Hawaiian Electric Co. has launched a pilot program for residential customers who want to be charged less for their energy use during the day and more for their energy use at night.

The state’s largest electric utility announced Wednesday that up to 5,000 customers at its three subsidiaries have the option to be a part of HECO’s time-of-use program, which charges three different electric rates throughout the day.

Oahu residents who enroll in the time-of-use program will pay 14.9 cents for every kilowatt-hour from 9 a.m. to 5 p.m.; 37.3 cents per kilowatt-hour from 5 p.m. to 10 p.m.; and 23.7 cents per kilowatt-hour from 10 p.m. to 9 a.m. The current flat rate on Oahu is 24.1 cents for every kilowatt-hour.

Traditionally, HECO and sister utilities Maui Electric Co. and Hawaii Electric Light Co. offer one rate, which does not change based on time of day.

A customer that uses roughly 600 kilowatt-hour per month, with nearly 60 percent of energy being used during midday, will save $13.97 monthly compared with normal residential rates, according to an example bill provided by HECO.

Brian Kealoha, executive director of Hawaii Energy, the state’s ratepayer-funded energy efficiency program, said he supports the program, but that most residents will face a lifestyle change to save money.

“Families will have to shift the bulk of their energy use to daylight hours, instead of at night when most people come home and cook dinner, have their lights on, shower, or wash clothes,” Kealoha said. “Without changing their habits, families could see their utility bills increase. Ideal candidates could be retirees who spend a lot of time at home and can shift how they utilize energy, or electric vehicle owners who are able to charge their cars during the day.”

In September, the state Public Utilities Commission ordered HECO and its sister companies to offer residential customers a time-of-use rate program. The PUC said the time-of-use rates would encourage residents to shift their energy use to the daytime when the most solar power is produced, which would allow more renewable energy to be added to the grid.

“This is where we as a system can capture that energy and shift it,” said Richard Wallsgrove, director of public policy at Blue Planet Foundation

Wallsgrove said the clean energy nonprofit supports the program.

“We’re a big fan of the time-of-use concept,” Wallsgrove said. “What is particularly appealing about this version of it is it’s totally opt in. It can’t hurt, it can only help. More choice is always good.”

Wallsgrove said residents who can put major appliances, such as washing machines, dishwashers and hot water heaters, on timers also can save money by choosing to sign up for the program.

The pilot program will run for two years.

Participating customers will receive information on their bills that compares their costs under the time-of-use program and the normal residential rate for electricity. HECO said customers have the option to stop using the program before the two-year pilot program is complete.