On October 31, 2025, FERC granted ISO New England’s (ISO-NE) request for a limited waiver of its Tariff and Billing Policy to refund, approximately $68,000 in Capacity Performance charges to Brookfield White Pine Hydro LLC (Brookfield). The waiver relates to six five-minute intervals during a June 24, 2025 Capacity Scarcity Condition in which Harris Hydro Station’s Unit 2 (Harris 2) was manually held below its EcoMax[1] because ISO-NE allowed a non-commercial Large Generating Facility to operate on a constrained transmission line, thereby limiting Harris 2’s output and triggering an underperformance assessment.
Under ISO-NE’s Pay-for-Performance Tariff provisions, capacity suppliers are financially rewarded or penalized based on whether they perform during Capacity Scarcity Conditions. ISO-NE’s Tariff provides that a Capacity Scarcity Condition occurs when real-time reserves fall so low that reserve prices reach their penalty factor caps. During such intervals, resources with capacity supply obligations, such as Brookfield, must perform in proportion to their commitments or face financial charges. On June 24, 2025, ISO-NE experienced a Capacity Scarcity Condition due to an operating reserve deficiency. During six five-minute intervals, Harris 2 was manually “held down” below its EcoMax output because ISO-NE allowed another non-commercial generator on the same transmission line to run. Although Harris 2 had the physical ability to produce more power, ISO-NE’s dispatch instructions prevented it from doing so. Because that event coincided with a Capacity Scarcity Condition, ISO-NE treated Harris 2 as underperforming and assessed a penalty.
On August 20, 2025, ISO-NE requested waiver of its Tariff and Billing Policy and explained that its dispatch decision directly affected Harris 2’s ability to perform during the scarcity event. In its requests, ISO-NE sought Commission approval to both refrain from assessing the Performance Payment Charge and to use the Late Payment Account under the Billing Policy to return the penalty amount to Brookfield.
FERC granted the waiver after applying its four-factor test. FERC found that (1) ISO-NE acted in good faith because it identified and reported the issue promptly; (2) the request was limited in scope since ISO-NE only sought to fix a single event affecting one unit; (3) the underlying problem was a concrete problem created by an ISO-NE operational decision rather than resource behavior; (4) and no undesirable consequences would result to third parties, including with respect to settlement impacts and use of the Late Payment Account.
Commissioner Lindsay See dissented, arguing the decision constituted retroactive ratemaking and violated the filed rate doctrine. The dissent highlighted that ISO-NE’s Tariff explicitly specified that “data handling errors that impacted unit commitment or the Real-Time dispatch will not be corrected.” The dissent further encouraged ISO-NE to revise its Tariff language to prevent similar events in the future.
A copy of the order, issued in Docket No. ER25-3253-000, can be found here.
[1] An Economic Max, or EcoMax, under ISO-NE’s Tariff represents the highest MW output a Market Participant has offered for a Generator Asset for economic dispatch.