Solar drying remains for developing African countries the only economical means of preserving foodstuffs for which post-harvest losses sometimes reach 60%. It was modeled in this work, the different elements that constitute a solar drying system by natural convection. This model is described by heat, mass and momentum balance equations between the different exchange media. The model initially made it possible to describe the dynamic behavior and calorific value of greenhouse-type solar dryers. The optimization study through simulations also made it possible to compare the drying power of more than 180 solar dryers. The analysis of the simulation results gave the dryer a small size (h = 2.5 m and l = 3 m) with large identical openings (inlet = loutlet = 25 cm) positioned at the two extremes: bottom for the inlet (Ye = 0.1 m) and high for the air outlet (Ys = 1.65 m), as an energy-efficient dryer (Taverage = 50.73 oC). The fluidity of the air (Vaverage = 0.58 m.s-1) in this dryer is also remarkable and could be used for drying food products.