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Interconnection queues and costs in the US

Who gets into the queue, who pays for the grid upgrades and how data centers get connected: the standing record of US interconnection reform, cost fights and large-load rules.

Updated · first published · 8 min read

Where things stand

As of October 6, 2026, the reformed US interconnection queues are moving, and the arguments have shifted to who gets cut, who pays for the upgrades and how data-center load gets in. At the end of 2025 about 8,200 projects sought a grid connection, 1,312 GW of generation and roughly 749 GW of storage, a 10% drop in active volume from a year earlier, per Lawrence Berkeley National Laboratory's Queued Up 2026 edition. Only 13% of the capacity that applied from 2000 to 2020 had reached commercial operation by then.

The rulebook is FERC's Order No. 2023, effective November 6, 2023, which moved transmission providers from serial queues to first-ready, first-served cluster studies: deposits, site control at the time of request and withdrawal penalties for developers, and penalties for providers that miss study deadlines.

PJM says no backlog remains from its old queues. Phase I of Cycle 01, its first reformed cycle, began September 28, 2026 with 617 projects and nearly 169 GW: storage leads the count with 265 projects, natural gas the capacity with 81.1 GW. FERC has upheld two of PJM's Cycle 01 removals, Oklo's 750-MW project on September 24 (one chance to cure) and Advantage Capital Renewables' storage project on October 1. Oklo had sought no rehearing as of October 6, and complaints by Agilitas Energy, RWE Americas and Lanyard Power remain pending.

Upgrade costs are the other gate. ISO New England's transitional cluster study put estimates of $672,500 to $540.6 million on 18 of its 23 projects, and East Point Energy pulled its 125-MW Tewksbury battery from the queue after the study put $65.3 million of upgrades on its queue position (our coverage); the state Siting Board had not ruled on its withdrawal motion as of October 6. In PJM, upgrade estimates for the last transition cycle fell $8.7 billion between study phases, mostly, PJM says, because of transmission its board approved in February. At the distribution end, Massachusetts replaces last-customer-pays charges with a $225 pooled fee for small solar and battery systems starting November 1, 2026.

Large loads come in by a different door. PJM has no load interconnection queue; utilities submit large-load adjustments to its forecast. PJM's October 6 proposal would make computational loads of 50 MW or more, with at least 25 MW served through power electronics, ride through grid disturbances, and MISO asked FERC on October 2 for a 120-day study that pairs loads of at least 200 MW with new generation in the same resource zone.

The large-load forecast is also the disputed number in PJM's capacity backstop. FERC accepted the Reliability Backstop Procurement on September 29 but suspended it to February 28, 2027 and told PJM to use up-to-date forecasts for a target of up to 6,831 MW; the Market Monitor, as the order summarizes it, puts the 2028/2029 shortfall at 3,055 MW after 4,017 MW of data-center load was cancelled or delayed (our coverage). PJM had not refiled as of October 6.

Timeline

202420252026Oct 6, 2026Oct 2, 2026Oct 2, 2026Oct 1, 2026Sep 29, 2026Sep 29, 2026Sep 28, 2026Sep 24, 2026Sep 14, 2026Sep 10, 2026Sep 8, 2026Sep 4, 2026Sep 1, 2026Aug 28, 2026Aug 12, 2026Aug 6, 2026Aug 3, 2026Jul 31, 2026Jul 22, 2026Jun 25, 2026Jun 18, 2026Jun 16, 2026Nov 6, 2023
23 dated events, 2023 to 2026. Jump to 2026, 2023.
  1. 2026

  2. PJM staff brought revised ride-through rules for large computational loads to the Planning Committee. They would cover facilities of 50 MW or more with at least 25 MW served through power electronics, apply to projects entering PJM's study process from January 16, 2027, and give facilities already operating, building, under agreement or in study before then until January 16, 2028 or a year after commercial operation, whichever is later; the deck schedules a Markets and Reliability and Members Committee consultation on October 28 and a FERC filing in November (deck).

  3. MISO filed its Large Load Addition Resource Study (LARS) in FERC docket ER27-25: a study of about 120 days for a load of at least 200 MW and new generation in the same local resource zone, ten applications per study period and three periods a year, with the pair bound together for at least 15 years and an entry milestone of $30,000 per MW. MISO asked for an order by December 2, 2026 so it can start the first study period in the first quarter of 2027, and says LARS also responds to FERC's June 18 show-cause order on its large-load rules (transmittal letter).

  4. ISO New England published a capacity heatmap and a queue map and said developers can submit requests for its first full cluster study between October 5 and November 19, 2026; battery storage, it says, forms the bulk of the current queue (ISO Newswire).

  5. FERC denied Advantage Capital Renewables' complaint over PJM's withdrawal of its Freshwater Dune storage project from Cycle 01 (197 FERC ¶ 61,006, docket EL26-99). The order finds the developer's cure submission left eight deficiencies unresolved and that PJM's Dynamic Model Development Guidelines are implementation details that need not be in the tariff; the developer can still try to cure the errors and submit the project to Cycle 02 (order).

  6. FERC accepted PJM's Reliability Backstop Procurement for filing and suspended it to February 28, 2027, sending cost allocation, transmission-owner exit rules and buyer collateral to a paper hearing; it anticipates holding that briefing in abeyance if PJM files a new section 205 proposal by October 29, 2026 (order). PJM said on September 30 the procurement would not begin as planned and that timing is to be determined (PJM).

