DE4108503C2 - Solar energy conversion device for the simultaneous generation of electrical and thermal energy - Google Patents

Solar energy conversion device for the simultaneous generation of electrical and thermal energy

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Publication number
DE4108503C2
DE4108503C2 DE4108503A DE4108503A DE4108503C2 DE 4108503 C2 DE4108503 C2 DE 4108503C2 DE 4108503 A DE4108503 A DE 4108503A DE 4108503 A DE4108503 A DE 4108503A DE 4108503 C2 DE4108503 C2 DE 4108503C2
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solar cells
tandem
cells
solar
heat transfer
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DE4108503A1 (en
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Adolf Prof Dr Goetzberger
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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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
    • H01L31/06—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 characterised by potential barriers
    • H01L31/068—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 characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • H01L31/0687—Multiple junction or tandem solar cells
    • 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
    • F24S10/70—Solar heat collectors using working fluids the working fluids being conveyed through tubular absorbing conduits
    • 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
    • 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
    • H01L31/0549—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising spectrum splitting means, e.g. dichroic mirrors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/40—Thermal components
    • H02S40/44—Means to utilise heat energy, e.g. hybrid systems producing warm water and electricity at the same time
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S99/00—Subject matter not provided for in other groups of this subclass
    • 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
    • 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
    • Y02E10/544—Solar cells from Group III-V materials
    • 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
    • Y02E10/60—Thermal-PV hybrids

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Sustainable Energy (AREA)
  • Sustainable Development (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Photovoltaic Devices (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Description

Die Erfindung betrifft eine Solarenergieumwandlungseinrichtung gemäß dem Oberbegriff des Anspruchs 1, wie sie in Lit. /1/ beschrieben ist.The invention relates to a solar energy conversion device according to the preamble of claim 1 as described in Ref. / 1 /.

Stand der TechnikState of the art

Die Umwandlung von Sonnenenergie in elektrische Energie kann auf zwei Wegen er­ folgen.There are two ways to convert solar energy into electrical energy consequences.

  • a) Solarzellen:
    Diese Festkörperbauelemente wandeln Strahlungsenergie direkt in Strom um.    a) Solar cells:
    These solid state components convert radiation energy directly into electricity.
  • b) Wärmekraftmaschinen in Verbindung mit konzentrierenden Kollektoren.b) heat engines in connection with concentrating collectors.

Solarzellen sind in ihrem Wirkungsgrad im wesentlichen durch den Bandabstand des Halbleiters begrenzt. Mit einem einzelnen Halbleiter liegt der an das Sonnenspektrum angepaßte optimale Bandabstand bei etwa 1,4 eV. Höhere Wir­ kungsgrade werden durch die Technik der Tandemzellen erreicht. Hierzu werden mehrere Solarzellen aus verschiedenen Halbleitermaterialien aufeinander gesta­ pelt dergestalt, daß das Material mit dem höchsten Bandabstand an der direkt dem Sonnenlicht zugewandten Seite angeordnet ist und dann sinkende Werte des Bandabstandes folgen mit dem niedrigsten Bandabstand zuunterst. Bis heute wurde mit einer Serie von zwei Solarzellen und konzentriertem Sonnenlicht maximal 37% Umwandlungswirkungsgrad erzielt. Der Rest der Energie fällt als Wärme an. Bei diesen Zellen ist es erforderlich, für eine gute Wärmeabfuhr zu sorgen, da der Wirkungsgrad der Solarzellen temperaturabhängig ist.The efficiency of solar cells is essentially due to the band gap of the semiconductor limited. With a single semiconductor that is optimal bandgap adapted to the sun spectrum at about 1.4 eV. Higher we Degree of efficiency is achieved through the technology of the tandem cells. To do this several solar cells made of different semiconductor materials stacked on top of each other pelt in such a way that the material with the highest band gap directly at the the side facing the sunlight and then falling values of the Band gap follow with the lowest band gap at the bottom. To date  with a series of two solar cells and concentrated sunlight maximum 37% Conversion efficiency achieved. The rest of the energy is generated as heat. At these cells, it is necessary to ensure good heat dissipation, since the Efficiency of the solar cells is temperature-dependent.

Es sind auch Überlegungen bekanntgeworden, Solarzellen in Konzentratorsystemen bei gleichzeitiger Nutzung der abgeführten Wärme in einer Wärmekraftmaschine zu verwenden. Der Stand der Technik ist in Lit. /1/ beschrieben.Considerations have also become known, solar cells in concentrator systems with simultaneous use of the dissipated heat in a heat engine use. The prior art is described in Ref. / 1 /.

