DE102008037965A1 - Device for producing electrical energy from sunlight, has foil arrangements that are designed on ground, where foil arrangements have Fresnel lenses, transducer, conductor and volume-variable elements - Google Patents

Abstract

The device has foil arrangements that are designed on ground, where the foil arrangements have Fresnel lenses (12), transducer (13), conductor and volume-variable elements. The Fresnel lenses are provided to focus the sunlight on transducer. The transducer converts sunlight into electrical energy. An independent claim is included for a method for producing electrical energy by sunlight.

Description

Object of the invention

aim The invention is the creation of a technology for low cost Production of electric energy from sunlight. In particular, this aims Invention on the profitable production of solar power at one low grid feed-in price (if possible below $ 0.05 / kWh), so that a considerable Share of electric energy demand generated by Germany and other countries can be and the enormous supply cheapest ecological electricity an explosive technological development allows.

Background of the invention

In the sunny regions (eg Spain, Sahara, California) an average of about 170 W / m ² sunlight fall. In many deserts and desert-like areas, the land consumption and thus the efficiency of the plant is often not decisive because of low land prices, but the capital dividend. At 10% efficiency and a grid feed-in price of z. For example, $ 0.03 / kWh can generate $ 4 / m ^{2 in} revenue each year. In order to make the electric energy production from solar energy interesting for investors, a capital doubling in the first year is to be striven for (if possible without subsidies). Accordingly, investments and operating costs in the first year should amount to a maximum of only $ 4 / m ² . Currently, thermocouple-based solar panels or photovoltaic panels cost about $ 600 / m ² . There are also costs for inverters and transformers. In order to reach a target of approx. $ 2 / m ² , the cost of the solar panels would have to be reduced by a factor of about 300.

On the other hand, household standard aluminum foils and plastic films are available for less than $ 0.1 / m ² . Such aluminum foils would be sufficient to transport 15 W / m ^{2 of} electrical energy. The plastic films would be sufficient to isolate voltages of a few 10V. Voltage breaches due to material defects could possibly even be self-healing, as thin layers of aluminum foil evaporate easily. A sandwich of some such films could already have considerable mechanical stability. The question is, it would be possible to produce from such or similar cheap films and a very small amount of high-tech materials directly electricity-generating solar panels with about 10% efficiency for $ 2 / m ^2?

Characteristic of the known state of technology

A currently very successful principle of solar power systems in sunny areas (eg California and Nevada) is the focus of sunlight by about 100 m ² parabolic mirrors on Stirling engines with about 30% efficiency, each driving a generator whose electricity directly can be fed into the grid via transformers. Alternatively, refrigerated high-performance photovoltaic elements are also used with about 30% efficiency (eg in Australia), the output of which, however, must be passed through an inverter. A bottleneck in both technologies are the very elaborate mirrors. For example, with only 100 m ² mirror surface typically several 1000 kg of material for the movable mirror holder expended, as this must be able to carry considerable wind loads due to the approximately vertical arrangement. With such a high use of material permanently high costs are to be expected, which can not be largely eliminated by technical advancements.

With 170 W / m ² sunlight, 80% land use and an alternative technology with an overall efficiency of 10%, approximately 13 MW / km ^{2 would be} generated, ie for the approximate present total electrical energy demand of Germany (approximately 60 GW) approx. 4600 km ² area required (suitable storage facilities required).

Netzeinspeisepreise of very economical power plants with sustainable technologies (eg from some very large hydropower plants) are typically around $ 0.08 / kWh in Germany (compared to often over $ 0.6 / kWh for conventional Photovoltaic systems and typically with about $ 0.12 / kWh for large wind power plants).

Description of the invention

According to the invention the solar panels essentially consist of wide but very thin foil arrangements, simply laid out on the ground and with hooks, nails, tent pegs or similar Fasteners (hereinafter referred to as "hooks") in to be attached to the earth. These foil arrangements contain integrated Fresnel lenses, transducers of sunlight in electric power and the electrical cables for power transport to busbars.

