E3 analyzed the grid impacts of charging light-, medium-, and heavy-duty electric vehicles (EVs) for the California Electric Transportation Coalition (CalETC), a consortium of automakers and utilities. To quantify the distribution system upgrades needed to accommodate residential charging of light-duty EVs, we mapped vehicle registration data with utility distribution system and load data for more than 81,000 circuits and feeders and 2,200 substations; we then modeled costs under different rate and charging scenarios.

Even with clustered EV adoption, distribution impacts were modest, and we found that managed charging reduced distribution upgrade costs by 60 percent. For most technologies studied, we showed that EV adoption can actually reduce rates for utility customers while providing net economic, environmental, and societal benefits for California. CalETC’s member utilities used our study to educate regulators and stakeholders about the benefits of EV adoption prior to seeking authorization to invest ratepayer funds in charging infrastructure and customer outreach.