Air pollution Harms India's Solar Energy Potential

According to Sagnik Dey, chair professor at the Indian Institute of Technology (IIT) Delhi, atmospheric pollution reduces solar power generation in two ways: by absorbing and scattering the sun's rays and by soiling solar panels.

Findings of Study:

According to a study conducted by IIT Delhi and published in March in Environmental Research Letters, between 2001 and 2018, India lost 29 percent of its solar energy potential due to atmospheric pollution, amounting to an annual loss of $835 million. According to Mercom India, India had only reached the halfway point of 50 gigatonnes of installed solar capacity as of March of this year.

"To put it simply, aerosols, which include fine particulate matter, dust, mist, and fumes suspended in the air, significantly reduce incoming solar radiation in what we call the 'atmospheric attenuation effect," says Dey, one of the study's authors. "This must be considered when embarking on large solar energy projects."

According to Dey, such projects also fail to account for the "soiling effect" of aerosols depositing on solar panels, which prevents solar radiation from reaching the photovoltaic cells. "Because air pollution in South Asia is on the rise, both effects must be addressed and mitigation measures implemented to maximize the benefits of solar power installations," he adds.

According to a previous study, particulate matter can reduce photovoltaic solar power generation by more than 50% in heavily polluted areas, with the majority of it causing panel soiling. Aerosols in the atmosphere also work against solar power generation by causing cloudiness and interfering with rainfall, which could wash particles away.

According to Bhupendra Das, an environmental researcher at Tribhuvan University in Kathmandu and the chair of Nepal Energy and Environmental Development Services, acid rain can corrode solar power equipment and support structures, increasing maintenance costs.

Pollutants such as sulphur dioxide and nitrogen oxides, which are primarily released through industrial and vehicular emissions, cause acid rain by rising high into the atmosphere and combining with water, oxygen, and other chemicals to form corrosive acid droplets before falling back as rain.

"Reducing air pollution would undoubtedly reduce smogginess, which can improve solar power generation, and modelling studies do suggest that polluted clouds have a longer lifetime and that aerosols inhibit precipitation," Das tells SciDev.Net. "However, it is important to remember that cloudiness is caused by factors other than air pollution."

The IIT Delhi study proposes a set of measures that, if implemented, could assist the Indian government in meeting its solar energy production targets. One of these is fixed panels that are optimally tilted to maximize solar radiation. Aerosol deposits do not accumulate as easily on tilted panels as they do on horizontally set panels.

Articulated panels with tracking mechanisms that constantly follow the sun are more expensive than fixed panels but have a higher resistance to aerosol deposit accumulation. According to the study, atmospheric attenuation affects all configurations.

According to the study, the best way to increase solar energy production is for the government to rigorously implement government initiatives such as the National Clean Air Programme, which was launched in 2019 with the goal of reducing fine particulate matter (PM2.5) concentrations by 20 to 30 percent by 2024 compared to 2017 levels.

Mitigating air pollution would "accelerate India's progress toward achieving its solar energy target at a lower installation capacity, avoiding additional expenditure for solar energy infrastructure expansion," according to the study.

According to the Swiss IQAir world air quality report for 2021, the entire northern Indian subcontinent exceeds the WHO standard of 10 micrograms per cubic metre for particulate matter by seven to ten times.

For the fourth year in a row, New Delhi was named the world's most polluted capital city by IQAir, and 34 other Indian cities were named among the world's most polluted urban centres.

According to IIT Delhi, this is the first study to quantify the impact of pollution on solar power generation in India, with previous studies focusing on the negative effects of poor air quality on public health and agricultural production.