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SC — Power Infrastructure Updated 2026-07-17

South Carolina

SERC Data Center PPAs Queue Bottlenecks Transmission Constraints

Last updated: 2026-07-17

1) Grid operator and market structure

  • No RTO/ISO; vertically integrated retail market. South Carolina remains a vertically integrated retail electricity market. A Brattle study prepared for the South Carolina Electricity Market Reform Measures Study Committee describes the state’s major balancing authorities and market structure, and the EIA state profile shows South Carolina retail sales are served by full-service providers rather than competitive energy-only suppliers. Sources: Brattle Group / South Carolina General Assembly, 2022-04-27; U.S. Energy Information Administration, 2026-06-10.
  • Primary utilities relevant to data-center load: The most relevant electric-service providers for current South Carolina data-center activity are Duke Energy Carolinas/Duke Energy Progress, Dominion Energy South Carolina, Santee Cooper, York Electric Cooperative, Lockhart Power, and county/municipal utility partners, depending on project site. York County’s QTS materials identify York Electric Cooperative as the power provider for the nine-building QTS campus, while Project Alpaca materials identify existing Lockhart Power infrastructure at Midway Green Industrial Park. Sources: QTS, 2026-06-10; Project Alpaca presentation, 2026-04.

2) Interconnection queue (status, reforms, data-center requests)

  • FERC baseline reform. FERC Order No. 2023 requires transmission providers to move toward cluster studies, readiness requirements, withdrawal penalties, and stricter study deadlines for generator interconnection queues; South Carolina utilities must comply for FERC-jurisdictional transmission interconnection processes. Source: Federal Energy Regulatory Commission, 2023-07-28.
  • Duke large-load intake and forecasting became more material in 2026. Duke’s Spring 2026 Large Load Report filed at the SCPSC states that Duke Energy Carolinas and Duke Energy Progress identified 43 advanced-development large-load projects totaling 7,946 MW of peak demand by the tenth forecast year, including 16 projects with executed electric service agreements totaling 4,337 MW, 24 projects with letter agreements totaling 3,259 MW, and 3 late-stage projects totaling 350 MW. Source: South Carolina Public Service Commission, 2026-04-17.
  • Wholesale large-load exposure is also growing. The same Duke filing states that the companies’ wholesale forecast includes two discrete large-load projects ramping to nearly 900 MW by 2035, reflecting potential municipal/cooperative large-load additions served by wholesale customers of Duke Energy Carolinas or Duke Energy Progress. Source: South Carolina Public Service Commission, 2026-04-17.
  • Public data-center-specific queue detail remains limited. Duke’s April 2026 filing quantifies large-load projects across the Carolinas but does not publicly identify which projects are data centers or which megawatts are South Carolina-only. Source: South Carolina Public Service Commission, 2026-04-17.
  • A project cancellation exposed a South Carolina power-delivery constraint. Stream Data Centers canceled its proposed $800 million Marion County campus on June 18, saying utility power could not be delivered on the project’s required schedule. The planned first phase comprised three 655,770-square-foot buildings, with room for at least three more. Source: Data Center Dynamics, 2026-06-18.

3) Ratepayer protection (large-load tariffs, cost allocation, PSC dockets)

