High-Efficiency Thermophotovoltaic System by Quasi-Monochromatic Thermal Radiation

Efficiency of solar-thermophotovoltaic (TPV) systems can be improved by controlling spectral property of thermal radiation to match the photovoltaic (PV) cells spectral response. We developed a spectrally selective emitter which can emit quasi-monochromatic thermal radiation to improve the efficiency of TPV systems. From the evaluation by the detailed-balance model for gallium antimonite (GaSb) TPV cells, the photovoltaic conversion efficiency over 50 % is achievable in the case of the emitter temperature over 1800K and emitter Q-value over 15. The numerical simulation based on Rigorous-Coupled Wave Analysis revealed that the quasi-monochromatic thermal radiation can be obtained by closed-end microcavity structure. A solar-TPV system equipped with a solar-simulator is fabricated to evaluate the effect of spectrally selective emitter. By using GaSb TPV cells and spectrally selective emitter based on dielectric layer coating, photovoltaic conversion efficiency of 26% and total efficiency of 7.7% are obtained at emitter temperature of 1654 K under 384 suns.