Wildfire smoke can slash California solar power output by nearly a third

By David R Baker | Bloomberg

The wildfire smoke that’s often seen blanketing California skies is more than just a problem for breathing — it can also drastically slash electricity generated by solar panels in a state that’s been struggling to meet all its power needs.

A new study from the National Center for Atmospheric Research shows that smoke can cut solar power production by nearly a third.

Scientists examined a period in September 2020, when smoke from some of the largest fires in California history shrouded much of the state in a sickly orange haze. Using data from the state’s power grid operator, they studied the output from the area’s vast solar farms and compared that to the same period in the prior two years. They also included data from monitoring stations that measure the amount of solar radiation hitting the ground.

Thick smoke cut solar energy production 10% to 30% between noon and 4 p.m., the researchers found. Even worse, the production forecasts that utilities and grid managers use to plan for electricity demand were thrown off by the smoke. Actual solar production averaged 27% less than forecasts, the researchers found. In late afternoons with heavy smoke, solar plants produced just half as much electricity as predicted.

“Given the increase in large wildfires and society’s greater reliance on solar energy, even regions far downwind of fires may need to consider the potential impacts of smoke,” Timothy Juliano, an NCAR scientist and the study’s lead author, said in a statement.

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