Page at a glance From sunlight to electricity Solar cells - how they work The discovery of photovoltaics

How does it work?
A PV array is made up of solar cells that convert the sunlight into electrical power. The solar cells consist of ultra-pure silicon which via selective doping receives the characteristics of a semiconductor. When sunlight shines on the surface of the solar cell a potential difference develops between the upper and lower sides of the cell. When the two sides of the solar cell are connected with each other, electricity flows and the cell produces power. To generate the desired voltage several cells are connected in series; the desired current is achieved by connecting the cells in parallel. The sum of the solar modules in an installation makes up the PV generator.

		Solar Energy is better for the environment than traditional forms of energy. Relying on the battery back up, a solar energy system can provide electricity 24x7, even on cloudy days and at night. more....

Thus a sufficiently high amount of tension and energy is produced to supply an entire household or building with electricity. But before the energy from sunlight can be used, it must be processed. The photovoltaic cells deliver direct current, which has to be transformed into useable 50Hz alternating current by a static converter. In the case of autonomous installations, the produced energy is stored in batteries - and that is how a reliable energy supply is guaranteed even at night.

Photovoltaics over the years In 1839, the physicist Edmund Becquerel discovered the photovoltaic effect: the direct conversion of light into electricity The breakthrough in solar research came in 1960s with the spacecraft. It required an ultra-reliable, autonomous, lightweight supply of energy leading to the solar sails Solar energy came into use in daily life with small applications such as solar-powered pocket calculators which no longer needed a battery In the 1980s solar power plants first came into use - primarily in the USA - as an autonomous source of energy for remote houses In the 1990s, government sponsorship programmes provided a further boost for demand in a few key countries