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The solar parabolic dish system is an effective means to concentrate and convert solar energy into usable forms.Systematical investigation on the energy efficiency is important to improve the cost effectiveness of the system.In this paper,the energy efficiency of the system has been investigated by experiment.During the period of the experiment,various incident solar irradiations and outlet water temperature were measured.Model of the energy efficiency of the system has been established based on the first law of thermodynamics.The results show that outlet water temperature and energy input linearly increase with increasing incident solar irradiations,but energy output non-linearly increases with increasing incident solar irradiation.The results also show that the maximum energy efficiency is 43.75% when the incident solar irradiation is 80 W/m2,whereas it has a minimum of 32.17% when the incident solar irradiation is 680 W/m2.