Partial U.S. eclipse produced similar daily solar energy losses to higher-obscuration European locations

The August 12 solar eclipse blocked much more sunlight over parts of Europe than over the northeastern United States, but the actual drop in solar energy for the day turned out similar in many spots on both sides of the Atlantic. In Europe, the eclipse's path of totality crossed Greenland, Iceland, and Spain, with much of Western Europe seeing over 80% of the sun blocked at its peak. In the northeastern U.S., the blockage never topped 20%. Even so, analysis of solar data found some eastern North American locations lost as much daily sunlight as European spots with far higher peak blockage. That's because the eclipse hit near midday in North America, when sunlight is strongest, but closer to sunset in Western Europe, when sunlight was already fading.

Clouds changed the picture in some places. Reykjavik, Iceland, sat in the path of totality and would have lost over 5% of its day's solar energy under clear skies, but cloud cover on the day cut that loss to under 1%. Most of Western Europe had clear skies during the eclipse, so cloud cover made little difference there.

Electricity prices reacted unevenly. Spain and France, both with high eclipse blockage, saw price increases during the eclipse window, though other market factors were also at play. In New York's Hudson Valley area, prices stayed within their normal range for a summer weekday despite the eclipse. None of this points to any near-term change for homeowners with rooftop solar, but it's a reminder that sun angle, season, and cloud cover matter as much as how much of the sun gets covered.