  • Santee Cooper large-load rate. Santee Cooper adopted a special experimental rate in April 2025 for data centers and other customers requiring 50 MW or more. Reporting on the board action says the rate requires large-load customers to sign 15-year contracts, allows higher charges during high-demand periods, requires ramp-up to full contracted usage within three years, and was justified as a way to prevent large-load costs from falling on other ratepayers. Source: Data Center Dynamics, 2025-04-28.
  • No statewide data-center tariff statute was enacted in the 2026 session. S.784, S.902, H.5215, and H.5484 proposed various combinations of minimum contract terms, financial assurance, PSC review, and cost allocation designed to prevent cross-subsidization, but none passed before the regular session adjourned sine die on May 14. Sources: South Carolina General Assembly, 2026-01-13; South Carolina General Assembly, 2026-02-10; South Carolina General Assembly, 2026-02-19; South Carolina General Assembly, 2026-04-01; South Carolina General Assembly, 2026-05-15.
  • PSC opened a generic large-load proceeding. On May 27, Duke Energy Carolinas and Duke Energy Progress petitioned the PSC to open Docket 2026-138-E to receive comments on issues associated with new large-load additions of 50 MW or more, following commitments made in the utilities’ 2025 rate cases. The docket remained open on July 17 with a broad participant list that included Dominion, Google, Lockhart Power, consumer and environmental groups, and industrial customers; no final tariff or cost-allocation ruling had issued. Source: South Carolina Public Service Commission, 2026-07-16.
  • Dominion was formally brought into the generic review. In Dominion Energy South Carolina’s general rate case, PSC Order No. 2026-374, issued July 2, approved a large-load stipulation under which Dominion agreed to join and participate in Docket 2026-138-E. The stipulation deferred questions involving new 50 MW-or-greater loads—including contract terms, collateral, exit provisions, generation and transmission cost treatment, interconnection costs, flexible interconnection, and clean-energy options—to the generic proceeding rather than deciding them in Dominion’s rate case. Source: South Carolina Public Service Commission, 2026-07-02.
  • PSC received a project-specific siting complaint. In Docket 2026-158-E, Concerned Citizens of Spartanburg County and the Southern Alliance for Clean Energy alleged that Valara Holdings was constructing a data center and approximately 450 MW gas-fired power plant without the certificate required by the South Carolina Utility Facility Siting and Environmental Protection Act. As of July 17, the PSC had not decided the merits; oral argument was scheduled for July 30. Sources: Southern Environmental Law Center, 2026-06-19; South Carolina Public Service Commission, 2026-06-23.
  • Dominion 2026 IRP docket is active. Dominion Energy South Carolina’s 2026 Integrated Resource Plan docket, Docket 2026-9-E, is open. Dominion filed the 2026 IRP on March 31, 2026; direct testimony was filed June 3, 2026; a procedural schedule was adopted June 4, 2026; a hearing is scheduled for November 9, 2026; and a final order is due January 25, 2027. Source: South Carolina Public Service Commission, 2026-06-04.
  • Duke rate-stabilization docket is not a data-center tariff docket. A March 2026 Duke Energy Progress docket, 2026-78-E, concerns application of the Electric Rate Stabilization Adjustment to DEP rates; it should not be characterized as a data-center large-load tariff docket. Source: South Carolina Public Service Commission, 2026-03-16.

4) Generation adequacy (major projects, storage, shortfalls)

  • Canadys Joint Resource received its final PSC certificate. Order No. 2026-350, issued June 12, granted Dominion Energy South Carolina and Santee Cooper a certificate for the approximately 2,180 MW, roughly $5 billion advanced-class combined-cycle plant and approved the lease needed for each utility to own 50%; the target commercial-operation date is in 2033. The order requires quarterly construction, permitting, pipeline, schedule, and cost updates beginning in Q3 2026. On July 16 the Commission rejected two reconsideration requests, leaving the certificate in place as of this update. Sources: South Carolina Public Service Commission, 2026-06-12; South Carolina Public Service Commission, 2026-07-16.
  • Santee Cooper load growth and resource need. Santee Cooper’s 2025 IRP Update was filed at the SCPSC in November 2025 and frames the utility’s resource planning around increased load and new resource needs. Source: Santee Cooper, 2025-11-21.
  • Large-load commitments are tied to resource procurement risk. In the Canadys docket, ORS testimony summarized Santee Cooper’s 2024 IRP update as including signed contracts in the base forecast and stochastic modeling for other load-forecast components, and stated that as large-load commitments are secured, Santee Cooper will continue to need new resources. Source: South Carolina Public Service Commission, 2026-02-17.
  • Duke’s next resource plan was still pending as of July 17. Duke Energy’s 2026 Carolinas Resource Plan page states that the next plan is to be filed in South Carolina by August 14, 2026, so the Spring 2026 large-load report remained the current public large-load update before the next full resource-plan filing. Source: Duke Energy, 2026-07-17.

