The connection of renewable energy distributed generators (DG) to radial feeders is assessed. Often, the long distance between renewable power sources and the transmission system, in addition to the small capacity of these generators, renders unprofitable the installation of private lines from the DG to that system. This situation motivates the DG owner to connect the generator to the distribution network. The distribution systems, however, are not usually designed to receive energy at the consumer end. This problem intensifies in developing countries where rural distribution systems are very limited. Thus, when connecting a DG to a radial feeder it is often necessary to upgrade the feeder. A methodology is proposed and developed to evaluate the costs of optimally upgrading the radial feeder when a DG is installed. © CIGRE2009.