South Texas Project is a two-unit pressurized-water nuclear station in Matagorda County, Texas. EIA reports 2,580 MW of net summer capability for Plant 6251. STP Nuclear Operating Company operates the site; current ownership is Constellation Energy (44%), CPS Energy (40%), and Austin Energy (16%). The units settle at ERCOT resource nodes STP_STP_G1 and STP_STP_G2 and connect through the site’s 345 kV switchyard.
EIA-reported net summer capability; other nameplate and seasonal ratings may differ.
Primary generation technology.
STP Nuclear Operating Co · Matagorda County · ERCOT
South Texas Project is operating.
ERCOT resource-node settlement points
STP_STP_G1_J01 · STP_STP_G1_J03 · STP_STP_G1_J04
South Texas Project is operating.
ERCOT
ERCOT · Matagorda County
Similar plants ranked by technology, capacity, and distance.
Operating generator records and technology attributes reported through EIA-860.
| Generator | Capacity | Technology | Operation | Status |
|---|---|---|---|---|
| 1 | 1,354.3 MW 1,300 MW summer | Nuclear Nuclear · ST | Aug 1988 | Operating |
| 2 | 1,354.3 MW 1,280 MW summer | Nuclear Nuclear · ST | Jun 1989 | Operating |
Monthly EIA generation history and recent market-resource behavior where linked telemetry is available.
Deterministic links to ERCOT market resources, price records, outage disclosures, queue records, and nearby infrastructure. Candidate joins remain labeled until corroborated.
Source-backed project transactions, agreements, land records, permits, and environmental disclosures. Portfolio and adjacent-project facts remain explicitly scoped.
Parties, market resources, and identifiers tied to this asset, with owner, operator, developer, EPC, compliance provider, and interconnecting entity roles kept separate.
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Project milestones and public references behind the asset profile.
NRC operating license issued for STP (operator listed as STP Nuclear Operating Co.).
Current ownership. CPS’s agreement to acquire another 2% remains pending in its FY2026 audited statements.
Monthly generation is reported through EIA-923. Capacity factor uses the current EIA nameplate capacity and is shown only for complete calendar years.
6 ERCOT market resources · Nuclear
Capacity factor is average output vs. this plant's observed peak.
Observed ERCOT settlement prices at STP_STP_G1 over 363 days (2025-09-12 to 2026-09-11). This plant is also crosswalked to STP_STP_G2; the point with the deepest price history is shown.
The TB2 figure is a price benchmark, not revenue: it values one perfect-foresight cycle per day between the 2 cheapest and 2 dearest hours of each day, gross of round-trip losses, and excludes ancillary services and any physical dispatch constraint. It describes what this node’s price shape was worth over the window — it is not this asset’s realized capture, and no dispatch is assumed or modelled.
Portfolio membership follows the latest EIA-860 reporting entity. It does not imply ultimate ownership.
EIA-860 lists generator 1 with this operating date.
EIA-860 lists generator 2 with this operating date.
NRG announced completion of the sale of its 44% interest in the South Texas Project to Constellation for $1.75 billion on November 1, 2023.
ERCOT SCED disclosure is delayed, so plant performance windows end at the latest disclosed interval.
Answered from the published record above. Questions whose inputs this profile does not carry are omitted rather than estimated.
South Texas Project has a reported capacity of 2,708.6 MW. Source: EIA Form 860.
South Texas Project is a nuclear facility in Matagorda County, TX, participating in the ERCOT market.
South Texas Project is in Matagorda County, TX, inside the ERCOT balancing area.
South Texas Project is operated by STP Nuclear Operating Co according to the EIA generator inventory. Reporting membership does not by itself establish ultimate ownership.
South Texas Project reported 20,247 GWh over the twelve months to 2026-06. Figures are net generation as filed to EIA-923.
South Texas Project settles at STP_STP_G1, interconnects at STP.
By capacity, South Texas Project ranks #5 of 54 operating plants of the same technology nationally. It ranks #1 of 2 in TX.
Plants within 25 km, nearest first, regardless of technology. Proximity is straight-line distance between mapped plant coordinates; it does not by itself establish a shared point of interconnection.
