HALIFAX -- Nova Scotia Power has won approval to install smart meters in homes and businesses across the province, saying they will modernize the system -- and allow for cheaper rates for people doing their dishes and laundry during off-peak hours.

"This will allow us to really modernize electricity usage," Karen Hutt, Nova Scotia Power's president and CEO, said Tuesday.

The $133-million plan was approved by the Nova Scotia Utility and Review Board, which said the new meters won't hike power rates.

The utility will save about $56.8 million over 20 years because of lower costs, including a meter-reading staff reduction of about 72 people, the review board said.

It said Nova Scotia Power will save an estimated $27 million by offering cheaper power at times of low demand, as offered in other provinces.

"With the cost of this project ... and the benefit that making this transition will create, there is actually a net reduction of about $38 million in our overall costs to deliver," Hutt said.

She said there should be benefits for customers who do their dishes and other chores during non-peak hours.

"If we can give them a cut ... we are absolutely interested in doing that because they are providing value back to us and the rest of the customers," she said.

Smart meters will allow NSP to automatically measure electrical consumption, in intervals as frequently as 15 minutes.

Hutt said the meters will also hasten power restoration after outages, by providing the utility with new, specific data.

Consumer advocate Bill Mahody said the meters will allow consumers to reap the benefits of controlling their electricity use.

"As this technology comes online, consumers will have a real opportunity to save and conserve energy at times when it's most expensive to supply it," said Mahody.

Emma Norton, an energy conservation co-ordinator with the Halifax-based Ecology Action Centre, applauded the ruling. But she lamented the lack of a direct tie-in with existing energy efficiency programs.

"Efficiency programs are very important for consumers to be able to benefit from these smart meters and it needs to be done well and thoughtfully," Norton said.

It would also be important to protect low-income and small business customers in the setting of time-of-usage rates, she said.

The review board said customers who don't want the meters will be able to opt out of the program, and the utility will have to provide up-front information on the costs of doing so. The utility must inform the board by Aug. 31 on what those costs will be.

"We have to design the specifics around the opt-out and that's part of our follow-up from the board's decision," said Hutt.

Installation of the new meters is expected to begin in January and be completed by the end of 2020.