ERCOT four-coincident-peak (4CP) charges allocate transmission costs based on a commercial customer demand during the four highest grid-peak hours of the prior summer. Curtailing during the forecasted 4CP windows can cut a year of transmission charges by 18 to 30 percent for large commercial customers. The 4CP forecast is published by ERCOT and updated daily during the summer peak season.
How 4CP allocation works
ERCOT identifies the four highest 15-minute grid-peak intervals from the prior June through September. Each commercial customer 15-minute demand during those four intervals sets their transmission charge allocation for the next year.
Curtailing or shifting load during the forecasted 4CP windows reduces the allocation. Forecasts are published daily during summer peak season.
Curtailment savings math
For a 1,000 kW commercial customer paying $14 per kW per month in transmission charges, full annual 4CP curtailment saves $168,000 a year if peak demand during forecasted 4CP windows is cut to 200 kW.
Best practice: assign a 4CP monitor during the summer peak window. Curtail to minimum operation during forecasted windows. Some commercial customers earn 40 to 60 percent of transmission savings by curtailing 1 to 2 hours per day during peak weeks.
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