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US installer REC Solar has connected Hawaii’s largest PV array to date, a 12MW installation on the island of Kaua’i that will also pioneer the integration of grid-scale battery storage with solar.

The system, in Anahola, will provide up to 20% of the island’s power during daylight hours, or 5% of its overall annual energy needs.

Hawaii is aiming to meet 100% of its energy needs from renewables by 2045, but has already begun to experience the negative impacts of having large levels of renewable capacity connected to the grid.

Because of Hawaii’s grid constraints, the Kaua’i plant will be coupled to a 6MW lithium-ion battery system, which is designed to smooth the integration of the solar power on the grid. The battery system was supplied by French firm Saft.

David Bissell, chief executive of Kaua‘i Island Utility Cooperative (KIUC), REC Solar’s client in the project, said: “This project represents a huge step toward achieving our goal of using renewable resources to generate at least half of Kauai’s power needs by 2023. Every megawatt we can generate using the power of the sun reduces our costs and our greenhouse gas emissions.”

The high penetration of renewables on Hawaii has forced the state to turn to storage, with Hawaii Electric Company (HECO) and KIUC both issuing requests for proposals for over 200MW of energy storage capacity in the past year. As a consequence the state is seen as something of a testing ground for new storage technologies.

Storage is also seen as a key solution to the future deployment of PV at a smaller scale in Hawaii. Last month Hawaii’s public utilities commission announced the closure of the island state’s net metering programme due to the increasing pressures placed on the grid by distributed solar. One of the proposed replacement tariffs, a “self-supply” option, would reward customers looking to consume their own solar power, most likely in combination with a storage unit.

“Hawaii is at the forefront of the electric grid transformation and solar energy is in the driver’s seat,” said Al Bucknam, REC Solar’s CEO. “REC has invested in understanding Hawaii’s unique market because we know commercial and utility-scale solar is an integral part of Hawaii’s ambitious 100 percent renewables goal.”

As revealed by PV Tech's sister site, PV Tech Storage, US installer SolarCity is planning a 13MW array on Kaua'i connected to a 52MWh batter storage unit.