According to the invention, the readjustment of the effect of the Fresnel lenses on the tiny transducers takes place automatically when the sun's position changes due to the sunlight itself, ie without an external control. To this end, the foil assemblies contain chambers or other suitable variable volume elements that change shape as sunlight changes, thereby altering the geometry of the foil assembly in a desired manner so that either (a) the light focus of the Fresnel lenses remains on the transducers at walls the sun during the day and in the course of months (ie the self-adjustment is essentially a self-focusing - see embodiment 1) or (b) during migration of the sun during the day and in the course of months only predominantly in the light focus or In the vicinity of the light focus located transducers are electrically connected (ie, the self-adjustment consists essentially in that the respective illuminated parts are electrically effective and the transducers in the unlit part of the arrangement are largely ineffective - see Embodiment 2). The chambers or other suitable variable volume elements may, for. B. consist of gas bubbles in plastic or between two metal layers that expand when heated. Such cavities can, for. B. produced by rolling of profiles in plastic films or metal foils or produced by using foamed materials. However, the bubbles must not be too large, so as not to hinder a heat transfer significantly.

Thereby eliminates expensive moving parabolic mirrors and other expensive and material-intensive Optical components, which are a major factor in many modern Represent solar power plants. By a large number of approximately the same Components with very low material use should be such Develop power plants at very low electricity prices.

The Focusing the effect on the transducer can be in one dimension (with strip-shaped converters) or in two dimensions (eg at nearly point-shaped transducers) respectively. The invention can be applied to inexpensive, sustainable and ecological Electric power generation.

embodiment 1

• Example according to 1 (The illustration is not to scale).

An array of Fresnel lenses ( 12 ) is with chambers ( 11 ) when exposed to sunlight ( 10 ) change their shape so that the transducers ( 13 ) in the focus of Fresnel lenses ( 12 ) stay. The tiny transducers ( 13 ) are preferably on a metal foil ( 14 ) (eg, 0.01 mm thick aluminum foil), which dissipates electricity and heat. Depending on the interconnection (in series or in parallel) of the transducers, a second metal foil may be contained in the foil arrangement (for example, the layer ( 14 ) in 1 a composite of two mutually insulated metal foils, in which the transducers are embedded, wherein the upper metal foil is punched out at the locations of the transducer - all z. B. made with simple rolling and printing techniques). Preferably, the chambers are formed by profiling of films. A lubricant ( 15 ) (eg viscous oil) can be used to reduce friction and seal. The top cover (with the Fresnel lenses) is preferably contiguous with the underside of the cavities (eg, bonded in the hot state) via thin webs (FIG. 16 ), which can bend slightly with horizontal displacement of the two layers against each other.

at a diameter of the Fresnel lenses of z. B. 0.2 mm, the thickness (Height) this film arrangement z. B. 0.3 mm, so that very little material is needed. If z. B. 5 × 5 each Fresnel lenses are combined into an array, then only tiny pieces of foil (with the Fresnel lenses) of about 1 mm edge length moved by a few 0.01 mm. The transducers then have z. Example, a diameter of 0.01 mm, which a highly effective heat transport to underlying layers (eg, 0.01 mm thick aluminum foil of about Household foil quality) allows and thus the application of a high factor of light concentration and therefore a relatively low proportion of expensive high-tech materials.

Solar panels with 10% efficiency for $ 2 / m ² could thus possibly after a very considerable development effort (especially for corresponding manufacturing processes using cheap films and rolling and printing techniques and a high concentration factor of the light and possibly with the use of horizontal thermal gradient thermocouples) on a very large scale (over more than 100 km ² ).

disadvantage this embodiment are, however, that at realistic precision the tracking the light focus with cost-effective Means the factor of light concentration can not be too high and the mechanics are still quite complicated and thus potentially prone to failure.

embodiment 2

• Example according to 2 and 3 (The pictures are not to scale).

