Maine's complaint at the Federal Energy Regulatory Commission challenges the extra 0.5% return that utilities can earn for voluntarily joining a regional transmission organization. Other New England states have now backed that complaint, according to Utility Dive.
The adder was designed to encourage utilities to join RTOs, but the complaint is part of a wider trend of states seeking to eliminate the incentive. Supporters of the challenge argue the adder is no longer necessary, while the outcome could affect how transmission investments are rewarded across the region.