Abstract:
The present invention discloses a system for a hybrid solar energy collector comprising a CIGS photovoltaic energy collector, the photovoltaic energy collector being thermally coupled to an energy absorbing working fluid casing for flowing heat out to heat sink The solar radiation is trapped in the photovoltaic collector, generating electrical power from the CIGS photovoltaic array, The array is cooled by the working fluid transferring unproductive heat away from the photovoltaic array and into an exterior heat sink via the cooling fluid circuit, thus making the photovoltaic array more efficient, while adding another energy source. Where thermal collection is not beneficial, a floating platform supported CIGS PV array may be cost effectively cooled to increase efficiency, by harnessing wave energy from a wave power device to flow cooling or evaporative spray water over the panel.

Description:
BACKGROUND 
     Field of the Invention 
       [0001]    The present invention generally relates to solar energy collectors and more specifically, to solar collectors using CIGS for photovoltaics, thermal working fluid heat collection and wave energy capture hybrid devices. 
         [0002]    The general area of solar collectors is not new. Some solar cells include selective coating on the top surface which increase absorption of the light energy within the desired wavelength range. Moreover, optical coatings are commonly used to reflect light of undesirable wavelengths such as that within the infrared range in order to reduce excessive heating of the cell. Also, since only about 20% of absorbed radiation results in electric current, the other 80% is converted to heat. This heat then makes the photovoltaic element 10-20 percent less efficient, since increased cell temperatures generally result in a decrease in cell efficiency for producing electricity. 
         [0003]    In the past there have been attempts to provide residential and industrial applications solar thermal collectors and solar photovoltaic cells, suitable for converting light energy into both electrical energy and thermal energy. These have had limited success mostly because of the added cost of the thermal portion designs and insufficient power output to cover these costs. 
         [0004]    There have been some combined electrical and thermal solar collectors proposed. Some use flow tubes below plates, with thin perpendicularly heat-conductive web of rigidly connecting plate to flow tubes, inlet and outlet headers at opposite ends of flow tube, making parallel flow tubes below plates, to keep temperature gradients sufficiently low. These all have costs; flow tubes, flow tube construction, manufacturing and building collector, pumping fluid, and insufficient temperature removal. 
         [0005]    Some proposed designs include a photovoltaic grid mounted on a copper plate that provide wider more uniform temperature dispersion across the plate and acts as a thermal radiator when the apparatus is used in the radiant cooling mode. This and a plurality of interconnected heat transfer tubes located within the enclosure and disposed on the plane below the copper plate but conductively coupled to the copper plate for converting the solar energy to thermal energy in a fluid disposed within the heat transfer tubes. Fresnel lenses can be affixed to the apparatus on mountings for concentrating the solar energy on to the photovoltaic grid and functioning as a passive solar tracker. These suffer from complexity and cost of manufacturing, requiring interconnected heat transfer tubes, a Fresnel lens, resistance calculations and bridge circuitry and more. Electronics and sensors have become better and cheaper, and the methods used are not current, keeping costs higher than other solutions. Others use flexible thermal solar collectors, instead of rigid collectors, but these are more expensive because of the flexibility of material and mounting is required. 
         [0006]    Still other designs hybridize solar energy collectors with a photovoltaic collector that generates electricity and a thermal collector which is semi-transparent, utilizing shorter-wavelength radiation while selectively transmitting medium- and long-wavelength radiation to the thermal collector. The collectors are separated by a thermal insulating barrier and have a transparent exterior glass surface and a transparent body, adding cost. These have photovoltaic energy collector thermally insulated from heat generated by the thermal energy collector, instead of optimally transferring the PV energy collector heat directly to the thermal collector for the dual purpose of cooling the PV and collecting thermal energy. 
         [0007]    Still other designs use a substantially unsealed enclosure, an array of photovoltaic cells for converting solar energy to electrical energy located within the enclosure, and a plurality of interconnected heat collecting tubes located within the enclosure and disposed on the same plane as the array of photovoltaic cells for converting solar energy to thermal energy in a fluid disposed within the heat collecting tubes. These again, are costlier tube constructs with interconnected heat collecting tubes located within the enclosure and disposed on the same plane as the array of photovoltaic cell, instead use open channels, slab geometry conduit and freon or other refrigerant gas working fluid. Open channel surface flow or slab geometry conduits with working fluid liquid or gas or both in the enclosure, or convective and conductive or capillary action energy transfer means may prove less expensive. 
