In this article, an original multi-criteria approach is applied to multi-source systems used for the design and the choice of the optimal alternative. The high number of alternatives and potential solutions when dealing with multi-source systems require a decision support method to be implemented and easy to use. Information data on the economic variables, energy performance and impact on the environment of the systems are presently data which analysis and quantification is difficult. To deal with this high level of complexity and uncertainty, an evaluation approach is needed. The multi-criteria decision support methodology concept is described (ELECTRE III) and then applied for a case study. The decision support algorithm has its bases on the developed models and makes the outranking of possible solutions. It is also shown that multi-criteria analysis can provide a technical-scientific decision-making support that is capable to justify the clearly rank of the alternatives in the renewable energy sector. The use of multi-criteria decision aid for assessing the multi-source systems showed encouraging results and interesting insights. (C) 2011 Elsevier Ltd. All rights reserved.