The electrical system of the International Space Station is a critical part of the International Space Station (ISS) as it allows the operation of essential life-support systems, safe operation of the station, operation of science equipment, as well as improving crew comfort. The ISS electrical system uses solar cells to directly convert sunlight to electricity. Large numbers of cells are assembled in arrays to produce high power levels. This method of harnessing solar power is called photovoltaics.

The process of collecting sunlight, converting it to electricity, and managing and distributing this electricity builds up excess heat that can damage spacecraft equipment. This heat must be eliminated for reliable operation of the space station in orbit. The ISS power system uses radiators to dissipate the heat away from the spacecraft. The radiators are shaded from sunlight and aligned toward the cold void of deep space.

Each ISS solar array wing (often abbreviated "SAW") consists of two retractable "blankets" of solar cells with a mast between them. Each wing is the largest ever deployed in space, weighing over 1,088 kilograms (2,399 pounds) and using nearly 33,000 solar arrays, each measuring 8-cm square with 4,100 diodes. When fully extended, each is 35 metres (115 ft) in length and 12 metres (39 ft) wide. Each SAW is capable of generating nearly 31 Kilowatts (kW) of direct current power. When retracted, each wing folds into a solar array blanket box just 51 centimetres (20 in) high and 4.57 metres (15.0 ft) in length.

Altogether, the eight solar array wings can generate about 240 kilowatts in direct sunlight, or about 84 to 120 kilowatts average power (cycling between sunlight and shade).

The solar arrays normally track the Sun, with the "alpha gimbal" used as the primary rotation to follow the Sun as the space station moves around the Earth, and the "beta gimbal" used to adjust for the angle of the space station's orbit to the ecliptic. Several different tracking modes are used in operations, ranging from full Sun-tracking, to the drag-reduction mode (night glider and Sun slicer modes), to a drag-maximization mode used to lower the altitude.^{[citation needed]}

Over time, the photovoltaic cells on the wings have degraded gradually, having been designed for a 15-year service life. This is especially noticeable with the first arrays to launch, with the P6 and P4 Trusses in 2000 (STS-97) and 2006 (STS-115).

STS-117 delivered the S4 truss and solar arrays in 2007.

STS-119 (ISS assembly flight 15A) delivered the S6 truss along with the fourth set of solar arrays and batteries to the station during March 2009.