The regulatory framework for climate and energy for the period after 2020 is of utmost importance for the further development of renewable energy. This dissertation presents the development of an approach to analyse and accompany the decision making processes among political actors in this field. The analysis focuses on the debate around European climate and energy targets for 2030, as well as the possible harmonisation of the diverse support schemes for renewable electricity in EU member states. The approach builds upon the multi-criteria decision aid method PROMETHEE to address the specific decision problem of support scheme harmonisation. It applies analytical frameworks from political science, such as the Advocacy Coalition Framework, to structure the surrounding policy landscape in which this specific decision problem is embedded.