Solar cells in space are damaged by exposure to energetic protons and electrons. These particles pass thorough protective coverings and disrupt delicate crystal lattices. System power output is continuously degraded over the mission life. Space power engineers need damage coefficients to predict solar cell power degradation and establish appropriate cover glass thicknesses.

These modules compute solar cell damage coefficients for solar proton, trapped proton, and trapped electron exposure. Damage coefficients for either GaAs or Si cells may be evaluated. Damage equivalents for short-circuit current, open-circuit voltage, and maximum power are reported.

The calculation is based on data from the JPL Green Book ¹ and Blue Book ² containing 1-MeV electron equivalents for protons and electrons of various energies behind several cover glass thicknesses. Intermediate cover glass thicknesses are interpolated.

Spacecraft in low-Earth orbits (LEO) are partially (or fully) shielded from solar protons by the Earth's magnetic field. Space Radiation computes the exact shielding factor applicable to your spacecraft orbit.

¹ H.Y. Tada, J.R. Carter, Jr., B.E. Anspaugh, and R.G. Downing, The Solar Cell Radiation Handbook, 3rd Edition, NASA/JPL Publ. 82-69 (1 Nov 1982)
² B.E. Anspaugh, GaAs Solar Cell Radiation Handbook, 1st Edition, NASA/JPL Publ. 96-9 (1 Jul 1996)