Solar energy comes from nuclear reactions occuring in the centre of our closest star. The released energy spreads through the universe in the form of light and heat. Only its small part reaches our planet and enables life. In optimal conditions it is possible to obtain approximately 1 kW/m² on the Earth surface, but the real value depends on the location, season, time of day and weather conditions. There are two ways of using the solar energy: photovoltaic cells and solar collectors.

Photovoltaic cells are semi-conducting elements which directly transform the energy of solar radiation into DC electricity. They are connected to electric power network via converters. They can be used on smaller ships, satellites, light houses and telecommunication transmitters which are dependent on an autonomous energy source. Apart from these smaller facilities with average installed capacity of a few kW, large facilities are also used in a so-called solar power plants with installed capacity of a few MW.

Solar collectors convert solar energy into thermal energy used for water heating or some other liquid which flows through the collectors during the day. Heated liquid is stored in adequate tanks for further usage which results in significant energy savings. Disadvantage of using these technologies is dependence on weather conditions and still existing rather large investment costs.