The Grid Just Changed the Rules on Data Centers. Here's What It Means for Power Pricing and Grid Congestion

On September 30, 2026, PJM Interconnection, the grid operator serving roughly 67 million people across 13 states and Washington, D.C., opens a capacity auction it has never had to run before: a backstop auction with up to $20 billion to spend and a price cap of $555 per megawatt-day, nearly 70% higher than the cap on its regular annual auction. It exists because PJM's most recent base auction, for the 2028/2029 delivery year, came in 6.8 gigawatts short of the grid's 20% reserve margin target, the second straight year PJM has missed that target and the third straight year its auction has hit the maximum allowable price.

Layered on top of that, PJM has asked federal regulators to approve a new rule that would change site selection math directly: starting June 1, 2027, any data center or other large load of 50 megawatts or more that connects to PJM's grid would have to either secure its own qualifying power supply or accept that it will be first in line for cuts when the grid is stressed. The rule isn't final; it's still awaiting a ruling from the Federal Energy Regulatory Commission. But for developers, it already collapses what used to be two separate research tracks, checking today's power pricing and checking grid congestion at a candidate site, into a single question that has to be answered before a site option is signed, not after.

Why PJM Is Running an Emergency Auction

The numbers explain the urgency. PJM's capacity price has gone from $28.92 per megawatt-day for the 2024/2025 delivery year to $329.17 for 2026/2027 (a jump PJM's own analysis attributed 63% to data center load growth) to $333.44 for 2027/2028, and now to $325 for 2028/2029, a price that only looks like a decline because it is once again pinned at the regulatory cap. Left uncapped, PJM estimates this year's auction would have cleared closer to $555 per megawatt-day, pushing total auction costs from $16.4 billion to nearly $30 billion.

The supply side isn’t keeping pace either. Only about 525 megawatts of new generation cleared in this year’s auction, down from 774 megawatts the year before, even as the reserve margin gap widened from 6.5 gigawatts to 6.8 gigawatts. Aurora Energy’s Julia Hoos has described the pattern as an "intervention doom loop," one that doesn’t yet reward the two things the grid needs most: new capacity and demand response. For an individual large customer, the dollar impact is direct. Unison Energy has estimated that a 10 megawatt industrial load’s monthly capacity charge could climb from roughly $6,000 in 2024 to roughly $70,000 by 2028, a more than tenfold increase driven almost entirely by the capacity price trend above.

The New Deal: Bring Your Own Power or Get Curtailed First

PJM filed its two-part response with FERC on July 31, 2026: a backstop auction to close the immediate 6.8 gigawatt gap (the one opening September 30) and a longer-term framework called Interim Resource Adequacy Service, built around what PJM is calling a "Bring Your Own New Capacity," or BYONC, pathway.

The mechanics matter for anyone evaluating a site, pending approval. As proposed, large loads connecting after June 1, 2027 would fall into interim resource adequacy service by default, meaning they'd be treated as unsupported demand and become the first candidates for curtailment during a declared grid emergency. A data center could avoid that exposure by designating new generation, storage, or another qualifying resource that matches its peak demand, backed by a firm Electric Service Obligation or Construction Commitment PJM can count in its own planning. PJM would also maintain a registry tracking each large load's location, peak demand, and backup capacity, and affiliated facilities within one mile of each other could be consolidated and evaluated as a single site, which has real implications for how campuses get phased and clustered. The comment period on the filing closed September 3, 2026, so a FERC ruling could land at any point from here forward, and the details above could still change before it does.

The reaction from grid advocates has been notably positive for a rule this consequential. The Natural Resources Defense Council’s Tom Rutigliano called requiring data centers to bring their own power "the single best thing they could have done to stabilize the grid." Whether it holds ratepayers harmless, though, depends on decisions individual states still have to make about how the resulting costs get allocated.

What This Means for Grid Congestion and Power Pricing Research

Historically, a site's electrical profile has been checked in two separate motions: Available Transfer Capacity (ATC), which measures how much power a substation can move through the grid without an upgrade, and offtake capacity, which measures how much power can actually be drawn from the grid for consumption. As LandGate has explained previously, confusing the two, or checking only one, is how projects end up stuck behind a multi-year interconnection queue after the land is already under contract.

