WO2009045141A1 - Solar concentrator - Google Patents

Solar concentrator Download PDF

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Publication number
WO2009045141A1
WO2009045141A1 PCT/SE2008/000533 SE2008000533W WO2009045141A1 WO 2009045141 A1 WO2009045141 A1 WO 2009045141A1 SE 2008000533 W SE2008000533 W SE 2008000533W WO 2009045141 A1 WO2009045141 A1 WO 2009045141A1
Authority
WO
WIPO (PCT)
Prior art keywords
parabola
solar
solar concentrator
cooling medium
solar panel
Prior art date
Application number
PCT/SE2008/000533
Other languages
French (fr)
Inventor
Björn EKLÖV
Original Assignee
Global Sun Engineering Sweden Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Global Sun Engineering Sweden Ab filed Critical Global Sun Engineering Sweden Ab
Publication of WO2009045141A1 publication Critical patent/WO2009045141A1/en

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Classifications

    • 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
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/79—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with spaced and opposed interacting reflective surfaces
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S10/00—Solar heat collectors using working fluids
    • F24S10/40—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
    • F24S10/45—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors the enclosure being cylindrical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S10/00—Solar heat collectors using working fluids
    • F24S10/90—Solar heat collectors using working fluids using internal thermosiphonic circulation
    • F24S10/95—Solar heat collectors using working fluids using internal thermosiphonic circulation having evaporator sections and condenser sections, e.g. heat pipes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S20/00—Solar heat collectors specially adapted for particular uses or environments
    • F24S20/20—Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
    • 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
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/71—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with parabolic reflective surfaces
    • 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
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
    • 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
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/77—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with flat reflective plates
    • 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
    • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
    • F24S23/80—Arrangements for concentrating solar-rays for solar heat collectors with reflectors having discontinuous faces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S30/00—Arrangements for moving or orienting solar heat collector modules
    • F24S30/40—Arrangements for moving or orienting solar heat collector modules for rotary movement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S30/00—Arrangements for moving or orienting solar heat collector modules
    • F24S30/40—Arrangements for moving or orienting solar heat collector modules for rotary movement
    • F24S30/42—Arrangements for moving or orienting solar heat collector modules for rotary movement with only one rotation axis
    • F24S30/428—Arrangements for moving or orienting solar heat collector modules for rotary movement with only one rotation axis with inclined axis
    • 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
    • H01L31/052—Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells
    • H01L31/0521—Cooling means directly associated or integrated with the PV cell, e.g. integrated Peltier elements for active cooling or heat sinks directly associated with the PV cells using a gaseous or a liquid coolant, e.g. air flow ventilation, water circulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S25/00—Arrangement of stationary mountings or supports for solar heat collector modules
    • F24S25/10—Arrangement of stationary mountings or supports for solar heat collector modules extending in directions away from a supporting surface
    • 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
    • Y02E10/40—Solar thermal energy, e.g. solar towers
    • Y02E10/47—Mountings or tracking
    • 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

