Interest in Hawaiian Electric Co.’s time-of-use pilot program is growing.

The utility reported Monday that 1,008 people have enrolled in the pilot program that was launched in October for residential customers who want to pay a fluctuating rate depending on the time of day. Generally customers will pay less for their energy use during the day and more at night.

HECO said Monday that the number signed up as of Friday for the pilot has reached 20 percent of the 5,000-household limit the state Public Utilities Commission set for the program.

All customers in HECO’s three subsidiaries — Maui Electric Co., Hawaii Electric Light Co. on the Big Island and HECO — have the option to be a part of the program, which charges three different electrical rates throughout the day.

Oahu residents who sign up for 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 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.

In September the PUC ordered HECO to provide residential customers a time-of-use rate program, looking to inspire residents to move their energy use to the daytime when the most solar power is available. The PUC said this would help add more renewable energy to the grid.

HECO said customers who do chores around the house during the day — cooking, laundry, or heating water —may be able to save through the program. Customers who charge electric vehicles or have energy storage systems also may see savings.

Customers who enroll in the time-of-use program will be able to compare how much it costs for them to be a part of the new program and the traditional flat rate option.

Time-of-use is a voluntary program and will run for two years. Customers have the option of leaving the program at any time without facing a penalty.

HECO said the pilot will run for two years and only residential customers are eligible to participate in the program.