Electricity and thermal energy are used extensively in residential buildings. Meeting these needs with different systems cause loss of efficiency, and an increase initial investment cost which are critical when making investment decisions. Therefore, photovoltaic thermal (PV/T) systems are used to reduce the economic burden of home users. In this article, it is aimed to determine the performance of the PV/T system and to make an economic analysis by considering the instantaneous electrical and thermal efficiency. Net present value (NPV), payback period (PBP) and levelized cost of energy (LCOE) values were used to evaluate the system economically. The novelty of this study is the efficiency of the PV/T collectors, the ambient temperature as well as the main water temperature was taken into consideration and the heat and electrical energy to be produced were calculated by taking the efficiency values calculated on an hourly basis. Also, the losses and the annual degradation of the entire system are included in the calculation. As a result of the analyses, the LCOE, NPV, PBP, average electrical and thermal efficiencies were found as 0.0911 €/kWh, 2718.5 €, 6 years, 14.7% and 62.3%, respectively, for a project size of 8.96 m2 in a 25-year life cycle.