         [0008]    Single thin-film solar panel technology is emerging, composed of flexible aluminum substrate, electrically conductive back metal contact layer which could be deposited on the anodized flexible aluminum substrate. An anodized surface electrically insulates the aluminum substrate from the electrically conductive back metal contact layer; a semiconductor absorber layer is deposited on the back metal contact. The semiconductor absorber layer is constructed from a film selected from the group of metals composed of Copper, Indium, Gallium and Selenium, thus its name, CIGS thin film. These are emerging but not yet competitive with the conventional photovoltaic solar panels offered. The CIGS suffer from the deficiency that as they heat up thermally, they become less efficient and therefore less cost effective. Thus CIGS photovoltaic panels suffer from high cost and lower efficiency at higher temperatures. 
         [0009]    Some companies have been engaged in the research and development of thin-film Cu(In,Ga)Se2 (CIGS) photovoltaic technology since 1991. Some have pursued a vacuum-based approach to CIGS production, using linear source technology and standard soda-lime glass substrates. The choices result in layers having controllable purity and low physical defects, and production without significant hazards. Considerations such as these are important in helping to minimize the processing costs of CIGS. Thin film PV technologies have advanced considerably, however, for technologies to survive, they must also perform well commercially. As a result of such fiscal pressures, a big market player shut down two sophisticated thin film lines using alternate methods. In some cases it maybe premature to discard some thin film CIGS technologies until all the costs and benefits are all totaled. Perhaps the highest yield technology will would be costlier than a hybrid with the lower cost CIGS but less efficient. This CIGS technology coupled with a complementary solar technology, may increase the total collector yield or give the total cost below a cost/benefit improvement over the higher efficiency CIGS technology. Thus, what is needed is hybrid technology which can be scaled and complementary to the CIGS thin film technology to maximize the utility of solar technology. 
         [0010]    Water is becoming a more precious commodity, in support of every growing population. However, in California alone, typical reservoir surface area normally exposes 647,200 acres, shrinking substantially in drought years and appreciably in the autumn of a normal year. The total average annual evaporation from these areas is 2.3 million acre-feet. This amounts to an average evaporation from reservoirs, in the neighborhood of 60 inches averaged over the whole state. Thus a need for water retention can be satisfied if the surface were partially covered, as vaporization occurs across the solar exposed water surface. But to cover the water surface, would be prohibitively costly and unjustified, therefore it is not contemplated. Recreation use would be affected, but there are bodies of water that do not have recreational use or only partial use. Therefore, what is needed are ways of saving water and capturing the solar energy generally rendered useless in evaporation. 
         [0011]    Generally, photovoltaic CIGS solar panels need a way of cooling the cell array in a cost effective manner and solar hybrid collectors need to be manufactured and made cheaper. Methods and designs for heat transfer and cooling photovoltaic without expensive insulation, manufacturing costs and smarter heat transfer designs, can harness thermal energy from the photovoltaics and collect the heat where it is needed. Such designs can be incorporated into photovoltaic raft structures that both shade reservoir water and produce higher efficiency PV generated electricity. 
         [0012]    Expensive real estate has priced out placing solar collectors in many markets. Hence many residential and commercial applications of solar are not contemplated. Meanwhile, precious water is lost by evaporation from solar energy action. What is needed are cheaper and more efficient solar hybrids, solar hybrids which can solve other problems such as water loss due to evaporation, or solar hybrids which can take advantage of other forms of energy. 
       SUMMARY 
       [0013]    The present invention discloses a system for a hybrid solar energy collector comprising: a outer thermal collector housing with one way exterior surface to trap solar radiation, housing a flat CIGS photovoltaic energy collector, the photovoltaic energy collector being thermally coupled to an energy absorbing working fluid casing for flowing heat out to heat sink The solar radiation is trapped in the collector, generating electrical power from the CIGS photovoltaic array. The array is cooled by the working fluid transferring unproductive heat away from the photovoltaic array and into an exterior heat sink via the cooling fluid circuit, thus making the photovoltaic array more efficient, while adding another energy source from waste heat. A water floating collector is also presented, adding yet the wave energy into the collector array. These may be more cost effective to cool the CIGS PV array panels using transpiration cooling spray pumped from onboard hybrid wave or wind power sources. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]    Specific embodiments of the invention will be described in detail with reference to the following figures. 
