EP1105923A2 - Photovoltaic device - Google Patents

Photovoltaic device

Info

Publication number
EP1105923A2
EP1105923A2 EP99950483A EP99950483A EP1105923A2 EP 1105923 A2 EP1105923 A2 EP 1105923A2 EP 99950483 A EP99950483 A EP 99950483A EP 99950483 A EP99950483 A EP 99950483A EP 1105923 A2 EP1105923 A2 EP 1105923A2
Authority
EP
European Patent Office
Prior art keywords
radiation
photovoltaic
photovoltaic device
water
liquid medium
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP99950483A
Other languages
German (de)
French (fr)
Inventor
Jürgen KLEINWÄCHTER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Power Pulse Holding AG
Original Assignee
Power Pulse Holding AG
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
Priority claimed from DE19923196A external-priority patent/DE19923196A1/en
Application filed by Power Pulse Holding AG filed Critical Power Pulse Holding AG
Publication of EP1105923A2 publication Critical patent/EP1105923A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • 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
    • 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

Definitions

  • the invention relates to a photovoltaic device with a front exposed to radiation and an opposite rear for converting radiation energy into electrical energy with a cooling device.
  • photovoltaic power generators are fixed in the direction of the main sun.
  • the systems are also equipped with one or two-axis sun tracking or sunlight concentrators are used.
  • the problem arises that the achievable efficiency drops at elevated temperatures on the photovoltaic device. This is due to the fact that some of the electrons released by the incident light photons are recombined thermally, thus reducing the usable external current flow of the photovoltaic module.
  • thermal baffles are provided to improve the heat dissipation. If higher temperatures occur, the photovoltaic modules are actively cooled by passing a coolant over the back of the modules.
  • the invention is therefore based on the object of developing a generic photovoltaic device in such a way that it has a higher efficiency.
  • the cooling device has a liquid medium which is arranged between the front and the radiation source.
  • cooling devices In order not to reduce the radiation incident on the photovoltaic device, cooling devices have always been proposed which are arranged on the rear of the photovoltaic device.
  • the invention is based on the knowledge that a cooling device realized with a liquid medium can also be arranged on the front of the photovoltaic device.
  • the liquid medium can be selected so that the area of the solar spectrum that can be used for the photovoltaic effects is not or only insignificantly absorbed by the liquid medium, while the radiation energy in the areas that are of secondary importance for the photovoltaic effects is absorbed by the liquid Medium is absorbed.
  • the liquid Medium thus allows the radiation energy usable for photovoltaic effects to pass and absorbs the remaining radiation energy.
  • liquid medium consisting essentially of water ⁇ .
  • oils, alcohols or similar substances can also be used. Substances which optimize the filter characteristic in solution or suspension are advantageously added to these media.
  • thermosiphon consists of a domestic hot water tank, in the lower area of which there is a cold water outlet. From here, cold water flows into the lower area of the photovoltaic device and rises within the photovoltaic device to its upper end, from where the water flows back into the storage tank. Since the warm water enters the storage at a higher point, a temperature gradient is formed in the water storage with cold water on the bottom and warmer water in the upper area. The heated water can be taken directly from the storage tank.
  • a domestic hot water heat exchanger is preferably arranged in the store in order to heat cold domestic water to the desired domestic water temperature.
  • the cooling device has a pump for the liquid medium. This allows the liquid medium to flow through the cooling device and thus continuously dissipate heat.
  • the cooling device has a thermostat with which the pump can be regulated. This makes it possible to combine sufficient cooling with effective hot water production.
  • the temperature set on the thermostat and the pump capacity are determined by the required hot water temperature and the required cooling capacity.
  • Particularly good cooling performance is achieved in that the liquid medium flows directly over photovoltaic elements.
  • An increase in efficiency can be achieved in that the liquid medium first flows over the back and then the front of the photovoltaic device. The still cool medium is heated on the back of the device and absorbs further thermal energy on the front of the device.
  • effective cooling of the photovoltaic device is achieved on the one hand and on the other hand a liquid medium with a relatively high temperature is made available for further use.
  • cooling devices connected in parallel or in series.
  • a preferred embodiment provides that a further cooling device is spaced apart is arranged to the front. While this spaced cooling device mainly serves as a selective filter, a cooling device arranged directly on the photovoltaic modules simultaneously enables filter effects and cooling of the modules.
  • the radiation-transmissive layer on the side facing the radiation source is preferably selectively coated in a radiation-permeable manner.
  • the filter characteristics must also be influenced by the choice of different coating materials and processes in order to achieve an optimal filter characteristic in a cost-effective manner.
  • fluoropolymer films are inexpensive to manufacture and are suitable both for conducting liquid cooling media and as radiation filters.
  • Good results have also been made with Acrylic, polycarbonate and glass are achieved because these materials offer a high degree of transparency in the incident spectrum, as well as being mechanically stable, weatherproof and waterproof. This can be achieved inexpensively, for example, with acrylic (PMMA) and polycarbonate double-wall sheets.
  • the radiation-transmissive layer forms an envelope surrounding the liquid medium.
  • This envelope thus represents a closed component that can be used as a filter and can be exchanged in a simple manner.
  • FIG. 1 shows the relative intensity of the solar spectrum over the wavelength and the permeability of a 5 cm thick water layer and a 100 ⁇ m thick fluoropolymer film over the wavelength
  • FIG. 2 shows a single-layer photovoltaic device
  • FIG. 3 shows a section of a photovoltaic module
  • FIG. 4 shows the temperature distribution over the layer thickness of the photovoltaic module shown in FIG. 3,
  • Figure 6 shows a two-layer photovoltaic device with a concentrator and precooler.
  • the relative intensity is plotted on the left ordinate 1, the radiation transmittance r in percent on the right ordinate 2 and the wavelength in nannometers on the abscissa 3.
  • the solar spectrum 4 and the region 5 of this spectrum 4 that can be used for photovoltaic effects are drawn into this coordinate system.
  • the transmission of a 5 cm thick layer of water is illustrated by line 6 and line 7 shows the transmission of a 100 ⁇ m thick fluoropolymer film.
  • the illustration shows that the 5 cm thick water layer allows almost all of the radiation in the spectral range usable for photovoltaic effects to pass through and only absorbs the longer-wave radiation.
  • the film allows the radiation to pass almost unchanged over the entire spectral range and only absorbs part of the radiation in the short-wave range.
  • a photovoltaic module arranged below the water layer is thus irradiated by almost all of the radiation that can be used for photovoltaic effects, while the longer-wave radiation is absorbed by the water layer and causes the water to heat up.
  • This effect is used in the photovoltaic device shown in FIG. 2.
  • a layer of water 11 flows over the photovoltaic module 10 and thereby cools it.
  • the water layer 11 is enveloped by a transparent film 12, so that the water in this film 12 is passed.
  • a pump 13 pumps the water from a reservoir (not shown) through the photovoltaic device 14 to a store 15, from which the water can be removed in a metered manner via the valve 16 at the outlet 17.
  • the heating coil 18 permits reheating of the water if the water heating generated by the photovoltaic device is insufficient.
  • a temperature sensor 19 is arranged, which controls the pump 13 such that heated fluid is pumped into the memory 15 and fresh, cool fluid flows into the arrangement when the temperature sensor 19 has reached a defined, adjustable limit temperature.
