New Delhi: Air pollution in Delhi reduced the power generation capacity of solar panels by 12% per year from 2016 to 2017—larger than the profit margins of some installations—recent research led by the Massachusetts Institute of Technology (MIT) has found.

The research, which highlights the serious economic implications of air pollution on solar power generation, was published in the journal Energy & Environmental Science. The study was primarily conducted in Delhi from where the data was gathered over a two-year period and was extended to 16 other cities around the world.

The total sunlight reaching the ground in Delhi during a year is reduced by more than a ninth because of air pollution, according to the study. This corresponds to 40 kWh m2 (Kilowatt-hours per square metre) of energy generated every year for a 20% efficient silicon solar panel.

“When you’re doing project planning, if you haven’t considered air pollution, you’re going to undersize and get a wrong estimate of your return on investment," said research scientist, Ian Marius Peters of MIT, Cambridge, Massachusetts, who led the study.

Delhi is enveloped by a thick haze every year, which not only leads to prolonged periods of reduced visibility, but has also become a serious health concern.

Over the course of two years, researchers collected data on both the amount of solar radiation reaching the ground and the amount of fine particulate matter (PM2.5) in the air, which causes haze.

The annual average level of reduction of the solar panel output was found to be about 12% in Delhi, while the impacts ranged from 2% for Singapore to more than 9% for Beijing, Dakha, Ulan Bator and Kolkata. “Unlike Singapore, the air pollution is constant in Delhi. There is never a day without pollution," said Peters.

In Delhi alone, lost revenue from power generation from planned photovoltaic installations could amount to $20 million annually, considering its current installation targets and increasing air pollution, according to the study.

The revenue loss is estimated to be about $16 million for Kolkata and $10 million annually for Beijing. For Shanghai it is about $10 million annually and at least $6 million for Los Angeles.

The research findings are significant in the wake of the government’s thrust on renewable energy and aggressive solar power installations targets. Earlier this year, the government announced that India would auction solar projects of at least 30 gigawatts every year till 2028.

As most of these installations are planned in urban areas, the impact of the reductions in output could be quite severe, the researchers say.

“Twelve per cent is considered to be larger than profit margins for some solar installations, and literally enough to make the difference between a successful project and one that fails," said the scientist.

The researchers highlighted that city-integrated solar panels offer opportunities of mitigating challenges related to the high power demand of growing urban areas. If these effects are not considered correctly, it could make solar powered applications underperform and become unreliable, which could be a threat to their wide-spread adoption.

“Major health benefits related to reducing levels of air pollution should be motivation enough for nations to take strong measures, but this study hopefully is another small piece showing that we really should improve air quality in cities, and showing that it really matters," added Peters.

The research was supported by Singapore’s National Research Foundation and US Department of Energy and National Science Foundation.

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