The forest fires are becoming more frequent and devastating, and beyond environmental and climate impacts, there is an often overlooked question: how do they affect our energy system? A new study, led by Colorado State University, has finally quantified the impact of wildfire smoke on solar radiation, showing that while the damage is significant for some solar technologies, photovoltaics are holding up better than you might imagine.
When it comes to solar energy, there are two basic types of radiation: the direct normal radiation (DNI)essential for concentrated solar thermal systems (CSP), and the global horizontal radiation (GHI)from which photovoltaic panels draw most of their energy. The study, published on Nature Communicationsanalyzed satellite data on smoke, aerosols and clouds, comparing conditions in 2019 (with low smoke emissions) to those in 2020, a year marked by record wildfires in California and other regions of the United States.
The researchers used data from National Solar Radiation Database (NSRDB)with a spatial resolution of 4 km and temporal resolution of 30 minutes, to calculate the impact of smoking at the state, regional and national levels. To distinguish between variations due to clouds or smoke, they compared “normal” days with those marked by heavy smoke.
The results are clear: wildfire smoke significantly reduces direct radiation (DNI) – up to 42% on a daily basis and 61% on a monthly basis – but has a more moderate impact on GHI, which suffers losses of between 11% and 17% daily, and a maximum of 25% monthly.
Photovoltaics and fires: less damage than you think
A particularly encouraging piece of data concerns the effect of smoke carried by the windwhich has a minimal impact on GHI nationwide, less than 5% even during an extreme wildfire year like 2020. This means that although wildfires can affect the local performance of PV panels, their large-scale effect is rather contained.
The conclusions of the study represent a breath of fresh air for photovoltaic energy: despite temporary losses in areas affected by fires, the system is holding up well, especially thanks to the growing diffusion of energy storage systems. These systems, in fact, allow the electricity produced during the hours of maximum solar exposure to be stored, mitigating the effects of oscillations in solar radiation.
Forest fires are set to become more frequent due to climate change, and knowing that photovoltaics can withstand these challenges is a positive note in an often bleak context. However, scientists warn: we must continue to invest in energy storage and diversification of renewable sources, because the climate is becoming less and less predictable.
The researchers conclude with a concrete hope:
The scale of GHI reductions means that, on a national basis, the impact of smoking on PV is limited. This is encouraging for the future of renewable energy in the United States and beyond.
The study, entitled “Solar energy resource availability under extreme and historical wildfire smoke conditions”was conducted in collaboration with Springfield College and NASA Langley Research Center, demonstrating once again how science can help us respond to global challenges.
