India curtailed green power enough to supply nearly 1.9 mn homes for a month in Sept

A few hours later, after sunset, the system needed more power to meet household and industrial demand. 5% September’s curtailment was equivalent to 1.28% of the country’s renewable generation, according to Grid-India data analysed by JMK Research & Analytics. One million units (MU) equals one million units of electricity. A cumulative 118.6 GW of renewable capacity was affected by curtailment instructions during the month — 96.9 GW of solar and 21.7 GW of wind.

JMK clarified that this figure is the cumulative sum of capacity affected on different days and does not mean 118.6 GW was switched off simultaneously. The mismatch assumes significance as India faced a 560-MU electricity shortage in September, the highest since August 2023, while peak demand touched 269 GW. The challenge is particularly sharp after sunset, when solar output falls and the grid has to depend more heavily on coal, hydro and other sources.

Most of September’s renewable curtailment was also not simply because transmission lines were congested. Of the 378.52 MU curtailed, 231.79 MU, or 61%, was through Emergency TRAS Down, where generators are asked to cut output to keep electricity supply and demand balanced. Another 146.73 MU, or 39%, was due to real-time system constraints, including congestion and operating limits. “This suggests that September’s curtailment was driven mainly by the need to balance the power system, rather than by grid congestion alone,” JMK Research said.

Wind curtailment stood at 64.98 MU, nearly three times the year-ago level, lifting its share of total curtailment to 17% from 4.7%. The problem was concentrated in two renewable-rich states. Gujarat curtailed 187.76 MU and Rajasthan 110 MU, together accounting for around 79% of the national total. Gujarat alone contributed 43.75 MU of wind curtailment, while Rajasthan’s entire curtailment was solar.

Karnataka recorded 21.07 MU and Tamil Nadu 12.93 MU. September did bring some relief. Curtailment fell 43.31% from 667.76 MU in August and was 24% lower than September 2025. But JMK cautioned that the decline was “seasonal relief rather than evidence of a structural improvement in grid integration.” Curtailment had peaked at 1,166.52 MU in July, while around 44.6 GW of solar capacity added in FY26 has increased pressure on transmission networks and the grid’s ability to absorb renewable electricity when it is available.

Battery storage could help bridge this daytime-surplus and evening-demand gap. JMK estimated September’s curtailed energy at an average 12.6 GWh a day, roughly equivalent to 3 GW of batteries capable of supplying power for four hours. In practical terms, such batteries could store excess solar electricity in the afternoon instead of switching it off, and release it after sunset when homes and businesses need more power.

JMK said strategically placed storage in Gujarat and Rajasthan, along with stronger transmission, flexible thermal generation, better forecasting and shifting some electricity demand to surplus hours, could reduce renewable-energy losses as India adds more solar and wind capacity.