The Solar Technology of Photovoltaic Systems
Photovoltaic cells, also known as solar cells, are semi-conductor devices that generate electricity when exposed to the sun. Most solar cells consist of mono- or polycrystalline silicon. This type of solar technology uses the photoelectric effect and converts selected wavelengths of light into electricity. An inverter converts the produced direct current into alternating current. The produced electricity can then be used directly. Manufacturers assemble the cells into modules, which can be installed as home solar systems.
How Solar Technology of Solar Thermal Systems Works
Concentrated solar power systems (CSP) are big solar thermal systems that convert sunlight indirectly into electricity. With high temperature collectors like lenses, mirrors, and tracking systems, a large area of sunlight is focused into a small beam. This solar technology transforms short wavelengths into long wavelengths and traps their energy in the form of heat. The energy is transferred and transported into a heat storage vault, which in this case is a fluid that is heated to a very high temperature (300°F to more than 1000°F). The heat or steam extracted from the fluid then powers a turbine power generator, a steam engine, or a Stirling engine.
Source: U.S. Department of Energy
Smaller, medium-temperature solar collectors are usually flat plates. This solar technology is used for heating water or providing supplemental space heating in residential solar and commercial solar buildings.
Low temperature collectors are also flat and can be used to heat water for direct use. They are generally used to heat swimming pools.