Kaua’i Island Utility Cooperative (KIUC) is about to go solar. The builder SolarCity has selected Tesla Energy and will utilize 52MWh of Tesla Powerpack lithium-ion battery storage systems for the solar array, marking the first utility-scale solar system in the U.S. that works incorporate with batteries.

The 52MWh stringed Powerpack batteries will feed up to 13MW of electricity onto the grid to “shave” the amount of conventional power generation needed to meet peak demand in the evening from 5 p.m. to 10 p.m. Furthermore, the SolarCity/Tesla project will be able to provide dispatchable, reliable solar energy all day long. As a result, the batteries will make solar a real replacement for diesel generators.

The battery-combined solar array will help KIUC reduce its use of imported fossil fuels as well as greenhouse gas emissions. With a 20-year PPA contract signed with SolarCity, KIUC will pay 14.5cents per kWh of solar electricity generated from the new solar array.

KIUC now owns two solar arrays totaling 12MW. Both the arrays generate power only during the day since they don’t work with energy storage systems.

The project has already received most of its required state and county approvals and is now awaiting approval by the Hawai'i Public Utilities Commission. KIUC and SolarCity have requested an accelerated timetable for review of the project so that construction work can begin by April with a goal of being in commercial operation by the end of 2016.