There are four different classes of solar array configurations: rigid planar arrays, flexible planar arrays, flexible thin film arrays, and concentrator arrays.
The rigid solar panel substrates are made with ~18 mm thick aluminum honeycomb core, covered with a woven, carbon fiber face sheet with the solar cell side insulted with kapton. This configuration of solar panel with hold down points and hinges gives the areal mass density of ~1.4 kg/m2. The flexible solar panel substrate consists of a graphite fiber reinforced plastic of ~0.13 mm thick composite, enveloped with two sheets of 0.05 mm thick Kapton on its outer surfaces. The flexible planar solar panel of this configuration gives the areal mass density of 0.65 kg/m2. Thin flexible film solar cell modules are directly deposited on flexible, thin, lightweight composite substrates using standard automated thin film deposition techniques. Structure mass calculations for the flexible thin film planar array give an areal mass density of ~0.35 kg/m2. Though there are different solar concentrator designs studied and developed, only few have seen the great maturity and used for operational spacecrafts.
For the present space applications, rigid planar arrays were used as substrate configurations for most of spacecraft solar arrays. Their areal mass densities are usually far greater than ~0.22 kg/m2 areal density of cover glass. So the solar cell radiation damages are mainly determined by front side irradiation through the coverglass for rigid planar arrays, whereas the back shielding is assumed to be infinite. However in the cases of flexible planar arrays and flexible thin film planar arrays, radiation damages from the back substrates must be considered, due to a comparable areal density between the cover glass and the back substrate.