  • the present invention relates to a solar concentrator which comprises at least one first parabola, at least one solar panel disposed in the focus region of the first parabola, means for cooling the solar panel by a cooling medium, preferably in liquid form, and means for supporting the first parabola and the solar panel relative to a substrate, which solar concentrator comprises at least one second parabola.
  • a solar concentrator known from US-A-6, 080, 927 comprises a parabola which concentrates the sun' s rays to an absorbing surface on which solar cells are mounted, thereby constituting a so-called solar panel.
  • the solar concentrator also comprises a frame which fixes the solar panel in correct position relative to the parabola.
  • the solar concentrator also comprises conduits for a cooling medium in liquid form, whereby the cooling medium flows to and from the solar panel.
  • the electricity from the solar concentrator can be used for conveying liquid through a heat exchanger. Surplus electricity can be stored or used locally.
  • a device and method for concentrating and accumulating solar energy are known from US 4,249,516.
  • the device comprises a number of parabolic reflectors, a central liquid lens and an accumulator which comprises solar cells.
  • the purpose of the liquid lens is to absorb, via a lens liquid situated in the liquid lens, the infra-red energy which is reflected by the reflectors. This helps to reduce the heat produced in the solar cells. Circulation of coolant through the solar cells to carry heat away also seems to be a known practice.
  • An installation which concentrates solar radiation and directs it towards electricity-generating solar cells is known from EP 0019016.
  • the installation comprises a first parabola, a solar cell, a secondary parabola/mirror and an absorber which takes the form of a pipe. Part of the radiation is reflected in the secondary parabola and part of the radiation passes through the secondary parabola and meets the solar cell, which is cooled by a cooling medium.
  • a further object of the present invention is that the parabolas which form part of the solar concentrator should be exposed to direct radiation from the sun.
  • Fig. 1 depicts a first perspective view of a preferred embodiment of a solar concentrator according to the present invention
  • Fig. 2 depicts a second perspective view of the solar concentrator according to Fig. 1
  • Fig. 3 depicts a side view of the solar concentrator according to Fig. 1
  • Fig. 4 depicts a perspective view of a unit which forms part of the solar concentrator according to Fig. 1
  • Fig. 5 depicts the principle of the beam pattern of the first and second parabolas which form part of the solar concentrator according to Fig. 1
  • Fig. 6 depicts a side view of the solar concentrator according to Fig. 1, illustrating an example of the path of the cooling medium through the solar concentrator;
  • Fig. 7 depicts a side view of an alternative embodiment of the solar concentrator according to the present invention, illustrating an example of the path of the cooling medium through the solar concentrator;
  • Fig. 8 depicts schematically in plan view an alternative embodiment of a solar concentrator according to the present invention, showing the beam pattern.
  • the solar concentrator depicted in Figs. 1-3 comprises ⁇ frame 1 itself comprising a number of supporting members 3 which radiate out from the centre of the frame.
  • the supporting members 3 are intended to abut against a substrate, e.g. a roof on which the solar concentrator is situated. It is implicit that the frame is anchored in a suitable manner in the substrate on which it is placed.
  • the frame 1 has a sun tracking function which is prior art and is therefore not described in more detail.
  • a linear device 5 forming part of the sun tracking equipment is depicted in Figs. 1-3.
  • the frame 1 also comprises a pillar 7 which is vertical in the position of use and which has its lower end rigidly connected to the region of the centre of the supporting members 3.
  • a bracket 9 for a first parabola 10 which is of conventional configuration is attached in the region of the upper end of the pillar 7.
  • the first parabola 10 depicted in Figs. 1-3 comprises a number of planar mirror elements 11 fitted in a faceted parabolic shape.
  • the height direction of the first parabola 10 is indicated by a double arrow H and its width direction by a double arrow B.
  • the solar concentrator according to Figs. 1-3 also comprises a bearing means 8 for the first parabola 10, which bearing means 8 comprises a rear element 12A and two bracing arms 12B which in the embodiment depicted are parallel and extend from the parabola 10 in a direction such that the ends 13 of the bracing arms 12 situated at a distance from the parabola 10 are on the concave side of the parabola 10.
  • the bracing arms 12 are generally situated in a common plane and parallel with one another in that plane.
  • a generally boxlike unit 15 which is a combined solar panel/second parabola is fitted in the region of the free ends 13 of the bracing arms 12.
  • the unit 15 extends between the ends 13 of the bracing arms 12.
  • the unit 15 is depicted in more detail in Fig. 4.
  • a solar panel 16 (not visible in Figs. 1-3) disposed on the side of the unit 15 which faces towards the first parabola 10 is situated in the common focus region for the mirror elements 11 which form part of the first parabola 10. This is described in more detail below.
  • the unit 15 also comprises a second parabola 17 which is generally of substantially smaller extent in the width direction B than the first parabola 10.
  • the extent in the height direction H is substantially the same for the first parabola 10 and the second parabola 17.
  • the unit 15 also comprises a vacuum tube 18 whose extent in the height direction corresponds generally to the second parabola 17.
  • a heat pipe is disposed within the vacuum tube 18.
  • the frame 1 is so configured that the sun tracking function ensures that the first parabola 10 and the second parabola 17 move synchronously with one another.
  • Fig. 5 generally depicts the beam pattern for the sun' s rays which are incident upon the first parabola 10.
  • the first parabola 10 and the second parabola 17 are mutually oriented in such a way that they face the same direction, i.e. the two parabolas 10, 17 receive direct radiation from the sun when the solar concentrator according to the present invention is turned towards the sun.
  • the solar concentrator according to the present invention is turned towards the sun.
  • the first parabola 10 is composed of a number of planar mirror elements 11.
  • Each mirror element 11 is so oriented relative to the solar panel 16 that a beam such as Sl incident upon the region of the left edge in Fig. 5 of a mirror element 11 will, after reflection in the first parabola 10, strike the region of the left edge in Fig. 5 of the solar panel 16.
  • a beam S2 incident upon the region of a right edge in Fig. 5 of a mirror element 11 will, after reflection in the first parabola 10, strike the region of the right edge in Fig. 5 of the solar panel 16.
  • the sunlight incident upon the solar panel 16 will be evenly distributed over the whole of the surface of the solar panel 16 which is turned towards the first parabola 10.
