Photovoltaic effect in a solar panel. Illustration showing the structure of a typical solar panel composed of photovoltaic cells. Solar cells convert the energy from light into electrical energy through the photovoltaic effect. Photons in sunlight hit the solar panel and are absorbed by layers of semiconducting material such as silicon. The semiconductor is 'doped' so that one layer contains mostly free electrons (n-type semiconductor) and one layer contains mostly free positively charged 'holes' (p-type semiconductor). The photons excite the electrons, creating an electric current as the excited electrons and the holes are swept in different directions by the inherent electric field across the layered semiconductor.