The transition to a low carbon economy requires the adoption of renewable energy. It is therefore important to know the speed with which these technologies spread in Portugal, in particular the delay in relation to the countries of origin, and the mechanisms in place in cases where the diffusion was more rapid. The adoption of renewable technologies in Portugal is compared with diffusion in the "Core" countries in terms of the moment of initiation, pace and scale. Next, the formation of the technological system will be analyzed by studying the structure and functions of the innovation system that influenced the diffusion.