Understanding the climatology and long-term trends in solar radiation using ground based in-situ observations in India

Understanding the variations of solar power potential over the country is essential for the optimum utilisation of solar energy in power generation, which demands accurate information of solar radiation and its variations. In the present study, we investigate the climatology and trends of global radiation (GR), diffuse radiation (DR), bright sunshine hours (BHS) and technical potential of solar power (Solar Photovoltaic potential; SPV potential) using in-situ data procured from India Meteorological Department for the period 1985-2019. GR is high (low) over the northwest and inland areas of peninsular (extreme north and northeast) India, whereas DR is high (low) over the coastal stations (extreme northern parts of the country). BHS is more (less) over northwest (north, northeast and southern peninsular) India. The country has SPV potential in the range of 1800-3400 Wm-2 with substantial regional variations. High (low) SPV potential is observed in the northwest regions (north, northeast and southern peninsular India). The GR and BHS (DR) have (has) a significant decreasing (increasing) trend in most parts of the country. However, the rate of decreasing (increasing) of GR (DR) has been weakened (strengthened) in the recent decade. The technical potential of solar power has a significant decreasing trend in most of the selected stations which is alarming. It necessitates the wide use of solar panels with better efficiency to meet the energy requirements from solar resources.