Experimental study on the effect of copper oxide nanofluid on thermal and electrical efficiency of the PV/T system

Various thermal collector designs have been investigated to enhance the thermal and electrical efficiency of photovoltaic/thermal (PV/T) systems. These designs often incorporate plates and tubes made of high thermal conductivity metals such as copper and aluminum. However, the use of large quantities of these expensive materials significantly increases the capital cost of PV/T systems. In this study, a simple and cost-effective thermal collector design is introduced. The proposed collector was fabricated using polyvinyl chloride (PVC) tubes to reduce costs, with the heat tranfer fluid (HTF) in direct contact with the backside of the PV module to maximize heat transfer. The PV/T system was tested using CuO nanofluids and pure water as the heat transfer fluids (HTFs). The impact of nanofluid concentration on PV/T performance was also studied. The highest electrical efficiency of the PV system was achieved using 0.15 wt% CuO nanofluid, with improvements in electrical efficiency ranging from 4 to 27.1% compared to the system using water, and 23.3–42% compared to a conventional uncooled PV system. The overall efficiency of the PV/T using CuO nanofluid was 5.9–11.6% higher than that of the corresponding system using water. Despite the superior performance of the nanofluid, water is recommended as the HTF in PV/T systems intended for applications requiring both electricity and heat. This recommendation is based on economic analysis, which shows a payback period of 7.2 years for the water-based system, compared to 11 years for the CuO nanofluid system. Additionally, the water-based system achieves a comparable annual cash flow with no significant difference relative to the nanofluid system.