Solar panels, c 1975.
© Science Museum / Science & Society Picture Library
These panels absorb the rays of the sun and act as a source of energy for generating electricity or heating. The solar energy can be converted into heat by heating water flowing through solar panels on the roof of a building. The higher temperatures needed to create steam for electricity generation are posible using mirrors to focus the sun's rays in a solar furnace. Direct conversion of solar radiation into electrical energy is posible using solar cells.