How Wildfire Smoke Reduces Solar Energy Generation

04-02-2025 | By Liam Critchley

Key Things to Know:

  • Expanding Solar Energy: The U.S. aims to increase solar energy’s share in the national grid from 3% to 45% by 2050 as part of its decarbonization efforts.
  • Wildfire Impact on Solar: Increasing wildfire activity poses a challenge to solar power generation by reducing solar irradiance due to smoke.
  • Solar Efficiency and Pollution: Particulate matter from smoke and pollution can significantly lower photovoltaic (PV) output, with local wildfires causing up to 61% loss in direct normal irradiance (DNI).
  • Grid Resilience and Planning: Long-term wildfire and smoke models must be integrated into solar farm planning to ensure grid stability and reliable energy production.

The US is looking to increase solar energy generation capabilities in the coming years, with the hope that solar will become a more dominant energy source in the grid. By 2050, it’s hoped that the fraction of the total electricity in the US generated by solar will increase from 3% to 45% as the US (and other nations) try to decarbonise the grid. Advances in the power conversion efficiency (PCEs) of different solar cell architectures have already decreased the cost of utility-scale solar cells by 82.1%, and this could be reduced further in the future. So, solar cells are a feasible large-scale clean energy solution. 

The US is seeing an increasing number of wildfires becoming commonplace―which has recently been demonstrated by the catastrophic wildfires in Los Angeles in January 2025. Alongside the many social and ecological issues and challenges that come with wildfires, wildfire smoke can also impact the ability of solar cells to generate photovoltaic (PV) power.  

If there’s to be a greater reliance on solar cells in the US energy grid, then the impact of wildfire smoke on energy generation is one of the many factors that need to be analysed to ensure that the grid will always remain stable and resilient.  Wildfire smoke is a potential big issue for PV generation because a number of studies have already shown that smoke can affect the energy generation capabilities of solar cells. 

Meeting the future targets of 45% energy production in the grid is going to require rapid deployment of solar energy systems, so suitable locations will need to be identified quickly that can house large-scale solar farms―while accounting for the current and future climate challenges land use, population growth, technological constraints and the potential adverse weather conditions/natural disasters. 

Pollution issues for PVs 

The performance of solar cells is assessed by how much shortwave direct normal (DNI) and global horizontal (GHI) irradiance a location receives. Solar farms use two main energy generation mechanisms―concentrating solar-thermal power (CSP) that relies on DNI and PV generation that relies on GHI.  

Human-caused pollution and dust are known to reduce PV generation because the absorption and scattering of light via interaction with particulate matter reduces the solar radiation that the panel receives. Additionally, prolonged or heavy exposure to pollution and dust will cause particulate matter to deposit on the surface of the solar cell, blocking a lot of solar radiation to the cell. Around the world, particulate matter reduces the global PV output by around 50% from its theoretical harvesting capacity, and the deposition of particulate matter on solar cells accounts for over two-thirds of lost solar energy.  

It’s thought that in some regions, the impact of particulate matter is the same as if the skyline is cloudy. Particulate matter is also widely found in smoke, so large amounts of smoke (such as those generated by wildfires) might have an impact on solar cell performance.  

Increase in the number of Wildfires Causing PV Problems 

Higher temperatures, earlier snow melting, and drier grounds have extended US wildfire seasons and produced fires that have burned longer since the 1980s. It’s expected that wildfires will become more frequent and last longer in the coming years due to the effects of climate change. 

Wildfire activity has increased in the Pacific Northwest and Southwest. The Southwest has the highest potential for large scale solar implantation in the US, but more active wildfire seasons will produce more smoke emissions. Smoke from wildfires can travel large distances and impact air quality across the contiguous US (CONUS). Even though air pollution is declining in the US due to decarbonisation efforts, air quality trends have show that wildfire smoke emissions are offsetting this decline. 

