How does the ISS work?

Answer 1

The source of electrical power for the ISS is the Sun: light is converted into electricity through the use of solar panels. Before assembly flight 4A (shuttle mission STS-97, November 30, 2000) the only power source was the Russian solar panels attached to the Zarya and Zvezda modules: the Russian segment of the station uses 28 volts dc (as does the Shuttle). In the remainder of the station, electricity is provided by the solar cells attached to the truss at a voltage ranging from 130 to 180 volts dc. The power is then stabilized and distributed at 160 volts dc and then converted to the user-required 124 volts dc. Power can be shared between the two segments of the station using converters, and this feature is essential since the cancellation of the Russian Science Power Platform. The Russian segment will depend on the U.S. built solar arrays for power.[13] Using a high-voltage (130 to 160 volts) distribution line in the U.S. part of the station allows smaller power lines and less weight. The solar array normally tracks the Sun to maximize the amount of solar power. The array is about 375 m² in area and 58 metres (190 ft) long. In the fully-complete configuration, the solar arrays track the sun in each orbit by rotating the alpha gimbal; while the beta gimbaladjusts for the angle of the sun from the orbital plane. (until the main truss structure arrived, the arrays were in a temporary position perpendicular to the final orientation, and in this configuration, as shown in the image to the right, the beta gimbal was used for the main solar tracking.) Another slightly different tracking option, Night Glider mode, can be used to reduce the drag slightly by orienting the solar arrays edgewise to the velocity vector.