           [0015]      FIG. 1  is a cross sectional diagram illustrating an a solar photovoltaic using CIGS layered on a thermal collector according to an embodiment of the present invention. 
           [0016]      FIG. 2  shows a thermal collector element for fluid heat transfer in accordance with an embodiment of the invention. 
           [0017]      FIG. 3 . illustrates CIGS PV with straight flow through collector hybrid a in accordance with an embodiment of the invention. 
           [0018]      FIG. 4  illustrates a floating solar hybrid in accordance with an embodiment of the invention. 
           [0019]      FIG. 5  illustrates a floating solar hybrid with wave energy booster in accordance with an embodiment of the invention. 
           [0020]      FIG. 6  illustrates a wave energy booster piston-cylinder in accordance with an embodiment of the invention. 
           [0021]      FIG. 7  illustrates a floating solar hybrid array in accordance with an embodiment of the invention. 
           [0022]      FIG. 8  illustrates a tethered floating solar hybrid array profile view in accordance with an embodiment of the invention. 
           [0023]      FIG. 9  illustrates a double side “W” reflector housing solar hybrid perspective view in accordance with an embodiment of the invention. 
           [0024]      FIG. 10  illustrates a double side “W” reflector housing solar hybrid front view in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. 
       Objects and Advantages 
       [0026]    The present invention is a system and method of converting solar energy to electrical energy via several parallel paths acting concurrently. 
         [0027]    Accordingly, it is an object of the present invention to provide a more efficient and cost effective solar technology, one that uses CIGS in combination with thermal collectors. 
         [0028]    It is another object of the present invention to provide embodiments designed for water surfaces, to take advantage of more affordable locations for solar arrays, reduce fresh water loss from evaporation, harness wave energy in parallel to increase efficiency, provide a heat sink cooling photovoltaics to increase conversion efficiency, provide a floating power source and for other benefits from locating solar platforms on inland or ocean sites. 
       Embodiments of the Invention 
       [0029]      FIG. 1  is a cross sectional diagram illustrating an a solar photovoltaic using CIGS layered on a thermal collector according to an embodiment of the present invention. A thin semi-transparent or one-way mirror layer  101  covers a glass or plastic collector cover  103 , held in place by a shallow housing  105  top and bottom  111 , not necessarily rectangular, for capturing impinging solar energy not necessarily only visible spectrum. The CIGS thin film layer  117  is deposited on a thermal conducting  115  working fluid casing  115 , from which a fluid can be forced or gravity fed through an opening  109 . In some configurations, the cooling can be panel externally applied fluid spray. The thermal conducting fluid casing  115  may be supported by insulation  113 , to encourage the heat to be collected by the fluid. Solar radiation is trapped after penetrating the one-way mirror layer  101 , bouncing around until it is absorbed by the CIGS layer  117 , where the electrical power is transferred  107  to an outside storage cell, or thermally conducts to the working fluid layer  115 , for hot water use or a working fluid thermodynamic energy transfer to a temperature sink, known to those skilled in the art. Thus an optimum recipe for the CIGS thin film is not necessary from the CIGS standpoint, as an aspect of the invention is to be able to use the less costly less efficient CIGS thin films in a higher efficiency hybrid solar design. 
         [0030]    Many methods of CIGS deposition; spray, sputtering, layers, rolling, special treatment, buffer combinations, buffer layers, junction formations, material compositions, composites, patterning, etc and substrates; production, interconnect methods, fabrication, etc are known to those skilled in the art. Some create higher efficiencies but may have higher costs. An objective of the invention is to use the least expensive approach which with the thermal heat harnessed as a part of the solar hybrid system, yields the highest total solar energy capture per unit cost. As with most all PV, the CIGS efficiency improves where the temperature can be maintained within certain levels. Thus, the temperature extracted in heat from the CIGS panel and harnessed in the thermal heat portion, the overall unit efficiency increases. 
         [0031]      FIG. 2  shows a thermal collector element for fluid heat transfer in accordance with an embodiment of the invention. The outlet  201  of the working fluid can be vertically higher than the working fluid inlet  211 . The working fluid casing  209  is constructed separate to the channels  207  and bonded or in one slab type construction upon which the CIGS layer can be deposited. The collector may by housed in a frame  203  and enclosed by semi-transparent cover facing the solar exposure and insulated on the opposite side to retain maximum heat removal through the working fluid. 
