The performance of a photovoltaic/thermal (PVT) system in Irbid -Jordan climate conditions is numerically investigated using TRNSYS Software. The PVT system is designed to produce both electricity and hot water simultaneously. In this research work, a PVT system is tested in Irbid, which is located in the northern region of Jordan (32.50 N, 35.90 E). The effects of the factors that affected the performance of PVT were theoretically studied. They included global solar radiation, water temperature, mass flow rate, wind speed, and tilted angle. The type of PV cell under consideration is polycrystalline (Po-Si). The results show that the maximum electrical efficiency was 18% and the thermal efficiency was 42%. The optimum tilt angle for thermal efficiency was nearly 28°, while electrical efficiency was 44%. The mass flow rate of water under which the thermal and electrical efficiencies are at their maximum is equal to 20 kg/hr. Also, the results reveal that as the temperature of the city water decreases, the electrical efficiency rises and the thermal efficiency drops.