A gigawatt of solar energy can now power homes and businesses served by Hawaii’s largest electrical utility.

Hawaiian Electric announced Thursday that it hit the milestone equal to 1 billion watts in 2021 with a 5% increase in private rooftop solar systems connected to its grids on Oahu, Hawaii island, Maui, Molokai and Lanai.

The 5% gain represented nearly 4,700 systems with a combined 51 megawatts of solar power capacity, and raised the utility’s total capacity from solar energy production to 1,019 megawatts as of Dec. 31.

“This accomplishment owes its success to the eagerness of our customers to be part of the solar movement, dedicated solar contractors and Hawaiian Electric’s work to smooth the way for more rooftop solar and to create new customer options,” Lani Shinsato, co-director of customer energy resources for the utility company, said in a statement.

In all, 92,504 photovoltaic systems can produce energy for Hawaiian Electric.

Nearly a third of the total power capacity, or 312 megawatts, is from grid-scale commercial facilities selling power to the utility.

By island, Oahu had 63,086 PV systems with 763 megawatts of capacity about evenly split between residential and commercial providers.

On Hawaii island there were 14,700 PV systems with a 116-megawatt capacity of which 66% was residential.

Maui County had 14,718 PV systems with a 140-megawatt capacity of which 59% was residential.

Hawaiian Electric also said it had 121 megawatts of battery storage connected to its grids.

The utility has a goal to have 50,000 more rooftop PV systems on homes and businesses over the next nine years.