Hubble Space Telescope solar generator design for a decade in orbit

The Space Telescope Solar Array (STSA), which is supplying the power for the Hubble Space Telescope (HST), is the largest flexible solar array built to date, carrying 48760 back surface field with reflector (BSFR) silicon cells. STSA is designed to survive at least five years in low Earth orbit (30000 thermal cycles) and will supply at least 4400 W at 34 V after four years. STSA had to be designed to survive the aggressive atomic oxygen (ATOX) environment. This was achieved by the development of an ATOX-resistant carrier substrate and of two different types of ATOX-resistant interconnectors. A 10 Ω-cm BSFR solar cell with all extremely smooth surface was developed to ensure a high-quality interconnector weld. The array is protected against shadowing and hot spots by solar cell shunt diodes. Thermal cycling was performed up to 65000 cycles, which demonstrated that the lifetime of the array should be in the order of ten years