The Kauaʻi Island Utility Cooperative in Hawai’i has signed a PPA with SolarCity for a dispatchable solar PV storage system.

The Kauaʻi Island Utility Cooperative (KIUC) signed the power purchase agreement (PPA) with SolarCity earlier this month, to provide electricity from the first dispatchable solar PV system in the US — a utility-scale solar array and connected battery storage system that is designed to supply power to the grid in the evening, when demand is highest. The “dispatchable” part is in the fact that the system can be relied upon to provide energy when it’s needed, and not simply when electricity is being generated.

Set to be developed next to KIUC’s existing Kapaia power plant, the 52 MWh battery system will be able to feed up to 13 MW of electricity onto the local grid at a time to “shave” the amount of conventional power generation that is needed to meet evening peak (which is between 5:00 pm and 10:00 pm).

The energy storage attached to the solar power plant is what allows the energy to be dispatched as necessary, and will not only reduce KIUC’s imported fossil fuels and greenhouse gas emission levels, but will also see KIUC pay a lower rate to SolarCity than if they were to rely on the current costs of conventional generation.

“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.”

“SolarCity is excited to bring the first dispatchable solar storage system to the island of Kaua‘i,” added Jon Yoshimura, Director of Policy and Electricity Markets for SolarCity. “Hawai‘i 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.”

The project is currently waiting on state and county approval, and hopes to begin construction before April 2016 and complete construction by December 31, 2016, so as to qualify for the federal investment tax credit.