DE202008010452U1 - Photovoltaic module and photovoltaic system - Google Patents

Abstract

Photovoltaic module (1) with
a) at least one photovoltaic cell (30) with a limited sensitivity range,
b) a transparent receiving device (20), which
- At least the einstrahlungsaktive top (31) of the at least one photovoltaic cell (30) covers, and the
- contains a translucent heat transfer medium (21) with wavelength-shifting properties, wherein the wavelength-shifting properties acting on the incident sunlight (A) are adapted to the limited sensitivity range of the photovoltaic cell (30) such that the light (B) converted by the translucent heat transfer medium (B) from the photovoltaic cell (30) is usable, and with
c) means (40) for keeping constant the translucent heat carrier (21) as possible in a for the at least one photovoltaic cell (30) optimal efficiency temperature range.

Description

The The invention relates to a photovoltaic module. The invention relates also a photovoltaic system, which consists of at least one such Photovoltaic module, but usually variety of interconnected Photovoltaic modules exists.

photovoltaic cells This type, also called solar cells, and these in the manner of a Housing containing Photovoltaic modules are used to generate electricity through Conversion of photons into electrons. In practice, these achieve Efficiencies, which are currently in a range of about 5-25%.

Of the reason for These relatively low efficiencies, on the one hand, are that Solar cells conventional Type often only for a narrow range from the spectrum of sunlight sensitive are. Such narrow regions are also called optical band gaps. It can So only the associated wavelength from the entire spectrum of sunlight transmitted by the Earth's atmosphere are used for electron generation while all other wavelengths are lost walk. So there are solar cells, which have a maximum of sensitivity z. B. in the wavelength range of the blue light, d. H. at about 465 nm. Other solar cells In turn, they have a sensitivity maximum z. B. in the wavelength range of green Light, that is about 540 nm. All these wavelength ranges but only small sections of the entire spectrum of visible light from about 380-780 nm dar.

One another reason for the relatively low efficiency of solar cells in practice lies in that their efficiency decreases with temperature. So he takes Efficiency z. B. a silicon solar cell at a temperature rise by 10 degrees about 4.4%. In practice this has the consequence that z. B. so-called solar roofs on radiation-intensive but also warm summer days in one unfavorable Operating point to be operated with poor efficiency.

to solution It is known from these problems to construct solar cells in such a way that this for more than one wavelength color of sunlight is sensitive. So z. B. in tandem cells several layers of solar cells, which each have a maximum of sensitivity in another Wavelength range of the light, one above the other arranged. Furthermore you can as so-called light-absorbing electron-conducting materials, also called ETM electron transport material, used in semiconductors which are more temperature resistant compared to crystalline silicon cells and thus have a low power loss when heated. A semiconductor material This type is z. Gallium arsenide.

These However, solar cells all have the disadvantage that their Compared to silicon-based cells, production is significantly more costly.

Of the Invention is based on the object of a photovoltaic module and a indicate photovoltaic system composed of such modules, which one compared to conventional solar cells or solar cell systems significantly higher Efficiency has.

These Task is solved by the photovoltaic module specified in claim 1, and by the In claim 16 specified photovoltaic system.

The Photovoltaic module according to the invention contains at least a photovoltaic cell with a limited range of sensitivity. Furthermore, a transparent receiving device is present, which at least the irradiation-active upper side of the at least one Photovoltaic cell covered, and the one translucent With heat transfer medium wavelength shifting Contains properties, wherein the wavelength-shifting energy acting on the incident sunlight Properties on the limited sensitivity range of the photovoltaic cell are tuned so that the translucent heat transfer medium converted light from the Photovoltaic cell is usable. Finally, means for keeping constant the translucent Heat carrier as possible in a for the at least one photovoltaic cell efficiency-optimal temperature range available.

