Investigation of CuO nanofluid as spectral splitters for concentrated Photovoltaic/Thermal systems

Abstract

Concentrated Photovoltaic/Thermal (CPV/T) systems offer a synergistic approach to solar energy utilization through spectral splitting technology and integrated energy harvesting of high-flux solar radiation. To address the high-temperature operational demands of CPV/T systems, this study employs copper oxide (CuO) nanofluids with superior chemical stability as the spectral splitter. The optical transmittance of CuO was calculated with an optical model governed by the Lambert-Beer law, showing CuO nanofluids exhibited strong absorption capabilities below 700 nm and high transmittance in the 700–1100 nm wavelength range, which matches with monocrystalline silicon cells to serve as the spectral splitters. A comprehensive experimental framework was developed to evaluate system performance through critical parameters including exergy efficiency and merit function (MF). Experimental results under non-concentrated conditions revealed optimal performance at 300 ppm concentration for CuO nanoparticles, yielding a MF of 2.174 with thermal and electric power densities of 662.77 W/m² and 66.50 W/m² respectively. The integration of optical concentration technology demonstrated substantial performance enhancements. At a concentration ratio of 4, a high MF value of 1.878 was achieved and the system exergy efficiency was increased by 44.3 % compared to non-concentrated operation, accompanied by elevated thermal and electrical power densities of 1,859.11 W/m² and 185.70 W/m², which can provide simultaneous electricity and thermal output to satisfy medium-to-high temperature heating demands.