Das bekannte System beruht auf einer Solarzelle, die auf einer Wärmesenke montiert ist. Die Wärme wird einer Carnotmaschine zugeführt, die ihrerseits elektrische Energie erzeugt. Somit addieren sich die beiden Wirkungsgrade zu einem relativ hohen Gesamtwirkungsgrad. Dieser ist durch das gegenläufige Tem­ peraturverhalten der beiden Komponenten begrenzt: Der Solarzellenwirkungsgrad sinkt mit steigender Temperatur, während gleichzeitig der Carnot-Wirkungsgrad ansteigt.The known system is based on a solar cell, which is based on a heat sink is mounted. The heat is supplied to a Carnot machine, which in turn generates electrical energy. Thus the two efficiencies add up a relatively high overall efficiency. This is due to the opposite tem temperature behavior of the two components limited: The solar cell efficiency decreases with increasing temperature, while at the same time the Carnot efficiency increases.

Für die Optimierung ist es wichtig, daß die Temperaturabhängigkeit des Solar­ zellenwirkungsgrades stark vom Bandabstand abhängig ist: Mit steigendem Bandabstand sinkt die Temperaturabhängigkeit des Wirkungsgrades. Andererseits wird mit steigendem Bandabstand ein immer geringerer Teil des Sonnenspektrums absorbiert, was den Wirkungsgrad reduziert. In Lit. /1/ wurde unter Berück­ sichtigung dieser Zusammenhänge ein maximaler Wirkungsgrad von 40% bei 700 K und einem Bandabstand von 1,6 eV sowie einer Lichtkonzentration von 1000 be­ stimmt. Der Wirkungsgrad kann noch erhöht werden, indem man eine Tandemzelle anstelle einer aus einem einzigen Halbleiter bestehenden Zelle verwendet. Dabei erweist sich, daß Halbleiter mit niedrigen Bandabständen nicht in Frage kommen, da sie bei hohen Temperaturen sehr niedrige Wirkungsgrade aufweisen.For optimization it is important that the temperature dependence of the solar cell efficiency depends strongly on the band gap: With increasing Bandgap decreases the temperature dependence of the efficiency. On the other hand becomes an ever smaller part of the solar spectrum with increasing bandgap absorbs, which reduces efficiency. In Ref. / 1 / under Berück considering these relationships, a maximum efficiency of 40% at 700 K. and a band gap of 1.6 eV and a light concentration of 1000 be Right. The efficiency can be increased even more by using a tandem cell instead of a single semiconductor cell. Here proves that semiconductors with low bandgaps are out of the question, because they have very low efficiencies at high temperatures.

Aufgabe der Erfindung ist es daher, den Wirkungsgrad der bekannten Solarenergieumwandlungseinrichtung zu optimieren. Dies geschieht erfindungsgemäß durch die Solarenergieumwandlungseinrichtung nach Anspruch 1.The object of the invention is therefore to improve the efficiency of the known To optimize solar energy conversion device. This is done according to the invention by the solar energy conversion device according to claim 1.

Vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen gekennzeichnet. Advantageous embodiments of the invention are in the Subclaims marked.  

Der Grundgedanke der hier beschriebenen Erfindung ist folgender:
Die Wärmekraftmaschine arbeitet zwischen einer hohen Temperatur TH und einer unteren Temperatur T0, wobei der Carnot-Wirkungsgrad ηcarn gegeben ist durchThe basic idea of the invention described here is as follows:
The heat engine works between a high temperature T H and a lower temperature T 0 , the Carnot efficiency η carn being given by

dementsprechend muß ein Wärmeübertragungsmedium, meist eine Flüssigkeit, durch Sonnenenergie von T0 auf TH erhitzt werden. Gemäß der Erfindung wird die Erwärmung in verschiedenen Stufen vorgenommen, wobei die verschiedenen Temperaturstufen mit verschiedenen Solarzellenanordnungen ver­ knüpft sind, dergestalt daß die niedrigeren Temperaturstufen mit Solarzellen von niedrigem Bandabstand thermisch gekoppelt sind. Entsprechend liegt die So­ larzelle mit dem höchsten Bandabstand auf der höchsten Temperatur. Somit fällt die gesamte Wärmeenergie bei der höchsten Temperatur TH an, während die Solar­ zellen bei abgestuften Temperaturen, die optimal den Bandabständen angepaßt sind, arbeiten.accordingly, a heat transfer medium, usually a liquid, must be heated from T 0 to T H by solar energy. According to the invention, the heating is carried out in different stages, the different temperature stages being linked to different solar cell arrangements in such a way that the lower temperature stages are thermally coupled to solar cells with a low band gap. Accordingly, the solar cell with the highest band gap is at the highest temperature. Thus, the total thermal energy at the highest temperature T H , while the solar cells work at graded temperatures that are optimally adapted to the bandgap.