In an array are each pairs of Fresnel lenses ( 20 ) with sunlight ( 25 ) a conductive layer ( 21 ), which expands when heated (eg by blistering in the layer ( 21 )). Due to the expansion, the conductive layer ( 21 ) in the hot spots ( 22 ) each contact with underlying thermocouples ( 23 ), in turn, with a conductive layer ( 24 ), which represents the cold side and is electrically interrupted at the location ( 26 ). Techniques to press thin conductive films extremely low interference million-fold elastic against each other, z. B. from the keyboards of computers known. To only to use very little high-tech materials, the thermocouples ( 23 ) not from contiguous layers, but from isolated particles with a poorly heat-conducting material in the interstices. This results in a very high thermal gradient even in very small particles (ie large temperature difference between the hot and cold side). On the other hand, the heat flow through a very thin layer of particles is sufficient even with only relatively low coverage of the surface: Required for solar radiation without further external concentrators only about 500 W / m ² peak power. In order to use only a small amount of material, the diameters (in the case of a strip shape measured transversely to the strip direction) of the Fresnel lenses and the total thickness of the arrangement are preferably only about 0.1 mm-0.5 mm. Accordingly, the thermocouple particles ( 23 ) preferably only sizes of about 0.005 mm-0.05 mm. In an area coverage of z. B. 3% are so only about 10 g / m ² thermocouple particles ( 23 ) or less required. The metallic layers are z. B. aluminum foils with about 0.01 mm thickness. Since usually two types of thermocouple particles ( 23 ) (eg p- and n-type silicon), the thermocouple particles ( 23 ) are printed as an emulsion. However, printing large areas with a movable printhead is expensive. Rolling of the thermocouple particles ( 23 ) without using a moving printhead, e.g. B. as a dry powder. Since many suitable materials for the thermocouple particles are refractory, very brittle, and highly intolerant of internal contaminants (ie, in volume), the thermocouple particles ( 23 ) z. B. ground from crystalline material and sieved. In this case, if appropriate, a grinding technique is used, which generates elongated crystal chips, which are transverse to the longitudinal axis in the conductive layer ( 21 ) are rolled. Too small particles increase the probability of a short circuit between the layers ( 21 ) and ( 24 ). For better electrical contact with the conductive layer ( 21 ), an electrically conductive auxiliary layer may be used (not shown) already connected to the top of the thermocouple particles ( 23 ) and is interrupted many times, so that it forms electrically conductive islands.

With the low thermoelectrically achievable voltages, contact resistances are critical. Since it is to be expected that many contacts will fail even with careful production, the converters are preferably interconnected so that many contacts can easily fail. For example, preferably converters are connected in parallel (for better tolerance against contact problems) and these parallel circuits are connected in series (for voltage accumulation). So that the layer ( 21 ) on expansion sufficient pressure on the transducer ( 23 ) are preferably non-conductive connections between the layer ( 21 ) and the converters ( 23 ) (not shown). Between the conductive layer ( 21 ) and the Fresnel lenses ( 20 ) is preferably a spacer, which also contributes to the mechanical stability.

In this embodiment, the foil assemblies with variable volume elements, transducers, and electroconductive foils are laid out as webs (e.g., on mountain-south slopes). Preferably, the traces already include series connections of the transducers or arrays of transducers to produce a higher voltage. Small gaps between the tracks absorb rain and dirt. The stream of the webs is fed directly into collective power lines and fed into the grid via inverters and transformers. Since such Fresnel lenses ( 20 ) can be produced at very large quantities for less than $ 1 / m ² (since the material use can be low and inexpensive materials can be sufficient and production by rolling is possible), replacement after damage can be inexpensive. Such Fresnel lenses ( 20 ) can also be less sensitive to scratches than mirrors.

Description to 3 : Tracks ( 30 ) of foil assemblies are laid out (eg on a mountain-south slope). The railways ( 30 ) of foil assemblies are connected to electrical busbars ( 31 ) connected to an inverter ( 32 ), which is connected to a transformer ( 33 ) is connected to the grid feed. The railways ( 30 ) include a rim (not shown) for piercing hooks into the ground. The edge is preferably mechanically reinforced.

For example, a 0.01 mm aluminum foil per m width has a cross section of 10 mm ² and can thus carry 50 A current. By interconnecting converters, voltages around 100V can be achieved, which can be isolated by a plastic sheeting of about household foil quality (eg, the stress accumulates in 2 when many such tiny arrays are connected in series and respectively for the transducers ( 23 ) on the right side a thermoelectric and each for the converter ( 23 ) on the left side the other thermoelectric is used). Thus, 5 kW peak power can be directly transported through the width of the webs without additional conductors (eg a track of 1 m width and 100 m length with a few cm edge for attachment in the ground by means of hooks). The solar energy of large areas can be converted directly and forwarded with films of approximately household film quality at low cost for power lines. The film arrangements can largely by simple Pro Like rolls are produced.

