India’s Solar Dreams Under Threat even after getting 300 sunny days a year

India's solar ambitions, fueled by over 300 sunny days annually, face a significant challenge. A study by IIT Delhi, published in iScience, reveals that air pollution is reducing sunlight reaching solar panels and shrinking land suitable for solar projects. Currently, only 29.3% of India's land is viable for solar installations, with aerosol pollution decreasing this by 0.21% annually. This results in a loss of 50GW of solar potential each year. Urgent action is needed to combat pollution and safeguard India's clean energy goals.

India, a nation endowed with over 300 sunny days annually, has long viewed its abundant sunlight as a key driver of its renewable energy revolution. With aspirations to reduce dependence on fossil fuels, solar power has emerged as a cornerstone of the country’s clean energy roadmap. However, a recent study has unveiled a stark reality: air pollution is casting a long shadow over India’s solar ambitions.

A detailed investigation by researchers at the Indian Institute of Technology (IIT) Delhi, published in iScience, reveals that rising pollution levels are not only limiting the sunlight reaching solar panels but are also reducing the land area suitable for solar energy projects. The findings underscore the urgent need for India to address this invisible barrier to its clean energy goals.

The Shrinking Solar-Ready Landscape

According to the study, just 29.3% of India’s landmass is currently viable for solar photovoltaic (PV) installations. This includes barren lands, scrublands, deserts, and areas suitable for rooftop solar systems in urban and rural regions. However, this percentage is steadily declining. Aerosol pollution—comprising tiny particles that scatter and absorb sunlight—is making an additional 0.21% of the land unsuitable for solar energy generation each year.

The implications of this are significant. The annual loss translates to 50 gigawatts (GW) of solar power potential or approximately 75 terawatt-hours (TWh) of electricity—equivalent to the annual energy consumption of a state like Jharkhand. The study also highlights that over 28% of India’s land already experiences solar dimming, with the eastern region being the most affected, followed by the western and northern regions.

Why Solar Energy is Central to India’s Future

India’s renewable energy strategy heavily relies on solar power. As of 2024, the country ranked fifth globally in installed solar capacity and is committed to generating 500GW of renewable energy by 2030, with 100GW specifically from solar. These goals are integral to India’s commitments under the Paris Agreement and its pledge to achieve net-zero emissions by 2070.

The nation has made remarkable strides in solar deployment, from massive solar parks in Rajasthan and Gujarat to rooftop systems and floating solar plants. However, these efforts are predicated on the assumption that India’s solar resource is abundant and stable—an assumption that the new findings challenge.

Insights from the Study

The study, spearheaded by researchers Sushovan Ghosh, Alok Kumar, Dilip Ganguly, and Sagnik Dey, analyzed data spanning from 2001 to 2018. Using satellite information from NASA’s Clouds and the Earth’s Radiant Energy System (CERES), combined with land-use and vegetation data, the researchers mapped India’s solar viability.

By examining three atmospheric scenarios—“all-sky” (clouds and aerosols), “clear-sky” (aerosols but no clouds), and “no-aerosol sky” (clouds but no aerosols)—the researchers isolated the specific impact of aerosols on solar radiation. Their findings were striking:

• Solar radiation is declining across 91% of India’s landmass.

  
  

• Clear-sky radiation, which isolates the effects of aerosols, is decreasing by 0.46W/m² annually across 98% of the country.

  
  

• In contrast, no-aerosol sky radiation is slightly increasing, confirming that aerosols, not clouds, are the primary driver of solar dimming.

  
  

The study also determined that only areas receiving at least 5kWh/m²/day of solar radiation qualify for PV installations. Rising pollution levels have caused this viable area to shrink. The researchers estimate that if aerosol pollution had remained at early 2000s levels, the solar-suitable land area could have increased to 37%, unlocking an additional 100GW of solar capacity.

Aerosols: The Silent Saboteur

While clouds were traditionally seen as the primary obstacle to solar energy, this study identifies aerosols—emissions from vehicles, industries, biomass burning, and dust—as the dominant challenge. Unlike clouds, aerosols persist longer in the atmosphere and scatter sunlight even on seemingly clear days. Their impact is most severe during winter, when smog levels peak, and in pre-monsoon months, due to dust storms and agricultural residue burning.

The Indo-Gangetic Plain, encompassing states like Delhi, Uttar Pradesh, Bihar, and West Bengal, is the most affected region. Ironically, this area has also attracted significant solar investments in recent years. Without pollution mitigation, the returns on these investments could fall short. By contrast, southern and western states such as Gujarat, Rajasthan, and Tamil Nadu continue to enjoy a solar advantage, thanks to clearer skies.

Future Challenges: Climate Change and Solar Efficiency

In addition to the current challenges, the study’s authors have contributed to another report published in Environmental Research Letters, which examines future climate scenarios. The report warns that rising temperatures could reduce solar panel efficiency by up to 2.3% by the 2040s. Solar panels, especially those in arid regions or on rooftops, tend to heat up beyond the air temperature, which diminishes their electricity output. Moreover, projected declines in wind speeds could impair natural cooling, further reducing panel efficiency.

Urgent Need for Policy Action

The researchers call for policymakers and solar developers to adopt a more dynamic approach to solar resource planning. This includes accounting for atmospheric trends, rising temperatures, and aerosol concentrations, in addition to traditional factors like land availability and sunlight averages. Future decisions on site selection, performance forecasting, and investments must treat the atmosphere as a critical variable.

Conclusion

India’s solar success story has been an inspiring one, but air pollution poses a significant threat to its continued progress. By addressing the growing impact of aerosols and adapting to climate challenges, India can ensure that its solar potential remains a beacon of hope in its journey toward a sustainable and greener future.

Source: This article draws on findings from a study published in iScience by researchers at IIT Delhi.