A solar thermophotovoltaic (STPV) system has both terrestrial and space applications because thermal energy storage can be utilized. Excellent properties (heat of fusion=1800 j/gm and melting temperature=1680 K) make silicon the ideal thermal storage material for an STPV system. Using a one dimensional model with tapering of the silicon storage material, it was found that several hours of running time with modest lengths (∼15 cm) of silicon are possible. Calculated steady‐state efficiencies for an STPV system using an Er‐YAG selective emitter and ideal photovoltaic (PV) cell model are in the range of 15%–17%. Increasing the taper of the storage material improves both efficiency and power output. ©1996 American Institute of Physics.