In this paper,exergy analysis method is developed to assess a Rankine cycle system,by using supercritical CO2 as working fluid and powered by solar energy.The proposed system consists of evacuated solar collectors,throttling valve,high-temperature heat exchanger,low-temperature heat exchanger,and feed pump.The system is designed for utilize evacuated solar collectors to convert solar energy into mechanical energy and hence electricity.In order to investigate and estimate exergy performance of this system,the energy,entropy,exergy balances are developed for the components.The exergy destructions and exergy efficiency values of the system components are also determined.The results indicate that solar collector and high temperature heat exchanger which have low exergy efficiencies contribute the largest share to system irreversibility and should be the optimization design focus to improve system exergy effectiveness.Further,exergy analysis is a useful tool in this regard as it permits the performance of each process to be assessed and losses to be quantified.Exergy analysis results can be used in design,optimization,and improvement efforts. In this paper, exergy analysis method was developed to assess a Rankine cycle system, by using supercritical CO2 as working fluid and powered by solar energy. The proposed system consists of evacuated solar collectors, throttling valve, high-temperature heat exchanger, low-temperature heat exchanger, and feed pump. The system is designed for Use evacuated solar collectors to convert solar energy into mechanical energy and hence electricity. order to investigate and estimate exergy performance of this system, the energy, entropy, exergy balances are developed for the components.The exergy destructions and exergy efficiency values ​​of the system components are also determined.The results that indicate solar collector and high temperature heat exchanger which have low exergy efficiencies contribute the largest share to system irreversibility and should be the optimization design focus to improve system exergy effectiveness.Further, exergy analysis is a useful tool in this regard as it permits the performance of each process to be assessed and losses to be quantified. Exergy analysis results can be used in design, optimization, and improvement efforts.