Rational energy planning under the pressure of environmental and economic problems is imperative to humanity. An evaluational framework is proposed in order to support energy planning for promoting the use of renewable energy sources. A multi-criteria decision analysis is adopted, detailing exploitation of renewable energy sources (including Wind, Solar, Biomass, Geothermal, and small Hydro) for power and heat generation. The aim of this paper is the analysis and development of a multilevel decision-making structure, utilizing multiple criteria for energy planning and exploitation of Renewable Energy Sources of at the regional level. The proposed evaluation framework focuses on the use of a multicriteria approach as a tool for supporting energy planning in the area of concern, based on a pool of qualitative and quantitative evaluation criteria. The final aim of this study is to discover the optimal amount of each Renewable Energy Source that can be produced in the region and to contribute to an optimal energy mix. In this paper, a case study for the island of Thassos, Greece is analyzed. The results prove that Renewable Energy Sources exploitation at a regional level can satisfy increasing power demands through environmental-friendly energy systems that combine wind power, biomass and PV systems. (C) 2012 Elsevier Ltd. All rights reserved.