ERCOT Strengthens Reactive Power Requirements

On January 5, 2026, ERCOT released an updated Reactive Study Guide, introducing clearer and more stringent reactive power and voltage support requirements for Intermittent Renewable Resources (IRRs) with a Signed Generator Interconnection Agreement (SGIA) on or after August 1, 2024. The update emphasizes stronger voltage support across all real-power levels even when resources operate at low or zero real power output. 

What’s Changing? 

Previously, ERCOT required resources larger than 20 MVA to demonstrate reactive capability only above a minimum real-power threshold (for example, 10% of nameplate capacity for Intermittent Renewable Resources (IRRs)). 

Key Update 

• IRRs with a signed Standard Generator Interconnection Agreement (SGIA) on or after August 1, 2024, excluding Type 3 wind turbine generators (WTGs), must be capable of providing reactive power at zero MW. 

Implications for Developers 

• IRRs subject to the new rules must provide reactive capability from 0 MW to full real-power output. 
• Type 3 WTGs are required to provide reactive support starting at 5% of maximum real-power output. 
• Per NP 3.15.3(12), IRRs that can provide net reactive power at zero MW may instead physically desynchronize from the ERCOT system when not producing real power. 
• IRRs with SGIAs before August 1, 2024 may continue demonstrating reactive capability at 10% of maximum real-power output and above. 
• ERCOT is also aligning registration and operational models by standardizing terminology, including replacing High Sustainable Limit (HSL) and Low Sustainable Limit (LSL) with High Reasonability Limit (HRL) and Low Reasonability Limit (LRL), and redefining the Low Output Point (LOP).  

Why This Matters  

These changes: 

• Enhance voltage stability across all operating conditions. 
• Align ERCOT with IEEE 2800-2022, standardizing IRRs resource performance expectations. 
• Support grid reliability as renewable penetration increases, particularly during low generation periods. 

How EPE Can Help 

EPE helps developers navigate these changes and avoid costly surprises by: 

• Interpreting how the updated Reactive Guide applies to your project. 
• Determining whether Q-at-night / zero-MW reactive capability is required under your interconnection agreement. 
• Performing reactive power studies and modeling.  
• Supporting interconnection studies, registration, and commissioning testing. 
• Coordinating between ERCOT, TSPs, inverter vendors, and EPCs. 

To discuss your project and ensure early alignment with the latest ERCOT reactive requirements, contact our team using the form below