Smoke from this summer’s wildfires is reducing the amount of sunlight reaching solar panels across the Americas, prompting forecasters to predict lower solar energy generation in affected regions.
“Whilst the fires raged, atmospheric aerosols have blown east and south” across North America, writes Dr. Hugh Cutcher, lead data scientist at Solcast.
“Aerosols impact irradiance by scattering and absorbing radiation in the atmosphere, and reduce solar generation even on a day with no clouds.”
In recent posts published by Solcast—a solar energy data and forecasting firm owned by the assurance and risk management company DNV—Cutcher explains how this summer’s fires in Canada, the western U.S., and Brazil have “smothered” solar energy generation in some regions of North and South America.
Solcast’s analysis showed that “clearsky irradiance” levels, “a measure of irradiance before cloud or other weather phenomenon,” were down by as much as 20% in some areas of Canada surrounding the fires in Alberta. The smoke spread through the atmosphere to affect the entire continent to some extent.
Recently, a separate analysis by Climate Central indicated that high temperatures around the time of the fires in Jasper, Alberta—which created conditions more susceptible to wildfire—were twice as likely to occur because of climate change.
Upper atmospheric conditions and the influence of Hurricane Beryl also affected the central and eastern U.S. by creating unstable cloud cover, which can also weaken irradiance. Meanwhile, on the U.S. West Coast, stable atmospheric conditions increased irradiance.
In the Southern Hemisphere, Brazil experienced 20 times as many wildfires in July as it did during the same time last year, after the combined impacts of climate change and El Niño “supercharged” wildfire conditions in areas that are otherwise typically lush, humid rainforest. Smoke from the wildfires reduced irradiance in surrounding areas, especially to the southeast.
Weather patterns increased irradiance in other parts of South America, including northern Brazil as well as Uruguay, Argentina, and Chile, while cooler winds at the southern tip of Chile reduced irradiance, Cutcher writes in another post.
While other regions may not be experiencing fires like those in the Americas, changing weather patterns are nevertheless affecting irradiance and, in some cases, may be weakening solar power generation. Above average monsoons, typhoons, and severe heatwaves reduced irradiance in India and Southeast Asia in July, while parts of China and Japan experienced higher than average irradiance amid reduced cloud cover brought on by “an abnormally strong subtropical ridge.”
Earlier in the summer, European solar output dropped 20% for about a week in June because of Saharan dust carried through the atmosphere. Throughout June, solar irradiance in Western Europe was 20% below average because of warm, moist air that created atmospheric instability and was “conducive to widespread storms, thick clouds, and heavy rainfall.” Meanwhile, Eastern Europe and the United Kingdom experienced sunny skies and high irradiance, wrote Cutcher.
