For remote island communities, the hybrid wind-diesel generation system is a very common solution to provide electricity. Nowadays, the energy storage systems have become increasingly viable. The energy storage system helps to balance the stochastic nature of renewable energy sources. Therefore, in the generation and expansion planning studies, both renewable sources and energy storage devices should be considered in a single optimization problem. This approach leads to highly complicated optimization models, especially when several uncertainty factors are included. This paper proposes a stochastic optimization model to determine optimal combinations of wind turbines and energy storage systems. The optimization takes into account the uncertainty in wind generation. The study is conducted based on an actual island power system.