Theoretical estimations of the efficiency of thermophotovoltaic systems using high-intensity silicon solar cells

Efficiencies have been calculated for (a) heat-mirror filter and (b) rear-mirror thermophotovoltaic systems using actual materials values for source emissivity ((λ)), mirror-filter transmissivity (τ_M(λ)) and intensity-dependent cell parameters V_oc and FF. The ratios of heat-mirror and rear-mirror efficiencies to direct sunlight impingement efficiency are estimated to be 1.6 and 1.9, respectively (2500°K thermal source), if mirror and other extraneous absorption are taken to be zero in both cases. The more realistic inclusion, for the first case, of 2 per cent light absorption in the filter/mirror and, in the second case, of 2 per cent absorption of low energy light in the cell and 8 per cent absorption at the rear mirror, plus a 2 per cent thermal loss directly from the hot source (for both), reduces the advantage of both to about a factor of 1.2.