Development of space solar cells at Spectrolab

High efficiency Inverted Metamorphic (IMM) and Semiconductor Bonded Technology (SBT) multi-junction solar cells have been under development at Spectrolab for use in space and near space applications. This paper will review the present state-of-the-art of this technology at Spectrolab with an emphasis on performance characterization data at operating conditions that these solar cells will experience in flight. Solar cell current-bias characteristics under illumination (LIV) at AM0 28°C are presented along with external quantum efficiency measurements that are used to verify the X-25 solar simulator LIV short circuit current density. A mechanical and thermal stress model has been used to predict mechanical stresses on a ultra-lightweight panel assembly in orbit and will be discussed.