When
the cell is exposed to direct sunlight at Earth’s distance from the Sun
(1 astronomical
unit (AU 93 million miles) a current of 1 ampere, at a quarter of a volt, can be
produced by a 2.4 inch silicon cell. Closer to the sun generates increased
power.
Prolonged
exposure to sunlight causes photovoltaic’s performance to degrade in the neighborhood
of a percent or two per year; this degradation happens more rapidly if the cells
are exposed to gas, dust or particle radiation from solar flares
Solar arrays
have also been used to generate atmospheric drag for
aerobraking operations