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India has made solar energy the backbone of its renewable push, with more than 123 gigawatts of installed capacity already feeding into the grid and vast new projects planned to meet the target of 500 GW of renewables by 2030. The country’s deserts, plains, and rooftops have become symbols of this transition, but scientists are warning that the sunlight itself may not remain as dependable as policymakers assume. A recent study projects that rising greenhouse gas emissions, higher aerosol loads, and changing cloud patterns could reduce surface solar radiation across much of India, especially in the south, centre, and east. Losses of up to 10 per cent by the end of the century are possible under high-emission scenarios. This decline could undermine solar generation, extend payback periods for investors, and weaken the reliability of the power supply at a time when demand is surging.
Solar Radiation on the Decline
A new study led by researchers from Pune University projects that under intermediate and high greenhouse gas emission pathways (SSP2-4.5 and SSP5-8.5), surface solar radiation (SSR) over central, southern, and eastern India could drop by up to 10 per cent by the end of the century. In more moderate emission trajectories, SSR loss is more minor, roughly 0.5-1 per cent per decade during the near-future (2021-2040) period, particularly over southern and western regions. Under the high emission scenario, decline rates in many parts of India exceed 1 per cent per decade, translating to a mean SSR loss of about 1.32 watts per square metre per decade over the whole country.
Historical data support that the decline has already begun. A study showed that between 2001 and 2018, India lost nearly 29% of its Global Horizontal Irradiance (GHI) potential because of aerosol loading. Another long-term examination reported surface insolation decreasing at a rate of −0.29 ± 0.19 W/m² per year over large parts of India in the first two decades of the 2000s. These trends are influenced by clouds, aerosol content, dust storms, biomass burning, land use changes and regional meteorology.
What It Means for India’s Solar Infrastructure
India has set ambitious solar targets. As of August 2025, its installed solar capacity exceeded 123,000 MW (123.13 GW), with the southern states contributing about 14 per cent of that capacity. Solar farms and photovoltaic plants are designed to last 20-25 years, assuming stable or slowly changing irradiance. SSR losses of 5-10 per cent over several decades mean that energy yield per panel will drop, financial returns will shrink, and payback periods will extend. Regions such as southern, central, and eastern India, often already facing higher cloud cover or air pollution, are likely to suffer greater reductions in output.
Rooftop solar, utility-scale PV, and concentrated solar power (CSP) installations are all affected. In the central Himalayas and high altitude zones, losses in energy can run into hundreds of kilowatt-hours per square meter per year when aerosol and cloud attenuation are considered. For instance, in the Nainital region, the loss in annual Global Horizontal Irradiance due to aerosols is up to 539 kWh/m² and due to clouds, more than 800 kWh/m² for certain months. That translates into financial losses of millions of rupees annually for even modest-scale plants.
The Role of Emissions, Air Quality, and Climate
Four key atmospheric factors drive down the solar radiation reaching panels: aerosols (from industry, biomass burning, vehicles), turbidity (dust and particles in the air), cloud cover changes, and changing climate-driven patterns such as shifts in monsoon or seasonal precipitation. This recent study points to increased atmospheric turbidity and enhanced cloud cover, especially post-monsoon, as primary culprits in many regions. Analyses over the Indo-Gangetic Plains, central India, and the eastern coast show that biomass burning and dust transport contribute strongly to aerosol optical depths that block sunlight.
Air quality thus plays a dual role: direct health implications for people, and indirect effects on renewable generation. Studies in urban and semi-urban Indian settings reveal that in some polluted cities, solar panels operate at much reduced efficiency, sometimes as much as 50% loss in output under heavy pollution and haze conditions. Further, radiative forcing (a measure of the effect of aerosols on sunlight reaching Earth’s surface) has been estimated at values between –45 and –150 W/m² in periods of biomass burning and dust storms in the Indo-Gangetic region.
Climate change adds further pressure. Rising temperatures reduce panel efficiency, while extreme weather (cloud-heavy days, unpredictable monsoon shifts) increases variability in generation. Under high emission scenarios, there is projected loss not just in the annual average SSR but also in greater seasonal swings. Policy, planning, and investment models that assume stable or slowly varying solar resource risk often underestimate costs or overvalue returns.
Building Resilience: Technology, Policy, and Hybrid Systems
To adapt India’s solar infrastructure to future declines in SSR, multiple strategies are essential. First technological improvements: higher efficiency panels (especially under diffused light), tracking systems, anti-soiling or self-cleaning coatings, and bifacial module designs that can capture reflected light. These can partly offset losses due to aerosols and cloud cover. Second, better forecasting and monitoring: incorporating satellite data, aerosol optical depth measurements, cloud cover projections, and seasonal variability into solar farm design, energy yield modelling, and maintenance scheduling.
Hybrid systems that combine solar with wind, storage, or other supplemental sources can help manage variability, especially in regions projected to face sharper declines in solar radiation. The study highlights north-west India as relatively stable and more reliable for long-term investment, making areas like Rajasthan safer bets for utility-scale projects. To secure the sector’s future, government policy must integrate climate projections into solar auctions, subsidies, and land allocation, while financial models should reflect potential losses in irradiance. At the same time, stronger emissions controls, improved air quality measures, dust management near solar parks, and afforestation efforts can reduce atmospheric loading and boost renewable output.
Rising greenhouse gas emissions and related air pollution in India are not only climate issues but also significant threats to the viability of solar energy infrastructure. Empirical data and future projections show that if emissions are allowed to increase unchecked, the solar resource base in many parts of the country could deteriorate over time. That decline will lower energy output, raise costs, lengthen payback periods and challenge India’s goals for renewable energy deployment.
References:
https://www.sciencedirect.com/science/article/pii/S2589004223019338
https://pmc.ncbi.nlm.nih.gov/articles/PMC10561047
Physical Achievements | MINISTRY OF NEW AND RENEWABLE ENERGY | India
https://www.mdpi.com/2072-4292/13/16/3248
Air Pollution Impacting Solar Panel Efficiency in India, say IIT, Delhi researchers.
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