Internal Market Monitor releases summer 2025 quarterly report

Despite lower demand, wholesale electricity costs increased this summer due to higher fuel prices, according to the latest quarterly report from ISO New England’s Internal Market Monitor (IMM).

The Summer 2025 Quarterly Markets Report, which covers the period from June 1 to August 31, presents an assessment of each of the region’s wholesale electricity markets, based on market data, performance criteria, and independent studies.

Key findings include:

• The total estimated wholesale market cost of electricity for summer 2025 was $2.61 billion, up 33% from $1.96 billion in Summer 2024. The main driver was an 83% year-over-year increase in the price of natural gas, the region’s primary energy fuel.
• Energy costs totaled $2.25 billion, 45% higher than summer 2024 costs. Total energy costs include costs associated with the Day-Ahead Ancillary Services market, which launched in March.
• Real-time energy prices averaged $49.65 per megawatt hour (MWh), up 33% from summer 2024. Day-ahead energy prices were up 37% year over year, averaging $53.31/MWh.
• Capacity costs totaled $216 million, down 35% or $121 million from summer 2024. The decrease was a result of less cleared capacity and lower clearing prices in the Southeastern New England region.
• Real-time load, a measure of electricity demand, was 2% lower compared to summer 2024. Summer 2025 was cooler on average than the previous summer. Additionally, the estimated real-time load reduction from behind-the-meter solar was 21% higher than in the previous summer.