ISO-NE market monitor issues 2025 report

Total wholesale electricity costs totaled $15 billion in 2025, nearly 50% higher than in 2024, according to the latest annual report from ISO New England’s Internal Market Monitor (IMM).

While the markets remained competitive, the IMM said, more expensive natural gas, tighter supply conditions, and changes to the resource mix and market design drove prices higher.

Published each spring, the Annual Markets Report reviews the development, operation, and performance of the region’s wholesale electricity markets. It also features the IMM’s recommendations for improving market design and rules.

The total wholesale cost of electricity in 2025 was $15.0 billion, the equivalent of $127 per megawatt-hour (MWh) of load served. The total cost was a 48% increase over the $10.2 billion recorded in 2024.

The average price in the Day-Ahead Energy Market was $71.81/MWh, a year-over-year increase of 73%. The average Real-Time Energy Market price increased by 67% from 2024, to $65.89/MWh.

Other highlights from the report include:

• Natural gas prices — the main driver of wholesale electricity costs — more than doubled, climbing from an average of $3.06 per million British thermal units (MMBtu) in 2024 to $6.27/MMBtu in 2025.
• Carbon pricing programs increased average load-weighted energy prices by an estimated $9/MWh in 2025 (up from $8/MWh in 2024), contributing about $1.1 billion to total energy costs.
• Continuing a multi-year trend, net imports declined further in 2025, reaching their lowest level in more than a decade due to reduced hydropower output and a prolonged nuclear plant outage in Canada. As a result, higher-cost resources inside New England more frequently set the marginal price.
• Recent and near-term transmission and offshore wind resource additions have the potential to significantly expand the region’s supply capability and could make a meaningful contribution toward meeting anticipated growth in energy use over the next decade.