Like many of the satellites in orbit around Earth, electricity on the ISS will be generated by solar power. Eight giant solar arrays collect energy from the Sun and transform it into electricity. When the ISS passes through the Earth’s shadow it is powered by three rechargeable battery stations. The ISS needs to be boosted periodically in order to prevent it losing speed and altitude. This is done by small rocket engines mounted on the command modules.
The International Space Station (ISS) obtains all of its power from the Sun. The ISS, like Earth, is 149 million kilometers (93 million miles) from the Sun. At that distance the power received from the Sun is about 1.367 kilowatts per square meter. That power can be gathered by arrays of solar cells. A solar cell utilizes the photoelectric effect. Photons from the sun strike a semiconductor surface, knocking loose electrons. Electrical conductors route those electrons along a path, creating an electrical current.
The US Segment provides eight large solar array wings (SAW) to absorb that solar energy. Each wing has two solar array blankets, each containing 16,400 photovoltaic cells. Each of these blankets provides about 105 square meters of solar cells, for a vehicle total of 1680 square meters. Altogether, at beginning of life, that totaled to 124 kilowatts of solar power (although 80 kW is typical). But that number varies depending on the angle of incidence to the Sun.
The Russian Service Module (SM) and Functional Cargo Block (FGB) also have solar arrays projecting from their sides, although the FGB arrays are currently retracted. The power from the American solar arrays is at a voltage of around 160 volts DC. A box called a DDCU (DC-DC Converter Unit) steps that voltage down to 124 volts for use in the US Segment. It is stepped down again for use in international partner modules, as required.
Picture Credit : Google