General aspects
Photovoltaic energy for heating

When the sun's rays strike a photovoltaic cell, some of the photon energy emitted by the sunlight is converted directly into electricity. This property is at the heart of every photovoltaic system.

The photovoltaic effect was first observed by A. Becquerel in 1839 between platinum and oxidized copper electrodes immersed in an acid electrolyte exposed to light.

In 1877, W.G. Adams and R.E. Day observed the same phenomenon on a solid: selenium.

In 1940, Adler showed that the open-circuit voltage of a battery varies as the logarithm of the illumination intensity, while the current varies linearly. In 1941, R.S. Ohl achieved the first realization of a p-n bond in silicon.