  • the filter 11, 12 described is selective since it only allows radiation with a certain wavelength to pass through. However, it is also recuperative since it essentially recuperatively recovers the heat flow occurring on the surface of the photovoltaic module 10 by two mechanisms. On the one hand, this is the heat exchange that takes place through the direct contact of the fluid with the hot top of the module. On the other hand, the module surface radiates with a radiation that is shifted towards the long-wave towards the long wave according to the Vienna displacement law. According to the invention, this is absorbed by the filter fluid, the water 11, and converted into heat.
  • the long-wave photons which cannot trigger a photo effect, are converted into heat even before reaching the module, while in the known photovoltaic devices they are absorbed in the module and the heat flow generated has to be extracted through the module.
  • the advantage of the photovoltaic device according to the invention is thus that the top layer, ie the side facing the radiation, is exposed to particularly intensive cooling. This is particularly relevant, since in a photovoltaic module - as shown in FIG. 3 - the light quanta 20 of the radiation 21 are absorbed in the top layer 22 of the photovoltaic module 23 of the layer thickness d and this creates a temperature gradient, as shown in FIG. 4 with the line 24 is indicated.
  • Line 24 shows the linear temperature profile between the bottom 25 of the photovoltaic module 23 with the temperature T u and the top 26 of the photovoltaic module 23 with the temperature T 0 .
  • This illustration clearly shows once again that the cooling of the module on the front side according to the invention is particularly advantageous since it acts directly on the hottest surface of the module 23.
  • FIG. 5 shows a further development of the photovoltaic device shown in FIG. 2.
  • this photovoltaic device 30 is a A first fluid layer 32 flows around the photovoltaic module 31 on the side facing away from the radiation and through a second fluid layer 33 on the side facing the radiation.
  • a pump 34 promotes a water flow 35 along the back 36 of the photovoltaic module 31 in the first layer 32 and the water cools the back of the photovoltaic module 31.
  • a deflection device 37 guides the water flow 35 at the lower end of the photovoltaic module 31 around the module to the top 38 where it flows up along the top 38 in the second layer 33.
  • the water further heated at the front then flows into a reservoir 39 and from there via a valve 40 to the outlet 41.
  • the rear water-carrying layer 32 can either be a pipe coil of suitable geometry that is in good thermal contact with the rear, or it can consist of a full-surface plate heat exchanger. In order to minimize the heat losses to the outside, the entire arrangement is additionally supplemented by an opaque heat insulation 42 and a second transparent cover 43. The second transparent cover 43 is arranged at a distance from the transparent fluoropolymer film 44.
  • the termostat control 45 enables the temperature increase of the cooling fluid to be set in a targeted manner. Depending on the application, the desired temperature at outlet 41 may be 30 ° C. for swimming pool heating, for example, while approx. 40 ° C. is required for shower water.
  • a module can be made from a surface element which previously generated electrical power with approximately 10% efficiency from the radiation supply, and which generates electricity and hot water with a total efficiency of approximately 60%.
  • FIG. 6 shows that the system according to the invention can in principle also be used on photovoltaic arrangements with sunlight concentration. Especially with increased energy density on the surface of the module, the described, inexpensive selective and recuperative heat extraction mechanisms come into play even more.
  • the energy content of the long-wave, non-photovoltaically usable part of the solar spectrum is used to heat water to relatively low temperatures. If the cooling water flow is heated to higher temperatures, the efficiency of the photovoltaic module is reduced.
  • This photovoltaic device 50 essentially consists of the concentrator lens 51, the precooler 52 and the cooled photovoltaic module element 53.
  • This concentration optics such as for example, a mirror system can be used.
  • the structure of the photovoltaic module 53 corresponds to that of the photovoltaic device 30 shown in FIG. 5.
  • the precooler 52 serves as a prefilter, which in the case of a linear concentrator consists of a transparent cuboid of the dimension of the focal line at this location. In the case of a punctiform concentrator, a transparent flat hollow cylinder of the dimension of the focal spot is used at this location.
  • Hollow cuboids or hollow cylinders 54 are flowed through by a fluid which, in addition to the selectivity shown in FIG. 1, has the highest possible boiling point so that the system pressure remains low.
  • a fluid which, in addition to the selectivity shown in FIG. 1, has the highest possible boiling point so that the system pressure remains low.
  • water with appropriate additives is used.
  • This water is heated in the hollow cuboid or hollow cylinder 54 to temperatures in the range of approximately 100 ° C. by means of the radiation 55 concentrated by means of the lens 51.
  • the temperature sensor 56 acts on the pump 57, so that new fluid flow is pumped into the cavity 54.
  • the heated water leaves via the pipe
  • the device 50 can thus use the primary radiated energy
  • thermodynamic machines can be converted into mechanical work or additional electrical current.
  • the amount of hot water generated on the photovoltaic module device 53 can also be further heated in the prefilter 52 by establishing a connection between the line end 61 and the pump 57.
  • the photovoltaic devices described are based on the correct selection of the fluid and the transparent sheathing materials. In the area of liquids, there are many options from water to oils, alcohol, etc. Since photovoltaic modules of various structures (e.g. silicon, GaAs, ZnS, etc.) can be used, the selective filter must be matched to the photovoltaically active spectral range required in each case. If necessary, this adjustment is implemented relatively exactly by the filter characteristics of the transparent wrapping materials and / or liquids. To vary the filter properties, the enveloping materials themselves can be selectively coated and additives can be added to the liquids.
  • photovoltaic modules of various structures e.g. silicon, GaAs, ZnS, etc.
  • a commercially available fluoropolymer film of 100 ⁇ m thickness was used as the covering.
  • This film is chemically inert, environmentally neutral and can be processed flexibly.
  • care must be taken to ensure that the appropriate mechanical support or channel-shaped subdivision of the a pillow-shaped bulge is avoided in order to form a relatively uniform thickness of the water layer over the entire surface.
  • Photovoltaic elements are usually covered on their top with a glass or plastic surface in order to protect the active photovoltaic surface from mechanical influences.
  • a covering for conducting liquids which rests on the active photovoltaic surface
  • the water-conducting elements take on the function of a protective surface.
  • so-called double-wall sheets can be used to guide the liquid on the photovoltaic elements and to protect the photovoltaic elements at the same time.
  • the glass plates conventionally used can also be provided with liquid-permeable channels running in the plane of the plate, or can enable a liquid-carrying layer as a double plate.
  • Water was used as the selective fluid in the exemplary embodiments described. Water is inexpensive and environmentally neutral. When using additives to the water, a heat exchanger for the production of hot water is necessary. However, the temperatures of the amount of hot water generated can also be set so that water without additives is used. The use of a heat exchanger can then be dispensed with.

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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)

Abstract

The invention relates to a photovoltaic device with a front side exposed to the radiation and an opposite rear side for converting the radiation energy into electrical energy, wherein a cooling device is used that is disposed between the front face of the photovoltaic module and the radiation source. The cooling device has a fluid medium, wherein water is preferably used as liquid medium. The water conducting layer and the water serve as selective filter allowing the passage of the radiation fraction used for the photovoltaic effect and converting the longer waved radiation into heat which is immediately dissipated in order to substantially prevent heating of the photovoltaic module.

