surfaces 76 and 78 which are planar, the side surfaces of the secondary concentrator may be concave as indicated diagrammatically by the numeral 86, or convex.
- The convex interface defined by the
surfaces coupler 38. A secondary concentrator having a convex interface as illustrated may be referred to as a secondary convex concentrator (SCC). - It will be understood that the SCC seen in
FIG. 3 will increase the concentration ratio further, implying high levels of solar concentration efficiency. - It will be appreciated that the SCC of
FIG. 3 could equally well be used to achieve highly efficient concentration of solar radiation onto a PV cell in place of thecoupler 38 andpipe 40.
Claims (23)
1. A non-tracking solar collector comprising:
a plurality of laterally spaced, radiation-transmitting prisms which are wedge-shaped in cross-section and which have major side surfaces converging at an acute angle to a relatively narrow end of the prism, each prism having an opposite relatively wide end; and
for each prism, a refractor arranged over the prism to refract solar radiation incident thereon onto the major side surfaces of the prism, as the sun moves relative to the earth, at angles allowing such radiation to enter the prism and be internally reflected therein towards a target at or adjacent the relatively wide end of the prism, the refractors being spaced laterally apart from one another.
2. A non-tracking solar collector according to claim 1 wherein the refractor is a linear refractor.
3. A non-tracking solar collector according to claim 2 wherein the refractor is a linear Fresnel lens.
4. A non-tracking solar collector according to claim 1 wherein the refractors are spaced apart from one another by radiation-transmitting panels which are continuous with the refractors.
5. A non-tracking solar collector according to claim 4 wherein the collector is configured to form part of a roof or wall cladding structure.
6. A non-tracking solar collector according to claim 5 wherein the linear refractors and radiation-transmitting panels form a corrugated expanse of roof or wall cladding.
7. A non-tracking solar collector according to claim 6 wherein the linear refractors are arranged at the crests of the corrugations and the radiation-transmitting panels at the valleys thereof.
8. A non-tracking solar collector according to claim 6 wherein the narrow edges of the prisms extend in the pitch direction of an expanse of pitched roof cladding.
9. A non-tracking solar collector according to claim 8 wherein the narrow ends of the prisms extend E-W in a pitched roof cladding structure the ridge cap of which extends N-S.
10. A non-tracking solar collector according to claim 4 wherein the linear refractors and radiation-transmitting panels form a flat expanse of roof or wall cladding.
11. A non-tracking solar collector according to claim 4 wherein the narrow ends of the prism's are adjacent to or in contact with the linear refractors.
12. A non-tracking solar collector according to claim 11 comprising reflector structures between the prisms.
13. A non-tracking solar collector according to claim 12 wherein each reflector structure includes a pair of convergent reflector panels arranged to reflect radiation which is transmitted by the radiation-transmitting panels onto the prisms for collection and concentration by the prisms.
14. A non-tracking solar collector according to claim 1 comprising a radiation transmitting secondary solar concentrator at the wider end of each prism.
15. A non-tracking solar collector according to claim 14 wherein the secondary solar concentrator has side walls which converge towards one another to a width less than that of the wider end of the prism.
16. A non-tracking solar collector according to claim 15 wherein the side walls of the secondary solar concentrator are planar or concave.
17. A non-tracking solar collector according to claim 14 wherein the secondary solar concentrator is made of a material with a higher refractive index than the material of which the prism is made.
18. A non-tracking solar collector according to claim 14 wherein the prism and secondary solar concentrator meet one another at a curved interface.
19. A non-tracking solar collector according to claim 18 wherein a convex surface of the secondary solar concentrator mates with a concave surface of the prism at the interface.
20. A solar collector according to claim 1 comprising a PV cell at the wider end of each prism.
21. A solar collector according to claim 14 comprising a PV cell at an end of the secondary solar collector remote from the prism.
22. A solar collector according to claim 1 comprising a pipe conveying a fluid which is to be heated at the wider end of the prism.
