Abstract:
A water integrated photovoltaic (WIPV) system including a plurality of interconnected photovoltaic cells covering at least a portion of a body of water, wherein at least some of the photovoltaic cells have a solar collecting surface covered by the water, and a processing unit electrically connected to and powered by the photovoltaic cells, the processing unit comprising a fluid connection from the body of water for processing the water.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to photovoltaic cells (solar cells), and particularly to a photovoltaic covering for a body of water that solar generates electrical power for various applications. 
       BACKGROUND OF THE INVENTION 
       [0002]    Photovoltaic (PV) technology available on the market today basically includes two commercial module technologies: 
         [0003]    1. Thick crystal products include solar cells made from crystalline silicon either as single or poly-crystalline wafers and deliver about 10-12 watts per ft 2  of PV array (under full sun). 
         [0004]    2. Thin-film products typically incorporate very thin layers of photovoltaic active material placed on a glass superstrate or a metal substrate using vacuum-deposition manufacturing techniques similar to those employed in the coating of architectural glass. Presently, commercial thin-film materials deliver about 4-5 watts per ft 2  of PV array area (under full sun). Although the current technology provides less power for a given area than thick crystal products, thin-film technologies may achieve lower costs due to much lower requirements for active materials and energy in their production when compared to thick-crystal products. 
         [0005]    A photovoltaic system is constructed by assembling a number of individual collectors called modules electrically and mechanically into an array. 
         [0006]    Building Integrated Photovoltaics (BIPV) is the integration of photovoltaic cells into a building envelope. The PV modules serve the dual function of building skin—replacing conventional building envelope materials—and power generator. By avoiding the cost of conventional materials, the incremental cost of photovoltaics is reduced and its life-cycle cost is improved. That is, BIPV systems often have lower overall costs than PV systems requiring separate, dedicated, mounting systems. 
         [0007]    A complete BIPV system may typically include: 
         [0008]    a. the PV modules (which may be thin-film or crystalline, transparent, semi-transparent, or opaque); 
         [0009]    b. a charge controller to regulate the power into and out of the battery storage bank (in stand-alone systems); 
         [0010]    c. a power storage system, generally including the utility grid in utility-interactive systems or a number of batteries in stand-alone systems; 
         [0011]    d. power conversion equipment including an inverter to convert the PV modules&#39; DC output to AC compatible with the utility grid; 
         [0012]    e. backup power supplies such as diesel generators (optional, typically employed in stand-alone systems); and 
         [0013]    f. appropriate support and mounting hardware, wiring, and safety disconnects. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention seeks to provide a photovoltaic covering for a body of water that solar generates electrical power for various applications, as is described more in detail hereinbelow. 
         [0015]    The present invention introduces the concept of WIPV (Water Integrated Photovoltaic) Technology/Systems. WIPV technology/systems/installations have the following advantages: 
         [0016]    1. Protect precious clean water sources from evaporation by using a WIPV floating solar cover made of prefabricated or field-installed geomembrane and solar cells and/or modular interconnected solar cells (flexible or other and modularly connected using interconnecting elements) that float or are buoyant and have direct contact with the water body. 
         [0017]    2. Large scale efficient energy creation system/power plant using any type of water surface area as opposed to expensive land area. 
         [0018]    3. Large scale efficient water creation, water delivery, water rehabilitation, water treatment system without requiring any onsite energy. 
         [0019]    4. Substantial increase of solar energy compared to non-WIPV solar array installations due to constant water cooling of solar cells from water bodies. 
         [0020]    5. Very environmentally friendly green technology (blends in perfectly with the environment) unlike solar arrays and wind turbines that are visible and interfere with the environment 
         [0021]    Other advantages of WIPV type installations/systems: 
         [0022]    Water bodies not only cool the solar cells, but also can be used for cleaning the solar cells from dust/dirt. The WIPV cells can be used as a natural solar concentrator because they can be immersed or be buoyant at a water level for maximum solar radiation. Alternatively for a floating WIPV installation, water can be sprayed on the panel creating millions of magnifying glasses that increase the solar radiation and concentrate the suns rays on the solar material. 
