October 23, 2026: Curtailment during September 2026 affected around 118 gigawatts (GW) of renewable energy capacity due to issues such as transmission constraints, limited battery energy storage system (BESS) capacity, and grid flexibility.

During September , 378.52 million units (MU) of variable renewable energy was curtailed, which is equivalent to 1.28 per cent of India’s total renewable energy generation, highlighting ongoing grid integration challenges, JMK Research $ Analytics said.

The curtailment affected a cumulative 118.6 GW of renewable energy capacity, comprising 96.9 GW of solar and 21.7 GW of wind capacity, it added.

“Key reasons for RE curtailment include demand-generation mismatches, transmission constraints, limited storage and grid flexibility, and seasonal overlaps between high renewable output and moderate demand,” it pointed out.

Curtailment surged amid solar capacity additions

Citing data, JMK Research & Analytics said curtailment rose sharply from May to August 2026, reaching nearly four times the level recorded in the same period of 2025. The addition of around 44.6 GW of solar capacity in FY26 has increased pressure on transmission infrastructure and grid flexibility.

Solar power accounted for 83 per cent of September 2026 curtailment, at around 314 MU. However, wind curtailment nearly tripled year on year to 64.98 MU, increasing its share of total curtailment from 4.7 per cent to 17 per cent, it added.

The curtailment remained below 50 MU per month during December 2025-February 2026, but rose from April onwards, peaking at 1,166.52 MU in July. October 2025 recorded the highest curtailment share at 4.32 per cent of the cumulative renewable energy generation.

September curtailment declined month on month

“Curtailment fell 43.31 per cent M-o-M to 378.52 MU in September 2026, down 24 per cent from September 2025. The share of generation curtailed also declined by 0.61 percentage points, from 1.89 per cent in August to 1.28 per cent in September. However, this decline offers seasonal relief rather than evidence of a structural improvement in grid integration,” JMK explained.

Last month, 146.73 MUs (39 per cent) were curtailed due to real-time system constraints, and 231.79 MUs (61 per cent) were curtailed due to Emergency TRAS Down in VRE.

Real-time constraints are back-down instructions issued on the day to manage congestion and operating limits, while emergency TRAS Down involves reducing generation to balance supply and demand. Its use for VRE indicates limited flexibility in the power system to accommodate available renewable generation.

Solar accounted for about 82 per cent of the energy curtailed through TRAS Down, suggesting September’s curtailment was driven mainly by the need to balance the power system rather than grid congestion alone, JMK Research emphasised.

Gujarat and Rajasthan account for nearly 79 per cent

State-wise, Gujarat (187.76 MU, 49.6 per cent) and Rajasthan (110 MU, 29.1 per cent) together accounted for around 79 per cent of the total curtailment.

Gujarat alone contributed about two-thirds of the wind curtailment (43.75 MU), while Rajasthan’s curtailment was entirely solar.

Karnataka and Tamil Nadu recorded technology-wise differences in curtailment, totalling 21.07 MU and 12.93 MU, respectively. Solar accounted for a larger share in Karnataka, while wind contributed more in Tamil Nadu.

Battery storage could help reduce curtailment

BESS can reduce curtailment by storing surplus renewable energy during midday and discharging it during evening peaks. September’s 378.52 MU of curtailment equates to an average of 12.6 (gigawatt-hour) GWh per day, or roughly 3 GW of 4-hour storage as an illustrative scale estimate, JMK Research said.

“Prioritising constrained nodes in Gujarat and Rajasthan, with storage sized to recurring surpluses and responsive to system operator signals, could also help absorb emergency downward reserves (TRAS Down) events,” it suggested.

(Source: Hindu Business Line)