PJM's hardest hour is moving to the winter morning, and the city feels it

I.Why the hardest hour moved to the winter morning

For decades the single highest-demand hour on the regional grid arrived on a summer afternoon, when air conditioners ran flat out across the Delaware Valley. That is still often true. But cold mornings have become a serious rival, and the hours of highest stress on the system, when available supply is tightest against demand, increasingly land in winter. PJM Interconnection, the regional transmission organization (the operator that runs the high-voltage grid for Philadelphia and twelve other states plus Washington, D.C., serving on the order of 65 million people), has said for several years now that winter risk is growing.

Two things drive it. More heating is moving onto the electric grid as homes and buildings swap gas and oil for electric heat pumps, so a hard freeze now pulls more power than it used to. And cold snaps are hard on supply as well as demand: during Winter Storm Elliott in late December 2022, PJM lost a large amount of generation to cold-related failures at the same moment demand spiked, and the grid came closer to rolling outages than it had in years. The worst squeeze tends to hit the dark, frigid hour after people wake, roughly six to nine in the morning, when heating load is high and rooftop solar is producing little or nothing.

II.What a winter peak does to a Philadelphia bill

Those few extreme hours matter to your bill out of proportion to how rare they are. PJM pays power plants and other resources, through what it calls the capacity market, to promise they will be available during the system's tightest moments. The cost of that promise is set partly by how high the peaks are expected to climb, and it flows through to customers. PECO, the utility serving roughly 1.6 million electric customers across southeastern Pennsylvania at last public report, buys that capacity and recovers the cost in the rates it charges.

The honest answer to how much a colder, peakier winter adds to a single rowhouse bill is: it depends, and not by a tidy amount you can read off a statement. Capacity prices in PJM's most recent auctions rose sharply compared with prior years, which puts upward pressure on the supply portion of bills across the region. How that lands on your meter depends on your usage, your rate, and whether you take PECO's default service or buy power from a competitive supplier. If you want the specific number, the place to find it is the supply line on your own PECO statement, not a regional average.

III.How demand response pays buildings to pull back

When the grid is squeezed, one of the cheapest ways to keep the lights on is to pay customers to use less for a short window instead of firing up another plant. PJM calls this demand response. A building agrees, usually through a middleman called a curtailment service provider (a company that signs up customers and bids their load reductions into PJM's markets), to cut power on short notice when PJM asks, and gets paid for standing ready and for actually cutting. Most of the money goes to larger commercial and industrial sites, a warehouse that can idle equipment, a cold-storage plant that can coast, an office tower that can dim and ease back on ventilation.

For a single rowhouse the direct payments are modest, but the door is not closed. Some residential demand response runs through smart thermostats and utility programs that nudge heating or cooling for an hour or two during a peak in exchange for a small credit. The sensible first step for a homeowner is to check what PECO currently offers, and for a business, to ask whether a curtailment service provider can get the building into PJM's program. Terms change year to year, so confirm the current rules rather than trusting last winter's pitch.

IV.Worth watching this month

1. PJM posts cold-weather advisories and emergency operations notices on its website ahead of Arctic outbreaks, so when a hard freeze enters the Philadelphia forecast it is worth checking pjm.com for a cold weather advisory, a routine but telling signal.

2. PJM's next capacity auction, the Base Residual Auction where the grid pays resources to be available years ahead, is the clearest read on how tight winter supply is expected to get, and the schedule has shifted before, so watch for PJM's published dates and results.

3. PECO renews its budget billing and customer assistance programs each fall, and the utility's winter-preparedness page is the place to confirm current enrollment windows before the cold sets in.

4. The Pennsylvania Public Utility Commission posts utility filings and winter service rules at puc.pa.gov, where a reader can follow PECO rate and service proceedings that eventually reach the bill.

Sources on the bench

PJM Interconnection, Demand Response (regional grid operator) How PJM's demand response programs work and who can participate, straight from the operator that runs the grid. · www.pjm.com/markets-and-operations/demand-response
PJM Learning Center (regional grid operator) Plain-language explanations of the capacity market, winter operations, and how peaks are measured. · learn.pjm.com
PECO (the Philadelphia-area electric utility) Current billing assistance, budget billing, and any residential energy programs, plus the supply line that sets your rate. · www.peco.com
Pennsylvania Public Utility Commission (state agency, .gov) Utility filings, rate proceedings, and winter service rules for PECO and other Pennsylvania utilities. · www.puc.pa.gov
Federal Energy Regulatory Commission (federal agency, .gov) Oversees PJM's markets and capacity auction rules, where the big regional decisions are reviewed. · www.ferc.gov