A study by researchers at IIT Delhi has found that air pollution and climate change will impair solar panel performance in India. It was published in Environmental Research Letters in November 2024.
According to the paper, India is the fifth-largest solar power producer worldwide. The country has set a target to produce 50% of its electric power from non-fossil fuel sources by 2030, and plans to install 500 GW of renewable energy capacity to this end by then. One-fifth of this capacity is expected to be in the form of solar power.
India also has plans to develop more solar parks and promote rooftop solar generation.
Solar power and climate
Like other forms of renewable energy sources are, solar photovoltaic energy is at the mercy of weather and climate.
“Accurately assessing future renewable energy resources, particularly solar energy in India, where solar deployment is expanding rapidly, is crucial for ensuring a sustainable and resilient energy future,” Sushovan Ghosh, lead author of the new study, then at the Centre for Atmospheric Sciences at IIT Delhi and now a researcher in the Earth Sciences Department of the Barcelona Supercomputing Centre, said.
The study is the first to examine how climate change will affect solar-cell efficiency in India. “Studies of this kind give impetus to the innovations towards mitigating greenhouse gases through the exploration of viable energy alternatives and, more importantly, improvements in photovoltaic cell design,” T.V. Ramachandra, faculty member at the Centre for Ecological Sciences of the Indian Institute of Science, Bengaluru, said.
India has 300 sunny days a year but their quality is declining due to air pollution. “Solar radiation at the earth’s surface is not stable over time but undergoes significant long-term variations, referred to as global dimming and brightening,” Ghosh said.
“This variation depends on atmospheric variables such as clouds, aerosols or particulate matter, water vapour, and radiatively active gas molecules such as ozone. Clouds reflect and aerosols either scatter or absorb incoming solar radiation reaching the surface. Therefore, on a cloudy or hazy day, due to particulate matter pollution, less solar radiation will impinge on the solar panel and reduce solar generation.”
Data from CERES
The team’s study used data from 1985 to 2014 to predict changes from 2041 to 2050, the middle of the current century. “Given that photovoltaic power plants generally have a lifespan of 20 to 25 years, analysing the 2040s aligns well with the operational lifetime of existing and planned installations,” according to Ghosh. “Beyond this period, the analysis may lose practical relevance.”
The team used global climate models. They tested their models against observations from NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project and the India Meteorological Department. CERES uses instruments in space to measure radiation coming from the earth and thus understand the role of cloud cover in climate change.
The team studied two scenarios. The first included a moderate level of efforts to control air quality and mitigate climate change. The second had weak climate change efforts but strong air pollution control measures.
Air pollution blocks solar radiation from reaching solar panels, resulting in less power produced. Rising temperatures due to climate change also lower the efficiency of solar cells.
Temperature to blame
The models found that by mid-century, the efficiency of solar panels in India will drop by 2.3% in the second scenario but by a greater amount in the first scenario. Based on current solar power generation levels, this amounts to a loss of at least 840 gigawatt-hours of electricity every year.
Losses from temperature were higher in the second scenario, which was expected because of weaker climate action.
“This study, based on radiation data from global climate models, provides vital insights into the likely impact of escalating air pollution on photovoltaic efficiency,” Ramachandra, who wasn’t involved in the study, said.
Solar cells perform best under bright sunlight. They also need lower ambient temperature and airflow over them for cooling. Any imbalance in these factors lowers solar cell performance.
The study found that solar radiation was the main factor affecting solar-cell efficiency. Temperature came next, followed by ambient wind speed, although it was much less impactful.
Cut emissions either way
The study also reported that the temperature of solar cells is expected to rise by 2 degrees C by the mid-century due to higher ambient temperatures. “It is important to distinguish between ambient air temperature and cell temperature, as solar cells can heat up significantly beyond the surrounding air temperature due to solar exposure,” Ghosh said.
The researchers also revealed that some parts of India’s northeast as well as Kerala will develop higher solar power potential in time. “This is really interesting. … This is because the cloud fractions are expected to decrease over these regions,” Ghosh said.
According to the paper, the models can help the government and industry players better pick sites for future solar power projects and allocate resources accordingly.
According to Ghosh, the study underscores the need to curb climate change and improve air quality. He advocated cutting greenhouse gas emissions in particular, which would mitigate climate change as well as remove particulate matter in the way of sunlight headed for solar panels: “This will help us fully utilise the future solar energy potential and create a path toward building climate-resilient nations.”
“At the individual level, public participation is crucial, through the adoption of electric vehicles and the use of public transport to reduce fossil fuel consumption. Tree planting and climate awareness efforts to enhance environmental sustainability are needed,” Ghosh added.
“While India has introduced commendable policies, the key challenge lies in accelerating their effective implementation from the ground level to top governance structures.”
Unnati Ashar is a freelance science journalist.
Published – March 17, 2025 05:30 am IST