Utilities such as Toronto Hydro are scrambling to ensure the aging grid can cope with the extra load from a growing fleet of electric vehicles.

Few public charging stations are available in cities like Toronto, so most electric vehicle owners such as Mel Ydreos charge their vehicles at home — something that Ydreos considers to be very convenient and a "real big plus" of owning a car like his Nissan Leaf.

"It's worked beautifully that I can come in at night at home, simply plug it in and by the morning when I get up, it's all charged up and I'm ready to go," he said.

The problem is that many of Toronto's older residential neighbourhoods, such as Bloor West Village and the Beaches, had their distribution put in decades ago — before big-screen TVs and air conditioners became typical household appliances. At that time, homes had relatively low electrical loads and neighbourhood transformers were designed accordingly, said Tom Odell, manager of capital projects and electric vehicles for Toronto Hydro.

"When an EV moves into that space, it's really a disruptive load," he said.

Charging EV uses 3 to 5 times power of typical home

That's because an electric vehicle can represent three to five times the power requirement of a typical inner city home while it's charging, Odell said.

Partly, that's because owners typically charge their vehicles at night, when the typical home isn't drawing much power. But it's also because, unlike other appliances such as stoves and dryers that are typically on for just a short time, electric vehicles may be charging for up to eight hours.

"That has an impact on the distribution grid," Odell added.

That means existing transformers in some neighbourhoods may need to be replaced earlier than anticipated or upgraded to a larger transformer.

Odell noted that the utility is willing to do what it takes to accommodate more electric vehicles. "We're very supportive of the electric vehicle program."

The problem is that Toronto Hydro has no way of knowing which neighbourhoods could be affected.

"We need an effective way to know where all of these electric vehicles are," he said. "We just want to know where these are landing so we can plan."

In addition to making changes to the distribution grid, utilities could also use other means to prevent electric vehicles from charging during periods of peak electricity usage, such as:

  • Offering a lower rate very late at night to make electric car owners charge their vehicles later than they do now.
  • Using technology to directly control when certain vehicles are charging.

Cara Clairman, president and CEO of Plug'n Drive, a non-profit organization dedicated to speeding up the adoption of electric vehicles, said most electric vehicle owners already charge at night, when there may even be a surplus of electricity that presents an opportunity.

Clairman estimates that there are currently about 1400 to 1500 electric vehicles in Ontario, about half of them in the Greater Toronto Area.

"There's no problem at this point," she said, adding that she doesn't think utilities are very concerned at the moment.

She acknowledged that electric vehicles may be a local concern in some municipalities where the transformers weren't built to accommodate modern power loads.

"Certainly, there'll be issues to manage the grid," she said, "but it certainly can be managed if we learn as we grow."