The aim of this work is to study a simple efficient and inexpensive solar batch dryer for agriculture products. During periods of
low sunshine a heater is used. The establishment of heat and mass balances leads to two sets of differential equations completed by
an empirical model, which represents the drying kinetics. Onion was chosen as the dried product because of its swift deterioration
property. The shrinking effect has been taken into consideration. The results showed that drying is affected by the surface of the
collector, the air temperature and the product characteristics. Significant improvements were registered in the results, after the heater
is added.