Impact of energy communities membership evolution on founding members’ expected benefits

The potential of Energy Communities (ECs) to foster local private investment in renewable energy production has been highlighted in various recent studies. Almost all these works assume that all investment decisions are taken at year 1, as well as static EC memberships throughout its lifetime. However, as part of a wider energy system, ECs may see their composition evolve with time as founding members may leave or other end-users may join. This uncertainty on the EC’s dynamic composition induces uncertainty on the real cost savings of its members. From this perspective, this work aims at quantifying the impact of newcomers on the profits from investments decided by founding members. To this end, an initial optimal sizing problem is solved before processing a Monte-Carlo analysis on the ECs composition’s evolution. Results collected on a test case composed of 92 end-users show that founding members can lose up to 25% of their expected savings by welcoming new members if no recourse actions are taken on top of the initial optimal investment.