Small case studies have shown that the smoke from severe local wildfires can reduce PV output over short time periods and at specific locations. For example, in Spain, wildfire smoke reduced the PV output of a PV plant by 34% over 2 days. On a larger scale, wildfires in the US throughout 2018 caused an 8.3% decrease in the PV output of over 53 utility-scale PV plants in the western US and 10-50% in Southern California solar plants throughout the 2020 wildfire season. These have all been local studies that have looked at the local impact, but wildfires have the potential to affect wide areas. 

Because smoke often travels form the US west coast and Canada across CONUS during wildfire season, determining how that smoke could affect solar energy production away from the local area (where local fires are adjacent to PV farms) is also important to for understanding the wider picture. 

Impact of Wildfires on PV Capabilities Across CONUS 

Researchers have now undertaken a study that looked at how a wildfire’s smoke has an impact on the average (known as the ‘baseline’) solar resource availability―i.e., the amount of DNI and GHI irradiance across different spatial and temporal resolutions. The researchers used a combination of radiative transfer model output, daily case studies, aggregated data, multi-year analyses, and satellite data (looking at aerosol, cloud and smoke observations) to quantify the impact of wildfire smoke impact on both the DNI and GHI a national, regional and state level. 

On a small scale, the researchers analysed the daily impact of localised smoke on solar irradiance in California throughout 2020. This primarily involved looking at how severely the thickness of smoke plumes would affect the irradiance of the solar cells compared to cloud-driven irradiance changes. 

On a larger scale, the researchers compared the national and regional solar resources under both low and high smoke conditions. This part of the study looked at how the daily smoke driven irradiance impacted the mean DNI and GHI each month and how the impacts varied for both local and transported wildfire smoke. 

The researchers used the mean irradiances to model the impact of wildfire smoke on the output of PV farms across 13 locations in CONUS. The analysis was expanded across a sixteen-year period (2006-2021) to look at the impacts of longer term and regional smoke irradiance to see historical data and how this might change in the future

At all levels (national, regional and state), the model showed that solar irradiance decreases as the level of smoke increases. This is to be expected given how solar cells are affected by other aerosol disturbances. The model showed the DNI Is more sensitive to smoke than GHI. In terms of numbers, there was a loss of 32-42% for DNI downwind, while GHI was only 11-17% in California due to the local smoke impact. 

When broken down into the local and transported smoke, there are some big differences in irradiance loss. It was found that there could still be a lot of irradiance loss downwind of a fire for DNI, but GHI was relatively unaffected. There is the potential for large GHI losses as well, but the mean GHI loss was below 5% due to transported smoke. However, at the local level―near the wildfire―it was found that solar cells could experience up to a 61% DNI loss and 25% GHI loss on average across the month. 

While there were some effects downwind due to transported smoke, the main solar energy losses were found to be near the location of the wildfire. Because of this, the small GHI reductions downwind imply that the average impact of smoke plumes on PV resources around CONUS would remain relatively stable―even in extreme wildfire seasons. This level of stability will only be further increased as more utility-scale battery storage is added to the grid to provide localised energy for when local smoke causes a large drop in solar irradiance in the short term (until the fire is put out and the smoke dissipates).  

To roll out new PV installations on a large scale to meet demand, the long-term smoke irradiance models need to be combined with projected fire vulnerability and average cloud conditions to look at which locations within CONUS are ideal for large-scale solar deployment. 

Reference: 

Corwin K. A. et al., Solar energy resource availability under extreme and historical wildfire smoke conditions, Nature Communications¸16¸(2025), 245. 

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By Liam Critchley

Liam Critchley is a science writer who specialises in how chemistry, materials science and nanotechnology interplay with advanced electronic systems. Liam works with media sites, companies, and trade associations around the world and has produced over 900 articles to date, covering a wide range of content types and scientific areas. Beyond his writing, Liam's subject matter knowledge and expertise in the nanotechnology space has meant that he has sat on a number of different advisory boards over the years – with current appointments being on the Matter Inc. and Nanotechnology World Association advisory boards. Liam was also a longstanding member of the advisory board for the National Graphene Association before it folded during the pandemic.