The paper describes possibilities and problems for penetration of supply systems based on renewable energy sources in liberalised markets. The analysis is based on recent development in EU with different models for support of installations based on renewable energy. These include feed-in models with guaranteed minimum tariffs, tender models for different bands of technologies, and green certificates trading models with obligatory consumer quota. The paper describes the market situation in selected European countries, including Germany, the UK, Holland and Denmark. An EU directive from September 2001 has postponed the decision on a possible harmonisation of promotional models until at least 2005 in order to obtain more practical experience with the different support schemes. A critical evaluation is given in this paper of the different models with proposals for a balanced development between environmental and trading concerns. It is argued that too much emphasis is presently given to the side of free trade at the expense of long range planning for a sustainable energy development.