Duke Energy Closes Bidding for 400 MW South Carolina Battery Storage Procurement

Duke Energy Carolinas and Duke Energy Progress closed the bid window August 5 for approximately 400 megawatts of new standalone battery storage in South Carolina, advancing a state-regulated procurement designed to add four-hour energy storage directly connected to the utilities’ transmission systems. The South Carolina battery storage RFP matters because it establishes a competitive pathway for substantial new dispatchable storage as electricity demand and capacity needs increase across the Carolinas.

The procurement targets approximately 200 MW of third-party-owned battery storage and 200 MW of utility-owned storage. All qualifying facilities must be new, located in South Carolina, directly interconnected with the Duke Energy Carolinas or Duke Energy Progress transmission system, and configured as four-hour battery energy storage systems.

The 400 MW procurement is divided between two ownership models

According to Duke Energy’s Carolinas RFP portal, the solicitation targets approximately 400 MW of new battery storage through a combination of utility-owned projects and third-party Energy Storage Services Agreement projects.

The two-track structure is intentional. Under the utility-owned track, developers can propose projects that ultimately become utility assets. Under the third-party track, project owners would retain ownership while providing storage services to the utilities under an Energy Storage Services Agreement.

The Public Service Commission of South Carolina’s May 15 order approved a framework targeting 200 MW in each ownership category.

The commission found that the split represented a reasonable approach to balancing utility-owned and third-party storage resources in the 2026 solicitation.

Projects must provide four hours of battery storage

The procurement is specifically for standalone four-hour battery energy storage rather than batteries paired directly with new solar projects.

At the targeted 400 MW procurement level, four hours of rated discharge would correspond to approximately 1,600 MWh of energy capacity if the full target is ultimately contracted at the required duration. Actual procured capacity will depend on the bids selected through the competitive process.

The 2026 South Carolina Battery RFP requires facilities to be located in South Carolina and physically interconnected with the Duke Energy Carolinas or Duke Energy Progress transmission system.

The resources must also be new. Facilities are required to enter service after August 5, 2026 and must be capable of completing facility construction within three years, although transmission network upgrades can follow a different schedule.

Interconnection was part of the August 5 deadline

Submitting a commercial proposal was only one component of the deadline.

Duke Energy’s official bidder guidance states that complete proposals due August 5 had to include the applicable bid input forms, supporting documents, required fees and an interconnection application for the RFP-specific Resource Solicitation Cluster.

That requirement connects resource procurement and transmission planning from the beginning of the evaluation process rather than selecting projects without accounting for how they would physically connect to the grid.

Projects are responsible for ensuring their sites are eligible to receive electric service for grid charging. Each facility must also use a single point of interconnection with the applicable Duke transmission system.

South Carolina regulators approved the procurement framework

The RFP follows South Carolina’s establishment of competitive procurement requirements for energy storage under Act 41 of 2025.

The Public Service Commission reviewed Duke Energy’s proposed procurement framework in Docket No. 2025-217-E. The regulatory process addressed issues including ownership structure, competitive evaluation and the balance between utility and independent storage development.

Commission records for the final RFP filing show Duke Energy Carolinas and Duke Energy Progress filed the 2026 battery solicitation and pro forma storage-services agreement in July following the commission’s order.

Charles River Associates is serving as the independent evaluator responsible for administering the competitive process and helping ensure proposals are treated consistently.

Four-hour batteries can address peak capacity and grid flexibility

The solicitation comes as utilities across the United States add battery storage to provide capacity, shift electricity across hours and improve flexibility as electricity demand grows.

A four-hour battery can charge when electricity is more readily available and discharge during periods of higher system need. Storage can also complement variable renewable generation and provide utilities with another dispatchable resource for balancing supply and demand.

The South Carolina procurement is notable because the batteries are being sought as standalone grid resources rather than solely as additions to renewable generation projects.

That allows the facilities to be evaluated based on their value as storage and capacity resources within the broader transmission system.

Bid closure does not mean 400 MW has been awarded

The August 5 milestone closes the proposal window. It does not mean Duke Energy has selected projects or committed to procure exactly 400 MW.

The utilities and independent evaluator must now review proposals under the competitive process. The approximately 400 MW figure is a procurement target rather than a guaranteed final award.

Project economics, interconnection requirements, technical qualifications and other evaluation criteria will influence which proposals advance.

The results will provide a clearer indication of how much new four-hour storage Duke Energy can add in South Carolina, where it will be located and how the final portfolio will be divided between utility-owned and independently owned facilities.