Local Focus: Electric vehicles force changes in electricity bills

Unison's network is built to meet peak demand times, but electric vehicles charging at this time could draw more power than the network can handle. Photo Patrick O'Sullivan

The rise of electric vehicles is a threat to the nation's power lines because it could increase consumption at peak times.

So Unison Networks has made changes to how it charges electricity retailers.

The change is designed to be cost neutral at present, so electricity bills for most consumers are not expected to change.

Unison hopes retailers will pass on time-of-use incentives to consumers, so consumers choose a different time to switch on.

"We have changed our pricing approach to give a different kind of reward structure to our customers for managing their loads, particularly with an eye to the future where we might see a lot of electric vehicles coming on to the network," Unison Networks general manager commercial Nathan Strong said.

Unison supplies power to more than 110,000 customers across Hawke's Bay, Rotorua and Taupō.

Line charges comprise about half of a typical electricity bill for consumers.

Unison's network is built to meet peak demand times - cold mornings and evenings when heaters and ovens are switched on.

The worry is electric vehicles charging at this time might draw more power than the network can handle.

A new charge for shoulder periods is designed to get people to reconsider when they might plug in their electric vehicle.

While shoulder periods have been introduced for the evening and daytime, the peak rate has dropped.

• Peak line charges: 7am-11am and 5pm-9pm each day.

• Shoulder charges: 11am-5pm and 9pm-11pm each day.

• Off peak times: 11pm-7am each day.

Strong said for the average user, the changes should be cost neutral, but have greater incentive to change behaviour.

"We have collected a lot of consumption data from our retailers which we then put through our pricing models to verify we are not getting additional revenues.

"We really wanted to create those price points where people think about: Do they use electricity during the day? Can they shift some of their consumption to the night-time when they get the lowest price?

"So for example if you were to heat all of your hot water during the night-time period, which is quite possible to do using time-shifting technologies, you can achieve quite substantial reductions in your bill."

But for now, most consumers won't receive an opportunity to make savings because most households are charged a flat rate by electricity retailers.

Strong says that situation should change.

"We've got one retailer that offers an hour of free power but otherwise you pay a flat rate for your electricity.

"We'll see other electricity retailers innovate around the way they set prices for charging electric vehicles.

"We have already seen two retailers develop electric vehicle-specific price plans that really encourage people to charge their vehicles overnight."

Unison estimates less than 80 per cent of electricity users have smart meters, which are needed for time-of-use charging.

Smart meters are usually installed by electricity retailers at no cost to consumers.

People can check the Government-funded website powerswitch.org.nz to investigate potential savings.

Unison Networks is owned by the Hawke's Bay Power Consumers Trust on behalf of electricity account holders in Napier and Hastings, who receive an annual dividend payment.

Unison provides network and financial services under a management contract to the Central Hawke's Bay Consumers' Power Trust, owner of the Central Hawke's Bay electricity distribution network Centralines.

Centralines has not introduced changes to its time-of-use charges this year.

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