This work describes a progressive strategy to achieve 100% penetration of intermittent renewables at minimal cost. The strategy works to optimally transform variable renewable energy (RE) into firm, effectively dispatchable generation. This functional dispatchability enables large-scale displacement of conventional generation at equal or lower production cost. By way of this strategy, we delineate a pathway for a full renewable energy transition of the Italian electric mix. In order to achieve 100% renewables in any grid, the fundamental imbalance between the supply of the resource and demand must be alleviated. We propose a transition that starts by addressing net load forecast imbalances resulting from renewables' prediction errors and ends with the transformation of intermittent renewables into firm, effectively dispatchable generation sources. (C) 2021 Elsevier Ltd. All rights reserved.