This paper introduces a new design of solar stills utilizing concentration, porous evaporation, internal condensation, and thermosephonic circulation. A steady-state mathematical model of the still has been proposed and simulated. The results of the study are presented in figures showing both efficiency and distillate rate. The simulation has shown that the decrease of wind speed and condenser temperature increases the efficiency of the still and distillation rates. The increase of ambient temperature increases the efficiency and the distillation rates. On the other hand, the increase of solar intensity increases the distillation rate; but the efficiency does not increase for entire intensity range. (C) 2015 Elsevier Ltd. All rights reserved.