The inventive photovoltaic module offers the advantage that on the one hand wavelength ranges of the incident Sunlight, which of the photovoltaic cell used not used directly due to their limited sensitivity range can be from the light conversion active heat carrier into usable, ie in the sensitivity range the photovoltaic cell lying wavelengths are converted. With Help of the invention can thus almost the entire spectrum of light wavelengths of incident sunlight for generating electrical energy be used. additionally but offers the light conversion active heat transfer the particular advantage that hereby the photovoltaic cell is also optimized for optimum efficiency, low temperature can be maintained, for. At 5-6 degrees Celsius. In summer, therefore, the temperature of the photovoltaic cell by cooling the heat carrier, or kept in winter by appropriate heating in the optimum range become.

Due to this combination effect of light-conversion active heat carrier can be achieved with the photovoltaic module according to the invention depending on the particular structural design of the module efficiencies of well over 50%. In this case, the structure of the photovoltaic module is particularly determined by the nature and effect of the thermal insulation used to hold at least the lichtumwandlungsaktiv substrate of the photovoltaic cell in a low-efficiency optimal temperature range and thus to avoid the normally rising in a heating of the photovoltaic cell increase in internal resistance can.

The Inventive photovoltaic module allows the use of photovoltaic cells, which have a limited sensitivity range but inexpensive and in big ones numbers can be produced. For the photovoltaic module according to the invention Thus, in principle, all photovoltaic cells are used, even if these only in a not very broadband wavelength range of the visible solar spectrum should be active. So z. B. silicon-based photovoltaic cells are used, which in blue or green Range of the visible spectrum are active. Of these, sunlight can be photons only from the to the sensitivity range related Wavelength components the entire light spectrum for conversion into electrons and thus be used in electrical energy. Thus, it is particularly suitable for example, normal polycrystalline, monocrystalline, amorphous or thin Silicon cells. Naturally can also find other photovoltaic cells use. On the other hand it is not necessary consuming, produced in multi-layer process or GaAs photovoltaic cells.

So can in a first execution the invention, the wavelength-shifting Properties of the translucent By heat carrier by at least an addition can be set so that an increase of certain wavelengths of the incident sunlight is effected. It can be advantageous the at least one addition of the translucent heat carrier is selected such that this is a conversion of short wavelengths of the incident Sunlight in usable by the photovoltaic cell light with longer or long Wavelength components causes. In practice, it is particularly important if the at least one Addition of the translucent Heat carrier one Conversion of UV wavelengths of incident sunlight in light with blue, green and / or yellow wavelengths causes. Such wavelength ranges are for a variety of conventional Photovoltaic cells are well usable because their sensitivity ranges There have optimal efficiency. In practice, this can be done z. B. fluorescent and / or phosphorescent additives used for the translucent heat transfer medium become.

Of the translucent Heat transfer medium in the photovoltaic module according to the invention thus generates a photon current with shifted wavelength spectral components, which on the limited sensitivity range of each used Photovoltaic cell are tuned.

at the photovoltaic module according to the invention will continue to be a translucent With heat transfer medium wavelength shifting Properties used. It is a translucent medium, which has at least a high specific heat capacity. Furthermore, can this medium advantageously also have a high thermal conductivity, and optionally in addition, over a large specific Enthalpy of fusion or a large Heat transfer coefficient feature. Such properties can by adding metal ions, eg. As copper ions are caused.

Farther It has proved to be advantageous if the translucent heat transfer medium Boiling point of about 5 degrees Celsius.

When Translucent heat transfer media have proven particularly suitable which have a cooling and / or Corrosion protection fluid as a base material. The light conversion activity of the heat carrier, ie its wavelength shifting Property can be caused by the addition of other ingredients and be adjusted in effect. This will be explained in more detail below.

With this can be filled as a transparent receiving device serving fluid container, which z. B. may be placed on the photovoltaic cell so that at least covers the irradiation-active upper side of the at least one photovoltaic cell is. In another embodiment the photovoltaic cell can also be completely inside the receiving device, which z. B. is designed as a glass container, almost floating in the translucent Stored heat transfer medium be. This version facilitates on the one hand, the photovoltaic cell with the help of the translucent heat carrier on to cool an optimum efficiency temperature range, z. For example, 5-6 Centigrade. Does the heat transfer in addition one electric conductivity on, so can especially in this embodiment, the contacting of Photovoltaic cell can be significantly improved by the so-called Dark zone of the photovoltaic cell is avoided, which is usually created by contact tracks on the cell top.

