Solar and battery system to power Kauai

Kauai Island Utility Cooperative, a member-owned electrical utility on Kauai, said Wednesday it signed a power purchase agreement with SolarCity to receive electricity from the first utility-scale solar array and battery storage system on the island.

The 52-megawatt-hour battery system will be linked to a 17-megawatt solar array. If fully charged, the system will be able to send up to 13 megawatts of electricity — enough to power about 2,132 homes — onto the grid from 5 to 10 p.m., when energy demand by Kauai residents is at its highest.

“KIUC has been investigating energy storage options for more than two years and price has always been the biggest challenge,” said David Bissell, president and CEO of KIUC. “This is a breakthrough project on technology and on price that enables us to move solar energy to the peak demand hours in the evening and reduce the amount of fossil fuel we’re using.”

KIUC said in July it is working to increase its renewable-energy use to 38 percent by the end of this year. By using the solar energy stored in the battery instead of diesel generators, KIUC said it will reduce its use of imported fossil fuels and also cut its greenhouse gas emissions. About 15 percent of KIUC’s electricity comes from renewable energy.

Under the terms of the 20-year contract, KIUC will pay San Mateo, Calif.-based SolarCity 14.5 cents per kilowatt-hour.

KIUC already has a 12-megawatt solar system and a 6-megawatt solar system. However, without energy storage, those systems are restricted to sending energy only during the day.

“SolarCity is excited to bring the first dispatchable solar storage system to the island of Kauai,” said Jon Yoshimura, director of policy and electricity markets for SolarCity. “Hawaii has been and continues to be at the forefront of new technology and research for solar and storage. This solution will allow for more efficient load balancing and will reduce dependence on fossil fuel-based power.”

SolarCity declined to provide the total cost of the system. The solar company said it is still deciding on a battery vendor.

KIUC said the proposed project is believed to be the first utility-scale system in the United States to provide solar energy after the sun goes down.

The solar system and battery storage facility will be installed on 50 acres of land owned by Grove Farm Co. The facility will be located adjacent to KIUC’s Kapaia power station off Maalo Road, just north of Lihue.

KIUC requested an accelerated approval by the state Public Utilities Commission, looking to qualify for federal investment tax credits. The solar projects have to be in operation before December 2016 to qualify for a federal 30 percent investment tax credit. Construction must begin by April for the project to be operational by the deadline.

SolarCity also was the contractor on KIUC’s first 12-megawatt solar array in Koloa, which went into commercial operation in September 2014 and supplies about 5 percent of Kauai’s electricity.

KIUC serves 33,000 customers. It was formed in 2002 and is one of 930 electric co-ops in 47 states. The co-op is governed by a nine-member, elected board of directors.