Air Pollution Impacting Solar Panel Efficiency in India say IIT, Delhi researchers

A team of researchers from the Centre for Atmospheric Sciences (CAS) at the Indian Institute of Technology (Delhi) have found that air pollution is reducing energy output of solar panels in the country. The decline in solar power generation could be as high as 52%.

Sagnik Dey, Dilip Ganguly and colleagues have modelled the particulate pollution impact on solar irradiance for the period of 2001–2018.

They found that air pollution is rising in almost all cities and towns of India. Each year, more cities join the league of most polluted ones on the world map. The CAS team says that solar panel efficiency is reduced by particulate air pollution in two ways. First, it causes atmospheric attenuation which means that the particulate matter in the air reduces the direct sunlight that reduces the efficiency of solar panels. Second, the particulate pollution causes soiling on the panels as its deposit builds up over time reducing efficiency yet again.

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The team has also held that increased levels of aerosol in the air leads to more cloud formation, more cloudy days and again reduced solar energy output from the solar panels.

NASA’s Clouds and the Earth’s Radiant Energy System (CERES) supplied data to the CAS team to calculate India’s solar irradiance and also five power grids; but verified with other independent data. The particulate pollution impact on the sunlight has been calculated through NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS).

A region wise impact was studied by CAS. The researchers concluded that the highest impact of both atmospheric attenuation and soiling found where India’s eastern power grid is located. The sunlight reduction in reaching the solar panels was 16% less.

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The regions that host the northern grid and the western grid, witness 12% reduced sunlight on solar panels. The least effect was in the regions hosting the southern and the north-eastern grids where the sunlight reduction was calculated at 10% and 11% respectively. As per the calculations of the researchers, India is losing hundreds of millions of dollars every year due to air pollution only in the solar power sector.

The team found that the air pollution effect on panels that are tilted or track the position of the Sun was higher. Eastern Grid’s dual-axis tracking panels received 52% less sunlight due to pollution. When calculated on an all India basis, the horizontal panels received 12% less sunlight and the dual-axis panels received 41% less sunlight.

National Clean Air Programme

The researchers have also held that if India can implement the National Clean Air Programme (NCAP) in letter and spirit, the solar power generation in the country could rise automatically between 6-16 TWh per annum.

The Central Government has launched NCAP as a long-term, time-bound, national level strategy to tackle the air pollution problem across the country in a comprehensive manner with targets to achieve 20% to 30% reduction in Particulate Matter concentrations by 2024 keeping 2017 as the base year for the comparison of concentration.

Under NCAP, 122 non-attainment cities have been identified across the country based on the Air Quality data from 2014-2018.

With current Solar capacity at ‘just 50 GW’, versus a target of close to 300 GW by 2030, India’s potential losses due to pollution could go up massively in just the solar sector. And this is without counting the health impact that will be exponentially higher. It is truly time to hold government’s accountable for the steps they take on the pollution front, starting with the air we breathe.