In this work, we study the effect of irradiation as in low Earth orbits on heterojunction technology structures (p)a-Si:H/(n)c-Si. To compare the photoelectric properties, three samples were created: the original (without electron irradiation) and two irradiated ones with the fluence of irradiation of 5·1014 cm–2 and 1·1015 cm–2. Catastrophic deterioration of photoelectrical properties were observed for this irradiation: short-circuit current falls almost by two times, and open-circuit voltage drops by 150–200 mV. By measurements of deep-level transient spectroscopy, formation of A-center (V-O, vacancy-oxygen) with 0.16–0.17 eV in silicon wafer in bulk material were shown, and its concentration increases with growth of irradiation dose. Its arising leads to degradation of solar cells.