In order that photovoltaic solar cells may be used more effectively to provide electrical power for spacecraft, it is desirable to refine the engineering design of solar cells and power systems, based on a better understanding of the space radiation environment and of radiation damage effects on semiconductor components. The objective of this handbook is to provide a summary of some of the useful analytical methods and test data which can be applied in designing radiation resistant power systems. It is found that the most serious obstacle which prevents accurate prediction of solar cell degradation for earth satellites is our inadequate knowledge of the fluxes and energy spectra of electrons and protons in the magnetosphere. When the space environment can be better defined, it will be possible to predict more accurately the degradation of present day types of silicon solar cells, for which the radiation damage characteristics have been quite well determined by laboratory research. As improved types of solar cells and materials become available, it will be necessary to make laboratory measurements of their radiation resistance to protons and electrons in order to predict their performance in space. Therefore, the performance data presented herein may become obsolete. However, it is hoped that the methods for data correlation and analysis presented here will be an aid to understanding the nature of the problems involved, and will be useful in the conduct of engineering analysis.