In this study, an experimental assessment is presented on the effects of employing serpentine tubes with three different cross-sections of circular, triangular, and rectangular, on the characteristics of a photovoltaic/ thermal (PV/T) unit in terms of energy and exergy efficiencies compared with a conventional PV system. The influences of adding magnetite nanoparticle to the base-fluid and employing a higher mass flow rate of the cooling fluid are examined. The results demonstrated that by comparing PV and PV/T units with a circular serpentine tube, the electrical efficiency improves by almost 12% due to adding coolant tube in addition of getting 22.6W extra thermal energy power. Furthermore, by changing the cooling tube configuration from conventional circular form to rectangular, electrical efficiency eases by 2% to reducing PV module temperature. Moreover, it was found that by adding nanoparticle to pure water to employ nanofluid as coolant fluid, overall energy and exergy efficiencies enhance by 6.6% and 0.7%, respectively, using nanoparticles with a volume concentration of 2% for the case of the rectangular serpentine tube for the flow rate of 20 kg/h. Furthermore, enhancing the mass flow rate has a positive trend on the PV/T performance in terms of both energy and exergy efficiencies.