Für die praktische Ausführung dieses Konzeptes werden nun drei verschiedene Versionen angegeben. In allen Fällen handelt es sich um Anordnungen mit hoher Lichtkonzentration.For the practical implementation of this concept there are now three different ones Versions specified. In all cases, the orders are high Light concentration.

Anordnung A (Abb. 1)Arrangement A ( Fig. 1)

Das Solarspektrum wird nach Lit. /2/ in verschiedene Teile aufgespalten. Hierzu dienen spektral selektive Spiegel 2 und 3. Der langwellige Teil des Spektrums wird ausgesondert und auf eine darauf angepaßte Solarzelle 4 niedrigen Bandabstandes gelenkt. Der mittlere Teil des Spektrums wird durch Spiegel 3 auf Solarzelle 5 mit mittlerem Bandabstand gelenkt und das durchgehende kurzwellige Licht trifft auf Solarzelle 6 mit hohem Bandabstand. Diese Anordnung für Solar­ zellen ist bereits in /2/ beschrieben. Die zusätzlich thermische Energiegewin­ nung erfolgt über Wärmesenken 7, 8, 9, auf die Solarzellen mit gutem Wärmekontakt montiert sind. Die Wärmeübertragungsflüssigkeit, die die Wärmesenken sukzessive durchfließt, tritt mit T0 in Wärmesenke 7 ein, wird dort auf T1 erwärmt, sodann in Wärmesenke 8 auf T2 und tritt mit Temperatur T3 aus 9 aus. T3 = TH ist die Arbeitstemperatur der Wärmekraftmaschine, die das Arbeitsmedium wieder auf T0 abkühlt. Bei dieser Anordnung ist darauf zu achten, daß die Wärmemengen, die in den ein­ zelnen Stufen abgegeben werden, den erforderlichen Temperaturdifferenzen bei kontinuierlichem Durchfluß des Mediums im Kreislauf 10 entsprechen. Die Aufspaltung des Spektrums kann auch mit einem ho­ lographischen Element nach Lit./3/ anstelle eines spektral selektiven Spiegels erfolgen.The solar spectrum is split into different parts according to Ref. / 2 /. Spectrally selective mirrors 2 and 3 are used for this . The long-wave part of the spectrum is separated out and directed onto an adapted solar cell 4 with a low band gap. The middle part of the spectrum is directed by mirror 3 onto solar cell 5 with a medium band gap and the continuous short-wave light strikes solar cell 6 with a high band gap. This arrangement for solar cells is already described in / 2 /. The additional thermal energy generation takes place via heat sinks 7 , 8 , 9 , on which solar cells with good thermal contact are mounted. The heat transfer fluid flows through the heat sinks successively occurs with T 0 in a heat sink 7, where it is heated to T 1, then in the heat sink 8 on T 2 and exits 9 with temperature T3. T 3 = T H is the working temperature of the heat engine that cools the working medium back down to T 0 . In this arrangement, care must be taken to ensure that the amounts of heat that are emitted in the individual stages correspond to the required temperature differences with a continuous flow of the medium in the circuit 10 . The spectrum can also be split with a ho lographic element according to Ref. / 3 / instead of a spectrally selective mirror.

