The importance of photovoltaic-thermal (PV / T) collector systems in renewable energy technologies is increasing for combined hybrid electrical heat applications. The efficiency of photovoltaic (PV) systems varies between 5-20%. On average, 15% of the solar radiation coming to the PV panel surface is converted to electrical energy and the remainder is lost. In this study, a PV/T collector was designed using two different fluids simultaneously and its efficiency was calculated numerically. PV/T collector systems are specifically designed for agricultural production and their advantages are discussed. In this study, numerical calculations of PV/T collector with a different design have been made. The results were compared with reference to another experimental study. Two different working fluids (air and water) were used in the calculations. The system where air is used as working fluid is called Mode 1 and the system where water is used is called Mode 2. It is aimed to achieve high heat transfer by using water pipes, air ducts and fins placed under PV panels. In this way, it is aimed to produce a more stable hot air and water. In addition, in order to investigate the effect of flow on the yield, different flow rates were calculated. As a result of the theoretical analyses and calculations made in consideration of literature, the total efficiencies of air flow mode (Mode 1) were calculated as 43.2%, 46,2% and 48.7% at 0.0067 kg/s, 0.0072 kg/s and 0.0077 kg/s mass flow rates, respectively. For water flow mode (Mode 2), these values computed as 52.81%, 53.83% and 55.04% at 0.023 kg/s, 0.036 kg/s and 0.054 kg/s mass flow rates, respectively. It was found that PV / T collector efficiency increased with increasing end flow. Designed collector system is preferable in terms of effective use of energy and it can be easily applicable in processes such as hot air-water preparation, drying and greenhouse heating.