Power Market Insights
MISO prints $10K cap as evening load, solar collapse, imports weaken — spurring an EEA2. The full rundown below & our Mosaic timeseries highlighting the convergence
MISO’s real-time market printed at the $10,000/MWh cap for multiple intervals during HE19-20 (6-8pm ET) on September 2nd, driven by a textbook late-summer scarcity setup rather than a discrete generation failure. Load came in 4,300-5,700 MW above the day-ahead forecast through the back half of the day as temperatures ran hotter than expected, while solar output collapsed (neon green shaded area) from a midday peak of ~18,350 MW to just 137 MW by HE20 — removing nearly 18 GW of supply exactly as load peaked. The combination, layered on reduced import availability (orange area) and transfer capability, pushed MISO from an EEA1 at 6:48pm to EEA2 by 7:11pm — a 23-minute escalation that signals how little headroom the system had left.
Batteries discharged into the event but were drawn down before the worst of it hit. Real-time at Indy Hub averaged $1,630.70 (HE19) and $4,118.32 (HE20) against DA prints of $347 and $257, respectively. We flagged but cannot confirm a generation dip around Fermi and other units during the event window; until telemetry vs. trip is resolved, we’re treating solar ramp-down, weaker imports and load beat as the primary, confirmed drivers.
Why it matters: No unit trip, no wind miss — just ordinary load forecast error (~5 GW) stacking on the routine evening solar ramp-down with weaker imports. That combination alone was enough to trigger EEA2 and hit the cap, which means the reliability margin has shrunk further than the market has priced in.
Critical risks going forward:
- Imports can’t be assumed as a reliable hedge during the evening ramp — if neighboring-system tightness or transfer constraints reduce import availability at the same hours MISO’s own margin is thinnest, that’s a correlated risk across the footprint, not a diversified one.
- Forward curves and RT vol should reprice — if somewhat routine variance can trigger caps, cap-hitting probability across the summer strip is higher than a single-event read would suggest.
