Confirmed: ISO New England began using four revised day-ahead market rules on October 22 for the October 23 operating day. Maine is part of this regional market.
The most important clean-energy change adjusts forecast demand to account for expected production from front-of-the-meter wind and solar that may not clear in the day-ahead market. ISO New England found that its prior method could undercount those resources and lead the market to procure more supply than needed.
The package also establishes a floor for an ancillary-services strike price, sets a $3 per megawatt-hour floor for a market-power test and removes a credit adjustment for certain compensation payments.
FERC approved the revisions as just and reasonable. Its order says the wind and solar adjustment would have reduced the hourly demand input by an average of 422 megawatts if it had applied during the market's earlier operating period. That is a historical estimate from the filing, not a promise of future savings.
Analysis: This is a practical correction. Maine customers help pay for the regional resources ISO New England secures ahead of each operating day. Counting expected renewable output more accurately should reduce needless procurement pressure. The reserve market still exists to prepare for outages and forecast errors. Mainers should not expect an immediate, visible bill cut from this rule change alone.