  • the solar panel 16 in a known manner converts the incident sunlight to electrical energy which is put to suitable use.
  • Fig. 5 also shows sunbeams S3 incident upon the second parabola 17 being reflected towards the vacuum tube 18 which is placed in focus for the second parabola 17.
  • a heat pipe is disposed within the vacuum tube 18.
  • a heat pipe being a closed pipe with liquid inside. The pressure in the pipe is such that the liquid vaporises at a suitable temperature (often just above room temperature) .
  • Heat pipes are used for conveying heat from the vacuum tube's solar collector to a water-borne central heating system, e.g. for heating of domestic hot water. In a heat pipe, heat can only be conveyed in one direction.
  • a heat exchanger arrangement 19 is disposed in the region for the upper end of the vacuum tube 18, i.e. where condensation of the liquid takes place in the heat pipe.
  • the solar concentrator according to the present invention involves having to cool certain elements of the solar concentrator, and the solar panel 16 is an element which needs cooling.
  • the solar concentrator according to the present invention is equipped with a cooling arrangement.
  • cooling pipes/cooling conduits are provided, as symbolised by continuous/broken lines 25, with arrows 26 indicating the direction of flow for a cooling medium preferably in the form of a liquid which vaporises at a certain temperature.
  • the cooling medium is circulated through the solar concentrator by a pump which is not depicted.
  • the cooling medium which is preferably in liquid form, enters the solar concentrator via the pillar 7. Thereafter the cooling medium is led via the pipe/conduit 25 downwards within the rear element 12A and out into the lower bracing arm 12B. The cooling medium proceeds thereafter up along the rear side of the solar panel 16 in order to cool the latter. Thereafter the cooling medium is conveyed through the boxlike space 20 situated between the solar panel 16 and the second parabola 17. Cooling of the whole of the solar panel 16 is thus assured in that the cooling medium comes into contact with substantially the whole rear side of the solar panel 16. The cooling medium undergoes a step of warming as it passes through the solar panel 16.
  • this heat exchanger arrangement 19 comprises a heat pipe, and the liquid present in the heat pipe vaporises and rises upwards to where it recondenses in the heat exchanger arrangement.
  • the condensation involves the liquid in the heat pipe imparting heat to the cooling medium, which thus undergoes a second step of warming as it passes through the heat exchanger arrangement 19.
  • the cooling medium thus subjected to two steps of warming is led thereafter along the upper bracing arm 12B, down along the rear element 12A, through the pillar 7 and on to a further heat exchanger arrangement (not depicted) in which the heat content of the cooling medium is extracted.
  • Fig. 7 depicts an alternative embodiment of a solar concentrator according to the present invention which differs from the solar concentrator described above in the configuration of the unit 115 which constitutes a combined solar panel/second parabola. This means that the pipe 125 for the cooling medium takes a different form in connection with the unit 115.
  • the portions of the solar concentrator according to Fig. 7 which are substantially identical with the solar concentrator according to Figs. 1-6 bear reference numerals corresponding to those used in Figs. 1-6.
  • the unit 115 comprises no heat pipe, but when the cooling medium has, via the pipe 125, passed along the rear side of the solar panel 16, it is led via the top of a pipe/conduit 125 into a vacuum tube which forms part of the unit 115, which pipe/conduit 125 with cooling medium is arranged in a loop within the vacuum tube.
  • the pipe/conduit 125 is led out from the vacuum tube in the region of the upper end of the vacuum tube. Thereafter the pipe/conduit 125 is led via the upper bracing arm 12B, the rear element 12A and the pillar 7 to a further heat exchanger arrangement in which the heat content of the cooling medium is extracted.
  • the embodiment of a solar concentrator according to the present invention depicted in Fig. 8 comprises two first parabolas 210, two solar panels 216 and a second parabola 217.
  • the two first parabolas 210 comprise planar mirror elements 211.
  • the solar panels 216 are parallel and so oriented relative to one another that a boxlike space 220 is defined between the solar panels 216.
  • the second parabola 217 is situated between the two first parabolas 210.
  • a vacuum tube 218 in which a heat pipe may be accommodated is disposed in the focus region of the second parabola 217.
  • the solar concentrator according to Fig. 8 is supported by a frame (not depicted) in a manner corresponding substantially to the embodiments described above in relation to Figs. 1-7.
  • the beam pattern depicted in Fig. 8 is substantially similar to that depicted in Fig. 5, using the corresponding reference notations for the beams Sl, S2 and S3.
  • first parabola 210 and second parabola 217 are mutually so oriented that they face the same direction, i.e. the two parabolas 210, 217 receive direct radiation from the sun when the solar concentrator according to the present invention is turned towards the sun. Thus all of the radiation coming from the sun is utilised in the solar concentrator according to the present invention.
  • the solar concentrator depicted in Fig. 8 functions in a manner corresponding substantially to the solar concentrator according to Figs. 1-6 in that the first parabola 210 focuses the sunlight on a relating solar panel 216.
  • the second parabola 217 reflects the incident sunlight towards the vacuum tube 218 situated in the focus region of the second parabola 217.
  • cooling medium passes between the solar panels 216 and is thereafter led away to the vacuum tube 218 in which the cooling medium is further warmed by a heat exchanger arrangement corresponding to that described above in relation to Figs. 6 and 7.
  • the pipe arrangement depicted in Figs. 6 and 7 for the cooling medium should only be regarded as an example. It is important that the cooling medium passes along the solar panel 16 in order to cool the latter and that the cooling medium is supplied with heat via the second parabola 17. Otherwise the pipe arrangement may be configured in many different ways.
  • the solar concentrator is disposed on a frame which supports the solar concentrator relative to a horizontal substrate.
  • the solar concentrator is of course also possible to conceive of the solar concentrator being wall-mounted.
  • the expression "substrate" used in claim 1 should therefore be regarded as comprising also a wall or the like.
  • the solar concentrator comprises a second parabola 17; 217.
  • the solar concentrator comprising two or more second parabolas, preferably disposed close to one another.
  • the two solar panels 216 are parallel with one another.
  • the solar panels 216 are angled relative to one another in plan view.
  • first and second parabolas referred to in the embodiments described are generally only to be regarded as examples .

