# A Game Theoretic Approach for Energy Sharing in the Italian Renewable Energy Communities
## 1 Introduction  
The clean energy for all Europeans package (also known as Clean Energy Package--CEP) is a set of eight legislative acts defining the European Union's legislative framework to achieve the energy transition. Among the many innovations provided in the CEP, an important novelty is the definition of the Renewable Energy Community (REC) provided by Directive 2018/2001 (For the sake of completeness, note that in the CEP two types of energy communities are defined: the REC in Directive 2018/2001 and the Citizen Energy Community (CEC) in Directive 2019/944. In this work we refer always to the REC.) According to the Directive, REC is a legal entity which is based on open and voluntary participation, is autonomous and is effectively controlled by shareholders or members that are located in the proximity of the community's renewable energy projects. Moreover, shareholders must be natural persons, small medium enterprises or local authorities, including municipalities. Generally speaking, the primary purpose of REC is to provide environmental, economic or social benefits to the community of members or for the local area where itoperates, rather than granting financial profits [1]. More details on the European legislative framework are reported in [2]. Energy communities (EC) are willing to bring closer Europeans to renewable energy projects and to make them actively participate to the clean energy transition [3]. Past experience in co-owned energy projects taught that the involvement of the population into the decision making process allowed to overcome their resistance (the so-called NIMBY syndrome) towards their implementation [4]. More local jobs are created and participants of the community feel more engaged in the promotion of renewable energy, making them more aware of their energy habits [5]. Most importantly, due to their non-profit nature, EC will tackle the issue of energy poverty, by performing energy efficiency measures to decrease consumption, reduce energy supply tariffs for vulnerable households or establish a fund within the community to help needing neighbourhoods [6]. In Italy, the evolution of collective energy project has not been straightforward [7], but it reached a milestone on first March 2020 when came into force the first Italian law that transposes Article 21 and Article 22 of the Directive 2018/2001 of the CEP, concerning self-consumption and REC [8]. EC members connected to the same low-voltage network (i.e., under the same Medium Voltage/Low Voltage transformer substation-MV/LV) can invest in new shared generators with a nominal power output of up to 200 kW, and they can share the energy produced consuming it immediately or by storing it in storage systems. This configuration has been defined also virtually since it does not require any physical change in the structure of the network: the users are connected to their Points Of Delivery (PODs) and the energy is shared using the public distribution network. The Italian Authority, adopting a cost-reflective approach, stated that some tariff components are not due for the energy shared and consequently are reimbursed to the community [9]. Furthermore, the policy maker has defined an incentivising tariff for the shared energy that will be recognized for 20 years. From the legislative point of view, energy sharing is a new concept for many European countries, as in a few cases the legislative framework was already open to this option [10]. On the other hand, in academic literature, energy sharing mechanisms have been already analysed in detail, especially with a focus on the trading of energy surplus in P2P local markets [11; 12; 13; 14; 15]. Nevertheless, these approaches are not applicable for the optimal planning of collective and politically driven renewable energy projects [16].