Still an emerging concept, energy communities have great potential for mobilising local players (local authorities, companies and citizens) in the energy transition by positioning themselves as trusted third parties in the area. Promoting the acceptability of projects, bringing flexibility to the energy system ... How can this concept play its expected role as a catalyst? What real cohabitation in the current energy system? Finally, what are the levers to convince more actors? Review and share experiences of energy communities in the service of the energy transition!