Renewable Energy News

India’s Grid Curtailed 118.6 GW of Solar and Wind Capacity in September

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India curtailed 378.52 million units (MU) of solar and wind generation in September 2026, according to JMK Research, as cooler weather and lower output eased the grid congestion that had pushed curtailment to record highs earlier in the year. The September figure is down 43.3% from August and 24% lower than September 2025, but JMK Research cautions the improvement reflects a seasonal lull in generation rather than a structural fix to the transmission bottlenecks behind India’s curtailment problem.

Energy curtailed versus capacity affected

JMK Research’s September data separates two measures that are often conflated in coverage of India’s renewables sector: the energy actually curtailed, at 378.52 MU, equal to 1.28% of total renewable generation for the month; and the installed capacity affected by curtailment at some point during the month, which JMK puts at 118.6 GW, made up of 96.9 GW of solar and 21.7 GW of wind. The 118.6 GW figure describes capacity exposed to curtailment events, not output lost — a distinction that matters given India’s utility-scale solar and wind fleet totaled roughly 160 GW as of mid-2026. Solar accounted for about 83% of September’s curtailed energy, at roughly 314 MU, while wind curtailment, though a smaller share, nearly tripled year-on-year to 64.98 MU.

A sharper picture after a difficult summer

September’s decline follows a much steeper curtailment spike over the summer. Curtailment rose steadily from April 2026 and peaked at 1,166.52 MU in July, nearly four times the year-earlier level for the same month, according to JMK Research; separate analysis from the Centre for Research on Energy and Clean Air estimated that roughly 1.835 billion units of renewable generation, mostly solar, were curtailed across July and August combined. JMK Research describes September’s relief as consistent with past seasonal patterns, when monsoon cloud cover and cooler temperatures reduce both solar output and peak demand simultaneously, rather than evidence that grid integration has structurally improved.

Transmission bottlenecks, not oversupply, are the binding constraint

JMK Research attributes the curtailment to a mix of demand-generation mismatches, transmission constraints, and limited storage and grid flexibility, with transmission singled out as the binding constraint on further renewable build-out. Rating agency ICRA has estimated that around a third of the 54.8 GW of renewable capacity commissioned recently was being evacuated through India’s temporary general network access route as of May 2026 — a stopgap connection method rather than dedicated transmission capacity. Energy think tank Ember has separately found that India met only about 80% of its annual transmission-build targets over the past five years, and estimates some 20 GW of renewable capacity could face grid-connection delays of more than four months in the 2026-27 fiscal year. On storage, CREA put operational battery capacity at just 9.1 GWh as of August 2026, against roughly 151 GWh of battery storage projects that had already been tendered — a gap that leaves little buffer to absorb midday solar output when transmission or demand falls short.

Why it matters for India’s renewable build-out

India has been adding utility-scale solar and wind capacity faster than its grid operators have been able to expand transmission links and flexible balancing resources, a mismatch that curtailment data has tracked closely through 2026. The government’s own storage pipeline points to the scale of the response underway: Indian financial services firm Nuvama has projected the country’s battery storage capacity could expand nearly 50-fold by 2032 as developers and state utilities move to pair storage with new renewable capacity specifically to cut curtailment losses, a strategy South Africa has also adopted by fast-tracking 4,600 MW of battery storage to address its own grid curtailment problem. Until new transmission lines and storage capacity catch up with generation additions, analysts expect curtailment to keep tracking the seasonal pattern seen this year — easing in the cooler months and spiking again as summer solar output and demand mismatches return.

Sources

JMK Research, “96.9 GW of Solar and 21.7 GW of Wind Capacity affected by curtailment in September 2026,” October 2026 — primary curtailment data, MU and GW figures, month-on-month and year-on-year comparisons.
PV Tech, “India curtails 96.9GW of solar PV in September,” October 2026 — independent secondary coverage of the JMK Research release.
Centre for Research on Energy and Clean Air (CREA), July-August 2026 curtailment analysis, and ICRA and Ember research cited therein — transmission and storage context.