Flight demonstration of inverted metamorphic triple-junction solar cells in space

The output parameters of InGaP/GaAs/InGaAs inverted metamorphic triple-junction (IMM3J) space solar cells have been collected for about 3.5 years in orbit. These thin-film solar cells were mounted on the small scientific satellite "HISAKI" (project name SPRINT-A), which was launched on September 14, 2013. We developed the satellite component that analyzes the solar cell behavior to investigate next-generation instruments for electrical power systems of satellites. The degradation trends of the IMM3J solar cells confirmed that the conventional method based on the relative damage coefficient can be applied to predict the degradation of IMM3J solar cells that have a thin-film structure. This is the first flight demonstration of IMM3J solar cells, which confirms the superior radiation stability of IMM3J solar cells in space.