Duke Energy says that it plans to spend $500 million over the next 15 years to deploy 300 megawatts (MW) of battery energy storage in its Carolinas service region.

The company announced its plans in its most recent integrated resource plan. At present, the utility says that North Carolina has about 15 MW of battery storage capacity in operation, and far less in South Carolina.

In a related move, the utility is asking North Carolina regulatory authorities for permission to build a solar facility in Madison County as part of a microgrid project. The Hot Springs Microgrid project would consist of a 2 MW solar facility and a 4 MW lithium-based battery storage facility. The microgrid is intended to provide energy and grid support, and is expected to defer maintenance of an existing distribution power line that serves a remote town in the western part of the state.

In its filing, the utility says that the proposed facility would consist of PV panels affixed to a ground-mounted, 20° fixed-tilt racking array, solar inverters, a microgrid controller and a lithium-based battery energy storage system. The nominal generation capacity for the PV generator will be around 3 MW DC/2 MW AC. The nominal storage capacity for the battery will be around 4 MW. The utility expects the facility to have a 25-year service life and says that the battery cells likely will need to be replaced after year 10, depending on degradation curves.

Other battery energy storage projects in the Carolinas include:

  • A 9 MW lithium-ion battery system to be placed at a Duke Energy substation site in Asheville, North Carolina.
  • In Haywood County, Duke Energy installed a 95 kilowatt-hour zinc-air battery and 10 kilowatt solar installation serving a communications tower on Mount Sterling in the Smoky Mountains National Park. The battery has been operating for more than a year.