This experimental investigation focuses on the thermal analysis of a flat plate solar collector with two different absorber plates; one absorber plate have been referred to Case 1 and Case 2 respectively. Case 1 has a thermal emissivity of 0.85, whereas the thermal emissivity of Case 2 is 0.05. The main objective of this investigation is to study the effects of varying Reynolds numbers on the thermal efficiency of the solar flat plate solar collector.