In this study, a PVT system equipped with a nanofluid-based collector is investigated from entropy generation viewpoint. The purpose of this study is characterizing a PVT system in order to enhance its performance. For this purpose, the effects of adding nanoparticles on entropy generation are investigated using a 2D-transient numerical model validated with experimental measurements. The experiments were performed for various nanofluids (Al2O3/water, TiO2/water and ZnO/water by 0.2 wt%, and SiO2/water by 1 wt% and 3 wt%) on a PV system equipped with a serpentine collector tube to increase its efficiency. A good agreement is observed between model calculations and those of the measurements. The effect of various metallic and metalloid nanofluid mass fractions on thermal (locally) and frictional fluid entropy generations, and the total entropy generation of the PVT system are investigated. The effects of various nanofluids on thermo-physical properties, coolant fluid heat transfer, and energy and exergy efficiencies are also examined. The results show that adding nanoparticles improves the thermal exergy efficiency of the system. ZnO/water had the highest and SiO2/water had the lowest thermal exergy efficiency. In addition, it is observed that by increasing the mass fraction of metallic-water nanofluids (Al2O3, TiO2 and ZnO/water) in the range considered in this study, less entropy is generated due to the improvement made in the nanofluid thereto-physical properties. For Al2O3/water nanofluid, the best performance in terms of thermal and total entropy generation is obtained. The ZnO/water nanofluid is also found to generate the least frictional entropy generation. However for metalloid nanofluid considered in this study (SiO2/water nanofluid) is found to have the most entropy generation which is not favorable.