This study presents the overall performance of a double-pass solar air heater (DPSAH) with three different configurations: (i) double-pass solar air heater without fins and heat storage (DPSAHWF), (ii) double-pass solar air heater with longitudinal fins and without heat storage (DPSAHLF), and (iii) double-pass solar air heater with longitudinal fins and heat storage (DPSAHLFHM). Five longitudinal fins on the upper channel and granular carbon at the bottom of lower channel as heat storage material were used for the analysis. Each configuration was examined for the following flowrates of air (ṁ1 = 0.008 kg/s, ṁ2 = 0.012 kg/s, and ṁ3 = 0.016 kg/s). The results show an improvement in thermal efficiency with an increase in the air flowrate. The outlet air temperature increases considerably with a decrease in flowrate, for all the three orientations. The lowest and the highest efficiencies during the peak sunshine hours were recorded as 33% and 65% for the conventional heater and the heater with fins and heat storage material, respectively. A maximum of 849 W/m2 of solar intensity was recorded during the test period. The system is also examined for thermal discharge after the sunshine hours to determine the effectiveness of the heat storage material.