Solar cells have many applications. They have long been used in situations where electrical power from the grid is unavailable, such as in remote area power systems, Earth-orbiting satellites and space probes, consumer systems, e.g. handheld calculators or wrist watches, remote radiotelephones and water pumping applications. A large no. of solar cells are combined in an arrangement called solar cell panel that can deliver enough electricity for practical use. Electricity produced by solar panels can be stored in rechargeable solar batteries, which is then drawn upon when required.