Research from Britain shows that aerosols will have reduced global solar energy production by 5.8% in 2023, equivalent to 111 TWh. Although China accounted for more than half of the global total in 2023, the country is the only major solar producing region to show a decline in annual losses.
Pollution from coal-fired power plants can significantly limit the energy output of solar power plants, especially in areas where power stations are located nearby, according to new research.
A British-based research team led by the University of Oxford And University College London used satellite data to map more than 140,000 solar installations worldwide, combining their dataset with atmospheric air pollution data to calculate aerosol-induced losses from solar power plants.
The team found that aerosols reduced global solar energy production by 5.8% in 2023, equivalent to 111 TWh of lost energy.
For the same year, the team calculated the average PV energy loss from potential production under optimal conditions to be 26.9%, with the remaining 21.1% coming from clouds. “Although clouds are the dominant source of atmospheric solar radiation reduction, aerosols have a disproportionate impact in densely populated, industrialized areas where solar energy deployment is concentrated,” the research paper explains.
The researchers also calculated that between 2017 and 2023, aerosol-related losses from existing PV systems reached 74.0 TWh, while capacity gains from new solar installations averaged 246.6 TWh per year.
To compare amounts across regions and years, the team used a loss-to-growth ratio, a calculation of annual aerosol-induced energy loss from existing systems divided by annual energy generation from new PV capacity, which averaged 30% during the study period.
“Aerosol-induced losses from the existing PV fleet are equivalent to almost one-third of the annual energy generated by new PV installations worldwide, which represents a magnitude not previously quantified and unexpectedly high,” the research report said.
Rui Song, an academic at the University of Oxford and corresponding author of the paper, said pv magazine one of the key findings was that coal and solar energy are increasingly growing side by side in some regions and are often co-located.
“Emissions from coal-fired power plants directly reduce the amount of sunlight reaching nearby solar panels, creating a previously underquantified drag on solar energy generation,” he explains.
The research shows that aerosol-related losses are highest in China, which the research paper attributes to persistent pollution and dense PV deployment. Losses caused by aerosols in China amounted to 61.3 TWh in 2023, equivalent to 54.9% of the global total and higher than all other countries combined, causing national PV generation to decline by 7.7%.
By comparison, the US, which has a limited number of co-located solar and coal-fired power plants, experienced a 3.1% loss from aerosols.
Despite recording the largest aerosol-related losses, China appeared to be the only major PV producing region with evidence of a sustained decline in such losses over the study period.
The figures in the paper show that losses in China are decreasing by 0.96 TWh per year. In comparison, losses increased by 0.15 TWh and 0.12 TWh in the US and Europe, while India continues to experience “persistently high losses due to severe air pollution,” the research report said.
“The modest global decline of −0.72 TWh per year was therefore almost entirely driven by improvements in China,” the article continues. “The observed decline in pollutants over PV sites in China does not reflect a phase-out of coal, but rather the effectiveness of aggressive emissions controls on a growing coal fleet.”
According to Song, this finding suggests that stricter pollution controls and ultra-low emissions technologies could partially reduce coal’s atmospheric impact in the short term. “But ultimately, maximizing the climate and energy benefits of solar still requires a transition away from coal itself,” he added.
Song told pv magazine the results suggest that energy policy should take into account not only the installed solar capacity, but also the atmospheric conditions that influence the amount of electricity that solar systems actually provide.
“In practical terms, this could include reducing the fossil fuel subsidies that continue to support coal production, strengthening carbon pricing and emissions trading, and creating stronger incentives for the retirement of coal-fired power stations,” he said. “Policies that better account for the air quality and health costs of coal pollution would also help address the hidden impacts of fossil fuels on renewable energy performance.”
Song added that investments in grid infrastructure, transmission capacity and energy storage are also essential to reduce continued reliance on coal-fired power plants as a backup for renewable energy systems. “Better spatial planning of solar infrastructure could also help minimize avoidable performance losses when coal and solar facilities are close together,” the researchers explained.
Their findings are presented in the research paper “Coal-fired power stations remain a major barrier to the global transition to solar energy”, available in the magazine sustainability of nature.
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