The internal market integration in the energy sector has been driven on without special attention to renewable energies. The climate policy rationale underlying the promotion of renewable energy sources in EU law has rather justified the adoption of purely national support schemes that in fact hinder cross-border trade of electricity from renewable energies. Given the rapid expansion of renewable electricity production not only in Germany, the question of a European approach to the promotion of renewable energies is increasingly being raised. Both the European Court of Justice and the European Commission had to answer this question in their recent decisional practice. The study analyses the legal development of the internal energy market and the EU's renewable energy policies. It examines the compatibility of national support schemes in the Member States and disucsses the potentials of Europeanisation in the light of the EU's competenicies in the realm of environment and energy policy.