The actual power system is undergoing a period of transformation. The introduction of renewable energy power parks in the grid started the transition from a high voltage connected generation model towards a model where part of the generation assets will be connected to medium and even low voltage grids. Furthermore, the fast-changing world of technology is starting to allow passive users to generate and manage electricity, and thus, take a new position towards the grid. This transformation entails new opportunities and challenges for a power system that was initially thought to be vertically integrated and with unidirectional power flows. Europe is already giving its directives to ease the transition towards a more decentralized power system; however, some member states are faster than others when transposing them. Taking advantage of the different speeds between member states, this thesis aims to analyse and compare those pioneering regulatory frameworks in terms of renewable energy sources connection to distribution grids. This should allow the thesis to identify which kind of measures are the best ones to increase the share of renewable energy sources. In order to carry out the research, a systematic review of technical and energy policy articles has been carried out consulting the ScienceDirect, the IEEE Xplore, and the ResearchGate databases, together with European directives and regulations in the field of energy policies and member states network codes for connection of generation assets. The core of the thesis is based on a few institutions and documents which we would like to highlight. To set the technical basis of the impact of renewable energy sources, the book Integration of Distributed Generation in the Power System has been used. In terms of conceptualizing the regulatory framework the Florence School of Regulation technical reports The EU Electricity Network Codes and the Clean Energy Package are essential to this thesis together with the European energy e-Directive and e-Regulation. The report The smartEn Map: European Balancing Markets Edition (2018) published by smartEn has been used as a reference point to study the state of the art of balancing markets. Finally, the network codes for Low Voltage Grid Connection of Generators from Italy, Germany and Denmark are the base for the development of the energy storage section. The European directives and regulations point towards a market-based approach to overcome the challenges and benefit from the opportunities that the transition towards a distributed power system will create. The thesis go from a holistic view, considering the new European guidelines, to a study of those member states that are already half-way on their transition towards a distributed power system based on renewable energy sources. This is will give an overview of the current regulatory framework and find the main outlines of the forthcoming one. Finally, comment that one of the outcomes of the research carried out during the thesis is the participation in the conference paper "RESOlvD: ICT services and energy storage for increasing renewable hosting capacity in LV distribution grids". The paper has been approved for publication, and it can be partially consulted in the Annex A of the thesis.
