ERCOT's $39.47/MWh evening puts late West discounts in focus

Today's lower Hub Average curve follows a fall in its 24-hour real-time average from $35.38/MWh to $15.86/MWh. The Oct 10, 6-9 PM CDT discount condition held at an average -$17.46/MWh; the positive-premium and South-separation conditions missed. That shifts attention from South's afternoon premium toward evening discounts. No new causal evidence changes the broad discount reading.

• Met: ERCOT Hub Average real time over day-ahead averaging below -$15.00/MWh, Oct 10, 6 to 9 PM (averaged -$17.46).
• Not met: South Hub real time over day-ahead beyond the typical hub above $15.00/MWh, Oct 10, 2 to 5 PM (peaked at $5.63, 3 PM).
• Not met: ERCOT Hub Average real time over day-ahead averaging above $20.00/MWh, Oct 10, 6 to 9 PM (averaged -$17.46).

For Oct 11's 7 PM CDT hour, the model puts Hub Average at a conditional $36.59/MWh, $2.88/MWh under the $39.47/MWh cleared benchmark. The forecast's 73,128 MW demand maximum comes at 5 PM CDT, before demand less wind and solar jumps 14,460 MW/h in the hour ending 7 PM CDT.

North's $11.30/MWh and South's $18.69/MWh bracketed Hub Average's $12.62/MWh real-time average over midnight-8 AM CDT; system demand averaged 50,702 MW during those hours. The outage forecast puts 22,446 MW out of service at issuance, keeping availability relevant to tonight's transition.

ERCOT's Taylor County manual-action notice came at 1:32 AM CDT; its Oct 10 geomagnetic advisory ran from 1:15 to 7 PM CDT, when canceled. The final Oct 11 delivery hour, 11 PM CDT, cleared $21.60/MWh. 3 sourcesSources for this statementGrid event: Operational InformationERCOTGrid event: Advisory: ERCOTERCOTGrid event: AdvisoryERCOT

West's Oct 10, 9 PM CDT hourly real-time-minus-day-ahead spread was -$16.54/MWh, $12.01/MWh below the typical hub's -$4.53/MWh and outside its $7.61/MWh usual hourly range. That pattern is consistent with congestion at KLNSW substation, where hourly average constraint shadow prices reached $216.01/MWh at 9 PM CDT after $94.92/MWh at 8 PM CDT.

Wind above the forecast available before day-ahead closed supported softer energy prices that hour. West was back above the typical hub on the same real-time-minus-day-ahead basis by 7 AM CDT; tonight's late discount would be a return.

• Hub Average real-time minus cleared day-ahead averaging below -$15.00/MWh during 6-9 PM CDT would extend evening softness against today's lower curve.
• Hub Average real-time minus cleared day-ahead averaging above $20.00/MWh during 6-9 PM CDT would reverse the evening discount.
• West Hub's real-time-minus-day-ahead gap beyond the typical hub below -$10.00/MWh during 9 PM-midnight CDT, versus its $7.61/MWh usual range, would revive late discounts.