This paper presents experimental work on utilising Nanofluid as a working agent for Photovoltaic Thermal Systems (PV/T). PV/T systems are one kind of hybrid systems in energy utilisation. They convert the incident solar radiation into two energy types; electricity and heat. In this research, experimental outdoor tests were directed to assess the execution of PV/T system that utilises water-based Multi Walls Carbon Nano Tubes "MWCNT" as a heat storage/heat absorption agent. The effect of varying Nanofluid volume concentration ratio was studied within the range (0%:0.3%) while fixing the circulation rate at 1.21/min. By analysing the experimental results, it can be noted that adding Nano Particles to the base fluid caused the thermal properties to have a significant increment leading the PV/T system to have a better thermal and electrical efficiency. The best system efficiencies were obtained at 0.075% V of MWCNTs-water based Nanofluid. At this concentration, a temperature reduction of 12 degrees C for the PV panel was attained at maximum incident radiation leading to an overall system efficiency of 83.26%. Also, an average temperature reduction of 10.3 degrees C was achieved over the daytime leading to an overall efficiency of 61.23%.