Farther can the translucent Heat carrier the fluid container also in a water-bound form z. B. complete as a gel.

It has shown that as a translucent heat transfer excellent light-active liquid heat transport media in the form of light conversion active cooling and / or corrosion protection fluids can be used which for active cooling at least of components with high power loss in computer systems are provided.

The Mode of operation of the photovoltaic module according to the invention was practically confirmed in the laboratory on different versions. there were exemplified light conversion active cooling liquid company "Aquatuning GmbH, DE-33689 Bielefeld, Beckheide 13 ". One to each used light conversion active coolant suitable photovoltaic cells for example from an "ARCO Solar Sample Circuit Set "the Company "ARCO Solar Inc., Camarillo CA 93010 USA ".

at In a first application example, the fluid container with a light conversion active clear coolant of the company "Aquatuning" type "AT-Protect UV blue (Art. No. 30026) and cooled to about 5 degrees. This coolant converts the UV wavelength component of visible light, which has a wavelength of about 300-430 nm in a blue light with a wavelength of about 430-500 nm around. This converted light can then be from a monocrystalline Standard solar cell of the company "ARCO Solar "from Type "6 Volt Battery Charging "optimal be used because this solar cell the highest efficiency, so the Sensitivity maximum, largely in the blue wavelength range of the light spectrum.

at Another example of use was the fluid container with a light conversion active clear corrosion inhibitor and coolant of Company "Aquatuning" type "UV Green FluoProtect (Item No. 30002) and cooled to about 5 degrees. This agent converts the UV wavelength portion of visible light in a green Light with one wavelength from about 540 nm. This converted light can then be from a monocrystalline standard solar cell solar cells of the company "ARCO Solar" type "Charging 2 Series Ni-CAD Battery "optimal be used because this solar cell the highest efficiency, so the Sensitivity maximum, largely in the green Wavelength range of Having light spectrum.

Farther became the fluid container for example, with a light conversion active red coolant the company "Aquatuning" of the type "AT-Protect-UV-red" (Art. Nr. 30028) and cooled to about 5 degrees. This agent converts the UV wavelength portion of visible light in a red light with a wavelength of about 625-780 nm around. This converted light can then be from a monocrystalline Standard solar cell solar cells of the company "ARCO Solar" type "Charging 1 Series Ni-CAD Battery Powering Fan Motor "Optimal be used because this solar cell the highest efficiency, so the Sensitivity maximum, largely in the red wavelength range of the light spectrum.

at another version the photovoltaic module according to the invention indicates the translucent Heat carrier for Setting the wavelength-shifting Features at least one addition on which a reduction of wavelength caused by the incident sunlight. Advantageously, the at least one addition of the translucent heat carrier be selected so that this is a conversion of long wavelengths of the incident Sunlight in the Fotovoltaikzel le usable light with shorter or short wavelengths causes. In practice, it is particularly significant if the at least an addition of the translucent Heat carrier one Conversion of IR wavelengths of incident sunlight in usable light with blue, green and / or yellow wavelengths causes.

So can z. B. nanoparticles as an adjunct for adjusting the wavelength-shifting Properties are used. Is a cooling and / or corrosion protection fluid as a raw material z. With nanoparticles in the form of neodymium crystals (Nd: YAG), this has a wavelength bisecting or frequency doubling Effect on the long-wave spectral component of the incident sunlight. Long-wave, lying in the infrared range light components of the incident Sunlight with one wavelength of about 1064 nm are in short-wave light with a wavelength of converted about 532 nm. This lies in the green spectral range of the visible Spectrum of light and photovoltaic cells, which one in this Range lying sensitivity maximum have immediate use.

It is particularly advantageous if the translucent heat transfer medium by the addition of suitable additives both the property of short-wavelength spectral regions of sunlight - in particular UV spectra with about 398 nm wavelength - in longer-wave z. B. green light with about 532 nm wavelength, as well as the property has very long-wavelength spectral regions of sunlight - especially IR spectra with about 1064 nm wavelength - in shorter wavelength z. B. also convert green light with about 532 nm wavelength. This can opti from a photovoltaic cell with a lying in the range of the green light spectrum at about 520-560 nm selectivity maximum to be used. By way of example, a monocrystalline standard solar cell of the "ARCO Solar" type "Charging 2 Series Ni-Cad Batteries" can also be used here.

