PHOTOVOLTAIC ARRAYS FOR MARTIAN SURFACE POWER

Missions to Mars will require electric power. A leading candidate for providing power is solar power provided by photovoltaic arrays. To des ign such a power system, detailed information on solar radiation avail ability on the Martian surface is necessary. The variation of the sola r radiation on the Martian surface is governed by three factors: (1) v ariation in Mars-Sun distance, (2) variation in solar zenith angle due to Martian season and time of day, and (3) dust in the Martian atmosp here. A major concern is the dust storms, which occur on both local an d global scales. However, there is still appreciable diffuse sunlight available even at high opacity, so that solar array operation is still possible. Typical results for tracking solar collectors are also show n and compared to the fixed collectors. During the northern hemisphere spring and summer the insolation is relatively high, 2-5 kW-hr/m2-day , due to the low optical depth of the Martian atmosphere. These season s, totalling a full terrestrial year, are the likely ones during which manned missions will be carried out.