Performance analysis of solar thermophotovoltaic conversion enhanced by selective metamaterial absorbers and emitters

By converting broadband sunlight into narrowband thermal radiation matched to the bandgap of thermophotovoltaic (TPV) cells, solar thermophotovoltaic (STPV) systems could potentially reach a high conversion efficiency far exceeding the Shockley-Queisser limit. However, actual STPV systems exhibit much lower efficiency due to non-idealities in solar absorbers, thermal emitters and TPV cells. In this work, the STPV system with selective metamaterial solar absorber and emitter is investigated, whose conversion efficiency is between 8% and 10% with concentration factor varying between 20 and 200. This conversion efficiency is remarkably enhanced compared with the conversion efficiency of less than 2.5% for the STPV system employing black absorbers and emitters. The sidewall emission losses from the absorber-emitter module and the non-unity view factor between the thermal emitter and TPV cell will diminish the performance of the STPV system, whose effects are also quantitatively discussed in this work. Furthermore, the non-planar STPV systems with larger emitter-absorber area ratios are investigated, whose conversion efficiency can reach up to 12.6% under 200 suns when the emitter is four times as large as the absorber. (C) 2016 Elsevier Ltd. All rights reserved.