Abstract

The present invention relates to a solar concentrator which comprises at least one first parabola (10), at least one solar panel (16) disposed in the focus region of the first parabola (10), means (25; 125) for cooling the solar panel (16) with a cooling medium, preferably in liquid form, and means (1, 3, 12A, 12B) for supporting the first parabola (10) and the solar panel (16) relative to a substrate. Distinguishing features of the solar concentrator according to the present invention are that at least one second parabola (17) is disposed close to the solar panel (16) and that means (18, 19) for warming the cooling medium, which is preferably in liquid form, are disposed close to the second parabola (17).

Description

SOIAR CONCENTRATOR
Technical field of the invention
The present invention relates to a solar concentrator which comprises at least one first parabola, at least one solar panel disposed in the focus region of the first parabola, means for cooling the solar panel by a cooling medium, preferably in liquid form, and means for supporting the first parabola and the solar panel relative to a substrate, which solar concentrator comprises at least one second parabola.
State of the art
A solar concentrator known from US-A-6, 080, 927 comprises a parabola which concentrates the sun' s rays to an absorbing surface on which solar cells are mounted, thereby constituting a so-called solar panel. The solar concentrator also comprises a frame which fixes the solar panel in correct position relative to the parabola. The solar concentrator also comprises conduits for a cooling medium in liquid form, whereby the cooling medium flows to and from the solar panel. The electricity from the solar concentrator can be used for conveying liquid through a heat exchanger. Surplus electricity can be stored or used locally. A device and method for concentrating and accumulating solar energy are known from US 4,249,516. According to a specific embodiment, the device comprises a number of parabolic reflectors, a central liquid lens and an accumulator which comprises solar cells. The purpose of the liquid lens is to absorb, via a lens liquid situated in the liquid lens, the infra-red energy which is reflected by the reflectors. This helps to reduce the heat produced in the solar cells. Circulation of coolant through the solar cells to carry heat away also seems to be a known practice. An installation which concentrates solar radiation and directs it towards electricity-generating solar cells is known from EP 0019016. The installation comprises a first parabola, a solar cell, a secondary parabola/mirror and an absorber which takes the form of a pipe. Part of the radiation is reflected in the secondary parabola and part of the radiation passes through the secondary parabola and meets the solar cell, which is cooled by a cooling medium.
Objects and features of the invention
A primary object of the present invention is to propose a solar concentrator of the kind defined in the introduction in which both electrical energy and thermal energy are extracted from the incident sunlight. Another object of the solar concentrator according to the present invention is that the cooling medium for the solar panel is warmed in a number of steps.
A further object of the present invention is that the parabolas which form part of the solar concentrator should be exposed to direct radiation from the sun.
At least the primary object of the present invention is achieved by a solar concentrator having the features indicated in the independent claim 1 set out below. Preferred embodiments of the invention are defined in the dependent claims.
Brief description of the drawings
Preferred embodiments of the invention are described below with reference to the attached drawings, in which: Fig. 1 depicts a first perspective view of a preferred embodiment of a solar concentrator according to the present invention; Fig. 2 depicts a second perspective view of the solar concentrator according to Fig. 1; Fig. 3 depicts a side view of the solar concentrator according to Fig. 1; Fig. 4 depicts a perspective view of a unit which forms part of the solar concentrator according to Fig. 1; Fig. 5 depicts the principle of the beam pattern of the first and second parabolas which form part of the solar concentrator according to Fig. 1; Fig. 6 depicts a side view of the solar concentrator according to Fig. 1, illustrating an example of the path of the cooling medium through the solar concentrator;
Fig. 7 depicts a side view of an alternative embodiment of the solar concentrator according to the present invention, illustrating an example of the path of the cooling medium through the solar concentrator; and
Fig. 8 depicts schematically in plan view an alternative embodiment of a solar concentrator according to the present invention, showing the beam pattern.
Detailed description of preferred embodiments of the invention
The solar concentrator depicted in Figs. 1-3 comprises ύ frame 1 itself comprising a number of supporting members 3 which radiate out from the centre of the frame. The supporting members 3 are intended to abut against a substrate, e.g. a roof on which the solar concentrator is situated. It is implicit that the frame is anchored in a suitable manner in the substrate on which it is placed.
The frame 1 has a sun tracking function which is prior art and is therefore not described in more detail. A linear device 5 forming part of the sun tracking equipment is depicted in Figs. 1-3.
The frame 1 also comprises a pillar 7 which is vertical in the position of use and which has its lower end rigidly connected to the region of the centre of the supporting members 3. A bracket 9 for a first parabola 10 which is of conventional configuration is attached in the region of the upper end of the pillar 7. The first parabola 10 depicted in Figs. 1-3 comprises a number of planar mirror elements 11 fitted in a faceted parabolic shape. In Fig. 2, the height direction of the first parabola 10 is indicated by a double arrow H and its width direction by a double arrow B.
