Photovoltaics, also called solar panels or PV, transform sunlight into electricity. Photovoltaic cells are made from materials called semiconductors. The most common semiconductor used in solar cells is silicon, which is found in sand and is abundant in the Earth's crust. When sunlight strikes the surface of the cell, some of the light particles are absorbed by the semiconducting material, causing negative electric charges to flow across the surface of the cell. The cell is designed so that the charges will uniformly flow in one direction and can be used to do electrical work.
Because solar panels are self-contained systems, they can be used in remote locations away from the electric grid, or they can be grid-connected. Solar panels are often used on roadways or on space satellites. Although photovoltaic panels are most commonly installed on building rooftops, they can also be integrated into the buildings as roofs, windows, curtain walls, and even parking canopies. Solar farms are increasingly being used for utility-scale production as well, although they require a large amount of space to collect utility-scale amounts of solar energy.
Because silicon is also used in circuit boards and must be chemically treated ("doped") to be a semiconductor, current photovoltaic technology is significantly more expensive than fossil fuels or many other renewable methods. New thin-film and "string ribbon" materials require far less silicon to do the same job as older cells. New generations of photovoltaics made from plastics and inks may soon make solar panels much cheaper or as easy to fabricate as printing a letter!View real-time data from the Museum's photovoltaic panels.