The current paper presents the study of coupling a wind-turbine with a fuel cell to improve the utilization of wind power in the non-interconnected Greek archipelago grid. A part of the energy produced by the wind-turbine is stored in the form of hydrogen and is then delivered to the consumption at constant power through a fuel cell. This decoupling between the wind potential and power delivery is necessary to increase the contribution of renewable energy sources to the small capacity grids of islands. The study presents the technology of the system and simulates its operation over a year using a specially developed software and actual wind speed input data. In this way, the energy availability can be estimated and is presented for hybrid installations of increasing size. The nominal size of the individual devices (electrolyser, fuel cell, hydrogen storage tanks) is then selected depending on the hybridisation level, that is the ratio of energy delivered directly from the wind-turbine over the energy delivered from the fuel cell. Results show that it is possible to replace conventional power stations with a hybrid system, delivering energy under constant power with fuel cell sizes that reach almost up to 1/3 of the nominal wind-turbine power and overall efficiencies that may exceed 60%.