Chapter IID-2 - Operation of Solar Cells in a Space Environment

Abstract

Space solar cells are designed and tested under an air mass zero (AMO) spectrum. This is in contrast to an air mass 1.5 as reduced by 1.5 times the spectral absorbance of the earth's atmosphere, which is the standard condition for testing terrestrial solar cells. Thus, cells intended for use in space will be optimized for a somewhat different spectrum. The change in spectral distribution will typically result in a decrease in overall cell efficiency, even though the intensity of light is somewhat higher (i.e., 1367 W/m2 in space as compared to 1000 W/m2 on earth). A 12% efficient silicon solar cell as measured under AM1.5 condition on earth would translate into an approximately 10% cell as measured under AM0. The solar intensity of course varies in time. However, since space solar cells are calibrated in near-space, the variation in the value of the solar constant primarily affects the predicted solar cell operational temperature in orbit.