To date, solar power, other than for propulsion, has been practical for spacecraft operating no farther from the than the orbit of. For example,,,, and used solar power as does the Earth-orbiting,. The, launched 2 March 2004, used its 64 square metres (690 sq ft) of solar panels as far as t. The electrical system of the International Space Station is a critical part of the (ISS) as it allows the operation of essential, safe operation of the station, operation of science equipment, as well as improving crew comfort. The ISS electrical system uses to directly convert sunlight to. Large numbers of cells are assembled i.