Abstract
The increasing penetration of Distributed Energy Resources is changing the energy system by empowering consumers with the capacity to generate the electrical energy they need and sell its excess. This trend follows the EU strategy towards increasing competition and flexibility on the electricity market, as well as pushing the role of customers, expanding their rights and their involvement in energy communities (ECMs). Peer-to-Peer (P2P) energy markets appear as one of the possible solutions to accomplish these goals by providing direct energy trading between peers. Although P2P are being extensively addressed in the literature (e.g., market structures and platforms, experimental projects), few works offer a broad perspective of the different aspects involved in the actual implementation of these structures, as well as the real benefits that this type of markets can have for the players and for the system itself. This paper reviews business models related with ECMs and P2P markets, and the system benefits and main regulatory issues.

Abstract
Renewable energy communities (REC) and local energy markets (LEM) emerge as entities capable, not only to promote the penetration of renewable energy sources into lower levels of the grid, but also to manage distributed energy resources (DER) and local energy exchanges between small players. This paper proposes a benefit assessment among different regulatory frameworks for LEM, considering network constraints and a virtual storage unit. Results show significant savings can be achieved, even without storage. Therefore, the continuous increase of DER can have considerable grid impacts if not complemented by other structures as storage or by alternative market services like flexibility.

Abstract
Energy communities and self-consumption are considered as major drivers to achieve the decarbonization of the power sector, contributing to further increase the penetration of renewables, and empowering end consumers by turning them more active and flexible regarding electricity consumption. Considering the relevance of this topic and given that the corresponding legislation is recent, this paper summarizes the European Regulation on self-consumption and renewable energy communities and describes, analyses and compares its transposition to the Portuguese and Spanish national regulations. The main regulatory barriers for renewable energy communities' rollout are identified and regulatory improvements are proposed to overcome them.