In 2025, wind generated 4% of the electricity used by the six New England states, utility-scale solar generated another 4%, rooftop (behind-the-meter) solar generated about another 4% measured as reduced demand, and hydropower generated another 6%.
That’s from ISO-New England’s annual resource report. It measures the total output in megawatt-hours over the course of the year, not merely how much each source is capable of producing at any give time.
The intermittent aspect of wind and solar means their annual output is less than you might guess looked at their one-time maximum – this is known as the capacity factor. The capacity factor is about 90% for nuclear (meaning over the course of the year they generate 90% of the maximum amount they could theoretically produce), about 60-65% for gas, between 20% and 40% for wind depending on whether onshore or offshore, and 15% to 20% for solar in New England.
The data means roughly one-sixth of the region’s electricity (depending on how you count rooftop) over the course of 2025 came from non-emitting renewable sources. A decade ago that would have been absolutely astonishing; these days it feels adequate at best.
Another 23% came from nuclear, a non-emitting but not renewable source.
The leader, of course, was natural gas (fossil gas, if you prefer) which generated 51% of our electricity. Various burned stuff – wood, trash, landfill gas, oil, methane – made up the rest.
