A powerful El Niño season upends global solar resource assumptions

This summer's strong El Niño weather pattern threw off how much sunlight reached the ground in many parts of the world, with some regions seeing 20 to 30 percent more or less sunlight than usual. New data from solar analytics firm Solargis shows the swings varied widely by location: parts of South America (the Paraná River Basin, northern Argentina, Uruguay, southern Brazil) got over 20 percent less sun than normal, while southern England, Wales, and Normandy got over 20 percent more. Northern Europe, Scandinavia, and Scotland ran below average, while parts of Kenya, Ethiopia, Madagascar, Southeast Asia, and China saw notably higher sunlight levels.

In North America, the picture was more mixed month to month, evening out over the summer overall, though the central United States ran especially hot, with temperatures over 2.5°C above the long-term average. Northern Canada was about 4°C warmer than usual, and the dry, hot conditions fed wildfires whose smoke can also cut down on solar panel output. Separately, a lack of rain near Dallas let dust and grime build up on solar panels, pushing modeled energy losses from dirty panels to their highest late-August level in 20 years, since there was no rain to wash panels clean.

None of this is really about home solar installations changing hands or new incentives. It is a reminder that year-to-year weather, not just the sun's average path overhead, affects how much power any solar setup produces, including a home system if you have one. A hazy, dry, or unusually cloudy season can mean measurably less output than long-term averages would predict, even with nothing wrong with the equipment itself.