The present invention discloses a plasmonic nanofluid for solar energy harvesting. The plasmonic nanofluid employs a significantly low mass concentration of about 0.001 wt% of a metal or metal-like nanoparticle having blended, fine-tuned nanomorphologies. The plasmonic nanofluid improves the photothermal energy conversion of a broadband solar spectrum to result in less settlement and sedimentation rates with no significant impact on pumping power. The plasmonic nanofluid selectively shifts a wavelength at a localized surface plasmon resonance between incident radiation and a collective electron cloud of the said metal or metal-like nanoparticle, causing increased absorption of the broadband solar spectrum at a reduced scattering.