Sun and wind renewable sources are intermittent and their use is limited by the lack of widespread and cheap storage systems. A possible solution to mitigate the problem is the combined use of different Renewable Energy Sources (RES), in order to make the production profiles as close as possible to the consumption curve. In this paper the actual load profiles and solar irradiance-wind speed data are used to design a grid-connected hybrid photovoltaic-wind power system. It is optimized by a suitable simulation that minimizes the power exchange with the grid to supply a tertiary-sector user with high consumption. The energy balance is calculated and benefits are assessed with respect to the use of a single source.