We saw ERCOT’s highest demand peak of the summer so far on August 18th at HE17, peak demand came in at 83.9 GW, with Amperon calling an 84 GW peak at 10 AM the day prior — a 0.14% APE. Conversely, ERCOT predicted an 84.9 GW peak at 10 AM the day prior, an APE of 1.25%, over forecasting demand by a GW.
To put this into perspective, the all-time summer record was set on August 10th, 2023, at 85.5 GW. This summer, we have consistently seen 2-3 GW of demand response across peak hours to avoid the 4CP interval. Yesterday, we were on track to possibly beat this record before large flexible load curtailments kicked in.
On top of this, Texas has not seen a major heat wave all summer. If demand is this high for a “mild” Texas summer day, think about how high demand levels in ERCOT could be if we saw a widespread heat wave. All we need is one scorching day to set a new demand record. Summer is not over yet.
Day-Ahead Prices: Where’d the Volatility Go?
The week began with higher than normal day-ahead prices, driven by strong loads and weak wind generation, which pushed net load toward record levels. At one point, the system came close to challenging the net demand record of 70,989 MW, set on February 20, 2025. The highest day-ahead prices cleared for Tuesday, August 19, reflecting expectations for the week’s tightest conditions, with wind generation topping out around 5 GW.
On Monday, August 18, DARTs were very positive during the evening peak, likely due to lower than expected net load. Tuesday followed a similar pattern: despite clearing the week’s highest day-ahead prices on expectations of net load above 70 GW, real-time prices barely surpassed $100, leading to another evening of extremely positive DARTs. What initially looked like a volatile price week ultimately turned out to be relatively subdued. The question remains, is this the new normal for Texas?
Amperon’s real-time price forecast excelled in this environment, with MAEs around 15% or less for the two-hour ahead forecast across most zones for the 18th and 19th.
Our day-ahead price forecast performed just as well, but the real standout is real-time, where prices are typically far harder to predict. Delivering such strong accuracy under these uncertain conditions highlights the strength of our forecasting approach.
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Reach out here to learn more about our Real-Time and Day Ahead Price Forecasts.
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