A framework is presented for the automated superstructure generation and optimization of distributed energy supply systems (DESS). Based on a basic problem description (specifying load cases, available technologies, and topographic constraints), the presented framework first employs the P-graph approach for the generation of an initial superstructure containing exactly one unit of each feasible technology. DESS, however, require to account for multiple redundant conversion units, and thus a successive approach is employed to automatically expand the initial P-graph superstructure. In addition, topographic constraints are incorporated. The expanded superstructure is automatically converted into a mathematical model using a generic component-based modeling approach. Here, a robust MILP formulation is used to rigorously optimize the structure, sizing and operation of DESS. The employed MILP formulation accounts for time-varying load profiles, continuous equipment sizing, and part-load dependent operating efficiencies. In the present implementation, a GAMS model is generated that can be readily optimized. The methodology is applied to a real-world case study. It is shown that the framework conveniently and efficiently enables automated grassroots and retrofit synthesis of DESS identifying unexpected and complex designs. (C) 2012 Elsevier Ltd. All rights reserved.