         [0032]      FIG. 3  illustrates CIGS PV with straight flow through collector hybrid a in accordance with an embodiment of the invention. A housing frame  301  supports a lip  303  firmly holding a slidable semi-transparent one-way plastic or glass cover. The housing bottom  307  supports insulation  309  upon which working fluid channels  311  rest. These are bonded with thermal conducting materials  313  to the CIGS cells  314 , which are connected electrically to conduct the electrical energy  315  out. The CIGS cells  314  can be manufactured in several ways, extrusion, printing press plastic membrane, liquid paint form deposit, sputtering onto stainless steel sheets or flexible foil, and other manufacturing processes using CIGS coatings known to those skilled in the art. Working fluid enters at an opening  317  and can flow naturally with gravity or force pumped against gravity inclines. 
         [0033]      FIG. 4  illustrates a floating solar hybrid in accordance with an embodiment of the invention. A primitive structure  409   405   403  keeps the solar cell array  407  floating above the water surface. The frame structure  409   405   403  is attached to pontoons  413   411  and electrical energy can be conducted out  401  by cable or wire  401 . The frame structure  409   402   405  can be more complex, having a motor elevating support beam  403  or withdrawing the support beam  403  and elevating support beams from the opposite side, under control of a automatic solar tracker and sensor. The automatic solar tracking can add 20%-40% more electrical power from the photovoltaics. Not shown are alternative exterior panel cooling from siphoned water spray, to contain the PV temperature yet another way, and without a contained thermal fluid. 
         [0034]      FIG. 5  illustrates a floating solar hybrid with wave energy booster in accordance with an embodiment of the invention. The solar panel  501  is shown supported  503   504  by simple rigid structures which can easily be motorized by one degree of freedom to adjust the panel  501  to a solar tracker, keeping the panel at optimal angle to the sun. The solar panel  501  floats on pontoon  505  structures which can be made from many materials and geometries. The solar panel  501  is shown above the water surface but since solar energy can transfer through water, a partially submerged embodiment can be contemplated. The solar photovoltaic cell array produces electrical energy transferred by wire or cable  507  to a junction or converter  513 , for external distribution  511 . A wave energy capture tube-piston device  509 , known to those skilled in the art, is coupled to the float  505  and must be at least partially submerged to trap the wave energy from the surface proximity. The wave energy tube-piston device  509  is directly coupled to a power extractor  515 , also known to those skilled in the art. Power from the wave device can be additive to the outgoing electrical power  511  at the converter/junction box  513  or diverted toward the solar hybrid functions such as pumping cooling water through the solar panel,  501 , evaporative spray cooling, powering the tracking device, or other on-board needs. Cooling of the solar array can boost electrical power output another 10%-15%, which can be a significant improvement even subtracting the power lost to pumping cooling fluid over the panel. 
         [0035]      FIG. 6  illustrates a wave energy booster piston-cylinder in accordance with another embodiment of the invention. The wave energy device is enclosed in a tube  605  with a piston  611  in a cylinder catcher  609 , piston  611  coupled to a power converter  617  via a shaft  615 . Wave action pushes the piston  611  up as the wave impinges and down the tube  605  as the wave recedes, draining fluid through openings  607  in the tube  605 . A small check valve  613  can reduce piston  611  resistance to wave receding. The power converter can be air-turbine, oil motor coupling-gearbox, or direct conversion, harnessing the moving piston energy from wave action to electrical energy. The power can be additive to outgoing contribution or on panel use for evaporative spray cooling of the panel for increasing panel efficiency. Not shown are analogous small wind power mills or turbines which can harness smaller amounts of wind energy for on panel or off panel contribution. 
         [0036]      FIG. 7  illustrates a floating solar hybrid array in accordance with an another embodiment of the invention. Solar collect panels  705  are coupled to floatation platforms  707  using support structures  711  which can be extended, or retrieved through a rack-an-pinion controlled solar tracker. The platform  711  would be coupled to another platform through a wave energy hinged joint device  713  known to those skilled in the art. 