Anordnung B (Abb. 2)Arrangement B ( Fig. 2)

Diese Anordnung entspricht einer konventionellen Tandem-Solarzellenanordnung. Verschiedene Solarzellen 4, 5, 6 mit Eg4 <Eg5 <Eg6 (mit Eg4 = Bandabstand der Zelle 4 etc.) werden durch konzentriertes Sonnenlicht 1 bestrahlt. Solarzelle 6 filtert den kurzwelligen Teil des Lichts aus, die folgenden Solarzellen absor­ bieren jeweils den nachfolgenden, längerwelligen Teil. Im Gegensatz zu be­ kannten Tandemanordnungen, bei denen die Zellen direkt oder mit optischen Kopp­ lern miteinander verknüpft werden, sind hier optisch transparente Wärmesenken 7, 8, 9 mit Durchflußkanälen 18 zwischen den Solarzellen angeordnet. Verbin­ dungsleitungen 19 und 20 verbinden die transparenten Wärmesenken. Um op­ tische Verluste zu minimieren, müssen die optisch transparenten Wärmesenken in ihrem Brechungs­ index gut an die Solarzellen angepaßt sein. Auch die in den Kanälen fließende Flüssigkeit muß transparent und im Brechungsindex an das Material der Elemente angepaßt sein. Anhand der Abb. 2 ist leicht zu erkennen, daß auch in dieser An­ ordnung die einzelnen Solarzellen auf verschiedenen Temperaturniveaus arbeiten und die gesamte frei werdende Wärme bei T3 abgenommen werden kann. This arrangement corresponds to a conventional tandem solar cell arrangement. Different solar cells 4 , 5 , 6 with Eg 4 <Eg 5 <Eg 6 (with Eg 4 = band gap of cell 4 etc.) are irradiated by concentrated sunlight 1 . Solar cell 6 filters out the short-wave part of the light, the following solar cells each absorb the following, longer-wave part. In contrast to known tandem arrangements in which the cells are linked directly or with optical couplers, optically transparent heat sinks 7, 8, 9 with flow channels 18 are arranged between the solar cells. Connection lines 19 and 20 connect the transparent heat sinks. In order to minimize optical losses, the optically transparent heat sinks must be well matched to the solar cells in their refractive index. The liquid flowing in the channels must also be transparent and match the refractive index to the material of the elements. Based on Fig. 2 it is easy to see that even in this arrangement, the individual solar cells work at different temperature levels and the total heat released at T 3 can be removed.

Anordnung C (Abb. 3)Arrangement C ( Fig. 3)

Diese Anordnung eignet sich besonders für linear konzentrierende Systeme, bei denen das Licht mit Hilfe eines Zylinderparabolspiegels auf eine Wärmesenke, die als langes Rohr ausgebildet ist, konzentriert wird. Das Wärmeträgermedium er­ wärmt sich bei Durchfluß durch das Rohr von T0 auf T4. Die einzelnen Ab­ schnitte des Rohrs werden nun mit Tandemsolarzellenanordnungen 12, 13, 14 belegt. Abschnitt 12 besteht aus Solarzellen, deren Bandenergien von hohen bis zu niedrigen Werten reichen, wobei die Bedingung ist, daß die unterste Solar­ zelle mit dem niedrigsten Bandabstand bei T1 noch einen guten Wirkungsgrad ha­ ben soll. In den folgenden Stufen wird mit steigender Temperatur laufend weni­ ger Energie photovoltaisch umgewandelt. Die Tandemzelle 13 endet unten mit einem höheren Bandabstand als 12. 14 stellt in diesem Beispiel eine Zelle aus nur einem Material mit hohem Bandabstand dar. Falls sehr hohe Austrittstemperaturen ange­ strebt werden, kann ein Abschnitt 15 nur als thermischer Absorber ausgebildet sein.This arrangement is particularly suitable for linearly concentrating systems in which the light is concentrated on a heat sink, which is designed as a long tube, with the aid of a cylindrical parabolic mirror. The heat transfer medium heats up when it flows through the tube from T 0 to T 4 . From the individual sections of the tube are now covered with tandem solar cell assemblies 12 , 13 , 14 . Section 12 consists of solar cells whose band energies range from high to low values, the condition being that the lowest solar cell with the lowest band gap at T 1 should still have good efficiency. In the following stages, as the temperature rises, less energy is converted photovoltaically. The tandem cell 13 ends at the bottom with a higher band gap than 12 . In this example, 14 represents a cell made of only one material with a high band gap. If very high outlet temperatures are desired, a section 15 can only be designed as a thermal absorber.

Beispielhafte AusführungExemplary execution

Für die Solarzellen eignet sich besonders das System Alx Ga1 -x As, bei dem der Bandabstand in weiten Grenzen durch den Parameter x variiert werden kann. Eine dreistufige Tandemzelle, die schon realisiert wurde, besteht aus InAs (Eg = 1.0 eV), GaAs (Eg = 1,42 eV) und AlGaAs (Eg = 1,93 eV). Weitere mögliche Halbleiter sind Si (1.12 eV) und GaP (2.25 eV).The system Al x Ga 1 -x As is particularly suitable for the solar cells, in which the band gap can be varied within wide limits using the parameter x. A three-stage tandem cell that has already been implemented consists of InAs (Eg = 1.0 eV), GaAs (Eg = 1.42 eV) and AlGaAs (Eg = 1.93 eV). Other possible semiconductors are Si (1.12 eV) and GaP (2.25 eV).

