Solar energy technologies have attracted a high level of interest in recent times in order to satisfy energy demands. Photovoltaic/thermal (PV/T) technology has become a very attractive option for solar-driven combined heat and power systems. Heat from a PV/T system can be stored and used in other time to drive an organic Rankine cycle (ORC) to produce electricity. In this study, a solar PV/T/ORC cogeneration system is analysed in two different time periods of a day. First, it is analysed in day time when the system produces power from solar photovoltaic panels. Solar collectors are coupled to a thermal storage unit to charge it with the solar heat gain. Second, it is analysed at night when the ORC uses the heat which is charged in day time in order to produce power even without solar irradiation. In order to investigate the effect of the operation parameters on system performance, a MATLAB model was developed to simulate the performance of the system with consideration of dynamic behaviour of thermal storage. The model is exemplified for a 40m² flat plate PV/T collector area with 800 litre tank volume, and the maximum PV output and PV daily total value were found 3.751kW and 21.51kWh. ORC daily total value was 1.616 kWh, work range was found between 1.038kW and 0.248kW for period of 181 minutes.