US solar manufacturer and developer SunPower and battery storage maker AES Distributed Energy will team up to build one of the largest solar and battery storage projects in the world on the Hawaiin island of Kaua’i.

The 28MW SunPower solar system will be accompanied by a 20MW, 5-hour battery storage system – making it the largest solar plus storage systems on the state of Hawaii and one of the largest battery storage installations in the world. Hawaii is aiming for 100 per cent renewables by 2045, although the state grid operator reckons it can be done by 2040. Hawaii is pushing for 100 per cent renewables because it faces a massive bill importing fuels to drive its generators, and because it wants to do its share on climate.

The AES system of 20MW/100MWh compares with the 100MW/129MWh system being built by Tesla in South Australia, although the Tesla battery is designed to perform a different function to the AES system – it will provide fast-response “stability” to the grid to respond to any major faults.

The AES system, on the other hand is designed to provide added capacity and flexibility to deal with peak demand.

Kaua’i is already becoming a centre for solar and storage projects. Tesla and its now fully owned SolarCity built a 13MW solar plant with a 52MWh battery system that delivers as much as 13MW of power to the island grid during the evening peak hours of 5pm to 10pm at the reported price per of US14.5c/kWh.

The SunPower/AES facility will deliver power for US11c/kWh – a drop of 30 per cent from the Tesla/SolarCity project in just over a year. When completed, Kaua’i will get over 50 per cent of its electricity from renewable sources.