The validity of a basic model widely used for the simulation of dynamic behavior of solar stills was experimentally investigated in the case of a real-scale greenhouse-type still. The different modes of heat and mass transfer were analyzed on the basis of continuous measurements of the main working parameters of the still. It is demonstrated that the Dunkles model can be used for the correlation of the mass transfer due to evaporation-condensation with convection by using different values of mass transfer-heat transfer proportionality constant in conditions of high mass transfer rates. The pertinence of a simplified dynamic model of the still, based on the use of an unified overall upward heat flow factor, was also investigated, leading to satisfactory results.