There is potential in using water energy especially in running river systems in most rural areas, but one of the problems of using such systems is the seasonal changes. In hot and dry seasons the water flow is low and the system is confronted with low energy production. For resolving this problem and to increase the potential for renewable energy in many cities, it is possible to use these energy sources in power plant to make up the power. Mashhad Sarrood power plant with a 61 kW capacity is selected as a case study. Due to the high potential of solar and wind energies in Iran, using these energies in the season that power decreases, wind and solar energy are introduced complementary. The Homer software used to create a model of the mentioned power plant to determine the best technical and economical hybrid to account for the variations in the river flow and solar energy. The results show that energy deficit improvement should be done using appropriate economic analysis. Increasing the use of renewable energy just to eliminate energy shortages may not be economically justified.