Thermophotovoltaic Converter Performance for Radioisotope Power Systems

The development of lightweight, efficient power for emerging NASA missions and recent advances in thermophotovoltaic (TPV) conversion technology have renewed interest in combining radioisotope heat sources with photovoltaic energy conversion for Radioisotope Power Systems (RPS) for spacecraft. TPV power conversion uses advanced materials able to utilize a broader, spectrally tuned range of wavelengths for more efficient power conversion than Si solar cells. Spectral control, through choices of selective radiant emitters, TPV modules, and filters, is key to high‐efficiency operation. This paper describes performance tests of an array of TPV cells with boundary conditions prototypical of an RPS. TPV performance tests were conducted at prototypical array size (≅100 cm²), emitter temperature (1350 K), and heat rejection temperature (300 K). Test hardware included InGaAs TPV cells at 0.60 eV band‐gap, with tandem plasma/interference filters for spectral control. At the target emitter temperature of 1350 K, a conversion efficiency of 19% has been demonstrated for the TPV module. Results are consistent with measured cell efficiency (28%), calculated spectral control efficiency (80%), and calculated thermal efficiency in the optical cavity (90%).