Stem Inc., an energy storage company, activated a set of closet-size batteries at Wet’n’Wild on Tuesday, one of 30 such systems it plans to install at businesses across the state.

Millbrae, Calif.-based Stem Inc. teamed up with Hawaii’s Energy Excelerator, a program that supports energy startups; Hawaiian Electric Co.; and the U.S. Department of Energy’s SunShotInitiative to install the system at Wet’n’Wild. The battery is part of a three-year pilot to deploy electric energy storage systems at 30 businesses on Oahu, Maui and Hawaii island.

The businesses that will get a Stem battery include Safeway, Whole Foods, the Honolulu Museum of Art and Watanabe Floral. Stem also plans to work with office buildings in downtown Honolulu as well as locally owned industrial clients like auto body shops.

Stem’s 108-kilowatt storage system at Wet’n’Wild will be the largest system in the pilot, making up about 10 percent of the overall battery capacity being deployed. Similar systems cost $216,000, according to Stem.

Wet’n’Wild does not have a solar system, but is using the battery to help manage its energy use at peak times. The batteries will draw power from the grid overnight — during off-peak hours — and use that power during the day.

“Our hours of operation are specifically during peak times,” said Jerry Pupillo, Wet’n’Wild Hawaii general manager, in a statement. “The batteries will kick in to decrease that peak usage spike we have always battled.”

Pupillo added, “This makes dollars and sense for us as a business as our peak use determines the rate we pay. Big picture: This could help the utility avoid building another power plant because with battery storage our electricity use can be more precise and controlled to help manage the grid.”

Shelee Kimura, vice president for corporate planning and business development at HECO, said the water park experiences major changes in demand as the rides turn on and off.

“This will be a great example of the value that energy storage can bring as it evens out those peaks,” she said.

The program is supported by $1 million in grant funding from Hawaii’s Energy Excelerator, which was created to commercialize game-changing energy technologies in Hawaii’s unique test bed and help companies scale globally.

With the system in place, HECO grid operators will be able to see and manage the batteries to the benefit of the entire grid.

“We can help them (Wet’n’Wild) manage how they use energy with technologies that have dual value, saving participating customers money and improving grid reliability and efficiency for all our customers,” Kimura said.

Tad Glauthier, vice president of Hawaii operations at Stem, said in a statement that the partnership between Wet’n’Wild and HECO is one way the state can get closer to its goal for the electrical utility to get 100 percent of its energy from renewable resources by 2045.

“Customer-sited storage is a valuable resource that delivers reliable capacity when it’s needed most and automatically reduces customers’ peak energy use and utility bills,” Glauthier said. “When utilities partner with companies that share this vision and commitment, we can build grid-scale batteries that compete with fossil-fuel-based resources. In this case, we can do it without taking up any more of Hawaii’s precious land or placing an extra burden on ratepayers.”

This is the third energy storage addition HECO has made to Oahu’s electric grid within a month.

On Monday HECO announced it will test a flywheel system from Union City, Calif.-based Amber Kinetics Inc. at Campbell Industrial Park. Flywheels use the energy from the motion of a rotor that spins in a nearly frictionless tank. When HECO needs backup power, the inertia from the spinning rotor can be converted to electricity and sent to HECO’s grid.

In September HECO added the first utility-scale battery system to Oahu’s electric grid. The $1.6 million system from Wyoming-based Altairnano has the capacity to provide 1 megawatt of power. The Hawaii Natural Energy Institute, a renewable-energy research unit at the University of Hawaii, paid for the battery, which will be studied over a two-year demonstration period.

Henry Curtis, executive director of Life of the Land, said he was glad to see additional storage connected to HECO’s grid.

“We’re all for all forms of storage coming online,” Curtis said. “Life of the Land certainly supports greater amounts of storage, but we just want to see a lot rather than tiny bits and drops here and there.”

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Correction: Wet’n’Wild is the eighth business to have a fully activated energy storage system from Stem Inc. on Oahu. An earlier version of this story and in Wednesday’s print edition said it was the first business to receive an installation.