A very light-weighted and extreme radiation hardness high-doping n(+)-i-p(+) InP solar cell is developed. The total thickness of its epitaxial layer is only 0.22 mum. It is more radiation hardened than many other structures so that it can provide the required output power for spacecraft even after a decade at 3200 km polar orbits. Its end of life efficiency is about 10% (AM0, I Sun); its highest power/weight ratio is about 130W/g (only the weight of epitaxial layers is considered). The surprising fact is that all of these are obtained from a very simple structure. (C) 2002 Published by Elsevier Science B.V.