Evaluation of the solar dryer showed that under no-load conditions optimum temperatures of 72.7°C and 69.0°C were attained for trials with and without airflow-restriction, respectively. The damper demonstrated effective control of internal cabinet temperatures, relative humidity, and airflow within the dryer. Thus, the shutter helps to control and maintain optimal drying temperatures. Tests performed while loaded with mango slices found that an average of 9.5 kg of mango could be dried from 84.5% (w.b.) down to 10.3% (w.b.) in only 36 h with optimum temperatures of 66.6°C. From these experiments, the collector, drying and system efficiency were determined to be 26.7%, 20.4%, and 25.9%, respectively. Furthermore, the thermal rock bed was found to effectively store and dissipate heat during periods of limited solar radiation. Although minimal, there still exists some overnight rewetting. The thermal rock storage also requires reacquisition of heat each morning, thus limiting available heat for drying. Solar-dried mango slices were found to have an average water activity of 0.55 and moisture content of 10.3% (w.b.) in agreement with the isotherm model. This indicated an effective level of preservation as compared with commercially-dried mangoes. Furthermore, color and texture were also preserved in these solar-dried slices. Thus, this dryer was found to be efficient and technically feasible for producing dried mango slices with the utilization of a widely available natural energy resource.