Photovoltaics is a method for transformation of solar radiation into direct current at the atomic level. This is done through a process, called photovoltaic effect, which is naturally occurring in some types of materials called semi-conductors.

The photoelectric effect was discovered in 1839 by the French physicist A. Becquerel, who noticed that some materials produce small amounts of electricity when exposed to light.

In 1905, Albert Einstein described the nature of the photoelectric effect, which solar technologies are based on, for which he was awarded a Nobel Prize in physics at a later stage.

The first photovoltaic module was constructed by Bell Laboratories in 1954. In 1960, the space industry started serious work on the use of this technology for providing power supply on board of space ships. The technology advanced through its use in space ships, its reliability increased and its price began to fall.

During the energy crisis in 1970, the photovoltaic technology started to establish itself as an energy source that is suitable for applications other than space. Today, the solar modules are produced by using monocrystalline, polycrystalline, amorphous silicon, cadmium telluride, copper, indium and gallium sulphide. Monocrystalline panels are more effective in converting solar radiation into electricity; however, in general, these are associated with higher production costs. Thin-film modules usually are less effective, but simpler and cheaper to produce.

 Today, photovoltaic power plants can be also installed in a smaller scale on different unused spaces - small yards, roofs, shelters, terraces and façades. The use of the sun as an energy source makes us less dependent on the constantly increasing prices of fuel and electrical power. Autonomous installations can provide energy in distant areas that are not connected to the public power transmission network. The necessary time for investment payback is constantly decreasing because of the rapid development of the technology.

 Bulgaria is located in a climate zone that is rich in solar radiation.

The production of energy from the sun provides an opportunity to meet the increasing energy demand and decrease the emissions of СО2 at the same time and preserve the planet's natural resources for a longer period.

The governments of an increasing number of countries all over the world, including Bulgaria, implement a policy of stimulating the investment in renewable energy sources and support their application.