Low intensity low temperature (LILT) measurements and coefficients on new photovoltaic structures

As RTGs have become increasingly less desirable for outer-planetary missions, solar cell performance data at very low temperatures and intensities are required. The authors have measured low intensity, low temperature (LILT) I-V data on single junction and multi-junction high efficiency solar cells, representing the state-of-the-art in photovoltaic technology. Using this LILT data to calculate I_sc, V_oc, and FF as a function of temperature and intensity, an accurate prediction of cell performance under the AMO spectrum can be determined. When combined with quantum efficiency at low temperature (QULT) data, one can further enhance the prediction by the addition of spectral variation. This paper presents an overview of LILT measurements taken at temperatures as low as -180°C and intensities ranging from 1 Sun to 0.02 Suns. The temperature dependency coefficients presented in this paper are experimental results intended to provide a guideline for array design