India’s power transmission gap is widening, with the latest official data flagging schedule slippages in 36 critical interstate transmission system (ISTS) lines.

The scheduled commercial operation dates (SCOD) for these under-construction transmission lines, with a combined length of 10,321 circuit kilometers (ckm), had elapsed as of April 30, 2026, according to the Central Transmission Utility of India (CTUIL).

The SCODs for another 33 critical transmission lines, totaling 6,948 ckm, fall within the next six months.

The list classifies transmission lines as critical if their SCOD was on or before the last day of the month under consideration, April 2026, or if their SCOD falls within the next six months.

Many of the SCOD-elapsed projects, awarded through tariff-based competitive bidding and the regulated tariff mechanism, are meant to evacuate power from the renewable energy-rich states of Rajasthan and Gujarat, two states that are key to India’s clean energy buildout.

The data is likely to heighten concerns among renewable energy developers, whose projects have faced heavy curtailment over the past year. A staggering 11.5 GW of renewable energy has been curtailed in Rajasthan alone since January this year, much of it due to transmission constraints, with March accounting for 8.3 GW.

CTUIL highlighted the gravity of the problem in April, informing the Central Electricity Regulatory Commission that it was facing challenges in providing grid connectivity for approximately 60 GW of renewable energy capacity in Rajasthan. It attributed the issue to structural constraints in transmission planning, noting that the state’s high concentration of renewable energy potential had saturated most conventional evacuation pathways to nearby load centers.

According to the Central Electricity Authority, India installed 12,139 ckm of transmission lines in the financial year 2026, achieving 78.9% of the cumulative target of 15,382 ckm.

Among the SCOD-elapsed lines, the northern region accounts for the largest share, with 14 lines totaling 5,313 ckm. The southern region has eight such lines aggregating 2,833 ckm, while the western region has 13 lines totaling 2,172 ckm.

The lines are being executed by both government-owned and private companies. POWERGRID accounts for the largest share of SCOD-elapsed lines, with 18 projects totaling 5,405 ckm. Sterlite/Resonia is executing six lines with a combined length of 1,695 ckm, while Adani is executing three lines totaling 1,196 ckm.

The largest SCOD-elapsed transmission element is Tata Power’s 692 ckm Bikaner-III–Neemrana-II 765 kV double-circuit line. This is followed by POWERGRID’s 682 ckm Bikaner-III–Neemrana-II 765 kV line, POWERGRID’s 666 ckm Neemrana-II–Bareilly 765 kV line, Adani’s 636 ckm Narendra New–Pune 765 kV double-circuit line, and Sterlite/Resonia’s 635 ckm Fatehgarh-3–Beawar 765 kV line.