The solar concentrator according to Figs. 1-3 also comprises a bearing means 8 for the first parabola 10, which bearing means 8 comprises a rear element 12A and two bracing arms 12B which in the embodiment depicted are parallel and extend from the parabola 10 in a direction such that the ends 13 of the bracing arms 12 situated at a distance from the parabola 10 are on the concave side of the parabola 10. In the embodiment depicted, the bracing arms 12 are generally situated in a common plane and parallel with one another in that plane.
A generally boxlike unit 15 which is a combined solar panel/second parabola is fitted in the region of the free ends 13 of the bracing arms 12. The unit 15 extends between the ends 13 of the bracing arms 12. The unit 15 is depicted in more detail in Fig. 4.
A solar panel 16 (not visible in Figs. 1-3) disposed on the side of the unit 15 which faces towards the first parabola 10 is situated in the common focus region for the mirror elements 11 which form part of the first parabola 10. This is described in more detail below.
The unit 15 also comprises a second parabola 17 which is generally of substantially smaller extent in the width direction B than the first parabola 10. The extent in the height direction H is substantially the same for the first parabola 10 and the second parabola 17. The unit 15 also comprises a vacuum tube 18 whose extent in the height direction corresponds generally to the second parabola 17. In the embodiment depicted in Fig. 4, a heat pipe is disposed within the vacuum tube 18.
It is worth noting that the frame 1 is so configured that the sun tracking function ensures that the first parabola 10 and the second parabola 17 move synchronously with one another.
The function of the solar concentrator according to the present invention will now be described below. The description refers first to Fig. 5, which generally depicts the beam pattern for the sun' s rays which are incident upon the first parabola 10. In this context it should be noted that the first parabola 10 and the second parabola 17 are mutually oriented in such a way that they face the same direction, i.e. the two parabolas 10, 17 receive direct radiation from the sun when the solar concentrator according to the present invention is turned towards the sun. Thus all of the radiation coming from the sun is utilised in the solar concentrator according to the present invention.
As indicated above, in the embodiment depicted the first parabola 10 is composed of a number of planar mirror elements 11. Each mirror element 11 is so oriented relative to the solar panel 16 that a beam such as Sl incident upon the region of the left edge in Fig. 5 of a mirror element 11 will, after reflection in the first parabola 10, strike the region of the left edge in Fig. 5 of the solar panel 16. In the corresponding manner, a beam S2 incident upon the region of a right edge in Fig. 5 of a mirror element 11 will, after reflection in the first parabola 10, strike the region of the right edge in Fig. 5 of the solar panel 16. By this arrangement, the sunlight incident upon the solar panel 16 will be evenly distributed over the whole of the surface of the solar panel 16 which is turned towards the first parabola 10. The solar panel 16 in a known manner converts the incident sunlight to electrical energy which is put to suitable use.
Fig. 5 also shows sunbeams S3 incident upon the second parabola 17 being reflected towards the vacuum tube 18 which is placed in focus for the second parabola 17. According to a preferred embodiment, a heat pipe is disposed within the vacuum tube 18. This is prior art, a heat pipe being a closed pipe with liquid inside. The pressure in the pipe is such that the liquid vaporises at a suitable temperature (often just above room temperature) . Heat pipes are used for conveying heat from the vacuum tube's solar collector to a water-borne central heating system, e.g. for heating of domestic hot water. In a heat pipe, heat can only be conveyed in one direction. The liquid at the lower end of the pipe vaporises and rises upwards to where the vapour condenses, and the resulting condensate runs down along the inside of the pipe and vaporises. A heat exchanger arrangement 19 is disposed in the region for the upper end of the vacuum tube 18, i.e. where condensation of the liquid takes place in the heat pipe.
Operating the solar concentrator according to the present invention involves having to cool certain elements of the solar concentrator, and the solar panel 16 is an element which needs cooling. To this end, the solar concentrator according to the present invention is equipped with a cooling arrangement. As illustrated in Fig. 6, cooling pipes/cooling conduits are provided, as symbolised by continuous/broken lines 25, with arrows 26 indicating the direction of flow for a cooling medium preferably in the form of a liquid which vaporises at a certain temperature. The cooling medium is circulated through the solar concentrator by a pump which is not depicted.
