Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/40—Optical elements or arrangements
  • H10F77/42—Optical elements or arrangements directly associated or integrated with photovoltaic cells, e.g. light-reflecting means or light-concentrating means
  • H10F77/488—Reflecting light-concentrating means, e.g. parabolic mirrors or concentrators using total internal reflection
• • 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
• • 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
  • F24S2023/83—Other shapes
  • F24S2023/832—Other shapes curved
• • 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
• • 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 sunlight concentrator for a photovoltaic generation system.
• one of the simplest photovoltaic generation systems is of the type comprising a photovoltaic receiver consisting, for instance, of a small photovoltaic cell panel, and a concentrator consisting of a curved reflecting surface disc, for instance paraboloidal, to concentrate a great amount of sunlight on the photovoltaic cell panel.
• Photovoltaic cells are preferably connected in series one to the other to increase the electric voltage provided by the panel .
• the cost of the photovoltaic cell panel is mainly due to the cost of the semiconductor the single photovoltaic cells are made of .
• the use of the concentrator serves to reduce the number of photovoltaic cells employed in the panel and therefore to reduce the cost thereof, depending on the desired electric power to be generated.
• photovoltaic cells are made of the same semiconductor again in order to reduce the cost of the panel.
• the concentrator does not ensure a uniform distribution of the flow of solar radiation on the whole area of the panel of photovoltaic cells. This results in the photovoltaic cells not being used efficiently, in the sense that less illuminated photovoltaic cells limit the ' production of current of more illuminated photovoltaic cells because of the above mentioned electric connection in series. This implies a reduction in the overall energy conversion efficiency of the system.
• FIG. 1 shows a photovoltaic generation system provided with the sunlight concentrator obtained according to an embodiment of the present invention according to a simplified longitudinal section view;
• - Figure 2 shows the photovoltaic generation system of Figure 1 according to an axonometric view;
• FIG. 3 and 4 show the photovoltaic generation system of Figure 2 provided with the sunlight concentrator obtained according to further respective embodiments of the present invention.
• FIG. 5 and 6 show the distribution of the solar radiation on a photovoltaic converter of the photovoltaic generation system of Figure 1 provided with a known sunlight concentrator and, respectively, provided with the sunlight concentrator obtained according to the present invention.
• numeral 1 generically indicates a photovoltaic generation system comprising a sunlight concentrator 2, which consists of a disc having a curved reflecting surface 2a and an optical axis 3 passing through an optical centre C lying on reflecting surface 2a and through a focal zone, in which the rays of sunlight that strike parallelly to optical axis 3 on reflecting surface 2a are ideally focused.
• the focal zone consists of an area (not shown) defined on a plane (not shown) perpendicular to optical axis 3 and centred in a point F of optical axis 3, which is hereinafter designated as focus.
• numerals 4 and 5 indicate the tracks of some of the incident rays which define an incident beam of sunlight
• numerals 6 and 7 indicate the tracks of corresponding reflected rays converging in the focal zone which define a concentrated beam of sunlight.
• Photovoltaic generation system 1 comprises a photovoltaic converter 8, which consists of a photovoltaic cell panel of the known type and is arranged between optical centre C and focus F to receive concentrated beam 6, 7 of sunlight reflected by concentrator 2 and convert received sunlight into electric energy.
• converter 8 is substantially square and is arranged so that optical axis 3 passes therethrough centrally and perpendicularly at a point P of optical axis 3 between optical centre C and focus F and at a short distance from focus F. Due to its arrangement, converter 8 intercepts incident beam 4, 5 therefore projecting a shadow 9 on reflecting surface 2a having the same shape as converter 8 and centred on optical axis 3.
• this curvature will hereinafter be designated as pseudoparabolic curvature.
• reflecting surface 2a has a substantially square front section in order to be • compatible with the shape of converter 8.
• the pseudoparabolic curvature of concentrator 2 allows to increase the distribution uniformity of the flow of solar radiation on converter 8 with respect to a parabolic curvature, as that used by solar concentrators of the known type and typically obtained by rotation of a parabola branch about the optical axis thereof.
• Figure 5 shows the distribution of the flow of solar radiation on converter 8 obtained with a parabolic concentrator known in the state of the art
• Figure 6 shows the distribution of the flow of solar radiation on converter 8 obtained with concentrator 3 which has a pseudoparabolic curvature .
• An improvement in the distribution uniformity on converter 8 by switching from a parabolic curvature ( Figure 5) to a pseudoparabolic curvature ( Figure 6) may be noted comparing Figure 5 with Figure 6.
• converter 8 is rectangular or hexagonal and accordingly concentrator 2 has a rectangular or respectively a hexagonal front section.
• the surface of concentrator 2 has a through-opening 11 centred on optical axis 3.
• opening 11 substantially has the same shape as shadow 9 proj ected by converter 8 on reflecting surface 2a and is sized so as to be totally covered by shadow 9.
• opening 11 has an edge 12 that remains totally within shadow 9.
• Opening 11 may be for instance obtained by cutting out a corresponding central portion of concentrator 2 already profiled according to the pseudoparabolic curvature. The purpose of opening 11 is to make concentrator 2 lighter and less sensitive to wind, the amount of received and converted sunlight being the same.
• edge 12 of opening 11 is defined by a vertex-free line ( Figure 4) or by a generic curved line and generatrix 10 consists of a branch of the curve described by function (1) which lies on a determined plane (not shown) .
• the pseudoparabolic curvature of reflecting surface 2a is ' generated by a movement of generatrix 10 along edge 12.
• the generating movement consists in a movement of -the plane of generatrix.10 such that an extreme point G of generatrix 10 moves along edge 12 and the line defining edge 12 always passes through this plane perpendicularly at extreme point G.
• the main advantage of above disclosed concentrator 2, and therefore ' of photovoltaic generation system 1 employing this concentrator 2, is to increase the photovoltaic conversion efficiency with respect to the known systems,- as concentrator 2 allows a better uniformity in the distribution of the light radiation flow on converter 8.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Photovoltaic Devices (AREA)
• Optical Elements Other Than Lenses (AREA)

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Family Cites Families (8)

• 2008
  • 2008-01-23 IT IT000041A patent/ITBO20080041A1/it unknown
• 2009
  • 2009-01-22 EP EP09704680A patent/EP2248187A2/de not_active Withdrawn
  • 2009-01-22 WO PCT/IB2009/000111 patent/WO2009093129A2/en not_active Ceased

Non-Patent Citations (1)

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