New England Clean Energy Connect (NECEC) entered commercial operation on January 16, 2026. The DC transmission line carries up to 1,200 MW of Hydro-Quebec hydropower into Lewiston, Maine.

NECEC met its contracted deliveries whenever it ran, and Maine priced below the rest of ISO-NE on every summer day the line was in service. Over the summer, Maine's day-ahead four-hour top-bottom (TB4) spread averaged $28/MW-day below the RTO-wide average on 78 online days. In contrast, the 14 days where NECEC was offline averaged only $3/MW-day below.

Maine's lower TB4 spreads concentrated in July 2 and 3, the summer's two most volatile days, when imports suppressed prices in the peak hours that drove volatility across the rest of the RTO.

Key takeaways

• NECEC ran as contracted baseload, averaging 1,075 MW when excluding two outages. The line's recorded summer delivery of 2,019 GWh equaled 75% of Maine's consumption.
• Maine's day-ahead price averaged $7/MWh below the rest of ISO-NE when NECEC was online, against $1/MWh below when it was offline. Congestion behind the Maine-New Hampshire interface accounted for half the discount.
• Phase II, another line between Hydro-Quebec and ISO-NE, flipped from importing an average of 221 MW to being a net exporter. Quebec still delivered a net 910 MW to ISO-NE across its three ties, up 640 MW year over year.
• Maine's lower spreads were most apparent on July 2 and 3, the summer's two most volatile days, when scarcity lifted the other zones' spreads far more than Maine's. The two days ran $946/MW-day and $686/MW-day below the seven-zone average.

NECEC delivered its contracted flows whenever it was online

NECEC is the newest of three Hydro-Quebec ties into New England. Phase II, a 2,000 MW line into Sandy Pond, Massachusetts, and the smaller Highgate tie into Vermont came decades earlier. Alongside New Brunswick and three New York connections, ISO-NE trades across seven external interfaces in total.

NECEC's imports averaged 915 MW across the summer, including outages. Excluding the 14 offline days, imports averaged 1,079 MW, within 1% of the contracted 1,090 MW. The hourly averages sat between 1,065 and 1,087 MW, representing consistent imports throughout the day. A day counts as online when NECEC's maximum hourly flow tops 300 MW, applicable to 78 of 92 summer days.

Three interruptions tripped NECEC offline in the past six months. The first ran April 7 to 17, before summer, and the others May 25 to June 8 and August 24 to 30. ISO-NE reported the May window as a planned outage of the Merrill Road to Larrabee delivery line. The August outage has no stated cause in ISO-NE reporting or press coverage.

NECEC transformed the broader Canada and New York interchange

New England's interchanges with Hydro-Quebec and NYISO changed behaviors when NECEC was brought online. Phase II went from importing an average of 221 MW in summer 2025 to exporting a net 42 MW toward Quebec. Highgate eased from 49 MW to 37 MW. In total, the three Hydro-Quebec ties still delivered a net 910 MW into New England, up 640 MW on last summer.

Net imports across all seven external interfaces nearly quadrupled, from 347 MW to 1,331 MW between the two summers. The other four interfaces added 344 MW, alongside the 640 MW from the Hydro-Quebec ties. The added imports brought cheap energy into ISO-NE and suppressed spreads. Summer hub day-ahead TB4 spreads fell 19% year over year, from $241/MW-day to $195/MW-day.

A binding Maine-New Hampshire interface turned Maine into a locally suppressed price zone

Maine's day-ahead energy price averaged $7/MWh below the load-weighted rest of ISO-NE on online summer days, against $1/MWh on offline days. Congestion accounted for $3.6/MWh of the discount and losses for $3.2/MWh.

ISO-NE attributes Maine's depressed early-July pricing to the binding Maine-New Hampshire interface. When that interface binds, Maine becomes a locally isolated price zone. NECEC's imports, nearly the size of Maine's average load, sit behind the constraint and suppress Maine's prices rather than ISO-NE's as a whole.

Spread suppression appeared only on the summer's two most volatile days

NECEC suppressed Maine's prices on every online day, but had an outsized impact on spreads only on July 2 and 3, the two most volatile days of the summer. On typical days the discount sat across all 24 hours, so Maine's top-bottom shape stayed intact. When scarcity made the Maine-New Hampshire interface bind, ISO-NE's peak pricing could not reach Maine, and the units setting prices elsewhere never set Maine's.

July 2 and 3 carried the widest pool spreads of the summer, with the seven-zone day-ahead TB4 average reaching $3,041/MW-day and $1,343/MW-day. Maine reached $2,095/MW-day and $657/MW-day. The two days accounted for 74% of Maine's online-day spread deficit.

On July 2, Boston passed 100F and ISO-NE demand peaked at 25 GW. CHPE delivered its full 1,250 MW evening block into New York City the same day. On July 3, imports held between 1,087 and 1,089 MW all day and Maine's spread ran less than half the pool's.

On July 2, the entire gap sat in the peak hours. Maine's four highest day-ahead prices averaged $568/MWh against $808/MWh across the other zones, while the four cheapest hours matched the pool's. The 11 other days that reached 90F in Boston sat $16/MW-day below the seven-zone average in day-ahead, in line with 2022-2025 hot days.

What does NECEC mean for Maine batteries?

NECEC averaged 915 MW across all summer hours, a 76% capacity factor. Modo Energy's July benchmark still modeled Maine BESS revenue at $14.5/kW-month, within 1% of the NEMA/Boston zone. Day-ahead ten-minute non-spinning reserve supplied 73% of that total.

For investors and developers underwriting ISO-NE, NECEC limits Maine’s arbitrage potential on the most volatile days. When NECEC ran at its contracted flows behind the binding Maine-New Hampshire interface, Maine cleared below the pool.

Reserves rather than spread capture carry the revenue case for BESS in ISO-NE. That owes more to the market's reserve design than to NECEC, and it will hold until the ancillary services market saturates with new, eligible BESS projects.