Die Arbeitstemperaturen können mit Hilfe eines Computerprogramms optimiert werden. Eine beispielhafte Serie istThe working temperatures can be optimized with the help of a computer program become. An exemplary series is

T1 = 400 K; T2 = 470 K; T4 = 550 K.T 1 = 400 K; T 2 = 470 K; T 4 = 550 K.

Für diesen Fall ergibt sich bei optimalen Solarzellenparametern und einem realistischen Wirkungsgrad der Wärmekraftmaschine von 1/2 des Carnot- Wirkungsgrades ein Gesamtumwandlungswirkungsgrad von mehr als 50%. In this case, with optimal solar cell parameters and one realistic efficiency of the heat engine of 1/2 of the Carnot Efficiency a total conversion efficiency of more than 50%.  

Literaturliterature

/1/ A. Goetzberger und W. Wettling, 7. Int. Sonnenforum 1990, S. 1335
/2/ R. C. Moon et al., Conf. Record, 13th IEEE Photovoltaic Specialists Conf. 1978, p. 822
/3/ W. H. Bloss et al., Proc. 3rd EG Photovoltaic Energy Conf. 1980, p. 401./ 1 / A. Goetzberger and W. Wettling, 7th Int. Sonnenforum 1990, p. 1335
/ 2 / RC Moon et al., Conf. Record, 13th IEEE Photovoltaic Specialists Conf. 1978, p. 822
/ 3 / WH Bloss et al., Proc. 3rd EG Photovoltaic Energy Conf. 1980, p. 401.

Claims (7)

1. Solarenergieumwandlungseinrichtung zur gleichzeitigen Gewinnung von elektrischer und thermischer Energie, bestehend aus einer Vorrichtung zur optischen Konzentration des Sonnenlichts und aus von einem Wärmeübertragungsmedium gekühlten, aus mindestens zwei Solarzellen unterschiedlichen Bandabstandes bestehenden Tandemsolarzellen, dadurch gekennzeichnet, daß die Tandemsolarzellen monolithisch oder getrennt derart angeordnet sind, daß die Temperatur des die Solarzellen (4, 5, 6) über Wärmesenken (7, 8, 9) kühlenden Wärmeübertragungsmediums im gleichen Sinne wie die Bandabstände der Solarzellen ansteigt. 1. Solar energy conversion device for the simultaneous generation of electrical and thermal energy, consisting of a device for the optical concentration of sunlight and of tandem solar cells cooled by a heat transfer medium and consisting of at least two solar cells with different band gaps, characterized in that the tandem solar cells are arranged monolithically or separately in such a way that the temperature of the heat transfer medium cooling the solar cells ( 4, 5, 6 ) via heat sinks ( 7, 8, 9 ) increases in the same sense as the bandgaps of the solar cells. 2. Einrichtung nach Anspruch 1, dadurch gekennzeichnet, daß das konzentrierte Sonnenlicht durch spektral selektive Spiegel (2, 3) auf einzelne Solarzellen (4, 5, 6) mit verschiedenen, an die spektralen Ausschnitte angepaßten Bandabständen gelenkt wird.2. Device according to claim 1, characterized in that the concentrated sunlight is directed by spectrally selective mirrors ( 2, 3 ) onto individual solar cells ( 4, 5, 6 ) with different band gaps adapted to the spectral cutouts. 3. Einrichtung nach Anspruch 1, dadurch gekennzeichnet, daß die Aufteilung des Sonnenspektrums durch ein holographisches Element erfolgt. 3. Device according to claim 1, characterized in that the division of the Sun spectrum is done by a holographic element.   4. Einrichtung nach Anspruch 1, dadurch gekennzeichnet, daß zwischen die Einzelzellen (4, 5, 6) eines Tandemstapels optisch transparente Elemente (7, 8, 9) mit Durchflußkanälen (18) für ein Wärmeträgermedium eingefügt sind (Fig. 2).4. Device according to claim 1, characterized in that between the individual cells ( 4, 5, 6 ) of a tandem stack optically transparent elements ( 7, 8, 9 ) with flow channels ( 18 ) for a heat transfer medium are inserted ( Fig. 2). 5. Einrichtung nach Anspruch 4, dadurch gekennzeichnet, daß das die Kanäle durchfließende Medium transparent ist und daß es im Brechungsindex den transparenten Elementen nahe ist.5. Device according to claim 4, characterized in that the Medium flowing through channels is transparent and that it is in the refractive index is close to the transparent elements. 6. Einrichtung nach Anspruch 1, dadurch gekennzeichnet, daß ein linear von einem Wärmeträgermedium durchflossenes Absorberrohr mit verschiedenen Tandemzellen (12, 13, 14) belegt ist, dergestalt daß die Zahl der Einzelzellen pro Tandemzelle mit steigender Temperatur abnimmt.6. Device according to claim 1, characterized in that a linearly flowed through a heat transfer medium absorber tube with different tandem cells ( 12, 13, 14 ) is occupied, such that the number of individual cells per tandem cell decreases with increasing temperature. 7. Einrichtung nach Anspruch 6, dadurch gekennzeichnet, daß die höchste Temperaturstufe als reiner thermischer Absorber (15) ausgebildet ist.7. Device according to claim 6, characterized in that the highest temperature level is designed as a pure thermal absorber ( 15 ).
DE4108503A 1991-03-15 1991-03-15 Solar energy conversion device for the simultaneous generation of electrical and thermal energy Expired - Fee Related DE4108503C2 (en)

