The objective of this study is to provide supporting evidence which analyses the role of renewable energy generation projects with regional impact as a driver for more successful implementation of the Fit for 55 package and the increased ambition for renewable energy and support the swift implementation of such projects. The study aims to assist the Commission in implementing the policy for support of the deployment of renewables in line with the European Green Deal objectives and the increased ambition for renewables by the revised Renewable Energy Directive, by utilising the untapped potential of the cooperation between Member States on renewables. This study provides a clear overview on the existing and planned concrete renewable energy projects having cross-border relevance, by defining a set of criteria for defining renewable energy projects that are relevant in a regional context. It identifies the various administrative, financial, political or legal barriers to regional and cross-border cooperation and propose solutions for overcoming them as wel as concrete means to support the implementation of such projects. The assessment focuses on the lessons learnt (what worked, what didn’t and why?) to derive recommendations for actors / EU Member States that may wish to engage in regional cooperation for RES deployment. This clear state of play of regional and cross-border projects and the options to address existing barriers aim to allow the Commission and the Member States to address such barriers, to share successful examples of policies and measures, and to agree on intensifying the cooperation in a more effective manner. This study aims to explore and analyse regional and cross-border cooperation in renewable energy within the European Union, focusing on the frameworks, practices, and impacts of these cooperations. Specific objectives include: • Defining the scope and criteria for what constitutes effective regional cooperation in renewable energy projects. - Mapping existing projects that fit the proposed scope and criteria. - Identifying barriers to effective cooperation and proposing solutions to enhance the efficacy of these cooperative efforts. - Highlighting successful cooperation models and extracting actionable insights that can guide future policy and implementation.