Among the instruments to support electricity generation from renewable energy sources (RES-E), feed-in tariff (FIT) systems are the most frequently used measure in the Member States of the European Union. Within the last 20 years several FIT designs have been implemented in the EU countries, leading to dynamically developing RES-E markets. This book investigates different feed-in tariff design options and describes their consequences for RES-E generators, investors and electricity consumers. Innovative solutions to reduce electricity generation costs, to promote certain technologies or to take into account local conditions of renewable energy sources are analysed. The author uses several examples from the Member States of the European Union to illustrate the different FIT options. The results shall provide a basis for countries planning the implementation or further development of feed-in tariff systems and serve as a source of information for readers interested in energy policy and RES-E support.