Description

Photovoltaikeinrichtung Photovoltaic device
Die Erfindung betrifft eine Photovoltaikeinrichtung mit einer der Strahlung ausgesetzten Vorderseite und einer gegenüberliegenden Rückseite zur Umwandlung von Strahlungsenergie in elektrische Energie mit einer Kühleinrichtung.The invention relates to a photovoltaic device with a front exposed to radiation and an opposite rear for converting radiation energy into electrical energy with a cooling device.
Photovoltaische Stromerzeuger werden in der Regel fix zur Hauptsonneneinfallsrichtung hin ausgerichtet. Vereinzelt werden die Systeme auch mit einer ein- oder zweiachsigen Sonnennachf hrung ausgerüstet oder es werden Sonnenlichtkonzentratoren eingesetzt.As a rule, photovoltaic power generators are fixed in the direction of the main sun. In some cases, the systems are also equipped with one or two-axis sun tracking or sunlight concentrators are used.
Insbesondere bei der Verwendung von Lichtkonzentratoren entsteht jedoch das Problem, daß bei erhöhten Temperaturen an der Photovoltaikeinrichtung der erzielbare Wirkungsgrad sinkt. Dies ist darauf zurückzuführen, daß die durch die einfallenden Lichtphotonen freigesetzten Elektronen teilweise thermisch rekombiniert werden und somit der nutzbare äußere Stromfluß des Photovoltaikmodules reduziert wird.Particularly when using light concentrators, however, the problem arises that the achievable efficiency drops at elevated temperatures on the photovoltaic device. This is due to the fact that some of the electrons released by the incident light photons are recombined thermally, thus reducing the usable external current flow of the photovoltaic module.
Dieses Problem wird im Stand der Technik dadurch gelöst, daß an der Rückseite der Photo voltaikmodule, ähnlich wie bei elektrischen Bauteilen, Wärmeleitbleche vorgesehen sind, um die Wärmeabgabe zu verbessern. Sofern höhere Temperaturen anfallen, werden die Photovoltaikmodule aktiv gekühlt, indem ein Kühlmittel über die Rückseite der Module geleitet wird.This problem is solved in the prior art in that on the back of the photovoltaic modules, similar to electrical components, thermal baffles are provided to improve the heat dissipation. If higher temperatures occur, the photovoltaic modules are actively cooled by passing a coolant over the back of the modules.
Sowohl die Verfahren zur aktiven als auch zur passiven Wärmeableitung sind jedoch konstruktiv aufwendig und werden daher nur selten eingesetzt.Both the methods for active and passive heat dissipation are structurally complex and are therefore rarely used.
Der Erfmgung liegt daher die Aufgabe zugrunde, eine gattungsgemäße Photovoltaikeinrichtung derart weiterzubilden, daß sie einen höheren Wirkungsgrad aufweist.The invention is therefore based on the object of developing a generic photovoltaic device in such a way that it has a higher efficiency.
Diese Aufgabe wird dadurch gelöst, daß die Kühleinrichtung ein flüssiges Medium aufweist, das zwischen der Vorderseite und der Strahlungsquelle angeordnet ist.This object is achieved in that the cooling device has a liquid medium which is arranged between the front and the radiation source.
Um die auf die Photovoltaikeinrichtung auftreffende Strahlung nicht zu reduzieren, wurden bisher immer Kühleinrichtungen vorgeschlagen, die auf der Rückseite der Photovoltaikeinrichtung angeordnet sind. Der Erfindung liegt die Erkenntnis zugrunde, daß eine mit einem flüssigen Medium realisierte Kühleinrichtung auch auf der Vorderseite der Photovoltaikeinrichtung angeordnet werden kann. Das flüssige Medium kann dabei so ausgewählt werden, daß der für die photovoltaischen Effekte nutzbare Bereich des Solarspektrums durch das flüssige Medium nicht oder nur unbedeutend absorbiert wird, während die Strahlungsenergie in den Bereichen, die für die photovoltaischen Effekte von untergeordneter Bedeutung sind, durch das flüssige Medium absorbiert wird. Das flüssige Medium läßt somit die für photovoltaische Effekte nutzbare Strahlungsenergie passieren und absorbiert die übrige Strahlungsenergie.In order not to reduce the radiation incident on the photovoltaic device, cooling devices have always been proposed which are arranged on the rear of the photovoltaic device. The invention is based on the knowledge that a cooling device realized with a liquid medium can also be arranged on the front of the photovoltaic device. The liquid medium can be selected so that the area of the solar spectrum that can be used for the photovoltaic effects is not or only insignificantly absorbed by the liquid medium, while the radiation energy in the areas that are of secondary importance for the photovoltaic effects is absorbed by the liquid Medium is absorbed. The liquid Medium thus allows the radiation energy usable for photovoltaic effects to pass and absorbs the remaining radiation energy.
Es hat sich herausgestellt, daß sich als flüssiges Medium besonders gut Flüssigkeiten eignen, die im wesentlichen^ aus Wasser bestehen. Je nach verwendetem Photovoltaikmodul können jedoch auch Öle, Alkohole oder ähnliche Substanzen eingesetzt werden. Diesen Medien werden vorteilhafterweise Substanzen zugesetzt, die in Lösung oder Suspension die Filterkennlinie optimieren.It has been found that particularly suitable liquids as the liquid medium consisting essentially of water ^. Depending on the photovoltaic module used, oils, alcohols or similar substances can also be used. Substances which optimize the filter characteristic in solution or suspension are advantageously added to these media.
Eine einfache Photovoltaikeinrichtung wird dadurch erzielt, daß das flüssige Medium aufgrund der Schwerkraftunterschiede zwischen warmem und kaltem Medium zwischen Vorderseite und Strahlungsquelle fließt. Diese unter dem Namen Thermosyphon bekannte Anordnung besteht aus einem Brauchwasserspeicher, in dessen unterem Bereich ein Kaltwasseraustritt liegt. Von hier fließt Kaltwasser in den unteren Bereich der Photovoltaikeinrichtung und steigt innerhalb der Photovoltaikeinrichtung auf bis zu deren oberem Ende, von wo das Wasser wieder zurück in den Speicher fließt. Da das warme Wasser an einer höheren Stelle in den Speicher eintritt, bildet sich im Wasserspeicher ein Temperaturgradient mit kaltem Wasser am Boden und wärmerem Wasser im oberen Bereich. Das erwärmte Wasser kann direkt aus dem Speicher entnommen werden. Vorzugsweise ist jedoch im Speicher ein Brauchwasserwärmetauscher angeordnet, um kaltes Brauchwasser auf die gewünschte Brauchwassertemperatur zu erwärmen. Eine vorteilhafte Ausführungsform sieht vor, daß die Kühleinrichtung eine Pumpe für das flüssige Medium aufweist. Dies erlaubt es, das flüssige Medium durch die Kühleinrichtung fließen zu lassen und somit kontinuierlich Wärme abzuführen.A simple photovoltaic device is achieved in that the liquid medium flows between the front and the radiation source due to the gravitational differences between warm and cold medium. This arrangement, known as the thermosiphon, consists of a domestic hot water tank, in the lower area of which there is a cold water outlet. From here, cold water flows into the lower area of the photovoltaic device and rises within the photovoltaic device to its upper end, from where the water flows back into the storage tank. Since the warm water enters the storage at a higher point, a temperature gradient is formed in the water storage with cold water on the bottom and warmer water in the upper area. The heated water can be taken directly from the storage tank. However, a domestic hot water heat exchanger is preferably arranged in the store in order to heat cold domestic water to the desired domestic water temperature. An advantageous embodiment provides that the cooling device has a pump for the liquid medium. This allows the liquid medium to flow through the cooling device and thus continuously dissipate heat.
