The aim of this work is to analyse the process of engagement in the creation of a Renewable Energy Community, especially in the moments when a preliminary evaluation is needed to understand the feasibility of the community and its performances. The proposed solution consists in developing a tool to simulate the electricity flows between the members of an energy community during a solar year. Users only need to provide an input file that gives an overview of the consumers, prosumers, production plants and public storage present in the community, with some brief information such as technical data or family composition. Then the software performs all the calculations of the consumption profile, randomly generated but matching the real profile; the production profile, getting the values from the PVGIS website; the use of the batteries, the sharing and the exchange with the public grid.