An experimental study was performed to evaluate the effect of the nano-fluid on the performance of the PV/Trombe wall system under the dry hot weathers. Nano-fluid (Al2O3/water) was used as a working medium of the heat exchanger of the PV/TW. Two concentration of the nano-particles (0.1% and 0.5%) were considered for various coolant flow rates and design configurations. It was recorded that the nanofluid concentration of 0.5% yields the most significant reduction in the solar cell and the indoor space temperatures. Moreover, an increment in the produced electrical power and overall system efficiencies was recorded under the same conditions. The maximum reductions were 9 degrees C and 14.4 degrees C for the solar cell and the indoor space temperature, respectively. In addition, it was observed that the presence of the fan and increasing the volume flow rate of cooling fluid in the heat exchanger leads to increase the electrical and thermal efficiencies. The highest electrical and thermal efficiencies of the system were 9.2% and 62.99%, respectively, at the operational conditions (with Fanthorn 300 L/day thorn Nano 0.5%). It can be concluded that the use of nano-fluids and increased flow of coolant in the heat exchanger is not a desirable option for indoor space heating. (C) 2020 Elsevier Ltd. All rights reserved.