Vorteilhaft ist es, wenn die Kühleinrichtung einen Thermostat aufweist, mit dem die Pumpe regelbar ist. Dies ermöglicht es, eine ausreichende Kühlung mit einer effektiven Warmwassergewinnung zu kombinieren. Die am Thermostat eingestellte Temperatur und die Pumpenleistung werden durch die benötigte Warmwassertemperatur und die geforderte Kühlleistung bestimmt.It is advantageous if the cooling device has a thermostat with which the pump can be regulated. This makes it possible to combine sufficient cooling with effective hot water production. The temperature set on the thermostat and the pump capacity are determined by the required hot water temperature and the required cooling capacity.
Besonders gute Kühlleistungen werden dadurch erzielt, daß das flüssige Medium direkt über Photovoltaikelemente fließt. Eine Erhöhung des Wirkungsgrades ist dadurch zu erzielen, daß das flüssige Medium zuerst die Rückseite und dann die Vorderseite der Photovoltaikeinrichtung überströmt. Das noch kühle Medium wird dabei an der Rückseite der Einrichtung erwärmt und nimmt an der Vorderseite der Einrichtung weitere Wärmeenergie auf. Dadurch wird einerseits eine effektive Kühlung der Photovoltaikeinrichtung erreicht und andererseits wird ein flüssiges Medium mit relativ hoher Temperatur zur weiteren Nutzung zur Verfügung gestellt.Particularly good cooling performance is achieved in that the liquid medium flows directly over photovoltaic elements. An increase in efficiency can be achieved in that the liquid medium first flows over the back and then the front of the photovoltaic device. The still cool medium is heated on the back of the device and absorbs further thermal energy on the front of the device. As a result, effective cooling of the photovoltaic device is achieved on the one hand and on the other hand a liquid medium with a relatively high temperature is made available for further use.
Weitere Wirkungsgradsteigerungen werden durch mehrere parallel oder in Serie geschaltete Kühleinrichtungen erreicht. Eine bevorzugte Ausführungsform sieht vor, daß eine weitere Kühleinrichtung beabstandet zur Vorderseite angeordnet ist. Während diese beabstandete Kühleinrichtung hauptsächlich als selektives Filter dient, ermöglicht eine direkt auf den Photovoltaikmodulen angeordnete Kühleinrichtung gleichzeitig Filtereffekte und eine Kühlung der Module.Further increases in efficiency are achieved by several cooling devices connected in parallel or in series. A preferred embodiment provides that a further cooling device is spaced apart is arranged to the front. While this spaced cooling device mainly serves as a selective filter, a cooling device arranged directly on the photovoltaic modules simultaneously enables filter effects and cooling of the modules.
Spezielle Filtercharakteristiken sind mit der Auswahl des Kühlmediums erreichbar. Als vorteilhaft hat sich herausgestellt, wenn zwischen dem flüssigen Medium und der Strahlungsquelle eine selektiv strahlungsdurchlässige Schicht angeordnet ist. Diese selektiv strahlungsdurchlässige Schicht dient einerseits der Leitung des Fluids und andererseits wird durch die Kombination von strahlungsdurchlässiger Schicht und flüssigem Medium eine auf das für photovoltaische Effekte zu nutzende Solarspektrum abgestimmte Filtercharakteristik erzeugt.Special filter characteristics can be achieved by selecting the cooling medium. It has proven to be advantageous if a selectively radiation-permeable layer is arranged between the liquid medium and the radiation source. This selectively radiation-permeable layer serves, on the one hand, to conduct the fluid and, on the other hand, the combination of the radiation-permeable layer and the liquid medium produces a filter characteristic which is matched to the solar spectrum to be used for photovoltaic effects.
Als vorteilhaft hat sich herausgestellt, wenn die strahlungsdurchlässige Schicht auf der der Strahlungsquelle zugewandten Seite vorzugsweise selektiv strahlungsdurchlässig beschichtet ist. Auch durch die Wahl unterschiedlicher Beschichtungsmaterialien und Verfahren ist die Filtercharaktristik zu beeinflussen, um auf günstige Art und Weise eine optimale Filterkennlinie zu erzielen.It has proven to be advantageous if the radiation-transmissive layer on the side facing the radiation source is preferably selectively coated in a radiation-permeable manner. The filter characteristics must also be influenced by the choice of different coating materials and processes in order to achieve an optimal filter characteristic in a cost-effective manner.
Umfangreiche Versuchsreihen haben gezeigt, daß eine Platte oder eine Folie aus einem Fluorpolymer als strahlungsdurchlässige Schicht zu besonders guten Ergebnissen führt. Insbesondere Fluorpolymerfolien sind günstig in der Herstellung und eignen sich sowohl zur Leitung flüssiger Kühlmedien als auch als Strahlungsfilter. Gute Ergebnisse wurden auch mit Acryl, Polycarbonat und Glas erzielt, da diese Materialien eine hohe Transparenz im einfallenden Spektrum bieten, sowie mechanisch stabil, witterungsstabil und wasserfest sind. Dies ist beispielsweise mit Acryl (PMMA)- und Polycarbonatdoppelstegplatten preisgünstig zu erreichen.Extensive series of tests have shown that a plate or a film made of a fluoropolymer as a radiation-transmissive layer leads to particularly good results. In particular, fluoropolymer films are inexpensive to manufacture and are suitable both for conducting liquid cooling media and as radiation filters. Good results have also been made with Acrylic, polycarbonate and glass are achieved because these materials offer a high degree of transparency in the incident spectrum, as well as being mechanically stable, weatherproof and waterproof. This can be achieved inexpensively, for example, with acrylic (PMMA) and polycarbonate double-wall sheets.
Vorteilhaft ist es, wenn die strahlungsdurchlässige Schicht eine das flüssige Medium umgebene Hülle bildet. Diese Hülle stellt somit ein abgeschlossenes Bauteil dar, das als Filter einsetzbar ist und auf einfache Art und Weise ausgetauscht werden kann.It is advantageous if the radiation-transmissive layer forms an envelope surrounding the liquid medium. This envelope thus represents a closed component that can be used as a filter and can be exchanged in a simple manner.
Die beschriebenen Ausführungsvarianten sind sowohl für unkonzentrierte als auch für konzentrierte Strahlung einsetzbar.The design variants described can be used both for non-concentrated and for concentrated radiation.
Erläuterungen und Ausführungsbeispiele zu der beschriebenen Erfindung sind in der Zeichnung dargestellt und werden im folgenden ausführlich erläutert.Explanations and exemplary embodiments of the described invention are shown in the drawing and are explained in detail below.
