The proposed study aims to examine the performance of a combined solar power generation system. The system comprises photovoltaic/thermal (PV/T) panels, a pump, a capacitor, and a turbine. R744, R170, and R41 were used as working fluids. The Engineering Equation Solver (EES) program is used to perform the performance evaluation of the system. Comparative thermodynamic analyzes and parametric studies are conducted to determine the best fluid. The results demonstrate that the highest power production rate of 0.4669 kW is calculated for the cycle using R41, followed by R744. Additionally, the highest energy efficiency and efficiency of exergy are calculated when R41 fluid is used, while the lowest energy and efficiency of exergy are calculated when R170 fluid is used. R170 is determined to have the highest irreversibility, with a destruction rate of exergy of 20.57 kW. According to the results of this analysis, the best working fluid was determined as R41. Parametric analyzes were performed to determine the effects of P1/P2 and solar irradiation on the performance of the system, like power production, efficiency of energy, destruction of exergy, and efficiency of exergy. It has been shown that power generation, energy efficiency, and efficiency of exergy increase with P1/P2 and solar irradiation for all fluids. While the destruction of exergy decreases with increasing pressure ratio, exergy destruction increases with increasing solar irradiation.