Real-Time TB4 spreads in PJM averaged $631/MW-day in October 2026, up 107% year-on-year. Day-Ahead spreads also rose, up 124% to $494/MW-day. October 13 and 14 alone made up 41% of the month's cumulative Real-Time spread. Without them, the month would have averaged $409/MW-day.

On October 13, unseasonable warmth pushed load to 108 GW while 61 GW of generation was offline (46 GW of it was scheduled for maintenance). PJM issued Capacity Advisories days ahead and a Maximum Generation Alert the day before. On the day, it called demand response and used a Department of Energy emergency order.

A month prior, PJM also experienced a confluence of heat and scheduled outages, but Day-Ahead missed it. This time PJM predicted it: Day-Ahead priced the 13th at $2,400/MW-day, then overpriced the 14th at $2,927/MW-day, against $1,280/MW-day in Real-Time.

Despite higher energy price volatility, Modo Energy's virtual BESS (vBESS) benchmarks put a 100 MW, 4-hour battery at $14/kW-month to $18/kW-month across ComEd, Dominion, and Penelec. That is 51% to 54% below October 2025. The drop was largely due to frequency regulation, whose price fell 44% and whose revenue fell from about $24/kW-month to under $4/kW-month. Higher Day-Ahead energy revenue could not cover the gap.

Key takeaways

• Modeled batteries in ComEd, Dominion, and Penelec earned $16/kW-month, $18/kW-month, and $14/kW-month, respectively. For only the third month since the beginning of 2025, Day-Ahead energy was the largest stream in all three stacks.
• Real-Time TB4 spreads averaged $631/MW-day, up 107% year-on-year. Day-Ahead spreads reached $494/MW-day, up 124% year-on-year.
• On October 13, Real-Time prices hit $1,640/MWh at 6pm, against $886/MWh in Day-Ahead. A day later, Day-Ahead overtook Real-Time, at $1,245/MWh against $563/MWh in the same hour.
• Regulation cleared $67/MWh, 44% below October 2025. Both months come after PJM's October 2025 regulation redesign, so this is the first like-for-like comparison. It is also the first year-on-year fall since the redesign.

vBESS benchmarks show a battery could have earned $14/kW-month to $18/kW-month

Day-Ahead energy led every vBESS revenue stack: $8.06/kW-month in ComEd, $10.38/kW-month in Dominion, and $6.88/kW-month in Penelec. Of the 22 months of vBESS data since January 2025, Day-Ahead energy led all three stacks in only three months: July, September, and October 2026. In ComEd and Penelec, Day-Ahead energy revenue was 67% and 78% above October 2025.

Regulation revenue fell to about 13% of its October 2025 level, the lowest of the 13 months since the redesign in all three zones. Lower prices explain only part of that fall. The regulation price fell 44%, while revenue fell 86% to 87%, which implies the modeled batteries also sold less regulation, shifting toward energy arbitrage instead.

Heat and autumn maintenance drove the October 13 spike

October 13 cleared a daily Real-Time TB4 of $4,873/MW-day, more than six times October 2025's highest day ($779/MW-day). That single day made up 32% of the month's cumulative Real-Time spread.

On October 13, temperatures reached 81°F in Philadelphia, 82°F in Washington DC, and 89°F in Cincinnati, 12°F to 20°F above their October 2025 average highs. Load peaked at 108 GW, 14 GW above the month's median evening peak of 94 GW.

Meanwhile, about 61 GW of generation was offline, 46 GW of which was scheduled for maintenance. PJM bars these scheduled outages through the summer peak season, so they cluster in autumn. Together, evening load and outages reached 169 GW to 170 GW on the 13th and 14th, the highest of the month.

PJM had been warning of the risk for days. It issued Capacity Advisories for October 12, 13, and 14, and recalled generators from maintenance outages. On October 12, it declared a Maximum Generation Alert for the 13th and later extended it to the 14th. The alert warns that PJM may need emergency generation and demand response to meet load, and asks generators how quickly they can return units from scheduled maintenance. PJM then called demand response on both days.

The squeeze came at sunset on October 13. Solar fell from 10.7 GW at 4pm to near zero by 7pm, while load held near 107 GW. Real-Time prices peaked at $1,640/MWh in the 6pm hour.

Reserves never fell below their requirement. Even so, synchronized reserve cleared at $300/MWh to $1,150/MWh from 5:55pm to 7:50pm as the margin thinned.

Day-Ahead priced October 13, unlike September 16

On September 16, PJM also faced warm weather while generators were on scheduled maintenance, and Day-Ahead missed it. This time, the market prepared for it.

Day-Ahead prices peaked at $886/MWh on the 13th and $1,245/MWh on the 14th. On September 16, they peaked at just $353/MWh.