As plug-in electric vehicles (PEVs) gain in popularity, the National Renewable Energy Laboratory (NREL) is assessing the strain home- charging may place on the electrical grid. Previous modernization studies have failed to account for this inevitable future.

“Previous research into the amount of energy required by homes hasn’t taken into account plug-in electric vehicles,” said Matteo Muratori, transportation and energy systems engineer at NREL, which is part of the Energy Department. “Given that more people are choosing to drive these types of vehicles and charging them at home, this additional demand should not be overlooked.”

Muratori authored the paper “Impact of Uncoordinated Plug-in Electric Vehicle Charging on Residential Power Demand” and created a computer simulation to explore the effects of in-home charging on the grid.

The simulation concluded that a PEV market share of up to 3 percent does not significantly impact the aggregate residential power demand. However, there was an issue when neighboring motorists began plugging PEVs in to recharge at similar times. Even without large numbers of PEVs on the road, this clustering effect “will significantly increase the peak demand seen by distribution transformers and might require upgrades to the electricity distribution infrastructure,” according to Muratori’s paper.

Muratori found that as more PEVs are added to a neighborhood, and a higher charging power is adopted, “the distribution infrastructure might no longer reliably support the local electricity demand.” He also noted the higher demand could shorten the expected life of a transformer.

“Matteo’s work raises important issues for a world with increasing electrification of the vehicle fleet, and leaves us with clear avenues for additional research,” said John Farrell, NREL’s laboratory program manager for vehicle technologies. “We need to continue looking at the synergies between electric vehicles and buildings, especially to make sure the grid remains safe and resilient.”