Es zeigtIt shows
Figur 1 die relative Intensität des Solarspektrums über der Wellenlänge und die Durchlässigkeit einer 5 cm dicken Wasserschicht und einer 100 μm dicken Fluorpolymerfolie über der Wellenlänge,FIG. 1 shows the relative intensity of the solar spectrum over the wavelength and the permeability of a 5 cm thick water layer and a 100 μm thick fluoropolymer film over the wavelength,
Figur 2 eine einschichtige Photovoltaikeinrichtung,FIG. 2 shows a single-layer photovoltaic device,
Figur 3 einen Ausschnitt aus einem Photovoltaikmodul, Figur 4 die Temperaturverteilung über der Schichtdicke des in Figur 3 gezeigten Photovoltaikmoduls,FIG. 3 shows a section of a photovoltaic module, FIG. 4 shows the temperature distribution over the layer thickness of the photovoltaic module shown in FIG. 3,
Figur 5 eine zweischichtige Photovoltaikeinrichtung und5 shows a two-layer photovoltaic device and
Figur 6 eine zweischichtige Photovoltaikeinrichtung mit Konzentrator und Vorkühler.Figure 6 shows a two-layer photovoltaic device with a concentrator and precooler.
In Figur 1 sind auf der linken Ordinate 1 die relative Intensität, auf der rechten Ordinate 2 die Strahlungsdurchlässigkeit r in Prozent und auf der Abszisse 3 die Wellenlänge in Nannometer aufgetragen. In dieses Koordinatensystem sind das Solarspektrum 4 und der für photovoltaische Effekte nutzbare Bereich 5 dieses Spektrums 4 eingezeichnet. Die Transmission einer 5 cm dicken Wasserschicht ist durch die Linie 6 verdeutlicht und die Linie 7 zeigt die Transmission einer 100 μm dicken Fluorpolymerfolie.In FIG. 1, the relative intensity is plotted on the left ordinate 1, the radiation transmittance r in percent on the right ordinate 2 and the wavelength in nannometers on the abscissa 3. The solar spectrum 4 and the region 5 of this spectrum 4 that can be used for photovoltaic effects are drawn into this coordinate system. The transmission of a 5 cm thick layer of water is illustrated by line 6 and line 7 shows the transmission of a 100 μm thick fluoropolymer film.
Die Darstellung zeigt, daß die 5 cm dicke Wasserschicht nahezu die gesamte Strahlung des für photovoltaische Effekte nutzbaren Spektralbereichs passieren läßt und nur die längerwellige Strahlung absorbiert. Die Folie läßt hingegen nahezu unverändert die Strahlung auf dem gesamten Spektralbereich passieren und absorbiert nur im kurzwelligen Bereich einen Teil der Strahlung. Ein unterhalb der Wasserschicht angeordnetes Photovoltaikmodul wird somit von nahezu der gesamten für photovoltaische Effekte nutzbaren Strahlung bestrahlt, während die längerwellige Strahlung von der Wasserschicht absorbiert wird und zu einer Erwärmung des Wassers führt.The illustration shows that the 5 cm thick water layer allows almost all of the radiation in the spectral range usable for photovoltaic effects to pass through and only absorbs the longer-wave radiation. The film, on the other hand, allows the radiation to pass almost unchanged over the entire spectral range and only absorbs part of the radiation in the short-wave range. A photovoltaic module arranged below the water layer is thus irradiated by almost all of the radiation that can be used for photovoltaic effects, while the longer-wave radiation is absorbed by the water layer and causes the water to heat up.
Dieser Effekt wird in der in Figur 2 gezeigten Photovoltaikeinrichtung genutzt. Hierbei wird das Photovoltaikmodul 10 von einer Wasserschicht 11 überströmt und dadurch gekühlt. Die Wasserschicht 11 ist von einer transparenten Folie 12 umhüllt, so daß das Wasser in dieser Folie 12 geleitet wird. Eine Pumpe 13 pumpt das Wasser von einem Reservoir (nicht gezeigt) durch die Photovoltaikeinrichtung 14 zu einem Speicher 15, aus dem das Wasser über das Ventil 16 am Auslaß 17 dosiert entnommen werden kann. Die Heizspirale 18 erlaubt eine Nacherwärmung des Wassers, wenn die durch die Photovoltaikeinrichtung erzeugte Wassererwärmung nicht ausreicht.This effect is used in the photovoltaic device shown in FIG. 2. In this case, a layer of water 11 flows over the photovoltaic module 10 and thereby cools it. The water layer 11 is enveloped by a transparent film 12, so that the water in this film 12 is passed. A pump 13 pumps the water from a reservoir (not shown) through the photovoltaic device 14 to a store 15, from which the water can be removed in a metered manner via the valve 16 at the outlet 17. The heating coil 18 permits reheating of the water if the water heating generated by the photovoltaic device is insufficient.
An der Photovoltaikeinrichtung 14 ist ein Temperaturfühler 19 angeordnet, der die Pumpe 13 derart steuert, daß immer dann erwärmtes Fluid in den Speicher 15 gepumpt wird und frisches, kühles Fluid in die Anordnung fließt, wenn der Temperaturfühler 19 eine definierte, einstellbare Grenztemperatur erreicht hat.On the photovoltaic device 14, a temperature sensor 19 is arranged, which controls the pump 13 such that heated fluid is pumped into the memory 15 and fresh, cool fluid flows into the arrangement when the temperature sensor 19 has reached a defined, adjustable limit temperature.
Das beschriebene Filter 11 , 12 ist selektiv, da es nur Strahlung mit bestimmter Wellenlänge passieren läßt. Es ist aber auch recuperativ, da es den an der Oberfläche des Photovoltaikmoduls 10 auftretenden Wärmestrom im wesentlichen durch zwei Mechanismen recuperativ zurückgewinnt. Zum einen ist dies der Wärmeaustausch, der durch den direkten Kontakt des Fluids mit der heißen Oberseite des Moduls erfolgt. Zum anderen strahlt die Moduloberfläche mit einer gemäß dem Wienschen Verschiebungsgesetz temperaturabhängig zum langwelligen hin verschobenen Strahlung. Diese wird erfindungsgemäß vom Filterfluid, dem Wasser 1 1 , absorbiert und in Wärme umgewandelt.The filter 11, 12 described is selective since it only allows radiation with a certain wavelength to pass through. However, it is also recuperative since it essentially recuperatively recovers the heat flow occurring on the surface of the photovoltaic module 10 by two mechanisms. On the one hand, this is the heat exchange that takes place through the direct contact of the fluid with the hot top of the module. On the other hand, the module surface radiates with a radiation that is shifted towards the long-wave towards the long wave according to the Vienna displacement law. According to the invention, this is absorbed by the filter fluid, the water 11, and converted into heat.