    Coverage FERC accepts PJM backstop procurement but suspends it to February 2027

  7. Twelve utilities presented large-load adjustments, primarily data centers, to PJM's Load Analysis Subcommittee for the 2027 load forecast. PJM now requires contract status to tell firm commitments from the rest, has hired Charles River Associates to assess data-center demand, and will publish the forecast in January (PJM).

  8. Phase I of PJM's Cycle 01 began with 617 projects and 168.6 GW of nameplate capacity, out of 811 applications and 715 accepted; PJM says 49 GW of generation already holds signed agreements, many of those projects not being built or slowed by permitting and supply chain backlogs (PJM).

  9. FERC denied Oklo's complaint over its 750-MW project (docket EL26-101), reading PJM's tariff as one opportunity to cure after a timely deficiency notice (order).

    Coverage FERC denies Oklo complaint; 750-MW project stays out of PJM's Cycle 01

  10. Oklo told FERC that the five-cycle fault test PJM ran is not in PJM's own modeling guidelines (answer).

    Coverage Oklo tells FERC that PJM's fault test is not in PJM's own guidelines

  11. Current Hydro withdrew, without prejudice, its September 1 complaint against PJM in docket EL26-102 (notice).

  12. PJM first proposed ride-through requirements for large computational loads: return to more than 90% of pre-disturbance consumption within 2 seconds after voltage recovers, and a continuous range of 58.8 to 61.2 Hz (deck).

    Coverage PJM proposes ride-through rules for data centers after 3,800 MW drop-off

  13. PJM asked FERC to deny Oklo's complaint, saying the cured model was unstable when the whole facility was tested at 750 MW and that reinstatement could delay Cycle 01's Phase I by as much as two months (answer).

    Coverage PJM says Oklo's fix left the 750-MW model unstable, asks FERC to deny

  14. Hillman Energy Center, East Point Energy's project company, moved to withdraw its Siting Board petition for a 125 MW / 500 MWh battery in Tewksbury, Massachusetts, saying it had also pulled the project from the queue because cluster study upgrade costs "greatly exceeded previous estimates, making this project economically unviable" (motion; docket).

    Coverage East Point withdraws 125 MW Tewksbury battery over grid upgrade costs

  15. Oklo filed an emergency complaint asking FERC to reinstate its 750-MW project of 150 MW advanced nuclear, 300 MW fuel cells and 300 MW natural gas, which PJM withdrew from Cycle 01 on August 3 (complaint).

    Coverage Oklo asks FERC to reinstate its 750-MW project in PJM's queue

  16. The Massachusetts Department of Public Utilities stamp-approved a non-refundable $225 Common System Modification Fee for listed inverter-based solar and battery systems of 25 kW or less, which pays up to $10,000 of upgrades for Eversource and National Grid customers and up to $1,450 for Unitil customers, effective November 1, 2026 (D.P.U. 26-57).

    Coverage Massachusetts swaps surprise solar upgrade charges for a flat $225 fee

  17. ISO New England's final Transitional Cluster Study report covered 23 projects totaling 4,826.5 MW of summer capacity; its estimates run from $672,500 to $540.6 million for the 18 positions that carry them, including $65.3 million for the Tewksbury position (report).

  18. PJM accepted 715 projects, 201.5 GW, into Cycle 01 from 811 applications (PJM).

  19. PJM opened its Expedited Interconnection Track for large generation projects backed by a primary siting authority that can start operating within three years, up to 10 requests per calendar year in 2026 and 2027 (PJM).

  20. A fault on one 230 kV line in the Dominion zone sent approximately 3,800 MW of northern Virginia data center load to backup power, the largest such transfer in PJM's history (deck; PJM review).

  21. Massachusetts Energy and Environmental Affairs Secretary Rebecca Tepper wrote to ISO New England that its cluster study identified "more than $3 billion in total interconnection costs"; ISO New England replied on June 29 that the transmission investment in the interim report "is driven by the volume and location of proposals in the TCS" (letters).

  22. FERC opened a section 206 proceeding on PJM's large-load transmission service, noting that "the Tariff does not specify ramp rate or ride-through requirements with which the transmission customer taking transmission service on behalf of the large load must comply" (order); it issued a show-cause order on MISO's large-load rules the same day, per MISO's LARS filing.

  23. PJM finished Phase II of its last transition cycle, 270 projects of about 30 GW, and said system network upgrade costs fell $8.7 billion from Phase I, mostly because of transmission its board approved in February and partly because 180 projects withdrew (PJM).

  24. 2023

  25. FERC's Order No. 2023 took effect, requiring cluster studies, readiness deposits, site control and withdrawal penalties, and replacing the reasonable-efforts standard with penalties of $1,000 to $2,500 per business day on late studies (Federal Register).

Next milestone

October 7, 2026: PJM said it would give a brief administrative update on the backstop procurement at that day's Market Implementation Committee, though the agenda posted September 30 does not list it. The firmer dates follow: the October 28 committee consultation on large-load ride-through; October 29, the end of FERC's 30-day window for a refiled backstop; November 19, when ISO New England's cluster request window closes; and December 2, the date MISO asked FERC to rule on LARS.

This is a maintained page: it is revised as the record changes, and every revision is reviewed before it goes live. Dates in the text are the dates the facts hold for, not the date you are reading it.

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