This paper presents an experimental study of the effectiveness of using a combined solar energy and heat rejected from a split-type air conditioner, for drying biomaterials. The experiments were carried out on biomaterial dryer using the combined solar energy and heat rejected from a split-type air conditioner. The effectiveness was evaluated based on the comparison of various drying methods, in terms of drying kinetics of the biomaterial being dried, under Thailand’s climate conditions. The banana was chosen as testing materials. The banana was dried by the dryer with using three drying methods: Heat rejected from an air conditioner; solar energy; and the combined solar energy and heat rejected from an air conditioner. The result shows that the combined solar energy and heat rejected for drying biomaterials were found to have a shorter drying time, higher energy efficiency, and more natural appearance of dried biomaterial compared to the conventional drying method.