ERCOT price cap (system-wide offer cap)

Because ERCOT has no capacity market, its generators earn their fixed costs from a relatively small number of very expensive hours. The system-wide offer cap sets how expensive those hours can get: it is the maximum offer, and effectively the maximum price, that the ERCOT energy market can produce.

A single cap number is not the whole story. How prices climb toward it changed when RTC+B took effect in December 2025. Before that, a standalone scarcity adder built on the operating reserve demand curve lifted prices as reserves thinned. Now energy and reserves clear together every five minutes, and ERCOT publishes a reliability deployment price adder as its own component of the real-time energy price. When the grid has plenty of cushion, prices sit near fuel cost; as it tightens, they rise toward the cap.

The cap's level is a deliberate policy trade-off, revisited after every crisis. A higher cap strengthens the investment signal for new capacity but concentrates enormous financial risk into single events — the February 2021 winter storm, when prices held at the then-cap of $9,000/MWh for days, bankrupted retailers and prompted the cap's reduction. Understanding where the cap sits, and how scarcity pricing approaches it, is essential to reading any extreme ERCOT price.