According to the embodiment depicted, the cooling medium, which is preferably in liquid form, enters the solar concentrator via the pillar 7. Thereafter the cooling medium is led via the pipe/conduit 25 downwards within the rear element 12A and out into the lower bracing arm 12B. The cooling medium proceeds thereafter up along the rear side of the solar panel 16 in order to cool the latter. Thereafter the cooling medium is conveyed through the boxlike space 20 situated between the solar panel 16 and the second parabola 17. Cooling of the whole of the solar panel 16 is thus assured in that the cooling medium comes into contact with substantially the whole rear side of the solar panel 16. The cooling medium undergoes a step of warming as it passes through the solar panel 16. When it reaches the upper end of the element 15, the cooling medium flows through the heat exchanger arrangement 19 disposed at the upper end of the element 15. As described above, this heat exchanger arrangement 19 comprises a heat pipe, and the liquid present in the heat pipe vaporises and rises upwards to where it recondenses in the heat exchanger arrangement. The condensation involves the liquid in the heat pipe imparting heat to the cooling medium, which thus undergoes a second step of warming as it passes through the heat exchanger arrangement 19. The cooling medium thus subjected to two steps of warming is led thereafter along the upper bracing arm 12B, down along the rear element 12A, through the pillar 7 and on to a further heat exchanger arrangement (not depicted) in which the heat content of the cooling medium is extracted. In this context it should be noted that the two steps of warming undergone by the cooling medium mean that the cooling medium may initially be at a lower temperature and therefore provide effective cooling of the solar panel 16. Fig. 7 depicts an alternative embodiment of a solar concentrator according to the present invention which differs from the solar concentrator described above in the configuration of the unit 115 which constitutes a combined solar panel/second parabola. This means that the pipe 125 for the cooling medium takes a different form in connection with the unit 115. The portions of the solar concentrator according to Fig. 7 which are substantially identical with the solar concentrator according to Figs. 1-6 bear reference numerals corresponding to those used in Figs. 1-6.
The unit 115 comprises no heat pipe, but when the cooling medium has, via the pipe 125, passed along the rear side of the solar panel 16, it is led via the top of a pipe/conduit 125 into a vacuum tube which forms part of the unit 115, which pipe/conduit 125 with cooling medium is arranged in a loop within the vacuum tube. The pipe/conduit 125 is led out from the vacuum tube in the region of the upper end of the vacuum tube. Thereafter the pipe/conduit 125 is led via the upper bracing arm 12B, the rear element 12A and the pillar 7 to a further heat exchanger arrangement in which the heat content of the cooling medium is extracted.
The embodiment of a solar concentrator according to the present invention depicted in Fig. 8 comprises two first parabolas 210, two solar panels 216 and a second parabola 217. The two first parabolas 210 comprise planar mirror elements 211. The solar panels 216 are parallel and so oriented relative to one another that a boxlike space 220 is defined between the solar panels 216.
As illustrated in Fig. 8, the second parabola 217 is situated between the two first parabolas 210. A vacuum tube 218 in which a heat pipe may be accommodated is disposed in the focus region of the second parabola 217. What was stated above with regard to the function of a heat pipe applies here also. The solar concentrator according to Fig. 8 is supported by a frame (not depicted) in a manner corresponding substantially to the embodiments described above in relation to Figs. 1-7. The beam pattern depicted in Fig. 8 is substantially similar to that depicted in Fig. 5, using the corresponding reference notations for the beams Sl, S2 and S3. In this context it should be noted that in this embodiment too the first parabola 210 and second parabola 217 are mutually so oriented that they face the same direction, i.e. the two parabolas 210, 217 receive direct radiation from the sun when the solar concentrator according to the present invention is turned towards the sun. Thus all of the radiation coming from the sun is utilised in the solar concentrator according to the present invention.
The solar concentrator depicted in Fig. 8 functions in a manner corresponding substantially to the solar concentrator according to Figs. 1-6 in that the first parabola 210 focuses the sunlight on a relating solar panel 216. The second parabola 217 reflects the incident sunlight towards the vacuum tube 218 situated in the focus region of the second parabola 217.
As regards the cooling arrangement for the embodiment depicted in Fig. 8, it should be noted that the cooling medium passes between the solar panels 216 and is thereafter led away to the vacuum tube 218 in which the cooling medium is further warmed by a heat exchanger arrangement corresponding to that described above in relation to Figs. 6 and 7.
Conceivable modifications of the invention
The pipe arrangement depicted in Figs. 6 and 7 for the cooling medium should only be regarded as an example. It is important that the cooling medium passes along the solar panel 16 in order to cool the latter and that the cooling medium is supplied with heat via the second parabola 17. Otherwise the pipe arrangement may be configured in many different ways.
In the embodiments described above, the solar concentrator is disposed on a frame which supports the solar concentrator relative to a horizontal substrate. Within the scope of the invention it is of course also possible to conceive of the solar concentrator being wall-mounted. The expression "substrate" used in claim 1 should therefore be regarded as comprising also a wall or the like. In the embodiments described above, the solar concentrator comprises a second parabola 17; 217. Within the scope of the present invention it is nevertheless possible to conceive of the solar concentrator comprising two or more second parabolas, preferably disposed close to one another.
In the embodiment depicted in Fig. 8, the two solar panels 216 are parallel with one another. Within the scope of the present invention it is nevertheless possible to conceive of the solar panels being angled relative to one another in plan view.
The numbers of first and second parabolas referred to in the embodiments described are generally only to be regarded as examples .

