The ISS has eight solar array wings. They are arranged as four pairs along the station’s Integrated Truss Structure and provide the electrical power needed for life support, experiments, computers, communications, and spacecraft operations.
Each wing consists of two photovoltaic blankets separated by a deployment mast. When fully extended, a wing is about 35 meters long and 12 meters wide. The arrays rotate on gimbals to track the Sun as the station moves around Earth.
The first pair of large U.S.-built arrays was installed in 2000. Additional pairs arrived during Space Shuttle missions in 2006, 2007, and 2009, completing the original eight-wing arrangement. Newer ISS Roll-Out Solar Arrays, or iROSAs, supplement the older panels, but they do not change the established count of eight original solar array wings.
A frequent mistake is counting four array pairs as four total wings. In ISS terminology, each individual deployable wing counts separately, so four pairs equal eight wings.