5) Utility load forecasts (data centers)

  • Duke’s load forecast incorporates an Economic Development Adjustment. Duke’s Spring 2026 report says the companies are continuing to apply an Economic Development Adjustment to capture large-load customer growth in the Carolinas and will incorporate the Spring 2026 advanced-development-project information into the Spring 2026 load forecast. Source: South Carolina Public Service Commission, 2026-04-17.
  • York/QTS load is contract-based but not publicly quantified by MW. QTS says it has a power agreement with York Electric Cooperative for nine buildings over three phases and that QTS will pay for needed energy infrastructure, but it does not disclose specific project power capacity for security and confidentiality reasons. Source: QTS, 2026-06-10.
  • Union/Project Alpaca was publicly described as 49 MW. Project Alpaca’s public presentation described the project as a 49 MW AI data center and claimed all needed transmission and generation capacity was already in place at Midway Green Industrial Park. Source: Project Alpaca presentation, 2026-04.
  • Public IRP materials still generally use “large load” or “economic development” categories, not data-center-only categories. The Duke and Santee Cooper materials quantify large-load pressure, but public versions do not isolate data-center-only megawatts for South Carolina. Sources: South Carolina Public Service Commission, 2026-04-17; Santee Cooper, 2025-11-21.

6) Behind-the-meter / co-location / direct procurement

  • Project Spero proposed self-contained/on-site power before withdrawal. TigerDC’s public statements for Project Spero said the project would use a self-contained power strategy intended to avoid strain on the local residential grid and would self-generate a portion of its power on site using natural gas as part of its reliability strategy. The project was withdrawn from Spartanburg County consideration on February 27, 2026. Sources: Who’s On The Move, 2026-01-27; WYFF, 2026-02-27.
  • Valara’s behind-the-meter generation became an active state proceeding. Valara applied to SCDES on March 4 for a second synthetic-minor air construction permit that would expand on-site gas generation from approximately 50 MW to approximately 450 MW; SCDES held a June 25 public hearing and extended comments through July 31. PSC Docket 2026-158-E separately asks whether the combined data center and power plant require a state siting certificate, so the project is no longer accurately described as having no active public proceeding. Sources: South Carolina Department of Environmental Services, 2026-06-25; Southern Environmental Law Center, 2026-06-19.

7) Transmission constraints and upgrades

  • Duke’s large-load growth affects both retail and wholesale planning. Duke reported 7,946 MW of advanced-development retail large-load projects and nearly 900 MW of wholesale large-load additions by 2035, indicating transmission and resource-planning pressure across the Carolinas system that includes South Carolina service territories. Source: South Carolina Public Service Commission, 2026-04-17.
  • Canadys approval includes gas-pipeline and cost-tracking conditions. The PSC’s Canadys directive requires updates on the Canadys resource and related gas-pipeline expansions, including the Mississippi Crossing/South System Expansion and Elba Express Bridge Project, until the pipelines and resource reach commercial in-service status. Source: South Carolina Public Service Commission, 2026-05-14.
  • Project-specific transmission claims remain mostly developer-specific. Project Alpaca’s developer materials claimed that all 49 MW of transmission and generation capacity was already in place, while QTS states that York Electric Cooperative confirmed reliable support for the York County site and that QTS will fund needed energy infrastructure. These are project/developer statements rather than independent PSC determinations. Sources: Project Alpaca presentation, 2026-04; QTS, 2026-06-10.
  • Marion cancellation shows that available capacity and delivery timing can be dispositive. Stream’s withdrawal of Project Liberty because utility power would take too long is the clearest public South Carolina example in this period of a proposed data-center campus failing over the power-delivery schedule rather than land-use approval alone. Source: Data Center Dynamics, 2026-06-18.

Notes on sources and method