A solar farm connected to a huge battery will be built on the Hawaiian island of Kauai to use solar in the evenings to meet peak demand, under a 20-year contract between SolarCity and an electric utility co-operative.

Imergy Power Systems, the California-based energy storage specialist, has received an order for four of its ESP5 vanadium flow batteries from Hawaiian renewables firm, Energy Research Systems.

The US-based solar division of Japan’s Kyocera and energy service start-up STEM have become the latest partnership to offer integrated solar-plus-storage to commercial customers in the US, beginning with sales in three states including California.

An “enormous” request for proposal (RFPs) put out by the Hawaii Electric Company (HECO) for up to 200MW of energy storage was responded to by more than 60 would-be developers.

The annual energy capacity of batteries used in utility-scale applications will be seen to increase by a factor of more than 100 between now and 2023, according to a new report published by US analysis firm Navigant Research.