Charge multiplication by hot carriers in semiconductors opens a new perspective for improved photovoltaic energy conversion. Here, we estimate the theoretical limit for the efficiency of solar cells that make use of the best possible carrier multiplication and have the lowest possible recombination loss, i.e., radiative recombination only. For a terrestrial cell under 100 mW/cm2air mass 1.5 global illumination, the uppermost efficiency amounts to 44.2%. Cells with internal carrier multiplication require a modified description of their saturation current density. ©1995 American Institute of Physics.