Desalination is a method used to produce water for human consumption and/or industrial use. Seawater treatment systems powered by renewable sources are regarded as sustainable methods for providing drinking water for coastal zones and islands where there is no electrical grid. This study evaluated the operations of seven different (off-grid) power systems (wind-photovoltaic-diesel-battery) used to satisfy the electrical energy demand of a small-scale reverse osmosis system with a capacity of 1 m(3)/h used on Bozcaada Island, Turkey. The hybrid optimisation model for electric renewable (HOMER) software was selected to perform techno-economic analyses of the systems. On the other hand, the reverse osmosis system analysis model (ROSA) was used to determine the energy requirement of the reverse osmosis system examined in this study. The results of this study showed that the electricity cost was $0.308/kWh for the optimal system consisting of wind turbines with a rated power of 10 kW, a 20 kW IN panel, and a diesel generator with a rated power of 8.90 kW, while the water cost was $2.20/m(3). Additionally, the results showed that combining the hybrid power system and reverse osmosis system could be a cost-effective method for remote areas with good wind and solar power potential.