Photovoltaic collectors

A truly zero-emissions hydrogen generating system using solar or natural sources is popular where the fuel is produced from an aggregate of photovoltaic collectors, wind generators, and biomass. This would allow a... 

Economics. The U.S. Department of Energy (DOE) has estimated that In order to be cost-effective, the Installed system price for residential photovoltaic systems In 1986 must be 1.60 to 2.20 per peak watt. In 1980 dollars. Of this, 0.80 per peak watt Is applied to the photovoltaic collector Itself. Typical costs for current photovoltaic systems are 20.00 per peak watt, of which 10.50 per peak watt Is allocated to the collector.( 1) Although strides are being made In the development of singlecrystal silicon photovoltaic devices, the potential for their low-cost manufacture remains an open question. The need to search for other materials which may result In cost-effective devices Is evident. The economic attraction of an organic polymer-based photovoltaic device Is Its use of small amounts of Inexpensive material and Its suitability for mass production. 

Panel (Solar) - A term generally applied to individual solar collectors, and typically to solar photovoltaic collectors or modules. 

Fiber-reiaforced panels covered with PVF have been used for greenhouses. Transparent PVF film is used as the cover for flat-plate solar collectors (114) and photovoltaic cells (qv) (115). White PVF pigmented film is used as the bottom surface of photovoltaic cells. Nonadhering film is used as a release sheet ia plastics processiag, particularly ia high temperature pressing of epoxy resias for circuit boards (116—118) and aerospace parts. Dispersions of PVF are coated on the exterior of steel hydrauHc brake tubes and fuel lines for corrosion protection. 

Solar cells, 22 220, 9 729, 23 32. See also Photovoltaic (PV) cells antimony compounds, 3 53-54 dye-sensitized, 26 878 degradation of, 22 139 economics of, 22 140 efficiency of, 23 15 for electricity generation, 23 26 hydrogenated amorphous silicon in, 22 135, 136, 138-139 materials for, 23 14-15 micromorph, 22 140 polymethine dyes in, 20 516-517 silicon for, 22 507-508 silicon purification for, 22 496 stacking, 23 38-39 vitreous silica in, 22 444 Solar collectors, 23 25 Solar constant, 23 2 Solar control coatings, 23 16 Solar desalination, 26 89-94 Solar electricity, 23 51, 52 Solar energy... 

Specialty Chromium-Plating Baths. Chromic acid baths using sodium chromate and sodium hydroxide to form a tetrachromate (92) have had limited use. Porous chromium is used in lubricated wear applications, and is made by chemically etching regular chromium plate, sometimes with light grinding after the etch. Black chromium is used on solar collector surfaces (see PHOTOVOLTAIC CELLS Solarenergy). Baths are sulfate-free, and include fluosilicic acid or acetic acid (91). 

The interfaces of importance in SECS are the solid/solid (S/S), solid/gas (S/G), and solid/ liquid (S/L) (4). The area-intensive nature of SECS components was established in the previous section. The major problem is collecting solar energy at a cost that is competitive with other energy forms. Thus, low initial cost is required for the materials, support structures, and production processes in the SECS of interest in Fig. 1 (6). This requires, for example, using thin films in mirrors, in photovoltaic systems, for antireflection coatings on windows, for passive collection, etc. in addition, these films must be made from inexpensive, durable, and easily processed materials (5). Inexpensive long-life materials in flat-plate collectors and durable, stable absorber coatings are also necessary. 

In evaluating the values of new processes or products, one should consider both their energy payback ratio (EPR) and their carbon emission payback period (CEPP). The EPR is the ratio of energy obtained to energy invested in manufacturing and assembling the product. The EPR of photovoltaic (PV)-type solar collectors is about 10 1. In contrast, the EPR of oil shale production is only 4 1. 

The global total of installed solar collector capacity today (2008) is about 60 GW and according to Emerging Energy Research and the Prometheus Institute, it will reach about 300 GW by 2020. As to their size and design distribution, the small (10-100 kW) photovoltaic (PV) units will total 170 gW, the medium-sized (1-10 mW) concentrating PV (CPV) units about 6 gW, the... 

In the Southwest region of the United States, the area requirements of smaller photovoltaic systems can be estimated at about 6 acres per mW or about 300 acres for a smaller city requiring 50 mW. In the same geographic location, if part of the roof area is covered with collectors and is connected to the grid, the system usually can make the home energy free, including transportation by charging the batteries of an electric car with the excess electricity. 

Flexible thin-film solar cell strips and collectors are also available. Figure 1.34 illustrates the rooftop installation of solar shingles developed by the National Renewable Energy Laboratory (NREL). U.S. Department of Energy s NREL reported in March 2008 that their researchers created a world record in efficiency for thin-film solar cells (19.9%), nearly tieing the record for traditional photovoltaics (20.3%). Thin cells require less expensive materials to build and use less of them. This results in a substantial cost reduction. 

Figure 2.128 describes the main components of a photovoltaic solar collector system that is connected to the grid. These include the AC service entrance, the AC and DC disconnect switches, the inverter, and the two kWh meters, one tracking the total solar production and the other tracking the electricity flow to (and from) the grid. 

For solar thermal and photovoltaic systems using flat plate collectors, energy collection is optimized for collectors tilted south (in the northern hemisphere) at approximately the latitude of the site. 

Standard test conditions prescribed in photovoltaic standards require a total hemispherical irradiance on flat plate collectors of 1000 Wm 2 (a value that can obtained on a clear day around noon). 

Figure 4.54. Schematic of a dye-sensitized photovoltaic cell. The Ti02-bound dye molecules act as the light harvester. Electrons are injected into Ti02, flow to the collector electrode and through the circuit to the counter electrode. The dye is regenerated by electron donation from the 13 /31 couple (0.536 V). Reproduced with permission from Inorg. Chem. 2005, 44, 6841. Copyright 2005 American Chemical Society.

Some 60 dyes have been selected as possible photovoltaic materials their electrochemical redox potentials, surface adsorption, spectroscopic properties, fluorescence yields, and acid-base properties have been measured. The aim of this work is to produce a low-cost panel for harvesting solar energy as electrical power. The physical principles of fluorescent solar collectors have been discussed by Raue and Harnisch and several classes of dyes examined. Coumarin dyes are suitable convertors, particularly if the amino-group is fixed by ring closure to the aromatic system. 

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