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ITRM920164A IT1263210B (en) 1991-03-15 1992-03-11 SOLAR ENERGY TRANSFORMATION PLANT.

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DE19634405A1 (en) * 1996-08-26 1998-03-05 Hne Elektronik Gmbh & Co Satel Solar module with light splitting unit
DE19837189C1 (en) * 1998-08-17 1999-09-09 Hne Elektronik Gmbh & Co Satel Solar energy conversion device for providing heat and electrical energy
DE102009060786A1 (en) 2009-12-21 2011-06-22 Rikker Holzbau GmbH, 71563 Mounting system for photovoltaic modules with integrated thermal solar system

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DE19902650A1 (en) * 1999-01-24 2000-07-27 Mueller Gerald Patrick Process for the recovery of solar energy comprises using a thin layer solar cell and removing thermal energy using an air heat exchanger or a water heat exchanger below the cell
DE102004021028A1 (en) * 2004-01-10 2005-08-04 Julian Donner Solar generator has transparent solar cells with rear tube or hose heat exchange system having a flowing heat transfer medium
DE102004005050A1 (en) * 2004-01-30 2005-08-25 Detlef Schulz Method for energy conversion of solar radiation into electricity and heat with color-selective interference filter mirrors and a device of a concentrator solar collector with color-selective mirrors for the application of the method
WO2008091290A2 (en) * 2006-07-28 2008-07-31 University Of Delaware High efficiency solar cell
DE102006059417A1 (en) * 2006-12-15 2008-06-26 Solartec Ag Photovoltaic device with holographic structure for deflecting incident solar radiation, as well as manufacturing method thereof
DE102007023583A1 (en) * 2007-05-21 2008-11-27 Solartec Ag Photovoltaic device with optical elements for deflecting incident solar radiation in a given spectral range on laterally mounted solar cells on the optical elements
DE102007052338A1 (en) * 2007-11-02 2009-05-07 Rev Renewable Energy Ventures, Inc. Photovoltaic installation has multiple level mirrors for concentration of sunlight on concentrator module with photovoltaic element, where mirrors are aligned together in form of Fresnel mirror field in parallel manner

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Publication number Priority date Publication date Assignee Title
DE19634405A1 (en) * 1996-08-26 1998-03-05 Hne Elektronik Gmbh & Co Satel Solar module with light splitting unit
DE19634405C2 (en) * 1996-08-26 2003-02-20 Hne Elektronik Gmbh & Co Satel solar module
DE19837189C1 (en) * 1998-08-17 1999-09-09 Hne Elektronik Gmbh & Co Satel Solar energy conversion device for providing heat and electrical energy
DE102009060786A1 (en) 2009-12-21 2011-06-22 Rikker Holzbau GmbH, 71563 Mounting system for photovoltaic modules with integrated thermal solar system

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ITRM920164A1 (en) 1993-09-11
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DE4108503A1 (en) 1992-09-17

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