​New England's Clean Energy Connect (NECEC), a 1.2 GW import line, began commercial delivery to ISO-NE on January 16, 2026. It carries cheap Canadian hydropower into Maine at a single node and was built to run near full output. From its start date through late May it ran near full output most days, with a multi-day outage in April and another outage in late May through early June. Those gaps let us compare the same grid with the line running and with it off.

Key takeaways

• NECEC lowered day-ahead prices across ISO-NE and made Maine the cheapest zone during every hour. Maine's discount to the pool doubled from $3/MWh in early 2025 to $6/MWh on online days.
• Day-ahead spreads, the money earned from storage that buys low and sells high, did not widen, and Maine gained no locational edge. During online spring days, day-ahead TB4 rose about 21% in Maine and 23% pool-wide.
• Real-time prices diverged from the day-ahead market. Online spring days saw Maine's real-time TB4 run $43/MW-day above the pool, against $19/MW-day without the line. That gap does not appear in day-ahead.
• The real-time premium is conditional. It depends on the roughly one online day in five when NECEC swings more than 300 MW. On steady-flow days the premium is modest, but on ramp/offramp days it jumps to +$57/MW-day in spring and +$125/MW-day in winter.

NECEC injects cheaper energy, with Maine the cheapest corner

A 1 GW injection of near-zero-cost supply lowers the clearing price across the region. Day-ahead prices fell most in the expensive hours of shoulder months, where the import displaces peaking generation. The energy lands in Maine, so Maine’s price separation was the largest. The New Hampshire–Maine interface often became binding, driving negative congestion. Maine's discount to the pool roughly doubled, from $3/MWh in early 2025 to $6/MWh on online days.

During the April and May outages the discount briefly disappeared, which is the clearest sign it comes from the line. The discount is applicable across all hours. Maine clears below every other ISO-NE load zone in every hour of the day, widest at midday near $10/MWh when imports and solar overlap.

Day-ahead spreads did not widen

On matched spring days the four highest-priced hours fell 7% when the line ran while the four cheapest rose, so day-ahead TB4 compressed rather than widened. For siting, the lift that did show up was uniform across zones. Maine and the rest of ISO-NE moved within two points of each other, and day-ahead hands Maine no locational edge.

Winter may haven widened, but could have been driven by a January 2026 cold snap. Alternatively, spring trends will hold as seasonal fluctuations impact both online and outage days.

Real-time tells a different story

Switch the same chart to real-time and Maine separates from the pool. On online spring days Maine's real-time TB4 reached $244/MW-day against $201/MW-day for the rest of ISO-NE, a $43/MW-day premium. Without the line that gap was $19/MW-day. The extra $24/MW-day shows up only in real-time, which the day-ahead schedule has already smoothed over.

The premium rides on cyclic operation

It’s unclear whether the real-time edge will last. Most online days NECEC runs at a constant level near 1,030 MW with almost no intra-day movement. On those steady days Maine's real-time premium is modest: about $39/MW-day in spring and $10/MW-day in winter. The premium concentrates on the days the line swings more than 300 MW, ramping from full off to full on or back. On those on/off cycle days the premium jumps to $57/MW-day in spring and $125/MW-day in winter.

A 1.2 GW block moving at one node is what moves the real-time price there. When the line holds steady, the node settles and the premium shrinks. When it cycles, real-time prices at Maine spike and recover in ways the rest of the pool does not see. The real-time edge tracks how reliably NECEC runs rather than how much it imports.