Classifications

• • 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
  • 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 photovoltaic generators which operate with concentration of incident light and which are protected against the effects of the additional heating induced by this concentration. It more specifically applies to photovoltaic generators used in artificial satellites and which operate on the basis of sunlight.
• This generator comprises a set of photovoltaic cells 101 covered with a transparent plate 102.
• This transparent plate serves on the one hand to protect the surface of the cells, and on the other hand to filter the direct solar radiation received 103 so as not to leave arrive on the cells as useful radiation 104 and reflect unnecessary radiation (infrared and ultraviolet for example) 105, because it cannot be absorbed by the cells to generate electricity. In practice this separation is imperfect and the reflection is not total. Part of the radiation 105 therefore penetrates into the layer 102 where it is largely absorbed, a small part arriving at the level of the cell where it is also absorbed there but without producing electricity.
• the solar flux 107 then arriving on this concentrator is reflected towards the surface of the layer 102 in the form of a reflected flux 108.
• the useful part of the radiation reflected enters the layer 102 in the form of a flux 109 to excite the cell 101.
• the other part is reflected in the form of a flux 110.
• the effects of the flux coming from the concentrator are the same as those of the flux direct and therefore cause additional heating of the solar panel, the greater the concentration.
• the concentrators 106 consist of simple reflecting surfaces, generally metallic, to be as light as possible. These surfaces practically do not absorb the incident flux 107 and return it entirely in the form of the reflected flux 108. Under these conditions, the operating temperature of the concentrators 106 is cold.
• the invention provides a concentrated photovoltaic generator, comprising at least one photovoltaic cell covered by a transparent protective layer, and a concentrator. reflecting, mainly characterized in that the concentrator is covered with a filter to eliminate in the light flux reflected by the concentrator towards the photoelectric cell most of the “useless” radiations which cannot excite the photovoltaic cell.
• the filter is formed of a layer made of materials absorbing the "useless" part of the radiation.
• the layer forming the filter is of constant thickness.
• the filter is formed of a layer whose outer face is oriented to deflect this "unnecessary" radiation outside the photovoltaic cell.
• the transparent layer is of decreasing thickness so that its outer face is not parallel to the reflecting surface of the concentrator.
• the outer face of the transparent layer forming the filter is etched in Fresnel steps.
• Figure 1 an end view of a generator according to the prior art x ;
• Figure 2 a view under the same conditions of a generator according to a first embodiment of the invention;
• Figure 3 a view under the same conditions of a generator according to a second embodiment of the invention.
• the invention therefore consists in placing on the concentrator panel 106 a filter which makes it possible to limit the radiation reflected towards the photoelectric cells essentially at the wavelengths usable by the latter.
• the radiation at the wavelengths thus eliminated are absorbed at the level of the concentrator to heat it so as to avoid it becoming a cold trap.
• the concentrator 106 is covered with a transparent layer 206 whose outer face 116 is inclined relative to the plane of the reflective face of the concentrator 106, so that the luminous flux 107 be divided into two parts.
• a first part 207 corresponding to the wavelengths useful for photoelectric conversion, enters the filter, is reflected by the concentrator 106 in the form of a flux 217, then emerges through the inclined face of the filter 206 to refract in forming a beam 208 directed towards the upper face of the transparent layer 102 which protects the cells 101.
• a second part 218 of the flux 107 is reflected by total reflection on the upper face of the filter 206 in the form of a stream 218 which is directed towards the space outside the photoelectric device.
• the flux 208 contains a certain percentage of non-useful wavelengths, a part of which is reflected in the form of a flux 210 and a residual part nevertheless contributes to the parasitic heating of the cells 101.
• this effect is weaker than in the absence of a filter.
• the necessary inclinations of the concentrator 106 relative to the cells 101 and of the external face 116 of the filter 206 relative to this concentrator are studied so that there is indeed total reflection of the unnecessary wavelengths on this inclined face 116 (we recall that the refraction when passing from one medium to another, and therefore the possible total reflection, depend on the wavelength of the light rays, which allows this separation), and so that the combination of the reflection on the concentrator 106 and of the refraction at the passage of the face 116 make it possible to direct the useful wavelengths towards the external surface of the transparent layer 102.
• the filter 206 is produced in the form of a relatively thick blade, the thickness of which decreases from one end to the other of the surface of the concentrator 106 in order to obtain the desired inclination. This causes a relatively large increase in the weight of the assembly, which is not necessarily desirable.
• the filter 206 will be formed of a transparent refractive layer whose average thickness will be substantially constant and as small as possible. To get the desired effect, the outer face 116 of this layer will be machined in Fresnel steps so as to locally obtain the desired effect while limiting the overall thickness of the filter.
• a filter 306 is used placed on the reflecting surface of the concentrator 106 and which is formed of a flat blade of uniform thickness.
• This plate is made of an absorbent material for the “useless” components of the incident solar flux 107, but transparent for the “useful” components of this same flux (those which make it possible to obtain a photoelectric conversion in the cells 101).
• angles and the refractive index of the material making up the layer 306 are chosen so that the path 307 of the solar flux in the layer 306 is the same on the outward and return path, the reflection on the concentrator 106 taking place in a direction normal to the surface thereof. This is only a special case and these paths may be different, in the same way as in FIG. 2.
• the solar flux 308 is therefore largely rid of these "unnecessary" components and it then strikes the outer surface of the transparent layer 102 to excite the cells 101 along a path 309 due to refraction.
• part of this “useless” flux is reflected on the surface of the transparent layer 102 to form a flux 310 which is lost in the stellar vacuum, and only a tiny part of this “useless” radiation "Is contained in flow 309 and contributes very little to the parasitic heating of cells 101.

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• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Photovoltaic Devices (AREA)

Applications Claiming Priority (3)

Publications (1)

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Citations (2)

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• 2002
  • 2002-04-11 FR FR0204528A patent/FR2838564B1/fr not_active Expired - Fee Related
• 2003
  • 2003-04-01 JP JP2003582829A patent/JP4564262B2/ja not_active Expired - Fee Related
  • 2003-04-01 WO PCT/FR2003/001002 patent/WO2003085745A1/fr active Application Filing
  • 2003-04-01 EP EP03740544A patent/EP1497870A1/fr not_active Withdrawn
  • 2003-04-01 US US10/510,183 patent/US8383928B2/en not_active Expired - Fee Related
  • 2003-04-01 AU AU2003260705A patent/AU2003260705A1/en not_active Abandoned

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Non-Patent Citations (1)

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