US utility San Diego Gas & Electric (SDG&E) has placed orders for additional energy storage capacity just weeks after bringing on line the world’s largest battery energy storage system.

SDG&E has placed orders with suppliers for 83.5 MW of storage capacity, divided between five projects. It has also signed a contract to add a 4.5 MW demand response program to its portfolio.

The storage systems will help the California-based utility to improve the flexibility of its grid system, maximise renewable energy use and enhance regional reliability. It has submitted the six contracts to regulators for approval.

SDG&E wants AES to construct a 40 MW storage facility similar to those commissioned for SDG&E earlier this year in Escondido and El Cajon, California. A 30 MW facility will be built in Miramar by Renewable Energy Systems Americas Inc. 

These two facilities will be owned and operated by SDG&E.

Three other storage projects totaling 13.5 MW will be owned by third parties including Powin Energy, Enel Green Power North America, and Advanced Microgrid Solutions, and constructed in Escondido, Poway and San Juan Capistrano.

“These projects will add more flexibility to the system and help us to ensure reliability while providing greater levels of clean energy to all of our local communities,” said Emily Shults, SDG&E’s vice president of energy procurement. “By building these projects, SDG&E will remain at the forefront of helping the state achieve its bold clean-energy and carbon-emission targets.”

The California Public Utilities Commission (CPUC) has set targets for investor-owned utilities to procure large amounts of energy storage by 2020, including 165 MW by SDG&E. 

The new facilities are expected to come on line between December 2019 and late 2021.