Solar cells for communication satellites in the van allen belt

The power output of solar cells on satellites passing through the Van Allen belt is constantly degraded due to the radiation damage. It thus becomes necessary to optimize the power output of the solar plant not initially but at a later time in the satellite life. The effect of the radiation environment on the expected life of solar cells has been investigated by electron and proton bombardment studies. Based on these experiments n-on-p solar cells have been specially developed for communication satellites. These cells have a moderate initial efficiency and are made very blue-sensitive, since the response to short wavelength light is considerably more resistant to radiation than the response to long wavelength light. A shielding of 0.25 g/cm has been found to eliminate the effect of electron irradiation with energies up to 1 MeV. Since most, if not all, electrons in the Van Allen belt have energies of less than 1 MeV, a trans parent protection of moderate weight can eliminate radiation damage due to electrons. For a typical orbit passing through the inner Van Allen belt, studies under proton bombardment indicate conversion efficiencies of approximately 8% after one year and on the order of 5% after 10 years. With such conversion efficiencies, long life communication satellites appear feasible with presently available solar cells.