Hawaiian Electric Co. officials said Friday they are seeking a contractor to build one or more large-scale energy storage systems that will help the utility absorb larger amounts of solar and other renewable energy on its Oahu grid.

Under HECO’s specifications the project would need to be able to store 60 to 200 megawatts of electricity for up to 30 minutes, according to a news release from the utility. Such a system would help offset the volatility of solar and wind energy that can negatively affect the quality of power on HECO’s power distribution grid.

A combination of both rooftop photovoltaic systems and utility-scale wind and solar projects provide electricity to more than 11 percent of HECO’s customers on Oahu, according to the utility.

“Energy Storage is one of the key missing elements in integrating high levels of renewable energy from variable sources like solar and wind,” said Colton Ching, HECO vice president for electricity delivery.

The deadline for bidders to submit proposals is July 21. The Kauai Island Utility Cooperative in March put out a similar request for bidders for an energy storage project, and received about 90 bids by an April 18 deadline.

Potential contractors will be evaluated on the overall cost of their proposals and non-price factors, such as design concept and feasibility, implementation and operational viability and operating flexibility, according to the news release.

HECO invited bidders to propose the “best available” technologies, including batteries, mechanical flywheels, capacitors, compressed gas systems, pumped storage hydro, or a combination of technologies.