ERCOT Restricts New IBR Generation in Hill County due to Stability Risk

On July 11, 2025, ERCOT issued an updated Market Notice reinforcing restrictions on new inverter-based generation at transmission voltage in  Hill County, Texas, located between Waco and Fort Worth. The restrictions will also apply to the nearby 345-kV area, known as the SAMSW Generic Transmission Constraint (GTC). 

ERCOT’s evaluation confirmed that allowing any new inverter-based resources, regardless of dispatch level, presents an unacceptable stability risk under certain multiple contingency conditions.  Consequently, any proposed generator that has not yet received Part 2 approval must: 

• Fully mitigate the associated stability risks, and 
• Provide proof of mitigation effectiveness through a study conducted by ERCOT or the applicable Transmission Service Provider (TSP). 

These requirements apply even to projects already in the interconnection or modification process. ERCOT is currently evaluating possible transmission upgrades that could allow for eventual removal of the constraint.  Once a solution is identified, ERCOT will update the SAMSW GTC methodology and publish the changes to the ERCOT MIS Secure Area. 

Why This Matters 

If you are pursuing or considering interconnection in the Hill County/SAMSW area, especially if your project includes inverter-based generation, this Market Notice could delay your synchronization timeline unless stability concerns are proactively addressed. Delays in securing Part 2 approval can cascade into schedule slippage and unwanted financial impact.  

Recommended Actions 

• Already in the queue? Review whether your project falls within the SAMSW GTC zone. If it does, initiate mitigation studies immediately to stay on track. 
• Entering the queue or evaluating sites? Factor the SAMSW constraint into your siting decisions. Be prepared to address stability risks proactively or shift to less constrained zones. 

How EPE Can Help 

Our team can support you with targeted technical studies and interconnection guidance to help preserve your timelines and avoid surprises.  Contact us to assess your risk and help you plan the right path forward. 

ERCOT November 1st QSA Reminder: Critical Deadline for Q2 2026 Projects 

If your project aims to synchronize in Q2 of 2026, you must plan now in order to meet the November 1st, 2025 QSA deadline.  Under the requirements established by PGRR112, all necessary QSA prerequisites must be satisfied by September 17, 2025, to be included in the QSA. 

What you will need by September 17: 

• Final FIS approval by ERCOT 
• Submission of both PSSE and PSCAD dynamic model packages (MQT-compliant) 
• Completion of Reactive Power study 

Missing this deadline will delay your project’s synchronization eligibility by a full year to Q3 of 2026. 

Don’t let tight timelines catch you off guard. At EPE, our expert team is here to support your interconnection journey. 

STEC Issues RFP for 500 MW of Firm, Dispatchable Capacity in ERCOT: 

The South Texas Electric Cooperative (STEC) is seeking to secure up to 500 MW of firm, dispatchable capacity in the form of dispatchable generation facilities or long-term power purchase agreements, tolling agreements, or other long-term contract structures.   

STEC will consider all generation technologies and fuel types, provided the assets are located within the ERCOT region, ideally near or within the service territory of one of STEC’s nine-member cooperatives. 

Key Parameters: 

• PPA Delivery Start Window: June 1, 2027 – December 1, 2028 
• PPA Contract terms: 20–30 years 
• Facility COD deadline (if not operational): December 1, 2028 
• Notice of Intent deadline: August 6, 2025 
• Initial proposals due: September 10, 2025 

Strategic Implications and Developer Considerations

This RFP represents a significant opportunity for developers and asset owners.  With a required COD of no later than December 1, 2028, time is of the essence for projects that are not yet online. Developers must consider ERCOT interconnection timelines, including modeling, stability assessments, and site-specific constraints that can affect both project viability and schedule. 

How EPE Can Help

At EPE, we support clients throughout the full lifecycle of ERCOT project development, from feasibility through commercial operation. For generation developers pursuing opportunities under this RFP, EPE’s support covers a broad range, including but not limited to: 

• Strategic POI evaluation to help you determine the most viable and timely grid connection points 
• Interconnection modeling and application preparation, including submission of all required dynamic models (PSSE, PSCAD) to meet ERCOT’s evolving requirements and milestones.  
• Guidance on ERCOT interconnection study schedules, including timing for Full Interconnection Study (FIS) milestones and Quarterly Stability Assessment (QSA) inclusion, in addition to securing a Production Load Date (PLD) for your project with the Full Registration Application.  

If you are evaluating a dispatchable project for submission under this RFP, reach out to EPE today. Our technical experts are ready to help position your project and explore timeline options.  

In Case You Missed It

As ERCOT continues adapting to changes brought by the One Big Beautiful Bill Act (OBBBA), developers face an evolving interconnection process. If you have not yet, check out our OBBBA article for a breakdown of key impacts on queue management, hybrid projects, and shared interconnection requests.