Energy communities are pivotal elements for the future energy transition, being able to collectively generate, distribute and consume energy, employing distributed renewable energy sources. The advantages of energy communities are multiple, ranging from giving an active role to energy end-consumers, to increasing the penetration of renewable energy sources in existing power system, as to foster the energy transition with multi-energy flow systems. The paper presents a case study concerning the establishment of renewable energy communities in the Northwest area of the Municipality of Rome, with the design of properly tailored shared photovoltaic system. The results clearly confirm the benefits of energy communities in terms of environmental impact and economic revenues for the participants.