A　very　light　weighted　and　extreme　radiation　hardness　high　doping　n+-i-p+　(sandwich-like　structure)　InP　solar　cell　was　developed.　Its　total　thickness　of　epitaxial　layer　is　only　0.22　mm.　It　is　more　radiation　hardened　than　any　other　structures　so　that　it　can　provide　the　required　output　power　for　spacecraft　even　after　a　decade　at　3200　km　polar　orbits.　The　calculation　demonstrates　that　its　EOL　(end　of　life)　efficiency　would　be　about　10%　(AMO,　lSun);　its　highest　power/weight　ratio　is　about　130　W/g　(only　the　weight　of　epitaxial　layers　are　considered).　The　surprising　is　that　all　of　these　are　obtained　from　a　very　simple　structure.