There are two basic policy tools for promoting renewable electricity: price regulation (feed-in tariffs) and quantity regulation (green certificates). In economic theory, they are equally efficient. Contrary to conventional thinking, the author demonstrates that under real-world conditions, price regulation is more efficient. EU law obliges Member States to put support schemes in place, but leaves their design to national authorities. They need, however, to comply with EU state aid and internal market rules, and their financing may not result in import duties and discriminatory taxation. This book provides a detailed analysis of the decisions practice adopted by the Commission and the case law of the Union Courts. As support schemes mature, has time not come for putting an end to regulatory competition? With huge efficiency gains to be expected, the author expertly examines the political obstacles and sets out three different pathways to achieve EU-wide harmonization.