Few things are more annoying than the power going out. But in the future, your lights could come back on, thanks to the car in your driveway.

Nissan recently demonstrated its Vehicle-to-Home (V2H) system, which uses the battery in the all-electric Leaf hatchback to provide power during outages, as well as offset expensive peak-hour electricity or even sell some back to the grid.

V2H is still in its infancy here, and faces considerable research and test projects before it could be available to consumers, but a version will go on sale in Japan later this month.

“As the grid grows and gets smarter, and as infrastructure comes on line, the consumer’s going to look for alternatives and flexibility,” says Allen Childs, president of Nissan Canada.

“This adds value in that it’s a supply source to the home when the normal supply is interrupted.”

V2H requires a special Power Control System, or PCS, provided by Nissan and wired into the house’s electrical panel. When the Leaf is plugged in, the PCS charges the car’s battery from the house current, just as happens now with the conventional house charger sold with the Leaf.

When the house needs power, though, the PCS reverses the direction, and electricity flows from the Leaf’s battery into the house system. Nissan says that a fully charged Leaf could run a typical house for a day.

Many Leaf owners charge their vehicles at night, when electricity is cheaper. Potentially, some of the car’s stored power could be “mixed in” with electricity from the utility company during peak periods when power is expensive, reducing the overall cost. Nissan also envisions a “smart grid” communicating with cars during periods of heavy use, “asking” them to sell their inexpensive stored electricity back to the utility company at peak-rate prices.

So how do you drive your electric car, if you’ve used or sold its stored charge? This is where driver, car, and grid will have to work together.

The driver programs in what she’ll need — say, 60 kilometres for the day’s commute. The car could use or sell its excess power, but stop before cutting into that 60-km range of battery power.

It takes about seven hours to fully charge the Leaf with its household charger, but a quick-charge DC system can provide up to 80 per cent capacity in 30 minutes. If these expensive DC units drop in price and become more widespread, drivers could also use or sell the battery’s power at peak rates, and later plug in half an hour before the car is needed again.

Batteries

•    Electricity is used as soon as it’s made, and large-scale storage is prohibitively expensive and impractical. Smaller-scale storage, such as electric car batteries, is one possible solution to heavy demand at certain times of the day.

•    Electric vehicle batteries that are too depleted to run a car still have considerable capacity, and research is underway to possibly use them for stationary power storage.