Hawaiian Electric officials said the company’s Battery Bonus incentive program on Oahu has hit 30% of its allotted capacity 18 months after its launch.

The program gives a cash incentive and bill credits to customers who add battery storage to their rooftop solar systems, according to the company.

The 30% mark means the program’s Tier 1 limit of 15 megawatts of installed capacity has been reached, so new customers enrolling in the program will now be assigned to Tier 2, which covers the next 15 megawatts. Tier 3 will cover the final 20 megawatts for the program, which is capped at 50 megawatts on Oahu, Hawaiian Electric executives said.

“It’s gratifying to see such a positive response to an innovative program like Battery Bonus that allows homeowners and businesses to enjoy the added benefits of energy storage while supporting the grid and Hawaii’s transition to a clean energy future,” Yoh Kawanami, the company’s co-director of customer energy resources, said in a news release.

Started in July 2021, Battery Bonus has a 10-year term and requires customers to use and/or export electricity stored in the battery during a two-hour period between 6 and 8:30 p.m., according to the company.

The incentives include an upfront payment to customers based on the size of their battery system. The one-time payment on Oahu drops to $750 per kilowatt of installed battery capacity in Tier 2, from $850 in Tier 1. In Tier 3 the payment will drop to $500.

Participants also receive bill credits for electricity exported to the grid, among other incentives.

The tier changes on Oahu do not affect the program on Maui, which is capped at 15 megawatts, the company said.

The program’s application period runs through June 20 on Oahu and June 30, 2024, on Maui, or until the cap is reached.