         [0023]    WIPV can be adapted to function in other industries such as gas creation, land fills, etc. The WIPV concept can be used in a great variety of applications, such as but not limited to, WIPV Power Plant, WIPV Water Plant, WIPV water channel, WIPV water pipe, WIPV reservoir, WIPV gas collection/power system, WIPV desalination plant, WIPV irrigation system, WIPV pumping system, WIPV water delivery system, WIPV open water desalination plant, WIPV water treatment plant, WIPV maritime energy system, WIPV maritime mobile water desalination system, WIPV maritime national border defense system, WIPV bridge, or WIPV water transportation system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0024]    The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: 
           [0025]      FIG. 1  is a simplified illustration of a water integrated photovoltaic system, constructed and operative in accordance with an embodiment of the present invention; and 
           [0026]      FIG. 2  is a simplified block diagram of the water integrated photovoltaic system of  FIG. 1 , in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0027]    Reference is now made to  FIG. 1 , which illustrates a water integrated photovoltaic (WIPV) system  10 , constructed and operative in accordance with a non-limiting embodiment of the present invention. 
         [0028]    The WIPV system  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  FIG. 1 ) or, in a preferred embodiment, floats partially submerged below the water surface (indicated by water level  6  shown in broken lines in  FIG. 1 ). For example, the combination of solar cell  12  on geomembrane  14  may be used on an open water source such as an artificial lake with the solar material integrated in the lining. When partially submerged, the water actually functions as a magnifying glass to amplify the suns rays that impinge upon solar cell  12 . Additionally or alternatively, a pump  17  may be provided that sprays water on the solar collecting surface of some or all of the photovoltaic cells. The water not only cools solar cell  12 , but also can be used for cleaning solar cell  12  from dust/dirt. 
         [0029]    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 . 
         [0030]    In accordance with an embodiment of the present invention, some or all of the solar cells  12  may be pivotally mounted on pivots, and additionally or alternatively, mounted on bearings. A system of one or more actuators and sensors may be used to tilt the pivotally mounted solar cells in accordance with the sun&#39;s tilt during the day. 
         [0031]    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. 
         [0032]    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). 
         [0033]    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 (ZnO x ) or tin oxide (SnO 2 ) 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. 
         [0034]    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. 
         [0035]    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. 
         [0036]    The WIPV system  10  may provide many synergistic benefits, heretofore unattainable with prior art solar cells. 
         [0037]    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 a processing unit  22 , also referred to as a water-related electrical device  22  or electrical device  22 . The term “water-related electrical device” as used in the specification and claims refers to an electrical device powered by the solar cell(s)  12  on the geomembrane  14  and which has a fluid connection  24  from the water for processing the water. 
         [0038]    The processing unit  22  is thus energized by electricity generated by the photovoltaic cells, thereby creating a WIPV (Water Integrated Photovoltaic) system. As seen in  FIG. 2 , the WIPV system can be used in a great variety of applications. The processing unit  22  may include or be used to operate, without limitation, 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 addition or alternatively, the electrical device  22  may include a general purpose electrical energy device, such as but not limited to, a power grid for home, industrial, lighting, etc., or any combination thereof. The processing unit  22  may include or be used to operate, without limitation, a WIPV Power Plant, WIPV Water Plant, WIPV water channel, WIPV water pipe, WIPV reservoir, WIPV desalination plant, WIPV irrigation system, WIPV pumping system, WIPV gas collection/power system, WIPV water delivery system, WIPV open water desalination plant, WIPV water treatment plant, WIPV maritime energy system, WIPV maritime mobile water desalination system, WIPV maritime national border defense system WIPV bridge, or WIPV water transportation system and any combination thereof. 
         [0039]    Another embodiment may include a low cost drinking water source. A reservoir covered with solar membrane liners or covers could be used for various applications, such as but not limited to, pumping undrinkable water from the reservoir and recycling the water through filtration/desalination/disinfection back into the reservoir until the water is drinkable, and delivering the water to consumers using booster pumps. 
         [0040]    Yet another application for the solar covers is in hydrogen creation in an electrolytic process. The oxygen may be tapped out and the hydrogen may be collected (in a container or trapped above the water and underneath the cover, for example), ready for use. For example, this embodiment may be a WIPV power plant, which may be offshore (ocean type WIPV) or near a shore of a sea water reservoir. In one example, a third of the area of the geomembrane together with the solar cells may produce energy to a power grid for a period of time during the day (e.g., 8 hour period). The other two thirds of the area of the geomembrane together with the solar cells may produce hydrogen and store it for the night time. The oxygen is fed to the atmosphere. When the sea water runs out it is replenished. During the night the stored hydrogen is used to run a generator that drives the grid. Thus, clean energy is generated on a 24 hour basis, which is equivalent to a 24 hour sun. 
         [0041]    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.