Low intensity low temperature (LILT) measurements of state-of-the-art triple junction solar cells for space missions

NASA has launched missions to the outer planets over the last 40 years, each mission increasing in complexity and power. Most of these earlier missions relied on nuclear power sources due to the lower amount of sunlight requiring prohibitively huge solar arrays. Newer missions include Rosetta, Dawn, and Juno are powered using solar energy [1,2]. Today, a shortage of plutonium coupled with improved solar cell efficiency and array structure design has led NASA to take another look at photovoltaics for planetary missions. Triple Junction (GaP/InGaAs/Ge) solar cells now exceed 28% AM0 1 sun efficiency and will soon surpass 30%, with newer IMM technology pushing 33% [3]. These cells are qualified for earth orbit missions but outer planetary missions require additional testing beyond this intensity and temperature range. This paper presents a summary of the performance of triple junctions solar cells under temperatures and intensities for the outer planetary missions, adding to previous work [4–7].