Results of some initial space qualification testing on triple junction a-Si and CuInSe2 thin film solar cells

A series of environmental tests were completed on one type of triple junction a-Si and two types of CuInSe2 thin film solar cells. The environmental tests include electron irradiation at energies of 0.7, 1.0, and 2.0 MeV, proton irradiation at energies of 0.115, 0.24, 0.3, 0.5, 1.0, and 3.0 MeV, post-irradiation annealing at temperatures between 20 C and 60 C, long term exposure to air mass zero (AM0) photons, measurement of the cells as a function of temperature and illumination intensity, and contact pull strength tests. As expected, the cells are very resistant to electron and proton irradiation. However, when a selected cell type is exposed to low energy protons designed to penetrate to the junction region, there is evidence of more significant damage. A significant amount of recovery was observed after annealing in several of the cells. However, it is not permanent and durable, but merely a temporary restoration, later nullified with additional irradiation. Contact pull strengths measured on the triple junction a-Si cells averaged 667 grams, and pull strengths measured on the Boeing CuInSe2 cells averaged 880 grams. Significant degradation of all cell types was observed after exposure to a 580 hour photon degradation test, regardless of whether the cells had been unirradiated or irradiated (electrons or protons). Although one cell from one manufacturer lost approximately 60 percent of its power after the photon test, several other cells from this manufacturer did not degrade at all