This paper presents the modeling and simulation of a hybrid renewable-energy system. The sizing, availability, and contribution of solar photovoltaic, wind energy and hydro energy can be simulated to determine the viability, stability, and cost effectiveness of such systems. The model allows the user to enter site specific data (hourly, daily, monthly, and annually) such as solar radiation, wind speed and precipitation. Users can select the type and size of wind turbine, hydroelectric turbine, photovoltaic panel and the electrical load placed on the hybrid renewable system. The simulation will determine the total power that can be produced on an hourly, daily, monthly and annual basis, the optimum combination of renewable energies, and usage/storage of each type of renewable energies, given the specified system and the collected data. With the help of HyRES, the model, one can determine which hybrid renewable energy system would best suit a specific site, and also help to determine which type of wind turbine, hydroelectric turbine, or photovoltaic panels would best complement each other for that site.