This article deals with the photothermal conversion performance of solar glycol – multiwall carbon nanotubes based nanofluids were studied with various weight concentrations and time. A broad investigation was performed with various nanofluid samples with the help of a sun simulator. The measurement was conducted with solar glycol-MWCNTs based nanofluids with 0.1%, 0.2%, and 0.3% volume concentration respectively. The heat loss was reduced by insulation material, whereas the nanofluid samples were heated with the help of a sun simulator. The difference in temperature of 7.7°C was attained for the 0.3 vol.% nanofluid as compared with solar glycol. Compared with solar glycol the temperature of MWCNT-SG based nanofluid at the volume concentration of 0.3% was augmented by about 69.21% with a light irradiation time of 10 min. The experimental results confirm that the SG\MWCNTs based can be used as the right replacement for heat transfer fluids for direct absorption solar collector system applications.