The book analyses how State aid law and the law of the free movement of goods apply to renewable energy support schemes, how they have impacted on the design and implementation of national support schemes, and how they have been instrumentalised to affect national renewable energy support policies. Legal theory and practice have not given a methodical answer to the following questions: when do renewable energy support schemes constitute State aid? When are they compatible with the internal market? When do they pose fiscal or nonfiscal trade barriers? And are such trade barriers justifiable? This book answers such questions from a theoretical and a practice-oriented point of view, and it aspires to elucidate how EU primary law should apply to support schemes. It critically analyses case law and it interprets and examines the practical application of primary EU law, secondary State aid legislation, as well as soft law State aid guidelines. This book will be of interest to practitioners, judges, academics, and students and policymakers who are interested in scrutinising the legality of renewable energy support schemes within the EU legal order.