A trade group representing multiple MISO power producers has lodged a complaint against retroactive pricing revisions in MISO’s 2025/26 capacity auction, joining Pelican Power in calling the repricing unlawful.

MISO ended its 10-year run allowing energy efficiency in its capacity market, as FERC allowed the change to take effect.

Louisiana-based power generator Pelican Power is the first to register a complaint over MISO’s yearslong miscalculation in its capacity auctions in an effort to stop the RTO’s retroactive pricing corrections.

MISO’s Independent Market Monitor said the recently uncovered, eight-year-old repeat error in the RTO’s capacity market that caused a $280 million impact in this year’s auction alone is unfortunate but insisted the resulting prices were efficient.

MISO said a yearslong software error caused it to clear more capacity than intended in past capacity auctions and which has resulted in an approximate $280 million impact to market participants in this year’s auction.

MISO members largely agreed that MISO’s new capacity auction structure — featuring individual seasonal auctions and a sloped demand curve — is better for the health of the system.

Vistra has agreed to pay $38 million to wind down a long-running FERC inquiry into whether it manipulated prices in MISO’s 2015/16 capacity auction.

MISO said it no longer will recognize energy efficiency as a capacity resource beginning with the 2026/27 auction.

MISO said starting with the 2026/27 planning year, it will require its demand response resources to demonstrate actual demand reductions through tests to weed out imposters in the capacity market.