Study looks at behaviors of EV drivers

New research from the Electric Power Research Institute (EPRI) may help grid operators prepare for widespread electric vehicle (EV) adoption.

The nonprofit research organization collaborated with the nonprofit Salt River Project (SRP) in Arizona to analyze charging and driving data collected from nine Tesla drivers for one year to better understand the grid impact of their charging behavior and driving practices.

“Knowing where, when, and how quickly EV drivers charge enables utilities to support EV owners and traditional utilities customers while planning for future electric demand and evolving load shapes,” said EPRI Technical Leader Jamie Dunckley, a principal investigator for this project. “Understanding EV adoption’s impact on load shape and how drivers respond to different rates for charging provides energy companies with actionable data to inform grid investment and development.”

Vehicle-mounted devices collected data as vehicles were charged and driven. The devices collected data total yearly kilowatt-hours (kWh) and whether charging occurred at home, at work, or in a public charging station. Other data included average kWh per charge, miles driven per kWh and grid-related data.

“This collaboration with EPRI has provided the critical information we need to focus on planning for the large increase in the number of electric vehicles set to arrive in the near future,” SRP Principal Environmental Scientist Kathy Knoop said. “It is crucial for SRP to understand how longer-range electric vehicles will impact our grid.”

The study found that Tesla owners used 2,380–7,159 kWh per year. A previous report, which included more EV brands, showed that participants used approximately 2,700–3,300 kWh per year.

The Tesla participants completed 63 percent of their charging at home, which is much lower than EPRI’s previous analysis. Public charging also represented about 20 percent of the charging, with nearly 80 percent of that taking place at DC Fast charging stations.

EPRI will next do a larger study to track 40 Tesla vehicles over 60 days.