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The reduction in efficiency of photovoltaic (PV) units due to increases in cell temperature occurs when a small part of the absorbed solar radiation is converted into electricity and the remaining part is lost as heat. Recently, the addition of a range of nanomaterials with high thermal conductivity to the cooling fluid in PV/T systems has been the subject of much research. In this study, three nanomaterials were added to water as a base fluid with several volume fractions to determine the best concentration and nanoparticle for this application. The PV/T system was setup in an indoor laboratory. Knowing which material has a better effect on the PV unit in particular, and the PV/T unit in general, is important for deciding which nanomaterial is more suitable for the system. The results reveal that nanofluid gives higher thermal conductivity with very little increase in the fluid density and viscosity compared with the base fluid. The studied volume fractions were 0.5, 1, 2, 3, and 4% and the selected nanoparticles were Al 2 O 3 , CuO, and SiC. It was found that silicon carbide nanoparticles have the best stability and the highest thermal conductivity compared to the other two nano-substances. Copper oxide nanofluid has higher thermal conductivity than aluminium oxide but lower stability, although it was found here that this material reliably stable compared to in other studies. The nanofluid reduced the indoor PV/T system temperature and enhanced its generated power. [ABSTRACT FROM AUTHOR]

The thermophysical properties of nanofluid composed of water and SiC nanoparticles without the use of a surfactant as a coolant for a PV/T system was investigated. It was observed that the addition of 3 wt% of these nanoparticles to water caused an increase in the resulting fluid density by up to 0.0082% and an increase of viscosity by up to 1.8%. Moreover, the thermal conductivity was enhanced by up to 8.2% for the tested temperature range of 25 °C–60 °C. The stability of the nanofluid was examined at intervals of three months and it was found that after six months the thermal conductivity reduced by up to 0.003 W/m K, indicating that the solution was stable and suitable for use for long periods. The use of 3 wt% SiC nanofluid increased the electrical efficiency by up to 24.1% compared to the PV system alone, while the thermal efficiency increased by up to 100.19% compared to the use of water for cooling. The final results indicated that the total effectiveness of the PV/T nanofluid system had a higher overall efficiency of about 88.9% compared to the separate PV system. [ABSTRACT FROM AUTHOR]