Throughout the world, but mostly in developing countries, there are presently regions where electricity supply is insufficient or non-existing. Innumerous authors affirm that this lack of access to electricity is a key factor in perpetuating poverty around the world and compromises the socio-economic progress of those places. Thus, improving energy access is a priority since 1.3 billion people around the world still lack access to electricity, 84% of them living in rural areas. However, the energy demand in developing countries is completely different from what is observed in the regions like Europe or North America. According to the International Energy Agency, the households in many non-OECD countries still rely heavily on traditional, non-marketed energy sources,, including wood and waste, for heating and cooking. Therefore, designing energy systems for developing countries presents a great challenge: designing from scratch a system that is both environmentally and economically viable and that enables social and economic development for the populations. This work focuses on the development of a system design methodology that optimizes the final solution taking into account a demand growth pathway that reflects the economic development associated with the introduction of electricity. (C) 2012 Elsevier Ltd. All rights reserved.