In this study, electric requirement of Gökceada, the biggest island of Turkey is analyzed that how can it be supplied with renewable energy sources. In order to consider the optimal system configuration of hybrid or non-hybrid renewable energy system, the HOMER program is used. At relevant studies which are done about renewable energy sources, it is seen that cost analysis are done according to annual average values. But in this study, HOMER program is used in order to make the system which is generated with computer, as real as possible. On the other studies, it is found out that various changes which are occurred in the year cannot be added to the system. With HOMER; the effect of values which vary by the time like electric load, wind speed and solar radiation, is considered and than the electric system are modelled. For each of these data, 8760 values are formed in HOMER. HOMER cannot model transient changes which is smaller than 1h. However; it is expressed that, hourly data are sufficient in order to analyze the system like this. In this study; systems which are composed of solar panels, wind turbines and batteries, auxiliary tools are modelled with considered various scenarios. Grid connection or diesel generators for backup power are also modelled. Values of components which form the renewable system of Gökceada, are determined by the simulations. The excess energy which occurs when the energy source is bigger than the load, can be sold to the grid and so, the cost of energy can be reduced. According to the simulation results; it is seen that, energy costs of wind energy systems are lower for Gökceada. It is revealed that wind energy is advantageous in Gökceada especially with grid sales according to the grid connected scenario.