This paper presents a general methodological framework for the formulation of an action plan for the large-scale integration of renewable energy sources (RES), The action plan is the output of a four-stage procedure: (a) identification and ranking of RES technologies according to various criteria, (b) formation of candidate sets of RES technologies that satisfy the goal of minimum interventions to the energy system and the balanced regional development through site selection rules of RES projects, (c) technical and economical analysis, and (d) social acceptance of the proposed action plan, The method is applied to the autonomous energy system of Crete and three alternative action plans are proposed.