1. Energy Sharing Mechanisms in the European Context

The possibility for citizens to share energy is a right established by European legislation. The Clean Energy for all Europeans Package has laid the foundations to transform consumers from passive actors into active "prosumers."

The two main regulatory pillars are:

• Renewable Energy Directive (RED II – Directive (EU) 2018/2001): Formally introduces and defines "Renewable Energy Communities" (RECs). It establishes that REC members have the right to produce, consume, store, and sell renewable energy, including through the sharing of energy generated by the community’s installations.
• Internal Electricity Market Directive (Directive (EU) 2019/944): Defines "Citizen Energy Communities" (CECs), a broader concept not limited to renewable sources. It guarantees the right of communities to participate in all energy markets, either directly or via aggregators, without discrimination.

These directives have required Member States to create an "enabling framework" that removes unjustified barriers and actively promotes the development of energy communities (Lowitzsch et al., 2020). The most revolutionary aspect introduced is the concept of virtual energy sharing.

Since REC members are connected to the public distribution network, the energy produced by a community installation (e.g., a photovoltaic system on a condominium or private roof) does not flow physically and directly to another member’s home. The energy is injected into the public grid and "drawn" by the members like any other consumer.

The sharing mechanism is therefore "virtual" and relies on hourly measurement and accounting of energy flows via smart meters. At a given hour, the shared energy is calculated as the minimum between:

• The total energy injected into the grid by all REC installations.
• The total energy drawn from the grid by all REC consuming members.

On this “virtually shared energy”, the State provides economic incentives and reductions in network charges, which constitute the main economic benefit for the community. This model has been adopted, with minor variations, by many European countries (Di Fazio et al., 2022).

Beyond sharing for self-consumption, RECs can adopt various strategies to valorize the energy produced, interacting directly with the electricity market. Cruz-De-Jesús et al. (2024) highlight several successful operational approaches in Europe:

• Peer-to-Peer (P2P) Market Platforms: In some pilot projects, such as in Eemnes, Netherlands, RECs use platforms (often blockchain-based) to trade energy directly between members at an agreed price. Although still experimental in many countries, this model maximizes the local value of energy.
• Sale to Suppliers and Energy Cooperatives: Many RECs, especially in countries with a strong cooperative tradition like France and Germany, sell their surplus energy to larger suppliers, often second-level cooperatives such as Enercoop in France. This cooperative buys energy from hundreds of citizen projects and resells it to its members, creating a sustainable and solidaristic energy ecosystem (Boulanger et al., 2021).
• Provision of Flexibility Services: RECs, by aggregating their members’ resources (batteries, electric vehicles, flexible loads), can offer services to the grid (e.g., balancing, peak load reduction). This is an evolving frontier that requires advanced digital platforms for the management and aggregation of these resources (Rodrigues et al., 2025).

Main source for this section: Cruz-De-Jesús, E.; Marano-Marcolini, A.; Martínez-Ramos, J.L. (2024). Participation of Energy Communities in Electricity Markets and Ancillary Services: An Overview of Successful Strategies. Energies.