Photovoltaic Cells

Photovoltaic cells are made of at least two layers of semiconducting material. The first layer has a positive charge; the next layer has a negative charge. When sunlight strikes the cell, the semiconducting material absorbs photons from the light. This process frees electrons from the negative layer, which move to the positive layer. This flow of electrons constitutes an electric current, which can be captured in a circuit connecting the two layers. The electricity generated by a photovoltaic cell can be used directly, stored in batteries or sold back to a utility company.