Environmental testing of inverted metamorphic solar cells for space

Inverted metamorphic (IMM) solar cells are being pursued for space applications. This work examines their extended performance under key environmental conditions. Electron irradiation with 1 MeV electrons found 81% of the power remained after exposure to 1e15/ cm
²
fluence. Test strings mounted on rigid panels were subjected to 11,000 thermal cycles without electrical degradation. Thermal soak testing at 250 °C identified 1% of efficiency loss, equivalent to production devices. No performance loss was found after 30 days of humidity exposure. These tests verify the integrity of IMM devices, while matching measurements by NREL confirm the quality of Spectrolab's IMM testing method.