What Is Datacenter Curtailment Stress Score? (2026 ERCOT Risk Guide)
Curtailment Stress Score (CSS) measures datacenter power reliability risk on a 0-100 scale. It factors in grid congestion, historical curtailment events, and renewable intermittency. Lower scores indicate lower risk. ERCOT zones range from CSS 25 (Dallas) to CSS 85 (West Texas).
- West Texas: CSS 70-85 (High Risk)
- South Texas: CSS 55-70 (Elevated Risk)
- Houston: CSS 45-60 (Moderate Risk)
- Dallas-Fort Worth: CSS 30-45 (Low Risk)
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Which ERCOT Zones Have Highest Curtailment Risk?
| Zone | CSS Range | Risk Level | Annual Curtailment | Key Risk Factor |
|---|---|---|---|---|
| West Texas | 70-85 | High | 150-250 hours | Transmission constraints, wind ramps |
| South Texas | 55-70 | Elevated | 80-150 hours | Solar intermittency, coastal load |
| Houston | 45-60 | Moderate | 50-100 hours | Industrial load, hurricane risk |
| Austin | 35-50 | Low-Moderate | 30-60 hours | Growing demand, LCRA constraints |
| Dallas-Fort Worth | 30-45 | Low | 20-40 hours | Strong grid, diverse generation |
Site Selection Insight
For AI inference and enterprise hosting, target CSS below 45 (DFW, Austin). For AI training with batch workloads, CSS up to 65 (Houston, South Texas) is acceptable with 15-20% power cost savings offsetting curtailment risk.
How Does Curtailment Affect Datacenter Operations?
Revenue Impact
- CSS 25-401-3% revenue at risk
- CSS 40-553-7% revenue at risk
- CSS 55-707-12% revenue at risk
- CSS 70-8512-20% revenue at risk
DSCR Impact
- 5% revenue reduction-0.05x to -0.08x DSCR
- 10% revenue reduction-0.10x to -0.15x DSCR
- 15% revenue reduction-0.15x to -0.22x DSCR
- Covenant breach riskCSS >65 requires mitigation
How Can Datacenters Reduce Curtailment Risk?
Physical Mitigation
- ✓Behind-the-meter generation (gas, solar+battery) for 50-100% backup
- ✓On-site battery storage (4-8 hours) to ride through events
- ✓Dual-feed transmission from separate substations
- ✓Load shedding automation for non-critical workloads
Contractual Mitigation
- ✓Firm power contracts vs interruptible (10-20% premium)
- ✓Financial hedges (congestion revenue rights, options)
- ✓Demand response revenue to offset curtailment cost
- ✓Multi-site redundancy across low-correlation zones
What Causes ERCOT Curtailment Events?
35%
Transmission Congestion
25%
Renewable Ramps
20%
Extreme Weather
15%
Generator Outages
5%
Grid Emergencies
Seasonal Pattern
June-September accounts for 65% of annual curtailment events due to peak cooling demand and evening solar ramp-downs. February is also high-risk due to winter storm potential (cf. Winter Storm Uri 2021).
Our Methodology
The Curtailment Stress Score (CSS) is calculated using:
- Historical data: 5 years of ERCOT curtailment events by zone
- Grid metrics: Transmission capacity, congestion patterns, LMPs
- Generation mix: Renewable penetration, thermal reliability
- Weather correlation: Temperature extremes, storm frequency
- Update frequency: Weekly CSS updates via platform
- Last updated: January 8, 2026
Limitations: CSS is a forward-looking risk indicator, not a guarantee. Actual curtailment varies by specific location, contract type, and load characteristics.
Frequently Asked Questions
What is acceptable curtailment risk for GPU datacenters?
For AI training (batch workloads), CSS up to 60 is acceptable as jobs can restart. For inference and enterprise hosting, CSS below 40 is preferred. Mission-critical facilities target CSS below 25 or use backup generation.
How does CSS affect power purchase agreements?
High CSS zones command 10-20% power price premiums for firm contracts vs interruptible. Datacenters in CSS 60+ zones should budget $0.01-0.02/kWh additional for reliability hedging or accept demand response obligations.
How can datacenters reduce curtailment risk?
Strategies include: (1) behind-the-meter generation (gas, solar, battery), (2) firm power contracts vs market exposure, (3) site selection in low-congestion zones, (4) load flexibility for demand response, (5) hedging with financial instruments.
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