Solar-Energy Conversion Plant

(Russian, solnechnaia energeticheskaia ustanovka), an apparatus that collects solar radiation and converts the radiant energy into thermal or electrical energy. A distinction is accordingly made between plants producing thermal energy and electric power plants.

Plants producing thermal energy were the first to be developed. The end product of such plants may be hot water, process steam, or potable water; the plants may also be used as cooling units.

Various types of solar electric power plants are distinguished according to the conversion principle used. The solar energy may be converted into electrical energy by photovoltaic means, as in solar batteries, by thermoelectric means, through thermionic emission, or through a thermomechanical cycle.

Low-temperature solar-energy conversion plants use solar radiation of natural density. The hot water, for example, produced by such plants has a temperature of 60°-70°C and is used to heat rooms. Vapors obtained from fluids with a low boiling point, such as Freon and chloroethane, are used to drive special turbines or to operate refrigerating machines. The efficiency of such plants can be improved by providing their absorbing surfaces with selective properties (seeSELECTIVE COATING).

In high-temperature solar-energy conversion plants, the radiation density is increased by a factor of 10²-10⁴. To effect this increase, optical concentrators (for the most part, reflectors) of solar radiation are used.

Solar-energy conversion plants have both terrestrial and space applications. As of 1975, terrestrial applications were very limited because of the high cost of such plants and because of restrictions imposed by climatic conditions. In space, solar power plants are used to provide power for artificial earth satellites and other space vehicles. Factors influencing the future development of solar-energy conversion plants include the depletion of reserves of mineral fuels, the growing urgency of the problem of maintaining a clean environment, and the increasing rate of exploration of the space around the sun.