Three interstate transmission system (ISTS) schemes awarded under the tariff-based competitive bidding (TBCB) framework were fully commissioned in the first quarter (Q1: April to June) of current fiscal year FY26.
While Power Grid Corporation of India Ltd (PGCIL) commissioned two schemes – both in June 2025 — one was commissioned by Adani Energy Solutions Ltd (AESL) in April 2025.
PGCIL
PGCIL commissioned an ISTS-TBCB scheme housed under “Powergrid ER NER Transmission Ltd” and officially termed as “System Strengthening Scheme for ER and NER [ERSS-XXV & NERSS-XV].”
Spread over Bihar, Assam and Arunachal Pradesh, this was a relatively small scheme with a capital outlay of Rs.342 crore. Significantly, the scheme was fully commissioned ahead of the scheduled date of October 2025.
PGCIL also fully commissioned a scheme spanning Odisha and Chhattisgarh, housed under “Powergrid ERWR Power Transmission Ltd.” This scheme experienced a time overrun of three months with the originally envisaged date being March 2025.
AESL
Adani Energy Solutions Ltd (AESL) fully commissioned an ISTS-TBCB scheme housed under KPSI Transmission Ltd. This scheme was originally won by Megha Engineering & Infrastructures Ltd (MEIL) but subsequently acquired by AESL. This scheme mainly involved augmentation of the Khavda Pooling Station-1 (KPS1) in Gujarat by a significant 6,000 MVA.
Capacity addition
According to preliminary estimates, the total infrastructure addition by these three schemes stood at 319 ckm of transmission lines and 7,320 MVA of transformation capacity, with capital expenditure of an estimated Rs.1,730 crore. The aggregate tariff of these three schemes stands at Rs.1,502.36 million per year. It may be noted that the three schemes in discussion were fully commissioned in Q1FY26. It is likely that some elements of these schemes were commissioned before Q1FY26. The capacity addition by such elements is attributed to the month in which they were commissioned.
ISTS-TBCB portfolio
As of June 30, 2025, the total portfolio of under-construction ISTS-TBCB schemes stood at 84 schemes envisaging 33,829 ckm of transmission lines and 312,420 MVA of transformation capacity. PGCIL had a dominant share of 44 schemes seeking to add 20,018 ckm of lines and 194,620 MVA of substation capacity.
Addition to ISTS network
Meanwhile, according to independent official statistics, the total addition to the ISTS network during Q1FY26 was 293 ckm of transmission lines and 12,320 MVA of transformation capacity. This includes ISTS projects awarded under the regulated tariff mechanism (RTM) and TBCB routes.
The total ISTS network, as of June 30, 2025, comprised of 214,677 ckm of transmission lines and 568,205 MVA of substation capacity. This represented 43 per cent and 42 per cent, respectively, of the country’s total power transmission network of 220kV or more.
Editor’s Note: In a separate story based on information released by Adani Energy Solutions Ltd (AESL), it was informed that AESL fully commissioned an ISTS-TBCB scheme housed under “Khavda II-A Power Transmission Ltd” in Q1FY26. However, according to official reports released by CEA, this scheme is said to have been commissioned in March 2025, which is in Q4FY25.
Also read: ISTS-TBCB schemes: PFCCL transfers three SPVs to winning developers
Featured photograph (source: Adani Energy Solutions Ltd) is for representation only