Spectral control through the use of selective emitters is an important means of improving the efficiency of thermophotovoltaic (TPV) systems. The availability of PV cells having a wide range of bandgap energies, along with the development of selective emitters having a range of emission band energies, gives the developer of TPV power systems a wide range of options. The rare earth aluminum garnet selective emitters developed in our laboratory offer a number of advantages when used in such systems [1–3]. In this paper, we present results of a detailed computational study of the effects of a number of design and operating parameters, including emitter film thickness, scattering within the film, and the temperature gradient across the film thickness, on the performance of three rare‐earth aluminum garnet selective emitters. Specifically, we present emitter efficiency, net emittance, wavelength‐dependent emittance, total output power, and the useful output power, for Er3Al5O12, Ho3Al5O12, and Tm3Al5O12emitters, as functions of the above parameters. © 2003 American Institute of Physics