Solar cell. Close-up of the surface of a solar (photovoltaic) cell, which converts light into electrical energy. The cell is made from silicon (blue), a semi-conductor. Because the silicon is a semi-conductor, the energy of photons of light is enough to release electrons from the silicon. The electrons are collected through a grid of wires (white), forming an electrical current. This cell contains numerous small silicon crystals, and so is called a polycrystalline (amorphous) cell. It is less efficient than a single-crystal cell, but is far cheaper to manufacture. Solar power is an environmentally-friendly energy source and does not pollute or use up limited resources.