Bei der erfindungsgemäßen Kühlung werden die langwelligen Photonen, die keinen Photoeffekt auslösen können, schon vor Erreichen des Moduls in Wärme umgewandelt, während sie bei den bekannten Photovoltaikeinrichtungen im Modul absorbiert werden und der erzeugte Wärmestrom durch das Modul hindurch entzogen werden muß. Der Vorteil der erfindungsgemäßen Photovoltaikeinrichtung liegt somit darin, daß die oberste Schicht, d.h. die der Strahlung zugewandten Seite einer besonders intensiven Kühlung ausgesetzt ist. Dies ist besonders relevant, da in einem photovoltaischen Modul - wie in Figur 3 gezeigt - die Lichtquanten 20 der Strahlung 21 in der obersten Schicht 22 des Photovoltaikmoduls 23 der Schichtdicke d absorbiert werden und dadurch ein Temperaturgradient entsteht, wie er in Figur 4 mit der Linie 24 angedeutet ist. Die Linie 24 zeigt den linearen Temperaturverlauf zwischen der Unterseite 25 des Photovoltaikmoduls 23 mit der Temperatur Tu und der Oberseite 26 des Photovoltaikmoduls 23 mit der Temperatur T0. Diese Darstellung zeigt nochmals deutlich, daß die frontseitige, erfindungsgemäße Kühlung des Moduls besonders vorteilhaft ist, da sie direkt an der heißesten Oberfläche des Moduls 23 angreift.In the cooling according to the invention, the long-wave photons, which cannot trigger a photo effect, are converted into heat even before reaching the module, while in the known photovoltaic devices they are absorbed in the module and the heat flow generated has to be extracted through the module. The advantage of the photovoltaic device according to the invention is thus that the top layer, ie the side facing the radiation, is exposed to particularly intensive cooling. This is particularly relevant, since in a photovoltaic module - as shown in FIG. 3 - the light quanta 20 of the radiation 21 are absorbed in the top layer 22 of the photovoltaic module 23 of the layer thickness d and this creates a temperature gradient, as shown in FIG. 4 with the line 24 is indicated. Line 24 shows the linear temperature profile between the bottom 25 of the photovoltaic module 23 with the temperature T u and the top 26 of the photovoltaic module 23 with the temperature T 0 . This illustration clearly shows once again that the cooling of the module on the front side according to the invention is particularly advantageous since it acts directly on the hottest surface of the module 23.
Die Figur 5 zeigt eine Weiterentwicklung der in Figur 2 gezeigten Photovoltaikeinrichtung. Bei dieser Photovoltaikeinrichtung 30 ist ein Photovoltaikmodul 31 auf der der Strahlung abgewandten Seite durch eine erste Fluidschicht 32 und auf der der Strahlung zugewandten Seite durch eine zweite Fluidschicht 33 umströmt. Eine Pumpe 34 fördert einen Wasserstrom 35 entlang der Rückseite 36 des Photovoltaikmoduls 31 in der ersten Schicht 32 und das Wasser kühlt dabei die Rückseite des Photovoltaikmoduls 31. Eine Umlenkeinrichtung 37 führt den Wasserstrom 35 am unteren Ende des Photovoltaikmoduls 31 um das Modul herum zur Oberseite 38, wo es in der zweiten Schicht 33 an der Oberseite 38 entlang nach oben strömt. Das an der Vorderseite weiter erhitzte Wasser fließt dann in einen Speicher 39 und von dort über ein Ventil 40 zum Auslaß 41.FIG. 5 shows a further development of the photovoltaic device shown in FIG. 2. In this photovoltaic device 30 is a A first fluid layer 32 flows around the photovoltaic module 31 on the side facing away from the radiation and through a second fluid layer 33 on the side facing the radiation. A pump 34 promotes a water flow 35 along the back 36 of the photovoltaic module 31 in the first layer 32 and the water cools the back of the photovoltaic module 31. A deflection device 37 guides the water flow 35 at the lower end of the photovoltaic module 31 around the module to the top 38 where it flows up along the top 38 in the second layer 33. The water further heated at the front then flows into a reservoir 39 and from there via a valve 40 to the outlet 41.
Die rückseitige wasserführende Schicht 32 kann entweder eine sich in gutem Wärmekontakt mit der Rückseite befindliche Rohrschlange geeigneter Geometrie sein, oder aus einem ganzflächigen Plattenwärmetauscher bestehen. Um die Wärmeverluste nach außen zu minimieren, ist die gesamte Anordnung zusätzlich durch eine opake Wärmeisolation 42 sowie eine zweite transparente Abdeckung 43 ergänzt. Die zweite transparente Abdeckung 43 ist in einem Abstand zur transparenten Fluorpolymerfolie 44 angeordnet. Die Termostatregelung 45 ermöglicht es, die Temperaturerhöhung des Kühlfluids gezielt einzustellen. Die am Auslaß 41 angestrebte Temperatur kann je nach Anwendungsfall beispielsweise für eine Schwimmbadbeheizung bei 30°C liegen, während für Duschwasser ca. 40°C benötigt werden. Diese beiden typischen Nutzungsarten von solargeheiztem Warmwasser finden in gemäßigten Breitengraden vorallem im Sommerhalbjahr Anwendung. Da die mittlere Photovoltaikmodultemperatur während dieser Jahreszeit über 50°C liegt, sorgt das erfindungsgemäße System nicht nur für elektrischen Strom und Warmwasser, sondern erhöht gleichzeitig den Stromwirkungsgrad.The rear water-carrying layer 32 can either be a pipe coil of suitable geometry that is in good thermal contact with the rear, or it can consist of a full-surface plate heat exchanger. In order to minimize the heat losses to the outside, the entire arrangement is additionally supplemented by an opaque heat insulation 42 and a second transparent cover 43. The second transparent cover 43 is arranged at a distance from the transparent fluoropolymer film 44. The termostat control 45 enables the temperature increase of the cooling fluid to be set in a targeted manner. Depending on the application, the desired temperature at outlet 41 may be 30 ° C. for swimming pool heating, for example, while approx. 40 ° C. is required for shower water. These two typical types of use of solar-heated hot water are used in moderate latitudes, especially in the summer half-year. As the average photovoltaic module temperature is above 50 ° C during this season, The system according to the invention not only provides electrical power and hot water, but also increases the power efficiency.
Erfindungsgemäß kann aus einem Flächenelement, das bisher mit ca. 10% Wirkungsgrad aus dem Strahlungsangebot elektrischen Strom erzeugte, ein Modul gemacht werden, das mit einem Gesamtwirkungsgrad von etwa 60% Strom und Warmwasser erzeugt.According to the invention, a module can be made from a surface element which previously generated electrical power with approximately 10% efficiency from the radiation supply, and which generates electricity and hot water with a total efficiency of approximately 60%.
Die Figur 6 zeigt, daß das erfindungsgemäße System grundsätzlich auch auf photovoltaische Anordnungen mit Sonnenlichtkonzentration anwendbar ist. Gerade bei erhöhter Energiedichte an der Oberfläche des Moduls kommen die beschriebenen, günstigen selektiven und recuperativen Wärmeextraktionsmechanismen noch stärker zum Tragen.FIG. 6 shows that the system according to the invention can in principle also be used on photovoltaic arrangements with sunlight concentration. Especially with increased energy density on the surface of the module, the described, inexpensive selective and recuperative heat extraction mechanisms come into play even more.
Bei der Verwendung einer in Figur 5 gezeigten Photovoltaikeinrichtung für konzentrierte Strahlung wird der Energiegehalt des langwelligen, nicht photovoltaisch nutzbaren Teils des Solarspektrums dafür verwendet, Wasser auf relativ niedrige Temperaturen zu erwärmen. Wenn der Kühlwasserstrom auf höhere Temperaturen erwärmt wird, wird der Wirkungsgrad des Photovoltaikmoduls gesenkt.When using a photovoltaic device for concentrated radiation shown in FIG. 5, the energy content of the long-wave, non-photovoltaically usable part of the solar spectrum is used to heat water to relatively low temperatures. If the cooling water flow is heated to higher temperatures, the efficiency of the photovoltaic module is reduced.
