How electric car charging behavior impacts utilitiesUnderstanding customer behavior patterns when charging electric vehicles can help utilities anticipate future infrastructure changes that will be needed to handle large vehicle charging loads.

This is the basis for an assessment by the US Department of Energy’s Smart Grid Investment Grant (SGIG) of six utilities and their operations and customer charging behaviours for in-home and public electric vehicle charging stations.

The energy companies involved in the evaluation included Burbank Water and Power, Duke Energy, Indianapolis Power & Light Company, Madison Gas and Electric, Progress Energy (now part of Duke Energy as a result of a merger in 2012) and Sacramento Municipal Utility District.

Aim of the EV study

While specific project objectives varied, the utilities evaluated the technical performance of the charging systems, the potential grid impacts of charging during peak periods, and the potential need for distribution system upgrades and capacity additions to meet expected electricity demand growth from rising adoption of plug-in electric vehicles.

The six SGIG projects evaluated more than 270 public charging stations in parking lots and garages and more than 700 residential charging units in customers’ homes.

When do most people charge their EVs?

Although based on a small sample of participating vehicles as there are still relatively few plug-in electric vehicles on the road today, the study showed that the vast majority of in-home charging participants charged their vehicles overnight during off-peak periods.

Where offered, time-based rates were successful in encouraging greater off-peak charging.

Public charging station usage was low, but primarily took place during business hours and thus increased the overlap with typical peak periods. Plug-in hybrid owners frequently used the (often free) public stations for short charging sessions to “top off their tanks.”

For the full findings, read Evaluating Electric Vehicle Charging Impacts and Customer Charging Behaviors.

(Pic credit: BMW)