Environmental problems due to climate change, that have been affecting our planet for years, are the main issues which prompted European Union to establish the ambitious target of achieving carbon neutrality by 2050. This occurrence encouraged all Member States to undergo significant changes of their energy sectors, favouring the extensive use of renewable energy sources. In this scenario, the European Union introduced Renewable Energy Communities, innovative energy systems based on a new model of renewable energy production, consumption and sharing, guaranteeing environmental, economic, energy and social benefits. The objective of this paper is twofold: firstly, to examine the regulatory framework of Member States and, secondly, to present a standardized procedure for the implementation of a Renewable Energy Community, an aspect not yet covered in scientific literature. The roadmap includes four main phases: a feasibility study involving an energy analysis of end users’ consumption and a general assessment; the aggregation of members as producers, consumers or prosumers forming a legal entity, considering different funding opportunities; the operating phase, involving plant construction and project validation by national authorities; the technical and economic management phase. The dynamic structure of the roadmap allows for adjustments to accommodate different regulatory contexts, member typologies and project aim.

In Europe, the recast of Directive 2018/2001 defined Renewable Energy Communities as innovative configurations for renewable energy sharing between different end user types. In this regard, this work aims to assess the benefits following the constitution of a Renewable Energy Community in the industrial area of Benevento (South of Italy), involving a mixed-use building and an industrial wastewater treatment plant. The alternative single end users’ configuration has been also examined, and both solutions have been compared with the current state where the users’ electric energy requests are fully met by the power grid. The users have been equipped with a 466 kW_p photovoltaic plant, modelled in HOMER Pro^®, providing in input experimental meteorological data (global solar radiation and air temperature) collected by one of the weather control units in Benevento. Real data about users’ electric energy demand have been gathered from their electricity bills, and when unavailable their electric load profiles on an hourly basis have been reconstructed based on the aggregated monthly data. Energy sharing has been proven to increase energy self-consumption and the users’ self-sufficiency. Annually, the primary energy demand is reduced by 577 MWh (1.2 MWh/kW_p), carbon dioxide emissions by 84 tCO₂ and operative costs by 101 kEUR.

The European Union has introduced Renewable Energy Communities as a key component of its strategy to transform the energy sector, aiming to achieve climate neutrality by 2050. This study presents case studies of Renewable Energy Communities based on numerical and experimental investigations across various application fields in Italy, highlighting different types of stakeholders and energy configurations. The implementation of RECs is subject to a range of challenges, including diverse procedural requirements, stakeholder roles, and legal and technical constraints, which must be addressed to secure approval from national authorities. The first case study examines a photovoltaic-based energy community in Southern Italy, designed to mitigate energy poverty by supporting families unable to meet their essential energy needs. A second case study explores the benefits of a Renewable Energy Community in the industrial area of Benevento (South of Italy), which integrates a mixed-use building with an industrial wastewater treatment plant, focusing on energy sharing and environmental sustainability. The final case study investigates a Renewable Energy Community that incorporates electric vehicle charging stations, demonstrating its potential to enhance their diffusion on the territory and increase the community's self-consumption rate. Overall, the establishment of a Renewable Energy Community provides superior outcomes compared to conventional configurations of end-users regardless of the application field or the typology of members, from an energy, environmental and economic viewpoint, with additional positive outcomes possible depending on local circumstances.