Temperature dependence of triple junction solar cells after high fluence irradiations

The NRL TacSat-4 Satellite was launched into a highly elliptical orbit on September 27
^th
2011. The solar panels are populated with Emcore ATJ cells. The solar panel was predicted to degrade 25% over the first year. Flight data show that the actual degradation is exceeding this prediction. Ground testing was conducted to more accurately determine the degradation and end-of-life (EOL) parameters. This consisted of irradiations of Emcore (SolAero) ATJ cells with 3 MeV protons at 8 different fluences ranging from 1 × 10
¹¹
to 1 × 10
¹⁵
p/cm
²
greater than any previously irradiated testing by orders of magnitude. This paper contains details related to the temperature coefficients of these cells and how they correlate to the Displacement Damage Dose (DDD). This data will help in predictions of solar panel performance in high radiation orbits.