India’s average solar irradiance ranges from 3.5–5.5 kWh/m²/day across the country, with nearly every state offering significant potential for solar energy generation. However, several states with high irradiance and ample wasteland have failed to tap into the opportunity.

Last September, the National Institute of Solar Energy (NISE) estimated a total feasible ground-mounted solar energy potential of a staggering 3,343 GWp, building on a 2014 figure of 748.98 GWp.

The gap between solar potential and capacity expansion is huge, even though India has made significant strides in solar capacity additions over the last few years, with 2025 witnessing an unprecedented 36.6 GW of installations. The numbers could have been far higher if some states had tapped even a small portion of their potential.

States such as Odisha, Chhattisgarh, and Jharkhand in the eastern and central Indian rust belt have conditions tailor-made for solar energy development. Together, the three states account for a potential of over 316 GW. However, their record in solar installations is dismal.

According to Mercom’s India Project Tracker, Odisha has an operational solar capacity of just 624 MW and a pipeline of 1,431 MW, against a potential of 139 GW. The state’s solar irradiance is in a healthy range of 3.76 to 5.24 kWh/m²/day.

The central Indian state of Chhattisgarh, with a solar potential of 126.48 GW, has an operational capacity of 1,142 MW and a pipeline of 282 MW. The state’s solar irradiance is in the 4.18 to 5.28/kWh/m2/day range.

Similarly, Jharkhand, which receives solar irradiance ranging from 3.7 to 5.21 kWh/m²/day, has only 140 MW of operational solar capacity and a pipeline of 490 MW.

All three states are home to energy-intensive industries, such as mining and mineral processing, and iron and steel.

Other states with significant solar potential include Bihar (32.99 GW), which has an operational capacity of 356 MW and a pipeline of 732 MW. The northeastern state of Assam is another with an identified potential solar capacity of 19.17 GW, but has only 299 MW of operational installations and a pipeline of 1,275 MW.

West Bengal is another laggard solar state, with 435 MW of projects in operation and a small pipeline of 131 MW, while NISE has estimated its total solar energy potential at 22.74 GW.

The NISE report integrates advanced geospatial datasets and refined methodologies, accounting for key development constraints, including terrain (slope and aspect), sustainable land use, solar irradiance, and proximity to roads and electrical substations. It identifies a total feasible ground-mounted solar potential of 3,343 GWp across India, derived from 27,571 km² of suitable wasteland.

Apart from the well-known regions of Rajasthan, Maharashtra, and Gujarat, which have vast wastelands and high irradiance, many other states also show significant capacity owing to favorable solar geometry and land-use efficiency, the report points out.