A mathematical formulation of the physical process of solar drying based on conventional heat and mass transfer equations is presented. The model Includes: a a technique of estimating the solar radiation on a south-facing tilted panel using the meteorological and geographical parameters for a typical location; b the procedures for obtaining the thermal performance of a solar air-heater for a flat-plate flow-over-absorber design; c an analysis of the drying process based on the Lewis analogy and the Equilibrium Moisture Content concept. Results predicted by the simulation model are presented.