This handbook is intended to furnish the reader with the necessary tools to permit him to predict the degradation of solar cell electrical performance in any given space radiation environment. It begins with an introduction to solar cell theory, describing how cells are manufactured and how they are modeled mathematically. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a Fortran listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.