23. A non-tracking solar collector according to claim 14 comprising a pipe conveying a fluid which is to be heated at an end of the secondary solar concentrator remote from the prism.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA2006/06284 | 2006-07-28 | ||
ZA200606284 | 2006-07-28 | ||
ZA200608651 | 2006-10-17 | ||
ZA2006-08651 | 2006-10-17 | ||
PCT/IB2007/052982 WO2008012777A2 (en) | 2006-07-28 | 2007-07-27 | Non-tracking solar collectors |
Publications (1)
Publication Number | Publication Date |
---|---|
US20100307480A1 true US20100307480A1 (en) | 2010-12-09 |
Family
ID=38981864
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/375,490 Abandoned US20100307480A1 (en) | 2006-07-28 | 2007-07-27 | Non-tracking solar collectors |
Country Status (3)
Country | Link |
---|---|
US (1) | US20100307480A1 (en) |
EP (1) | EP2052194A2 (en) |
WO (1) | WO2008012777A2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101681949B (en) | 2007-05-01 | 2013-03-27 | 摩根阳光公司 | Light-guide solar panel and method of fabrication thereof |
WO2010134069A1 (en) | 2009-05-21 | 2010-11-25 | Yohanan Frederic Zweig | Light concentrator, redirector and distributor |
JP5705691B2 (en) * | 2011-09-14 | 2015-04-22 | 信越ポリマー株式会社 | Daylight lens sheet |
Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3467840A (en) * | 1966-07-05 | 1969-09-16 | Melvin Weiner | Solar thermionic convertor |
US4108540A (en) * | 1976-06-17 | 1978-08-22 | Minnesota Mining And Manufacturing Company | Refractor-reflector radiation concentrator |
US5877874A (en) * | 1995-08-24 | 1999-03-02 | Terrasun L.L.C. | Device for concentrating optical radiation |
US5977478A (en) * | 1996-12-05 | 1999-11-02 | Toyota Jidosha Kabushiki Kaisha | Solar module |
US6061181A (en) * | 1997-06-09 | 2000-05-09 | Fereidooni; Fred | Nontracking light converger |
US6104446A (en) * | 1996-12-18 | 2000-08-15 | Blankenbecler; Richard | Color separation optical plate for use with LCD panels |
US20010002918A1 (en) * | 1999-12-03 | 2001-06-07 | Sumitomo Electric Industries, Ltd. | Surface temperature sensor head |
US6256153B1 (en) * | 1999-08-11 | 2001-07-03 | Souhei Suzui | Circumscribing ray route lens, the system condensing light therewith, and the lighting therewith |
US20050011549A1 (en) * | 2003-07-09 | 2005-01-20 | Kozo Miyoshi | Substrate for solar battery, and solar battery using same |
US20060180194A1 (en) * | 2005-02-17 | 2006-08-17 | Shiro Mitsunari | Solar cell array having three dimension multiple structure |
US20070035847A1 (en) * | 2005-08-11 | 2007-02-15 | Micron Technology, Inc. | Method and apparatus providing graded-index microlenses |
US20080135087A1 (en) * | 2007-05-10 | 2008-06-12 | Rangappan Anikara | Thin solar concentrator |
US20090301469A1 (en) * | 2006-07-28 | 2009-12-10 | Angus Muir Edington Scrimgeour | Solar collectors |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4111608A1 (en) * | 1991-04-10 | 1992-10-15 | En Techno Grimm Gmbh | Hybrid solar radiation collector - has tubular absorber, surrounded by optical elements to deflect and concentrate sunlight |
JP2002031035A (en) * | 2000-07-13 | 2002-01-31 | Yozo Oko | Solar power generator |
-
2007
- 2007-07-27 US US12/375,490 patent/US20100307480A1/en not_active Abandoned
- 2007-07-27 WO PCT/IB2007/052982 patent/WO2008012777A2/en active Application Filing
- 2007-07-27 EP EP07805249A patent/EP2052194A2/en not_active Withdrawn
Patent Citations (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3467840A (en) * | 1966-07-05 | 1969-09-16 | Melvin Weiner | Solar thermionic convertor |
US4108540A (en) * | 1976-06-17 | 1978-08-22 | Minnesota Mining And Manufacturing Company | Refractor-reflector radiation concentrator |
US5877874A (en) * | 1995-08-24 | 1999-03-02 | Terrasun L.L.C. | Device for concentrating optical radiation |
US5977478A (en) * | 1996-12-05 | 1999-11-02 | Toyota Jidosha Kabushiki Kaisha | Solar module |
US6104446A (en) * | 1996-12-18 | 2000-08-15 | Blankenbecler; Richard | Color separation optical plate for use with LCD panels |
US6061181A (en) * | 1997-06-09 | 2000-05-09 | Fereidooni; Fred | Nontracking light converger |
US6256153B1 (en) * | 1999-08-11 | 2001-07-03 | Souhei Suzui | Circumscribing ray route lens, the system condensing light therewith, and the lighting therewith |
US20010002918A1 (en) * | 1999-12-03 | 2001-06-07 | Sumitomo Electric Industries, Ltd. | Surface temperature sensor head |
US20050011549A1 (en) * | 2003-07-09 | 2005-01-20 | Kozo Miyoshi | Substrate for solar battery, and solar battery using same |
US20060180194A1 (en) * | 2005-02-17 | 2006-08-17 | Shiro Mitsunari | Solar cell array having three dimension multiple structure |
US20070035847A1 (en) * | 2005-08-11 | 2007-02-15 | Micron Technology, Inc. | Method and apparatus providing graded-index microlenses |
US20090301469A1 (en) * | 2006-07-28 | 2009-12-10 | Angus Muir Edington Scrimgeour | Solar collectors |
US20080135087A1 (en) * | 2007-05-10 | 2008-06-12 | Rangappan Anikara | Thin solar concentrator |
Also Published As
Publication number | Publication date |
---|---|
WO2008012777A3 (en) | 2008-06-19 |
EP2052194A2 (en) | 2009-04-29 |
WO2008012777A2 (en) | 2008-01-31 |
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