Für konzentrierte Strahlung wird daher die in Figur 6 gezeigte Photovoltaikeinrichtung vorgeschlagen. Diese Photovoltaikeinrichtung 50 besteht im wesentlichen aus der Konzentratorlinse 51 , dem Vorkühler 52 und dem gekühlten Photovoltaikmodulelement 53. Anstelle der Konzentratorlinse 51 kann auch eine andere Konzentrationsoptik, wie beispielsweise ein Spiegelsystem eingesetzt werden. Das Photovoltaikmodul 53 entspricht im Aufbau der in Figur 5 gezeigten Photovoltaikeinrichtung 30. Der Vorkühler 52 dient als Vorfilter, das im Falle eines linearen Konzentrators aus einem transparenten Quader der Dimension der Brennlinie an diesem Ort besteht. In Falle eines punktförmigen Konzentrators wird ein transparenter flacher Hohlzylinder der Dimension des Brennfleckes an diesem Ort verwendet.For concentrated radiation, the photovoltaic device shown in FIG. 6 is therefore proposed. This photovoltaic device 50 essentially consists of the concentrator lens 51, the precooler 52 and the cooled photovoltaic module element 53. Instead of the concentrator lens 51, another concentration optics, such as for example, a mirror system can be used. The structure of the photovoltaic module 53 corresponds to that of the photovoltaic device 30 shown in FIG. 5. The precooler 52 serves as a prefilter, which in the case of a linear concentrator consists of a transparent cuboid of the dimension of the focal line at this location. In the case of a punctiform concentrator, a transparent flat hollow cylinder of the dimension of the focal spot is used at this location.
Hohlquader oder Hohlzylinder 54 werden von einem Fluid durchflössen, das neben der in Figur 1 dargestellten Selektivität einen möglichst hohen Siedepunkt besitzt, damit der Systemdruck niedrig bleibt. Im vorliegenden Fall wird Wasser mit entsprechenden Zusätzen verwendet. Dieses Wasser wird im Hohlquader oder Hohlzylinder 54 über die mittels der Linse 51 konzentrierte Strahlung 55 auf Temperaturen im Bereich von etwa 100°C erwärmt. Bei Erreichen der vorbestimmten Temperatur wirkt der Temperaturfühler 56 auf die Pumpe 57, so daß neuer Fluidstrom in den Hohlraum 54 gepumpt wird. Das erhitzte Wasser verläßt über die LeitungHollow cuboids or hollow cylinders 54 are flowed through by a fluid which, in addition to the selectivity shown in FIG. 1, has the highest possible boiling point so that the system pressure remains low. In the present case, water with appropriate additives is used. This water is heated in the hollow cuboid or hollow cylinder 54 to temperatures in the range of approximately 100 ° C. by means of the radiation 55 concentrated by means of the lens 51. When the predetermined temperature is reached, the temperature sensor 56 acts on the pump 57, so that new fluid flow is pumped into the cavity 54. The heated water leaves via the pipe
58 den Hohlraum 54. Dadurch werden im Brennfleck der Linse 51 sehr hohe Temperaturen erzeugt und zur Erwärmung eines selektiv strahlungsdurchlässigen Fluids verwendet.58 the cavity 54. As a result, very high temperatures are generated in the focal spot of the lens 51 and are used to heat a selectively radiation-permeable fluid.
Mit der Einrichtung 50 kann somit aus der primär eingestrahlten EnergieThe device 50 can thus use the primary radiated energy
59 elektrischer Strom 60, Brauchwasserwärme 61 und Hochtemperaturprozeß wärme 62 erzeugt werden. Die Exergie der Hochtemperaturwärme kann hierbei beispielsweise über geeignete thermodynamische Maschinen in mechanische Arbeit oder zusätzlichen elektrischen Strom gewandelt werden.59 electrical power 60, hot water 61 and high-temperature heat 62 are generated. The exergy of the high-temperature heat can, for example, be suitable thermodynamic machines can be converted into mechanical work or additional electrical current.
Die an der Photovoltaikmoduleinrichtung 53 erzeugte Warmwassermenge kann jedoch auch im Vorfilter 52 weiter erwärmt werden, indem eine Verbindung zwischen dem Leitungsende 61 und der Pumpe 57 hergestellt wird.However, the amount of hot water generated on the photovoltaic module device 53 can also be further heated in the prefilter 52 by establishing a connection between the line end 61 and the pump 57.
Die beschriebenen Photovoltaikeinrichtungen basieren auf der richtigen Auswahl des Fluids und der transparenten Ummantelungsmaterialien. Im Bereich der Flüssigkeit existieren viele Möglichkeiten von Wasser über Öle, Alkohol usw.. Da Photovoltaikmodule verschiedenen Aufbaus (z.B. Silicium, GaAs, ZnS usw.) zum Einsatz kommen können, muß das selektive Filter auf den jeweils notwendigen photovoltaisch aktiven Spektralbereich abgestimmt sein. Diese Abstimmung wird bei Bedarf relativ exakt durch die Filterkennlinien der transparenten Umhüllungsmaterialien und/oder Flüssigkeiten realisiert. Zur Variation der Filtereigenschaften können die umhüllenden Materialien selbst selektiv beschichtet sein und den Flüssigkeiten können Zusatzstoffe beigegeben werden.The photovoltaic devices described are based on the correct selection of the fluid and the transparent sheathing materials. In the area of liquids, there are many options from water to oils, alcohol, etc. Since photovoltaic modules of various structures (e.g. silicon, GaAs, ZnS, etc.) can be used, the selective filter must be matched to the photovoltaically active spectral range required in each case. If necessary, this adjustment is implemented relatively exactly by the filter characteristics of the transparent wrapping materials and / or liquids. To vary the filter properties, the enveloping materials themselves can be selectively coated and additives can be added to the liquids.
In den beschriebenen Anwendungsbeispielen wurde als Umhüllung eine handelsübliche Fluorpolymerfolie von 100 μm Dicke eingesetzt. Diese Folie ist chemisch inert, umweltneutral und flexibel verarbeitbar. Bei der Verwendung von Folien ist darauf zu achten, daß durch eine geeignete mechanische Abstützung oder kanalförmige Unterteilung der wasserführenden Schicht ein kissenförmiges Ausbeulen vermieden wird, um eine relativ gleichmäßige Dicke der Wasserschicht über die gesamte Fläche auszubilden.In the application examples described, a commercially available fluoropolymer film of 100 μm thickness was used as the covering. This film is chemically inert, environmentally neutral and can be processed flexibly. When using foils, care must be taken to ensure that the appropriate mechanical support or channel-shaped subdivision of the a pillow-shaped bulge is avoided in order to form a relatively uniform thickness of the water layer over the entire surface.