Of the translucent With heat transfer medium wavelength shifting Properties can therefore be a UV or IR active coolant or a UV as well as IR active combination fluid represent.

According to one further execution According to the invention, the photovoltaic module has means for reducing of reflections in the area of the irradiation-active upper side of the photovoltaic cell on. Is z. B. the transparent receiving device formed as a glass body, so z. B. on the incident sunlight facing surface the inside be provided with an anti-reflective coating. A comparable one Effect is through a surface roughening this area causes. This causes reflection losses of the incident sunlight, but also scattering losses of wavelength-shifted in the heat transfer medium Light avoided, and are thus optimally to the photovoltaic cell diverted.

One further advantage of the photovoltaic module according to the invention in that due to the keeping constant of the temperature of the photovoltaic cell the Occurrence of microcracks and thus the aging of the photovoltaic cell is significantly slowed down. Continue to practice the wavelength shifting Properties of the translucent Heat transfer a protective effect for the Photovoltaic cell made by the action of harmful and limiting the lifespan Spectral components, in particular of short-wave UV spectral components, is lowered sharply.

A Photovoltaic system has at least one, but usually a variety of photovoltaic modules according to the invention of the type described above. It contains at least means for circulation a cooling medium for the Photovoltaic modules. Integrated into these are means of implementation the heat energy the coming from the photovoltaic modules of the system cooling medium in mechanical energy by evaporation of the cooling medium. Furthermore, funds for cooling of the cooling medium by condensation and means of converting the mechanical energy present in electrical energy. Finally, an electric Storage and / or converter unit, in particular a battery-buffered inverter, for the electrical energy generated by the photovoltaic modules of the plant available.

at the means of implementing the heat energy of the cooling medium in mechanical energy, it may be z. B. a heat pump act.

at a particularly advantageous embodiment of a photovoltaic system is in the circulation means a turbine for the implementation of heat energy integrated into mechanical energy. This has a capacitor for cooling of the cooling medium by condensation. The turbine is finally a generator connected to generate electrical energy. Such System comes complete without external energy, in which the pressurized and one low boiling point at about 5-6 degrees Celsius having cooling medium is relaxed when entering the turbine and this drives. With Using a condenser, the coolant is then completely liquefied, and can z. B. by support with a passive cooling again as a refrigerant in fed back the circulation circuit become.

ever after execution it can be with the coolant z. B. to act an alcohol-water mixture, which in a light-transmissive heat transfer inside the photovoltaic modules circulated separate circuit. on the other hand is possible, too, that the translucent and wavelength shifting Heat carrier directly as a refrigerant in the Circulation cycle acts, and all photovoltaic modules and their Photovoltaic cells washed over a large area.

advantageous versions The invention thereof will be explained in more detail with reference to the figures. there demonstrate

1 an exemplary embodiment of a photovoltaic module according to the invention in a perspective side view, and

2 an exemplary photovoltaic system consisting of six series-connected photovoltaic modules according to the invention in a plan view.

This in 1 illustrated exemplary photovoltaic module 1 has an irradiation-active top 10 into which sunlight A is incident with the wavelength spectral components transmitted by the earth's atmosphere. This enters a transparent receiving device 20 a, which z. B. can be designed as a fluid container made of glass. The recording device 20 is according to the invention with a transparent heat transfer medium 21 filled, which has wavelength-shifting properties, for. B. a light conversion active cooling or corrosion protection fluid. The inner surface of the irradiation-active upper side is advantageous 10 additionally as a reflector surface 22 educated.

Below the transparent receiving device 20 is a photovoltaic cell 30 arranged, z. B. a monocrystalline standard solar cell silicon-based, which according to the invention a limited, on the wavelength-shifting properties the heat carrier 21 has a matched sensitivity range. The radiation-active top 31 the photovoltaic cell 30 is thus of the transparent recording device 20 at least covered. The light-transmissive heat carrier 21 converted light B with at least one shifted wavelength spectral component thus enters the irradiation-active upper side 31 one and can from the photovoltaic cell 30 be converted into electrical energy. The electrical connections of the photovoltaic cell 30 are in for better clarity 1 not shown.

