What just happened? Solar power crossed an important threshold in May, as a rapidly expanding fleet of photovoltaic projects supplied more US electricity than coal for the first time on record. New data from global energy think tank Ember shows that US solar generation climbed to 45.5 terawatt-hours in May 2026, the highest monthly total ever recorded and a 17% increase from May of last year. That output gave solar 12.8% of all US electricity for the month, just enough to edge ahead of coal at 12.2%. For a technology that only recently accounted for a small share of the mix, it has now become a central part of the system.

Five years make the shift look even sharper. In May 2021, coal supplied 19.7% of US electricity, while solar accounted for just 5.4%. Today, solar's share of the mix has risen to the point where coal is no longer ahead of it on the grid.

May also marked the first time solar ranked as the third-largest individual source of electricity in the country, behind only natural gas and nuclear. When grouped with other renewables, the category becomes the second-largest source overall. For utilities and grid planners, that is more than a change in rankings; it signals that solar must now be treated as a central part of the US power mix.

The seasonal pattern behind the May record aligns with broader trends in solar output. Solar generation often peaks in June or July, when sunlight is strongest, but its share of the generation mix tends to peak in spring. Longer, sunnier days and milder temperatures keep cooling loads lower, allowing solar to account for a larger share of total demand. This dynamic requires grid operators to manage a resource that ramps up quickly in the middle of the day and falls off in the evening.

Coal is moving in the opposite direction. Coal-fired generation fell to an all-time monthly low of 39.3 terawatt-hours in April 2026, then rose slightly to 43.4 terawatt-hours in May. Even with that increase, coal output was still 11% below May 2025 levels and lagged far behind solar's expansion.

The May crossover is not the only recent milestone. In March, renewables as a group generated more electricity than gas in the US for the first time. Taken together, these milestones show how quickly clean energy is reshaping the US grid, even as the Trump administration continues to target clean energy projects and policies.

For Ember, the latest numbers are part of a longer arc, not a one-month blip. "US solar power continues to set new records," said Nicolas Fulghum, senior data analyst at Ember. "Overtaking coal for the first month on record shows just how far solar has come, from a niche contributor to the third-largest and fastest-growing source of power in the US electricity system."

The latest data points to a power system in which solar plays a much larger role than it did just a few years ago, and that role is still growing.