Can electric vehicles aid the renewable transition? Evidence from a field experiment incentivizing midday charging

Electric vehicles are key to decarbonizing transportation, but, as batteries-on-wheels, they present novel challenges and opportunities for grids simultaneously transitioning to renewable energy. In a field experiment tracking 390 electric vehicles minute-by-minute, we show that time-based charging incentives dramatically shift not only when vehicles are charged, but also where. Incentives to increase charging during solar energy generation hours lead to a 34% rise in charging—mostly outside the home. Incentives to reduce peak time charging result in 17%—27% lower charging—mostly at home. Participants demonstrate multiple responses to incentives, including shifting time and location of charging, reducing charging by driving less, and lowering their battery state-of-charge. We find stronger midday charging responses for commuters and those with fast home chargers, and suggestive evidence that commuters increase use of workplace charging. Tariffs and charging infrastructure, therefore, need to be designed in tandem to manage the critical time and location imbalances brought about by the net-zero transition.