Hawaiian Electric Co.’s time-of-use program, which makes energy use cheaper during the day and more expensive at night, is proving popular among retirees.

Nearly 70 percent of the households enrolled in the program since its Oct. 19 start have at least one retired person.

“Retirees are able to take advantage of (the program) because they can be home and use more energy in the daytime,” HECO spokeswoman Shannon Tangonan said.

The time-of-use (TOU) program charges residents three different rates instead of one flat rate.

The state Public Utilities Commission ordered HECO to offer a time-of-use program to encourage residents to shift their energy use to the daytime when the most solar power is produced. The program is aimed at helping add more renewable energy to the grid.

“Having lower rates during the day to use the energy output from all the private solar will benefit everyone, and that is the goal,” Tangonan said in an email. “Any customer who is able to use more energy during the day should take advantage of the lower daytime TOU rates.”

In April, Oahu residents enrolled in the time-of-use program paid 17.4 cents for every kilowatt-­hour from 9 a.m. to 5 p.m., 39.8 cents per kilowatt-hour from 5 to 10 p.m. and 26.2 cents per kilowatt-­hour from 10 p.m. to 9 a.m. In March the flat rate on Oahu was 26.6 cents for every kilowatt-hour.

Some 1,432 customers were using the TOU program as of March 31, according to a quarterly report HECO submitted to the PUC on Thursday. The current program has a limit of 5,000 customers. A total of 1,510 residents signed up, but 78 chose to go back to the regular rate structure. Customers are allowed to leave at any time without a penalty.

The way the program is set up, electrical customers who head into the office during the day are less likely to see a financial benefit if they enroll.

Kaimuki resident Vincent Collins, 49, said he wouldn’t be interested in the program because he is usually at work from 9 a.m. to 5 p.m.

“I’m a total night owl,” he said. “During the day I’m at work or out and about.”

Waialua resident Ruth Holmberg, 73, said she decided the program wouldn’t benefit her because it doesn’t fit with her energy use. Holmberg is retired but said she uses most of her electricity later in the day, watching television from 5 to 9 p.m. and cooking dinner.

“I spend much of the day without using electricity,” Holmberg said. “It sounds like it may work for some people. I use so little energy anyway, it wouldn’t make much of a difference.”

Holmberg said she called HECO after reading about the program on her electrical bill. “I’m always looking at ways to save energy.”

Tangonan said the utility is working to build more interest in the program.

“What we have seen (in enrollment numbers) is likely normal. Our goal is to get 5,000 customers enrolled to really test how TOU rates work for many customers,” she said.

Tangonan said HECO is working on a direct mail campaign to inform more customers about the program.

Most of the customers enrolled are on Oahu, where 1,008 have signed up for the pilot. Some 194 customers elected to use the program on Maui, and 230 on Hawaii island.

Solar companies want HECO to offer a time-of-use program that pays solar customers more money for power sent to the grid at night.

That would encourage solar customers to add battery systems, charge them during the day and send their power to the grid at night when demand is high, said Colin Yost, principal at RevoluSun, a Honolulu solar company.

“If you offer to pay more for people to export during peak, then you will get people adding a battery and exporting their systems at night, as opposed to exporting during the day when the grid doesn’t need it as much,” he said.

HECO TIME-OF-USE PROGRAM

>> Began: Oct. 19

>> Savings: 44 percent off price of power between 9 a.m. and 5 p.m.

>> Enrolled: 1,432 as of March 31

>> Those with retired person at home: 69 percent

Source: HECO