EV charging tariff design | San Diego Gas & Electric, 2014–15

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E3 supported San Diego Gas & Electric (SDG&E) in its successful application to the California Public Utilities Commission to launch a pilot program that uses pricing to efficiently integrate electric vehicle (EV) charging in an increasingly renewable grid without contributing to local distribution capacity shortages. SDG&E devised a dynamic vehicle grid integration rate to encourage EV charging at times when high renewable generation depresses wholesale energy prices. The tariff also discourages charging during peak distribution hours. E3 used its EV Grid Impacts Model  to show that EV owners that shift their charging in response to the proposed rates would reduce their per-vehicle charging costs to under $600 annually from around $1,400 per year on the current time-of-use rate. The modeling used projected wholesale energy prices in high-renewable scenarios developed using E3’s stochastic production simulation tool, Renewable Energy Flexibility Model (REFLEX). The commission approved a modified version of the proposed program in 2016, and SDG&E is now implementing the pilot.