Solar Thermal Systems for Heating Buildings and Water – Solar thermal systems use solar collectors to absorb solar radiation to heat water or air for space and water heating. Between 1975 and 1985, sales of solar thermal energy collectors grew dramatically due to Federal and State income tax credits for the installation of solar energy equipment. When the Federal tax credits ended in 1985, sales dropped. In the past few years, however, there has been an increase in sales of relatively low-cost collectors for heating swimming pools.
Solar Thermal-Electric Power Plants – Solar thermal-electric power plants use concentrating solar collectors to focus the sun’s rays to heat fluid to a high temperature. This working fluid can then be used to generate steam to operate a turbine, which is then used to produce electricity in a generator. The three types of solar-thermal power systems deployed or developed in the United States are parabolic trough, solar dish, and solar power towers. The parabolic trough is used in the largest solar power facility in the world located in the Mojave Desert at Kramer Junction, California. This facility has operated since the 1980’s and accounted for the majority of solar electricity produced by the electric power sector in 2004. DOE and industry partners built and successfully operated a demonstration solar power tower near Barstow, California, during the 1980’s and 1990’s. Solar dish technologies have been developed but are still not fully commercialized.
Photovoltaic Systems – Photovoltaic (PV) systems are based on solar electric cells, which convert solar radiation directly into electricity. Individual PV cells are configured into modules of varying electricity producing capacities. PV applications range from single solar cells for powering watches to large installations with hundreds of modules for electric power production. Until a few years ago, most PV systems were installed where utility power line extensions or the use of fossil fuel generators was technically or financially infeasible. Financial incentives in several States have led to the installation of these systems on houses and buildings that are connected to electric utility power lines. These “grid-connected” systems are now a major application of PV in the United States.
Source: Energy Information Administration