According to the invention, the exemplary photovoltaic module 1 from 1 medium 40 for cooling the translucent heat carrier 21 in the fluid container 20 on. This can be z. B. be executed in the form of a piping system for supply, discharge and discharge of a cooling medium, for. B. a mixture of water and alcohol. In another embodiment, the translucent heat transfer medium itself serve as a cooling medium and z. B. all over the receiving device 20 be conveyed through.

In 2 is a photovoltaic system 50 shown which exemplifies six photovoltaic modules 1a - 1f is constructed. This thermally connected in series, in which a cooling medium via a flow line 51 fed, via circulation pipes 52 passed from module to module and finally via a return line 53 is collected again.

In the circulation circuit of the cooling medium is a turbine 57 switched on. This will do this via the return line 53 collected, due to the incident sunlight in the photovoltaic modules 1a - 1f the system heated and advantageously supplied under pressure cooling medium. With entry of the cooling medium into the turbine 57 this is evaporated and thus performed mechanical work to drive the turbine. Due to the Ent voltage, the cooling medium is thereby cooled at the same time and can be completely liquefied again via an advantageous additional downstream capacitor. It is now on the low temperature level again on the line 51 for feeding into the chain of photovoltaic modules 1a - 1f to disposal.

The one in the turbine 57 Finally, mechanical work becomes available via a coupled generator 58 converted into electrical energy, which via a feed line 59 z. B. can be supplied to an electrical power distribution network. Furthermore, the DC voltage outputs of the photovoltaic modules 1a - 1f the system via a wiring 54 summarized and to an electrical storage and / or converter unit 55 connected, z. B. an inverter with battery buffer. The voltage generated by the inverter can also be supplied via an infeed line 56 z. B. are supplied to an electrical power distribution network.

A photovoltaic system of in 2 shown type has a particularly high efficiency, since both in the photovoltaic modules 1a - 1f occurring solar thermal heat as well as the irradiated by the sunlight photon stream is converted in the photovoltaic modules into electrical energy. In addition, such a system can be operated without external energy. Finally, it is possible that in the circulation circuit of the lines 51 . 52 . 53 fluid conveyed through the photovoltaic module is at the same time the heat carrier with the wavelength-shifting properties.

A

incident Sunlight with the wavelength spectral components transmitted by the Earth's atmosphere

1

photovoltaic module

10

Active radiation Top of the module

20

transparent Receiving device, in particular fluid container

21

translucent heat transfer medium with wavelength shifting properties

22

reflector surface

30

photovoltaic cell with a limited range of sensitivity, z. B. a monocrystalline solar cell based on silicon

31

Active radiation Top of the photovoltaic cell

40

medium for cooling the translucent heat carrier

B

converted Light with at least one of the translucent heat carrier shifted wavelength spectral component

50

Fotovoltaikanlage

1a-1f

photovoltaic modules the photovoltaic system

51

supply line for one cooling medium

52

circulation line

53

Return line

54

cabling the voltage outputs the photovoltaic modules

55

electrical Storage and / or converter unit, z. As an inverter with battery backup

56

feeder of the inverter z. B. in an electrical power distribution network

57

turbine with downstream capacitor

58

a coupled electric generator

59

feeder of the generator z. B. in an electrical power distribution network

Claims (17)

