Over the last few years the electric sectors worldwide have been the scenario of several technological changes, with the growing share of variable renewable energy generation sources (mostly wind and solar photovoltaic) acting as the most striking feature. A large portion of this installed capacity being added through distributed generation (DG), mostly by rooftop generators. This movement is challenging the traditional operation of the Brazilian electric sector, which was built for more than a century over principles of top-down centralized generation and mostly controllable energy sources, usually far off from the consumption centers, and is acting as a disruptive force. By the current regulation, a significant diffusion of DG during the period between rate recalibrations (usually done after every four years) might imply in large losses to the distribution utilities in face of a significant uncertainty concerning the diffusion rate. This paper analyzes the role of the Brazzilian rate structure for electricity in this scenario of DG diffusion. It is found that the current rate strutcture is inadequate for dealing with such diffusion, creating cross subsidies and threating the important economic equilibrium of the services of distribution.