PJM's new framework adds a third layer that used to live in a different spreadsheet entirely: capacity price exposure. A site with plenty of open offtake capacity today can still carry a steep and rising capacity charge, and after June 1, 2027, that same site can carry real curtailment risk unless the project brings qualifying capacity of its own. Grid congestion data (can this substation take the load) and power pricing data (what will it cost, and is it protected from cuts) now have to be evaluated together rather than sequentially.

That's the gap LandGate's Powered-Land Due Diligence Checklist for Data Center and Renewable Developers is built to close, pairing data center due diligence reports with the underlying interconnection and pricing data so a site can be scored on both dimensions before capital is committed.

What Due Diligence Teams Should Check Before the Backstop Auction Clears

A handful of questions belong at the top of every data center and renewable site evaluation between now and the December 2 results date:

Capacity price exposure. What rate class and capacity charge trajectory applies to this site's utility footprint, and how does it compare to the roughly tenfold increase industrial loads have seen since 2024?

Interconnection timing relative to June 1, 2027. A project that can reach commercial operation before that date avoids Interim Resource Adequacy Service exposure entirely. One that can't needs a BYONC plan in place well before then, not after.

BYONC feasibility. Does the site support on-site generation, battery storage, or behind-the-meter natural gas at a scale that can plausibly match peak demand, or is qualifying capacity going to have to be procured elsewhere?

Clustering and consolidation rules. Because affiliated facilities within one mile can be evaluated as a single load, campus phasing plans need to account for how PJM's registry will treat them collectively, not project by project.

Backstop and base auction results. The September 30 to October 21 backstop auction and the standard base auction for the 2029/2030 delivery year that follows it will both move the pricing and capacity picture again; this isn't a one-time reset.

The Takeaway

PJM's backstop auction is a short-term fix for a 6.8 gigawatt hole. The Bring Your Own New Capacity framework behind it is the longer-term signal: grid operators are done treating large loads as passive customers, and starting in mid-2027, power pricing and grid congestion data stop being separate checks and become the first filter a data center or renewable site has to clear.

See Where Your Site Stands Before the Auction Clears

Between now and the December 2 backstop auction results and whatever FERC decides on the BYONC framework, the sites that get optioned safely will be the ones where power pricing and grid congestion were checked together, not sequentially. LandGate's Offtake Capacity and ATC Data tools show both at the point of interconnection, and its Data Center Due Diligence Reports layer that on top of environmental and title risk so a candidate site can be scored before capital is committed.

Request a Demo to see how your own shortlist looks against this data. 

FAQ

What is PJM's backstop capacity auction and when does it happen?

It's a one-time reliability procurement PJM is running from September 30 to October 21, 2026, with up to $20 billion available and a price cap of $555 per megawatt-day, meant to close a 6.8 gigawatt shortfall against PJM's 20% reserve margin target. Results are expected December 2, 2026.

Why are power prices going up for data centers in PJM?

PJM's own analysis attributes the majority of recent capacity price growth to data center load, and the grid operator's base auction has hit its price cap for three consecutive delivery years as demand has outpaced new generation. A 10 megawatt industrial load's monthly capacity charge has been estimated to rise from roughly $6,000 in 2024 to roughly $70,000 by 2028.

What is PJM’s "Bring Your Own New Capacity" (BYONC) requirement?

It's part of a framework PJM filed with FERC on July 31, 2026, and it isn't final yet. As proposed, starting June 1, 2027, large loads of 50 megawatts or more that don't secure their own qualifying generation, storage, or capacity commitment would be treated as unsupported demand and become the first candidates for curtailment during a grid emergency.

How can I check grid congestion and power pricing before choosing a data center site?

Grid congestion is typically checked through a substation's Available Transfer Capacity (how much power it can move without an upgrade) and offtake capacity (how much power can be drawn for consumption), while power pricing depends on the applicable capacity rate class and charge trajectory. Under PJM's new framework, both now need to be checked alongside a site's BYONC feasibility before a site is optioned.

What's the difference between ATC and offtake capacity?

Available Transfer Capacity (ATC) measures how much power a substation can move through the grid without needing an upgrade, the number renewable developers typically check before interconnecting. Offtake capacity measures how much power can be drawn from the grid for consumption, the number that determines whether a data center campus can actually be energized.