This paper contributes to the analysis made by an article recently published in this journal . The purpose of this manuscript is to bring new contributions to this complex subject, namely the limits to the penetration of variable renewable energy (VRE) into national grids. A detailed and advanced model has been used in this work in order to add further contributions to De Jong et al.  findings. For example, by applying an optimization model, we were able to show that the high wind penetration (65%) almost without curtailment found by  might not happen, mainly due to inflexibility constraints in Brazilian power plants and also to transmission limits.