Over 35% efficient GaAs/GaSb stacked concentrator cell assemblies for terrestrial applications

It has been previously noted that GaSb infrared-sensitive cells can be stacked behind transparent GaAs cells to boost solar cell energy conversion efficiencies to well over 30% for space and terrestrial applications. Verified spectral response and current versus voltage data for both GaAs and GaSb cells along with Sandia National Laboratories clear-day solar spectral data for Albuquerque, US, are used to calculate the stack performance for various spring, summer, fall, and winter days in Albuquerque at both 25 degrees C and at projected cell normal operating temperatures (NOT). It is found that the stack annual average energy conversion efficiency is 35.6% at 25 degrees C and 32.5% at NOT. During the year, the tandem stack efficiency at 25 degrees C varies by a small amount, from a low of 35.3% to a high of 35.8%.<
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