A comparative numerical analysis of an organic Rankine cycle using supercritical CO2 and assisted by evacuated solar collectors is presented in this study. In the system, natural working fluid CO2 is used which is non-flammable, non-toxic and environmentally friendly. The proposed system consists of 15 sets of evacuated solar collectors for heating up the working fluid to a supercritical stage, a turbine for power generation, a feed pump for circulating the fluid and two heat exchangers. The first heat exchanger is a high-temperature heat exchanger used for recovering heat to be used for applications such as absorption refrigeration cycles, hot water preparation, etc., while the second heat exchanger is a low-temperature heat exchanger used for condensation of the CO2. The characteristics and the specifications of the proposed system are based on an experimental setup which was previously constructed in Doshisha University. The numerical analysis of the organic Rankine cycle for power and heat generation is carried out using the meteorological data of two cities for comparison purposes, Kyoto, Japan and Isparta, Turkey. The performance characteristics of the proposed system are investigated under different working conditions. The analysis is made for the whole year in order to simulate the performance for different climate conditions. The results of the study show that the proposed system has great potential for green and sustainable power and heat generation.