         [0037]    The solar photovoltaic panels transmit the electrical power to shore via cable  703 . As a wave passes down the length of floatation panel  707  array, the hinged joints  713  on the power conversion modules, known to those skilled in the art, allow the floatation panels  707  to move up and down and side to side. The motion of the solar floatation platforms  707  relative to each other, drives pumps that turn generators inside the hinge wave energy harnessing device  713 . The electricity flows via a cable  703  to a shore-based grid. Some harnessed energy can be used to pump cooling or evaporative spray water over the solar panels  705  to increase their efficiency, as cooling CIGS cells to optimal temperatures can increase efficiency by 10%-20%. For some situations, it is estimated that the power needed to pump cooling or evaporative spray water over the panels is much less than the incremental power produced by the photovoltaics at the cooler temperatures, thus synergistically justifying the energy cost of pumping. 
         [0038]      FIG. 8  illustrates a tethered floating solar hybrid  811   809  array profile view in accordance with an embodiment of the invention. The solar photovoltaic panel  811  is supported on the floatation platform  809  coupled by the wave energy devices  813 . The array must be flexibly anchored to allow wave action be harnessed by the array simultaneously with electrical power from the photovoltaic array. To add flexibility, the hybrid array ends are tethered to submerged free floaters  807   815  and then to surface float anchors  805   817  for a less active cable  803  segment connection to the bottom anchors  801   819 . This type of flexible anchor arrangement is known to those skilled in the art. The water depth and the wave action are factors which is considered in such an arrangement, as the cable  803  and power transmission costs play a roll in how far offshore the array is flexibly anchored  801   819   
         [0039]      FIG. 9  illustrates a double side “W” reflector housing solar hybrid perspective view in accordance with an another embodiment of the invention. The housing  901   909   911  is formed in the configuration of the letter “W” from the front edge  909  and extruded along a longitudinal axis in parallel with the CIGS coated photovoltaic array  903   907 . The “W” housing configuration would have a reflecting inside surface  901   911  such that all solar radiation not impinged or reflected from the CIGS coated photovoltaic cell surface  903  directly facing the sun side, would be trapped and reflected onto the opposite CIGS coated photovoltaic side facing cell array  907 . CIGS coatings constituting the photovoltaic cell array panels  903   907  would be electrically coupled to storage and/or converters for internal or external electrical power. The CIGS photovoltaic panel is further cooled to a temperature to optimize the power out. The cooling can be provided by a simple fluidic channel  905  between the two opposing panels  903   907  flowing coolant in  913  and out  915  coupled through and adaptor  917 . The cooling fluid would deliver the heat to a water heater or other thermo fluid exchanger. 
         [0040]      FIG. 10  illustrates a double side “W” reflector housing solar hybrid front view in accordance with an embodiment of the invention. The CIGS photovoltaic cell is coated with a layer of CIGS  1001  material on substrate  1005  material which is known to those in the art. The substrate  1005  is bonded by a thermal conducting agent  1006  to a thermal conducting fluid channel  1007 , channel made of material with good thermal conducting properties, for conducting heat to a flowing cooling thermofluid  1009  through the channel having inlet  1013  and outlet conduits flowing the cooling thermofluid to a heat sink. The channel  1007  can be partially constructed from thin metallic sheets, also acting as the substrate for the CIGS photovolatiac. Although shown as such, the channel cross section need not be necessarily rectangular and can be many other or variable cross section. Moreover, many other thermal conducting materials can be used. Minimum cost material and fabrication will dictate materials. The thermofluid  1009  can be water, coolant, refrigerant or other, where heat transfer properties efficiently retain the heat from the photovoltaic layers and quickly move out reducing the photovoltaic cell  1001  temperature to a more energy efficient range. The opposite side of the channel will be like wise layered with CIGS layer  1011  first to catch non direct impinging solar radiation, and held to a substrate  1015  which is bonded by a thermal conducting agent to the channel wall  1007 . The channel can be the same as the opposite side or a partitioned channel carrying cooling fluid  1009  in the opposite direction. 
         [0041]    The housing  1003  is configured in a shallow “W”, with a reflecting inside surface, for catching solar rays not impinging on the outer cell  1001  structure, but finding the opposite CIGS surface  1011  by reflection. The “W” housing  1003  configuration provides a structurally stronger housing less costly materials and manufacturing. Using a shallow “W” housing can focus solar radiation from a 3 to 1 advantage, since the area of the “W” will reflect light to the smaller area of the array  1001 . not a strict requirements, as drain holes can be designed into the “W” shape corners should the collect rain or other fluids in the trough like housing structure. 
         [0042]    Therefore, while the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this invention, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Other aspects of the invention will be apparent from the following description and the appended claims.