Claims

Claims
1. A solar concentrator which comprises at least one first parabola (10; 210), at least one solar panel (16; 216) disposed in the focus region of the first parabola (10; 210) , means (25; 125) for cooling the solar panel (16; 216) with a cooling medium, and means (1, 3, 12A, 12B) for supporting the first parabola (10; 210) and the solar panel (16; 216) relative to a substrate, which solar concentrator comprises at least one second parabola (17; 217), c h a r a c t e r i z e d in that the two parabolas (10; 210 and 17; 217 respectively) are so oriented that they receive direct radiation from the sun and that means (18, 19; 218) for further warming of the cooling medium coming from the solar panel (16; 216) are disposed close to the second parabola (17; 217) .
2. A solar concentrator according to claim 1, c h a r a c t e r i z e d in that the cooling medium is in liquid form.
3. A solar concentrator according to claim 1 or 2, c h a r a c t e r i z e d in that the means for conveying the cooling medium comprise a heat pipe disposed in the focus region of the second parabola (17; 217) and a heat exchanger arrangement (19) disposed close thereto.
4. A solar concentrator according to claim 3, c h a r a c t e r i z e d in that the heat pipe is disposed within a vacuum tube (18; 218) .
5. A solar concentrator according to any of the above claims, c h a r a c t e r i z e d in that the second parabola (17; 217) is of smaller extent in the width direction (B) than the first parabola (10; 210) .
6. A solar concentrator according to any of the above claims, c h a r a c t e r i z e d in that the second parabola (17; 217) is disposed close to the solar panel (16; 216) .
7. A solar concentrator according to any of the above claims, c h a r a c t e r i z e d in that the first parabola (10; 210) is composed of planar mirror elements (11; 211).
8. A solar concentrator according to any of the above claims, c h a r a c t e r i z e d in that a space (20) through which the cooling medium passes is formed between the solar panel (16) and the second parabola (17) .
9. A solar concentrator according to any of the above claims, c h a r a c t e r i z e d in that the solar panel (16) and the second parabola (17) are supported by bracing arms (12B) which extend out from the first parabola (10).
10. A solar concentrator according to claim 1, c h a r a c t e r i z e d in that the cooling medium is led in a loop in the focus region for the second parabola (17) .
PCT/SE2008/000533 2007-10-01 2008-09-30 Solar concentrator WO2009045141A1 (en)

