Analysis of the UNISAT-3 solar array in-orbit performance

A technological experiment to assess the in-orbit performance of non-space-rated solar arrays is onboard the microsatellite UNISAT-3. These include terrestrial-technology monocrystalline silicon and low-efficiency triple-junction solar arrays, assembled using commercial off-the-shelf materials and following conventional non-space-rated procedures. A space-rated monocrystalline silicon solar array is also onboard, used for comparison of the achieved results. The manufacturing process is described and the solar array performance is evaluated based on the data collected in the first two-and-a-half years of operation in orbit. For both terrestrial-technology and low-efficiency triple-junction solar arrays, the observed solar array degradation is very fast in the first half-year, in which approximately one-fourth of the initial efficiency is lost. Then degradation stabilizes, showing a long-term decaying rate with a time constant of ten years, which makes the suggested technology suitable for small scientific and educational low-Earth-orbit spacecraft.