Hawaiian Electric signed up 471 customers in just a week for its new, optional  Time of Use (TOU) rate program; which will charge residential customers less for power used during the day — when solar insolation is highest — and more at night, the utility has confirmed to Pacific Business News.

At the current rate of enrollment, the program would reach capacity in just over two months.

Hawaiian Electric announced the rates for its TOU program on October 19 – outlining that, overall, the utility would allow 5,000 customers to participate in its two-year pilot program, effective immediately.

Developed under the direction of the Hawaii Public Utilities Commission (PUC) (Docket No. 2014-0192) and approved on September 16 (Order No. 33923), the new rates are intended to encourage customers on the islands of Hawaii, Lanai, Maui, Molokai, and Oahu to use electricity when solar power is abundant and to speed up cost-effective integration of renewable energy.

Under the TOU rate structure, the utility has carved out a mid-day period from 9.a.m. through 5 p.m.; an on-peak period from 5 p.m. through 10 p.m.; and an off-peak period from 10 p.m. through 9 a.m.

As an example of the breakdown of the costs, on Oahu the regular October rate is 24.1 cents per kilowatt-hour (kWh). Under TOU, it is 14.9 cents/kWh from 9 a.m. to 5 p.m., 37.3 cents/kWh from 5 p.m. to 10 p.m., and 23.7 cents/kWh from 10 p.m. to 9 a.m., according to Pacific Business News.

The amount of any savings will depend on how much customers change their usage. As a result, this program may not fit the needs of all customers.