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FR2950681A1 (en) * 2009-09-28 2011-04-01 Guy Delcroix Panel type solar radiation concentrating sensor for use with e.g. solar tracking device, has mirrors formed with plane reflective surfaces whose dimensions and shapes are chosen in correspondence to active surface
WO2011054017A3 (en) * 2009-11-04 2011-10-27 Gasparyan, Karen Concentrating transducer of solar energy (variants)
NL2007048C2 (en) * 2011-07-05 2013-01-08 Solfence Holding B V Solar power installation.
WO2013044981A1 (en) * 2011-09-30 2013-04-04 Siemens Aktiengesellschaft Solar thermal interconnetion system with a linear fresnel mirror collector, use of the solar thermal interconnection system and solar thermal power plant with the solar thermal interconnection system
FR2990499A1 (en) * 2012-05-14 2013-11-15 Andre Jean Marie Philippe Cabarbaye UNIFORMLY DISTRIBUTED SOLAR CONCENTRATION DEVICE
US9923109B2 (en) 2012-02-29 2018-03-20 Yair Matalon Self-powered light-seeking apparatus and photovoltaic cells with light concentrating means
EP3252944A4 (en) * 2015-01-29 2018-12-19 Obshchestvo S Ogranichennoj Otvetstvennostyu "Soleks-R" Combined concentrator photovoltaic installation

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US4173213A (en) * 1976-09-15 1979-11-06 Kelly Donald A Solar power system, with high concentration, linear reflective solar panels
US6057504A (en) * 1994-10-05 2000-05-02 Izumi; Hisao Hybrid solar collector for generating electricity and heat by separating solar rays into long wavelength and short wavelength
US20030037814A1 (en) * 2001-08-24 2003-02-27 Cohen Gilbert E. Multiple reflector solar concentrators and systems

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US4173213A (en) * 1976-09-15 1979-11-06 Kelly Donald A Solar power system, with high concentration, linear reflective solar panels
US6057504A (en) * 1994-10-05 2000-05-02 Izumi; Hisao Hybrid solar collector for generating electricity and heat by separating solar rays into long wavelength and short wavelength
US20030037814A1 (en) * 2001-08-24 2003-02-27 Cohen Gilbert E. Multiple reflector solar concentrators and systems

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2950681A1 (en) * 2009-09-28 2011-04-01 Guy Delcroix Panel type solar radiation concentrating sensor for use with e.g. solar tracking device, has mirrors formed with plane reflective surfaces whose dimensions and shapes are chosen in correspondence to active surface
WO2011054017A3 (en) * 2009-11-04 2011-10-27 Gasparyan, Karen Concentrating transducer of solar energy (variants)
NL2007048C2 (en) * 2011-07-05 2013-01-08 Solfence Holding B V Solar power installation.
WO2013006054A1 (en) * 2011-07-05 2013-01-10 Solfence Holding B.V. Solar power installation
WO2013044981A1 (en) * 2011-09-30 2013-04-04 Siemens Aktiengesellschaft Solar thermal interconnetion system with a linear fresnel mirror collector, use of the solar thermal interconnection system and solar thermal power plant with the solar thermal interconnection system
US9923109B2 (en) 2012-02-29 2018-03-20 Yair Matalon Self-powered light-seeking apparatus and photovoltaic cells with light concentrating means
FR2990499A1 (en) * 2012-05-14 2013-11-15 Andre Jean Marie Philippe Cabarbaye UNIFORMLY DISTRIBUTED SOLAR CONCENTRATION DEVICE
WO2013171385A1 (en) * 2012-05-14 2013-11-21 Cabarbaye Andre Uniformly distributed solar concentration device
EP3252944A4 (en) * 2015-01-29 2018-12-19 Obshchestvo S Ogranichennoj Otvetstvennostyu "Soleks-R" Combined concentrator photovoltaic installation

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SE531566C2 (en) 2009-05-19

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