This paper theoretically analyses entropy generation, heat transfer enhancement capabilities and pressure drop for a flat-plate solar collector operated with single wall carbon nanotubes (SWCNTs) based nanofluids as an absorbing medium. Specific heat (Cp) of the nanofluid was measured using a PerkinElmer DSC 4000, and a density meter was used to measure the density of the nanofluid. Second law based exergy analysis was carried out to evaluate the efficiency of the flat plate collector. It is observed that the SWCNTs nanofluid reduced the entropy generation by 4.34% and enhance the heat transfer coefficient by 15.33% theoretically compared to water as an absorbing fluid. Pumping power penalty of nanofluid operated solar collector found to be 1.20% higher than the water as a working fluid. (C) 2014 Elsevier B.V. All rights reserved.