Patent Application
20070283999
The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:
Reference is now made to
The solar cell geomembrane assembly 10 includes one or more solar cells 12 (referred to simply as solar cell 12 and alternatively referred to as photovoltaic cell 12) integrated with (e.g., disposed on) a geomembrane 14. Geomembrane 14 is a flexible floating cover material suitable for floating in or on water surfaces. The solar cell geomembrane assembly 10 may float on a water surface (indicated by water level 4 in
Geomembrane 14 may include the Pondgard® EPDM Liner or the blended Medium Density Polyethylene (MDPE) geomembrane, both commercially available from GSI, or any other suitable liner, membrane or other flexible substrate (all the terms being used interchangeably throughout). Another suitable geomembrane flexible floating cover material is manufactured by Comanco Company, 4301 Sterling Commerce Drive, Plant City, Fla. 33566 (www.comanco.com). Geomembrane 14 may be inflatable.
The solar cell 12 may include a roll-print solar cell. Technology exists for printing solar cells on rolls. For example, NanoSolar of Palo Alto, Calif. (www.nanosolar.com) has developed proprietary technology that makes it possible to simply roll-print solar cells that require only 1/100th as thick an absorber as a silicon-wafer cell (yet deliver similar performance and durability).
A description of the NanoSolar process is found in PCT published application WO2006033858, corresponding to US Patent Application 20040782545, the disclosures of which are incorporated herein by reference, which describes photovoltaic devices, and more specifically, processing and annealing of absorber layers for photovoltaic devices. A typical Copper-Indium-Gallium-diSelenide (CIGS) solar cell structure includes a back electrode followed by a layer of molybdenum (Mo). A CIGS absorber layer is sandwiched between the Mo layer and a cadmium sulfide (CdS) junction partner layer. A transparent conductive oxide (TCO) such as zinc oxide (ZnOx) or tin oxide (SnO2) formed on the CdS junction partner layer is typically used as a transparent electrode. US Patent Application 20040782545 describes fabrication of CIGS absorber layers on aluminum foil substrates. For example, a photovoltaic device includes an aluminum foil substrate, an optional base electrode and a nascent absorber including material containing elements of groups IB, IIIA, and (optionally) VIA.
Other non-limiting examples of photovoltaic cells that may be used to carry out the invention include, but are not limited to, advanced amorphous silicon photovoltaic modules, e.g., multi-junction amorphous silicon modules. For example, UNI-SOLAR brand silicon modules based on triple junction solar cells perform excellently under western European climatic conditions, with yields and performance ratios significantly higher than present crystalline silicon technologies. This effect is especially pronounced under low light conditions and under non-ideal orientations.
The triple junction technology provides unprecedented levels of efficiency and stability for amorphous silicon solar cells (stabilized aperture area cell efficiency of 7.0-7.5%). Each cell is composed of three semiconductor junctions stacked on top of each other. The bottom cell absorbs the red light, the middle cell the green/yellow light and the top cell absorbs the blue light. This spectrum splitting capability is one of the keys to higher efficiencies and higher energy output, especially at lower irradiation levels and under diffuse light. The cells are produced in a unique roll-to-roll vacuum deposition process on a continuous roll of stainless steel sheet, employing only a fraction of the materials and energy of the production of standard crystalline silicon solar cells. The result is a flexible, light weight solar cell. The solar cells are encapsulated in UV-stabilized and weather-resistant polymers. The polymer encapsulation includes EVA and fluoro-polymer TEFZEL (a DuPont film) on the front side. The resulting modules are exceptionally durable. By-pass diodes are connected across each cell, allowing the modules to produce power even when partially shaded.
The solar cell 12 may be embedded, tied, bonded (with an adhesive), fastened with one or more mechanical fasteners 16, joined or otherwise attached to the geomembrane 14. Some or all of solar cells 12 may be flexibly mounted to one another. Solar cell 12 is sealed to geomembrane 14 with a seal 23 at edges of solar cell 12. This is advantageous because without the seal 23, water and debris may accumulate between the solar cells and the geomembrane and degrade performance.
Another alternative is shown in
The combination of the solar cell on the geomembrane may provide many synergistic benefits, heretofore unattainable with prior art solar cells.
The combination of the solar cell 12 on the geomembrane 14 may be embodied as a new renewable energy generator that utilizes the existing area of a very large water reservoir 20 (or open sea) for numerous water related applications which are local to the water reservoir 20. For example, solar cell 12 may be electrically connected to an electrical device 22. In one embodiment, the electrical device 22 is a water-related electrical device, such as but not limited to, a water pump, a water desalination unit, a water booster, a water treatment device, water delivery and management apparatus, filtration system, etc., or any combination thereof. In another embodiment, the electrical device 22 is a general purpose electrical energy device, such as but not limited to, a power grid for home, industrial, lighting, etc., or any combination thereof.
Reference is now made to
The best tilt angle for any photovoltaic array is the one that produces the highest annual energy output for that particular location. The primary reference point is the latitude but other factors are involved as well. The arc of the sun varies with time of year so, typically, the shallow tilt angles produce more energy in the summer months while the steeper angles produce more energy in the winter months. The best, fixed angle is the compromise between the extremes that allows for the greatest delivered energy on an annualized basis. Tilt angle is especially important with crystalline PV technology, which is much more sensitive to the angle of the incident light as well as dust and dirt accumulations than amorphous silicon PV. Azimuth, or deviation from True South, has a similar impact on energy production as with tilt angle. Optimum performance is typically obtained with the tilted array aligned with True South. Deviations from True South skew the peak output curves in the direction of the deviation (East or West of True South). Generally, the steeper the tilt angle, the greater the effect that the deviation from True South has on the annual energy output.
It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of the features described hereinabove as well as modifications and variations thereof which would occur to a person of skill in the art upon reading the foregoing description and which are not in the prior art.
| Number | Date | Country | |
|---|---|---|---|
| 60811439 | Jun 2006 | US |
