Conjunction of photovoltaic and thermophotovoltaic power production in spacecraft power systems

Abstract

This research examines the potential for the conjunction between photovoltaic (PV) and thermophotovoltaic (TPV) technologies for spacecraft power production. There is sufficient overlap between the sources of energy used for these devices and the function of the devices themselves that either PVs or TPVs could gain improvements in efficiency from the integration of the other type of device, or that a hybrid device could be developed. As a proof of concept, a GaAs PV cell and GaSb TPV cell were modeled in a tandem design using Silvaco ATLAS, with varying PV cell substrate thicknesses, and simulated under the AM0 spectrum to determine the potential range of efficiency gains for a PV device integrated with a TPV device. The same design was then tested under a 2000 K blackbody spectrum—to approximate use in a radioisotope thermoelectric generator (RTG)—to determine if similar efficiency gains could be seen for a TPV device integrated with a PV device. The possible gains with a PV-TPV design under AM0 are clear, potentially resulting in cells with a 30–34% overall efficiency. The possible gains for a PV-TPV device utilizing a blackbody spectrum are less clear, and would benefit from further design and investigation.