Due to the enormous number of identical or almost identical components, development costs for the individual components would only make a very small contribution per lane. Due to the very low use of materials, enormous savings can be achieved through technical further development for most subcomponents. For example, the Fresnel lenses ( 20 ) are pressed in large quantity very quickly and inexpensively from cheap plastic between two rollers. High-tech materials are almost only needed in the transducers and there only in very small quantities. Land purchase costs are comparatively low in desert and other inhospitable areas. With proper electrical circuitry, a larger number of transducers or tracks can fail without requiring immediate maintenance. With a suitable structure, voltage breakdowns can often be self-healing by evaporation of a portion of the metal layers.

The Fresnel lenses preferably have their structuring predominantly on the bottom and are relatively smoother on the top. Thereby Dust gets worse on the top and the focus of the Fresnel lenses has at an angle Idea a better quality.

Solar panels with 10% efficiency for $ 2 / m ² could be possible after a considerable development effort (especially for corresponding manufacturing processes using cheap foils and rolling techniques) on a very large scale (to more than 100 km ² ).

In this embodiment Many parameters and subcomponents are specified very precisely. However, these specifications are only examples of a better one understanding of the principle to see and the technical parameters and the choice of Subcomponents can also completely different. In particular, of course, z. B. other geometries Fresnel lenses, types of transducers from sunlight to electrical energy, Overall geometries of the system, power densities, converter densities, converter interconnections, Tensions, currents, Cable types and cable arrangements are used. The same applies for the embodiment 1.

Claims (15)

Equipment and methods for generating electrical energy from sunlight, characterized in that - foil arrangements are designed on the ground, - the film assemblies include Fresnel lenses, transducers, conductors and volume variable elements, - the Fresnel lenses focus sunlight on transducers, - Transducers remain largely in the focus of the Fresnel lenses when the sun's position changes in one or two dimensions, characterized in that variable volume elements are heated differently at different levels of sunlight and change their shape with changing sunlight exposure, - convert the converters sunlight into electrical energy. equipment and method for generating electric energy from sunlight, according to claim 1, characterized in that - said variable volume Elements of gas-filled cavities between profiled layers, - The cavities expand when heated and such a predominantly horizontal displacement of a layer containing the transducer cause a layer containing the Fresnel lenses, - The cavities with a thick Lubricants are sealed. equipment and method for generating electric energy from sunlight, characterized in that - Foil arrangements are laid out on the ground, The foil arrangements Fresnel lenses, Including transducers, conductors and variable volume elements, - the Fresnel lenses Focus sunlight on transducers, - the variable volume Elements cause in the Focus of the light or nearby the focus of the light located converter electrically connected are (ie to generate electricity), - the variable volume Elements cause that far away from the focus of the light located converter not electrically are connected, - said variable volume Elements effect that when changing the position of the sun in one or two dimensions and thus change the focus of the light continues to be in the focus of the light Transducers are electrically connected, - said converter sunlight convert into electrical energy. Equipment and methods for generating electric energy from sunlight, according to claim 3, characterized in that - said variable volume elements contain gas-filled cavities between profiled layers or material with variable in temperature changes inclusions, said said cavities expands when heated NEN and thus cause a predominantly vertical extension of a layer against transducer. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - said Foil arrangements on mountain slopes with gaps designed and fastened with hooks in the ground. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - said Foil assemblies a width of more than 50 cm and a thickness of less than 1 mm. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - each more than 100 transducers in the foil assemblies for generating a higher Voltage connected in series. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - said Transducers in the film assemblies photoelements or thermocouples are. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - The current is fed from said film assemblies in manifolds, which feed into an inverter which is connected via a transformer in the power grid feeds. Equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized in that - the manufacturing cost of said film assemblies is less than $ 5 / m ² and the total efficiency of conversion of solar energy to electrical energy of said film assemblies is greater than 8%. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - the feed-in price into the grid under $ 0.05 / kWh. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - converter based on the thermoelectric effect and powders of thermoelectric Use materials that are ground from crystalline material. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - powder of thermoelectric materials has an average particle size of less than 0.2 mm. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - thermoelectric Materials in one layer with less than 10% area coverage be used and the more than 90% spaces in this layer average At least 20 times lower heat conduction than the thermoelectric Have materials. equipment and method for generating electric energy from sunlight, according to at least one of the preceding claims, characterized that - cheaper used to counter the further devastation of land Act.