Air pollution cut India’s solar power output by 9.6% in 2023, study says

Aerosols in the air reduced the amount of solar power generated in India by 9.6% in 2023, equivalent to around 15 terawatt-hours (TWh), according to a new analysis published in Nature Sustainability. The same study reported that the global average loss due to the same cause in 2023 was 5.8%.

Between 2017 and 2023, pollution-related electricity generation losses from existing installations averaged 74 TWh a year — roughly one third of the electricity generated every year by new solar capacity.

According to the study, India’s loss is one of the world’s highest, with the most electricity generation potential lost in the country’s heavily polluted north.

The researchers assembled what they called the first global facility-level database of solar photovoltaic generation and losses, totalling 1.4 lakh facilities worldwide. They analysed the numbers together with satellite data, atmospheric data, and machine-learning.

Aerosols are fine particles of sulphates and carbon, among other constituents. Major human sources of it include coal plants, road transport vehicles, and industries.

Smog — which is a mix of aerosols and gases — directly reduces the amount of sunlight reaching solar panels, thus undermining an important source of power meant to replace coal in India.

India’s neighbour with an even bigger appetite for power, China, lost the most power generation potential in 2023, 61.3 TWh, but which was lower than India’s as a fraction of the total generation (7.7%). In fact, China both illustrates the scale of the problem and a way through it.

China generated 793.5 TWh of solar electricity in 2023 and accounted for 54.9% of aerosol-related losses worldwide. Many of the country’s solar farms lie within 30 km of coal power plants, increasing the former’s exposure to pollution that blocks sunlight.

However, China reduced pollution-related loss of solar power by around 1.4% a year from 2013 to 2023 and at the same time it expanded coal power. It reduced the losses by retrofitting coal plants with high-efficiency filters that curtailed sulphur dioxide and particulate emissions.

A key technology in reducing these emissions is flue-gas desulphurisation (FGD), which removes sulphur dioxide from flue gas vented into the air.

India’s aerosol-induced losses in solar power production did not decline from 2013 to 2023, staying flat. In 2025, the Indian government also significantly weakened a target to install FGD units by limiting them to coal plants near major cities and, on a case by case basis, plants in critically polluted areas.