Photovoltaic module ( 1 ) with a) at least one photovoltaic cell ( 30 ) with a limited sensitivity range, b) a transparent receiving device ( 20 ), which - at least the irradiation-active upper side ( 31 ) of the at least one photovoltaic cell ( 30 ), and the - a translucent heat transfer medium ( 21 ) with wavelength-shifting properties, wherein the wavelength-shifting properties acting on the incident sunlight (A) affect the limited sensitivity range of the photovoltaic cell ( 30 ) are tuned so that the light-transmissive heat carrier ( 21 ) converted light (B) from the photovoltaic cell ( 30 ) and with c) means ( 40 ) for keeping constant the translucent heat carrier ( 21 ) preferably in one for the at least one photovoltaic cell ( 30 ) Efficiency-optimal temperature range. Photovoltaic module according to claim 1, wherein the transparent heat transfer medium ( 21 ) for adjusting the wavelength-shifting properties has at least one addition which causes an increase of wavelengths of the incident sunlight (A). Photovoltaic module according to claim 2, wherein the at least one addition of the translucent heat carrier ( 21 ) is selected such that this is a conversion of short wavelength proportions of the incident sunlight (A) in of the photovoltaic cell ( 30 ) causes useful light (B) with long wavelengths. Photovoltaic module according to claim 3, wherein the at least one addition of the translucent heat carrier ( 21 ) causes a conversion of UV wavelength components of the incident sunlight (A) into usable light (B) with blue, green and / or yellow wavelength components. Photovoltaic module according to one of the preceding claims 2 to 4, wherein the transparent heat transfer medium ( 21 ) has at least one fluorescent and / or phosphorescent additive for adjusting the wavelength-shifting properties. Photovoltaic module according to one of the preceding claims, wherein the transparent heat transfer medium ( 21 ) for adjusting the wavelength-shifting properties has at least one additive which causes a reduction of wavelengths of the incident sunlight (A). Photovoltaic module according to claim 6, wherein the at least one addition of the translucent heat carrier ( 21 ) is selected such that it is a conversion of long wavelength proportions of the incident sunlight (A) in of the photovoltaic cell ( 30 ) causes usable light (B) with short wavelengths. Photovoltaic module according to claim 7, wherein the at least one addition of the translucent heat carrier ( 21 ) causes a conversion of IR wavelength components of the incident sunlight (A) into usable light (B) with blue, green and / or yellow wavelength components Photovoltaic module according to claim 8, wherein the transparent heat transfer medium ( 21 ) has nanoparticles as at least one additive for adjusting the wavelength-shifting properties. Photovoltaic module according to one of the preceding claims, wherein the transparent heat transfer medium ( 21 ) has a cooling and / or corrosion protection fluid as a base material. Photovoltaic module according to one of the preceding claims, wherein as a transparent heat transfer medium ( 21 ) a light conversion active cooling and / or corrosion protection fluid is used, which is used for active cooling of at least components with high power loss in computer systems. Photovoltaic module according to one of the preceding claims, wherein the transparent heat transfer medium ( 21 ) has a boiling point of about 5 degrees Celsius. Photovoltaic module according to one of the preceding claims, wherein the transparent heat transfer medium ( 21 ) is electrically conductive. Photovoltaic module according to one of the preceding claims, with means ( 10 ) for the reduction of reflections in the area of the irradiation-active upper side ( 31 ) of the photovoltaic cell ( 1 ). Photovoltaic module according to Claim 14, having an antireflection coating ( 10 ) in the region of the irradiation-active upper side ( 31 ) of the photovoltaic cell ( 1 ). Photovoltaic system ( 50 ) with at least one photovoltaic module ( 1a - 1f ) according to one of the preceding claims, with a) means ( 51 . 52 . 53 ) for the circulation of a cooling medium for the at least one photovoltaic module ( 1a - 1f ), and with b) into the circulation means ( 51 . 52 . 53 ) integrated means For the implementation of that of the at least one photovoltaic module ( 1a - 1f ) heat energy contained in the cooling medium into mechanical energy by evaporation of the cooling medium, - for cooling the cooling medium by condensation, and - to convert the mechanical energy into electrical energy ( 59 ), and with c) an electrical storage and / or conversion unit ( 55 ) for the at least one photovoltaic module ( 1a - 1f ) generated electrical energy ( 56 ). Photovoltaic system ( 50 ) according to claim 16, with a) one in the circulation means ( 51 . 52 . 53 ) integrated turbine with capacitor ( 57 ) as means for converting the heat energy into mechanical energy and for cooling the cooling medium by condensation, and with c) one to the turbine ( 57 ) connected generator ( 58 ) for generating electrical energy ( 59 ).