# South Texas Project

ERCOT asset profile · https://askthegrid.com/assets/facilities/south-texas-project

STP Nuclear Operating Company · Matagorda County · ERCOT

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.

## Profile

- **Market nodes:** STP_STP_G1 · STP_STP_G2.
- **Ownership:** Constellation Energy 44% · CPS Energy 40% · Austin Energy 16%. CPS has agreed to acquire another 2% from Constellation, but CPS’s FY2026 audited statements say the transaction remains pending.
- **Physical build:** Two Westinghouse four-loop pressurized-water reactor units, each licensed by the NRC at 3,853 MWt, connected through the site’s 345 kV switchyard.

## Metrics

- **Reported capacity:** 2,580 MW — EIA-reported net summer capability; other nameplate and seasonal ratings may differ.
- **Technology:** Nuclear — Primary generation technology.
- **Registry anchor:** Plant 6251 — STP Nuclear Operating Co · Matagorda County · ERCOT
- **Operating status:** Operating — South Texas Project is operating.
- **Market nodes:** STP_STP_G1 · STP_STP_G2 — ERCOT resource-node settlement points
- **Resource stack:** 6 resources — STP_STP_G1_J01 · STP_STP_G1_J03 · STP_STP_G1_J04

## Facts

- **Operating status:** operating — South Texas Project is operating. · confidence: medium
- **Location:** Matagorda County — ERCOT · confidence: high
- **Operator:** STP Nuclear Operating Co · confidence: high
- **Asset role:** nuclear — ERCOT · Matagorda County
- **Owner:** Constellation 44% · CPS 40% · Austin 16% — Current ownership. CPS’s agreement to acquire another 2% remains pending in its FY2026 audited statements. · confidence: high

## Related parties

- **Operator:** STP Nuclear Operating Company (STPNOC) — Operator for South Texas Project ([source](https://stpnoc.com/))

## Sources

- [South Texas Project](https://stpnoc.com/) — STP Nuclear Operating Company · other — Official station overview and current ownership.
- [South Texas Project, Unit 1](https://www.nrc.gov/info-finder/reactors/stp1) — U.S. Nuclear Regulatory Commission · regulatory — Unit 1 license, reactor type, operator, and licensed thermal rating.
- [South Texas Project, Unit 2](https://www.nrc.gov/info-finder/reactors/stp2) — U.S. Nuclear Regulatory Commission · regulatory — Unit 2 license, reactor type, operator, and licensed thermal rating.
- [NRG completes sale of South Texas Project interest](https://investors.nrg.com/news-releases/news-release-details/nrg-completes-sale-its-interest-south-texas-project) — NRG Energy · other — Completion of the $1.75 billion sale of NRG’s 44% interest to Constellation.

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Canonical page: https://askthegrid.com/assets/facilities/south-texas-project
Website: [STP Nuclear Operating Company](https://stpnoc.com/)
Profile published: 2026-07-17T03:34:49.713Z
Source: Ask the Grid — https://askthegrid.com/