Photovoltaikelemente sind üblicherweise an, ihrer Oberseite mit einer Glas- oder Kunststoffläche abgedeckt, um die aktive Photovoltaikfläche vor mechanischen Einflüssen zu schützen. Bei der Verwendung einer Umhüllung zum Leiten von Flüssigkeiten, die auf der aktiven Photovoltaikfläche aufliegt, kann auf eine weitere Abdeckung der Photovoltaikelemente verzichtet werden, da die wasserleitenden Elemente die Funktion einer schützenden Oberfläche übernehmen. Beispielsweise können sogenannte Doppelstegplatten verwendet werden, um die Flüssigkeit auf den Photovoltaikelementen zu führen und die Photovoltaikelemente gleichzeitig zu schützen. Verständlicherweise können die herkömmlich verwendeten Glasplatten auch mit in Plattenebene verlaufenden flüssigkeitsdurchlässigen Kanälen versehen sein oder als Doppelplatte eine flüssigkeitsführende Schicht ermöglichen.Photovoltaic elements are usually covered on their top with a glass or plastic surface in order to protect the active photovoltaic surface from mechanical influences. When using a covering for conducting liquids, which rests on the active photovoltaic surface, there is no need to cover the photovoltaic elements further, since the water-conducting elements take on the function of a protective surface. For example, so-called double-wall sheets can be used to guide the liquid on the photovoltaic elements and to protect the photovoltaic elements at the same time. Understandably, the glass plates conventionally used can also be provided with liquid-permeable channels running in the plane of the plate, or can enable a liquid-carrying layer as a double plate.
Als selektives Fluid wurde in den beschriebenen Ausführungsbeispielen Wasser verwendet. Wasser ist preisgünstig und umweltneutral. Bei der Verwendung von Zusatzstoffen zum Wasser ist ein Wärmetauscher zur Brauchwassererzeugung notwendig. Die Temperaturen der erzeugten Warmwassermenge können jedoch auch so eingestellt werden, daß Wasser ohne Zusatzstoffe Verwendung findet. Auf den Einsatz eines Wärmetauschers kann dann verzichtet werden. Water was used as the selective fluid in the exemplary embodiments described. Water is inexpensive and environmentally neutral. When using additives to the water, a heat exchanger for the production of hot water is necessary. However, the temperatures of the amount of hot water generated can also be set so that water without additives is used. The use of a heat exchanger can then be dispensed with.

Claims

Patentansprüche claims
1. Photovoltaikeinrichtung (14) mit einer der Strahlung ausgesetzten Vorderseite und einer gegenüberliegenden Rückseite zur Umwandlung von Strahlungsenergie in elektrische Spannung mit einer Kühleinrichtung, dadurch gekennzeichnet, daß die1. photovoltaic device (14) with a front exposed to radiation and an opposite rear for converting radiation energy into electrical voltage with a cooling device, characterized in that the
Kühleinrichtung ein flüssiges Medium (1 1) aufweist, das zwischen der Vorderseite und der Strahlungsquelle angeordnet ist.Cooling device has a liquid medium (1 1), which is arranged between the front and the radiation source.
2. Photovoltaikeinrichtung nach Anspruch 1 , dadurch gekennzeichnet, daß das flüssige Medium (1 1) im wesentlichen Wasser ist.2. Photovoltaic device according to claim 1, characterized in that the liquid medium (1 1) is essentially water.
3. Photovoltaikeinrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das flüssige Medium (1 1) aufgrund der Schwerkraftunterschiede zwischen warmem und kaltem Medium zwischen Vorderseite und Strahlungsquelle fließt.3. Photovoltaic device according to one of the preceding claims, characterized in that the liquid medium (1 1) due to the gravity differences between warm and cold medium flows between the front and radiation source.
4. Photovoltaikeinrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Kühleinrichtung eine Pumpe (13) für das flüssige Medium (1 1) aufweist.4. Photovoltaic device according to one of the preceding claims, characterized in that the cooling device has a pump (13) for the liquid medium (1 1).
5. Photovoltaikeinrichtung nach Anspruch 4, dadurch gekennzeichnet, daß die Kühleinrichtung einen Thermostat (19) aufweist, mit dem die Pumpe (13) regelbar ist. 5. Photovoltaic device according to claim 4, characterized in that the cooling device has a thermostat (19) with which the pump (13) can be regulated.
6. Photovoltaikeinrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß das flüssige Medium (11) zuerst die Rückseite (36) und dann die Vorderseite (38) überströmt.6. Photovoltaic device according to one of the preceding claims, characterized in that the liquid medium (11) first flows over the back (36) and then the front (38).
7. Photovoltaikeinrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Kühleinrichtung oder eine weitere7. Photovoltaic device according to one of the preceding claims, characterized in that the cooling device or another
Kühleinrichtung (52) beabstandet zur Vorderseite angeordnet ist.Cooling device (52) is arranged spaced from the front.
8. Photovoltaikeinrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß zwischen dem flüssigen Medium (11) und der Strahlungsquelle eine vorzugsweise selektiv strahlungsdurchlässige Schicht (12) angeordnet ist.8. Photovoltaic device according to one of the preceding claims, characterized in that a preferably selectively radiation-permeable layer (12) is arranged between the liquid medium (11) and the radiation source.
9. Photovoltaikeinrichtung nach Anspruch 8, dadurch gekennzeichnet, daß die strahlungsdurchlässige Schicht (12) auf der der Strahlungsquelle zugewandten Seite vorzugsweise selektiv strahlungsdurchlässig beschichtet ist.9. Photovoltaic device according to claim 8, characterized in that the radiation-permeable layer (12) on the side facing the radiation source is preferably selectively coated radiation-permeable.
10. Photovoltaikeinrichtung nach einem der Ansprüche 8 oder 9, dadurch gekennzeichnet, daß die strahlungsdurchlässige Schicht (12) eine Fluorpolymerfolie oder -platte aufweist.10. Photovoltaic device according to one of claims 8 or 9, characterized in that the radiation-permeable layer (12) has a fluoropolymer film or plate.
11. Photovoltaikeinrichtung nach einem der Ansprüche 8 bis 10, dadurch gekennzeichnet, daß die strahlungsdurchlässige Schicht (12) eine das flüssige Medium (1 1 ) umgebende Hülle bildet. 11. Photovoltaic device according to one of claims 8 to 10, characterized in that the radiation-permeable layer (12) forms a shell surrounding the liquid medium (1 1).
EP99950483A 1998-08-05 1999-08-05 Photovoltaic device Withdrawn EP1105923A2 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE19835304 1998-08-05
DE19835304 1998-08-05
DE19923196A DE19923196A1 (en) 1998-08-05 1999-05-20 Recuperative selective liquid filter for photovoltaic modules
DE19923196 1999-05-20
PCT/DE1999/002366 WO2000008690A2 (en) 1998-08-05 1999-08-05 Photovoltaic device

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CN (1) CN100385687C (en)
AU (1) AU6325199A (en)
BR (1) BR9912966A (en)
DE (1) DE19981515D2 (en)
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CN100385687C (en) 2008-04-30
US20010007261A1 (en) 2001-07-12
WO2000008690A2 (en) 2000-02-17
TR200100362T2 (en) 2001-05-21
AU6325199A (en) 2000-02-28
US6407328B2 (en) 2002-06-18
CN1322380A (en) 2001-11-14
BR9912966A (en) 2004-08-03
JP2002522908A (en) 2002-07-23
WO2000008690A3 (en) 2000-05-11

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