An experimental investigation has been conducted to determine the thermal performance of a spherical dimple plate solar air heater (SDPSAH) and a flat plate solar air heater (FPSAH) at distinctive environmental conditions at IIT (ISM) Dhanbad (23.79 degrees N), India. The study has been conducted for a mass flow rate of air varying from 0.009 kg/s to 0.028 kg/s. The results indicate that the SDPSAH shows the highest heat transfer rate, which is about 1.51 to 1.64 times higher than the corresponding FPSAH. The maximum rise of the outlet temperature of the SDPSAH is about 4.6 degrees C greater than the corresponding FPSAH for 0.009 kg/s mass flow rate of air. The instantaneous thermal efficiency of the SDPSAH is about 23.45% to 35.50% greater than the corresponding FPSAH.