FERC denies battery waiver; four Massachusetts projects leave ISO-NE queue

The Federal Energy Regulatory Commission on October 16, 2026 refused to pause the deadlines facing five Massachusetts battery developers who say ISO New England's Transitional Cluster Study charged them for grid upgrades they did not cause. Within four days, four large Massachusetts battery projects left ISO New England's interconnection queue: Moraga Storage's 180 MW project in Worcester County and River Mill Storage's 500 MW project in Middlesex County on October 19, then two Essex County projects of 200 MW and 225 MW on October 20. The four positions carried $1.29 billion of estimated interconnection costs between them, by our arithmetic from the study's final report.

That is about 40% of the roughly $3.2 billion the August 6 report estimated for its 23 projects, as FERC's order tallies it, and it includes the largest single-project estimate in the study: $540.6 million for the 200 MW Essex County position, QP1555. River Mill's $425.6 million was next. Neither Essex County project belongs to the five complainants, and the queue records withdrawal dates, not reasons.

What FERC decided

What the five developers wanted was time. Moraga Storage, River Mill Storage, Hecate Energy Medway Energy Center, Brough Storage and Partridge Storage asked FERC to suspend four tariff requirements until it ruled on the complaint they filed on September 30, among them the 60-day window to sign an interconnection agreement or be deemed withdrawn, a deposit of 20% of estimated network upgrade costs, and a withdrawal penalty of nine times a project's study costs since entering the queue. For River Mill, the developers told FERC, the deposit alone would be about $85.1 million. The order (197 FERC ¶ 61,041, docket EL26-112) rules only on that request.

FERC said it "has repeatedly denied" waivers of queue deposit, security and penalty rules, because complying with them "in order to retain an interconnection queue position is not a concrete problem warranting waiver." Calling the study defective, the order said, assumes what the complaint has yet to prove, and "at this early stage, we decline to assume for the sake of argument whether Project Companies' complaint would succeed on the merits." Granting the pause would also have hurt the projects staying in the cluster, FERC found: they would face about four months of uncertainty over whether the complainants would leave, and whether that would force a restudy and re-cut their shared upgrade costs. A waived penalty would also not be there to cushion them if the complainants left anyway.

The complaint itself, which asks FERC to order a restudy under a different method, is still pending, and ISO New England's answer is due October 30. ISO New England has told FERC the developers want the study redone "with a different study methodology that they find more to their liking," as the order paraphrases it.

Who has gone, and who has not

The complaint's lead affidavit said each of the five project companies would withdraw unless the study was redone. Two have. The other three were still listed as active in the queue on October 23: Hecate's 300 MW Medway project in Norfolk County and CleanCapital's Brough (290 MW) and Partridge (136 MW) projects in Berkshire County. The queue does not show which of the October 20 options they took: signing an agreement, asking for it to be filed unexecuted at FERC, or entering dispute resolution.

Across the whole cluster, 12 of the 23 positions in the final report are now listed as withdrawn, ten of them since the report came out on August 6. Among them is East Point Energy's 125 MW Tewksbury battery, which left on August 31 after a $65.3 million estimate (our coverage). The 11 positions still active account for 2,637.9 MW of the report's 4,826.5 MW of summer capacity, by our arithmetic from its project table.

The New England states split. Massachusetts' Department of Energy Resources backed the waiver, Connecticut's energy department backed it if it would not delay ISO New England's next study, and the Maine Public Utilities Commission and New Hampshire's Department of Energy opposed it. Massachusetts, home to most of the cluster's batteries, is pursuing 5,000 MW of energy storage by 2030 under Section 83E, Energy and Environmental Affairs Secretary Rebecca Tepper wrote to ISO New England on June 25, warning that if the interim study's cost and construction timeline estimates were finalized, they "will have a significant chilling effect on investment in Massachusetts and across the New England region for years to come." The four projects that withdrew on October 19 and 20 add up to 1,105 MW, a little over a fifth of the 2030 figure.

What comes next

ISO New England will decide whether the departures require a restudy "on or soon after November 4, 2026," when deposits for signed agreements fall due, according to a September 28 memo to developers. Projects that asked for unexecuted agreements owe their deposits on October 30. Any restudy, the memo says, "will be performed consistent with the methodology used for the conduct of the TCS," so the remaining projects would be re-priced by the same method the complaint attacks.

The penalties paid by projects that leave are the other open question. The tariff does not yet say how they are spent. ISO New England's proposal would use them first to pay for any restudy once forfeited request deposits run out, then to offset upgrade cost increases for remaining projects that shared upgrades with the ones that left, and return the rest to the withdrawn projects. It shelved its planned October 14 presentation of that design to stakeholders, saying in an October 7 memo that "the ISO will be focusing its resources on addressing the litigation." It now promises the full design "as soon as practicable."

The next round is already open. ISO New England reopened its queue on October 5 for its first regular cluster study, and the request window closes on November 19, per its study calendar. The complaint's fallback request is a changed method for that study; ISO New England's September 28 memo says it "will continue efforts to examine lessons learned from the TCS and examine its study methodology in advance of the beginning of the first Cluster Study." Our What is an interconnection queue? explainer covers how cluster studies assign upgrade costs.