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As India dons the role of a solar superpower, a crucial hurdle in the country’s journey to self-reliance in this sector is the availability of the key raw material—polysilicon. It is a semiconductor that helps convert photons to electricity, thereby forming the brick of solar cells. The production of polysilicon—an energy-intensive material—requires copious amounts of high-quality silicon. While silicon is abundantly found in India and the rest of the world, competition for the mineral is extremely high.

PM2.5 is one of the major contributors to air pollution in India, resulting in poor air quality and human health issues. The current study explores the applicability of TTAinterfaceTrendAnalysis (an ‘R’ language-based Graphical User Interface package) in estimating the annual and month-wise trends in PM2.5 over five Indian megacities (New Delhi, Kolkata, Mumbai, Hyderabad, and Chennai). The package offers a one-stop solution for various statistical analyses such as data imputation, outlier detection, trend analysis, data smoothing, diagnostic tests, etc.

In 2021, the World Health Organization (WHO) air quality guidelines were revised for six key air pollutants. The new guideline levels for PM2.5 and O3 may be unattainable for many countries due to natural sources and background levels. Reductions in NO2 may increase O3 due to atmospheric chemistry. Regional-specific scientific expertise is necessary to guide local air quality management towards more appropriate WHO interim targets and controls on modifiable factors especially considering atmospheric chemistry.

Lower-cost air pollution sensors can fill critical air quality data gaps in India, which experiences very high fine particulate matter (PM2.5) air pollution but has sparse regulatory air monitoring. Challenges for low-cost PM2.5 sensors in India include high-aerosol mass concentrations and pronounced regional and seasonal gradients in aerosol composition. Here, we report on a detailed long-time performance evaluation of a popular sensor, the Purple Air PA-II, at multiple sites in India.

So far in this series, we discussed different aspects of India’s solar PV sector, including taxation, policies, and the journey towards sustainability. In this concluding piece, we focus on popular technologies, innovations, challenges, and opportunities.