New Delhi: India curtailed 378.52 million units (MUs) of variable renewable energy (VRE) in September 2026, equivalent to 1.28 percent of total renewable energy generation, as grid integration challenges continued to constrain the utilisation of available solar and wind power, JMK Research said on Friday. A total of 118.6 GW of renewable energy capacity was affected by curtailment during the month, comprising 96.9 GW of solar and 21.7 GW of wind capacity, the statement said.
Follow Energy Watch on X
Solar power accounted for approximately 83 percent of the curtailed energy, at around 314 MUs, while wind curtailment reached 64.98 MUs. Wind-related curtailment nearly tripled year-on-year, increasing its share of total curtailment from 4.7 percent to 17 percent.
Despite the rise in wind curtailment, overall renewable energy curtailment declined 43.31 percent month-on-month in September, from August's levels, and was 24 percent lower than in September 2025. The share of renewable generation curtailed also fell from 1.89 percent in August to 1.28 percent in September.
However, JMK Research cautioned that the decline reflected seasonal relief rather than a lasting improvement in grid integration.
Renewable energy curtailment rose sharply between May and August 2026, reaching nearly four times the level recorded during the corresponding period in 2025. Curtailment peaked at 1,166.52 MUs in July 2026, while monthly levels remained below 50 MUs between December and February.
October 2025 recorded the highest curtailment share during the period under review, at 4.32 percent of renewable energy generation. The addition of around 44.6 GW of solar capacity in FY2026 has further increased pressure on transmission infrastructure and grid flexibility, according to the statement.
JMK Research attributed renewable energy curtailment to several factors, including demand-generation mismatches, transmission constraints, inadequate storage and limited grid flexibility. Seasonal overlaps between high renewable energy output and moderate electricity demand also contribute to the problem.
Data from Grid-India categorises variable renewable energy curtailment according to the operational instructions issued to generators. These include back-down instructions to address real-time system constraints and Emergency Tertiary Reserve Ancillary Services (TRAS) Down, which involves reducing generation to balance electricity supply and demand.
Of the total renewable energy curtailed in September, 146.73 MUs, or 39 percent, resulted from real-time system constraints. The remaining 231.79 MUs, accounting for 61 percent, was attributed to Emergency TRAS Down.
Solar power accounted for approximately 82 percent of the energy curtailed through TRAS Down. The figures indicate that the month's curtailment was driven primarily by the need to balance the power system, rather than by transmission congestion alone.
Gujarat and Rajasthan together accounted for around 79 percent of India's renewable energy curtailment in September 2026. Gujarat recorded 187.76 MUs of curtailment, representing 49.6 percent of the national total, while Rajasthan accounted for 110 MUs, or 29.1 percent.
Gujarat contributed approximately two-thirds of the country's wind curtailment, at 43.75 MUs. In contrast, Rajasthan's reported curtailment was entirely solar. Karnataka recorded 21.07 MUs of curtailment, with solar accounting for the larger share, while Tamil Nadu reported 12.93 MUs, with wind contributing more significantly.
The concentration of curtailment in Gujarat and Rajasthan highlights the importance of addressing constraints at specific grid locations, alongside broader measures to improve the flexibility of the electricity system.
Battery storage could help absorb surplus renewable power
JMK Research highlighted battery energy storage systems (BESS) as one of the options for reducing renewable energy losses. Batteries can store surplus solar and wind generation when output is high and electricity demand is relatively low, then discharge the stored energy during evening demand peaks.
September's curtailment of 378.52 MUs translates to an average of approximately 12.6 GWh of curtailed energy per day. As an illustrative scale estimate, this is equivalent to around 3 GW of four-hour battery storage capacity, although actual storage requirements would depend on the timing, location and duration of surplus generation.
The statement pointed to Gujarat and Rajasthan as priority locations for storage deployment because of their high curtailment levels.
Strategically located battery systems, particularly those co-located with renewable energy projects, could help absorb recurring surpluses and respond to system operator instructions during TRAS Down events.
However, storage would need to complement other interventions, including transmission network upgrades, flexible thermal generation, improved renewable energy forecasting, demand shifting and electricity markets that reward flexibility.
With further renewable energy capacity additions expected to increase the challenge of managing seasonal and location-specific generation surpluses, the strategic deployment of battery storage could help reduce renewable energy losses and protect project revenues.
The September figures underscore the need to match renewable energy expansion with investments in transmission, storage and system flexibility to ensure that more of the clean electricity generated can be utilised.