Official statistics suggest that over 3,000 ckm of interstate transmission system (ISTS) transmission lines are currently under construction, through projects awarded under the tariff-based competitive bidding (TBCB) mechanism.
Latest statistics released by Central Electricity Authority (CEA) point out that 33,179 ckm of transmission lines were under construction, as of April 30, 2025, through 84 ISTS-TBCB schemes.
These 84 projects, with aggregate investment outlay of around Rs.2,16,040 crore, also aim to add 3,11,240 MVA (around 311 GVA) of transformation capacity to the ISTS network.
Much of this transmission infrastructure will be fully commissioned by end of FY27, which is by March 31, 2027.
To put this in perspective, India added 6,283 ckm of ISTS transmission lines in FY25, while the ISTS transformation capacity addition in the same period stood at 39,335 MVA. However, this addition was from ISTS schemes awarded under both the modalities – TBCB and RTM (regulated tariff mechanism) whereas the present story discusses ISTS-TBCB projects alone. [More details presented ahead in this story.]
Dominant FY25
It is interesting to note that of the 84 ISTS-TBCB schemes under construction as of April 30, 2025, as many as 45 were awarded in FY25 alone. This has been discussed in detail in T&D India’s exclusive report accessible here.
Of the 84 ISTS-TBCB schemes, Power Grid Corporation of India Ltd (PGCIL) had a share of 45 schemes with the remaining 39 being distributed amongst several private developers including Adani Energy Solutions Ltd (AESL), Resonia (formerly Sterlite Power), Apraava Energy, IndiGrid, G R Infraprojects, Tata Power, Torrent Power, Techno Electric & Engineering Company, Renew Transmission Ventures, Dineshchandra R. Agarwal Infracon Pvt Ltd, Megha Engineering & Infrastructures Ltd and Resurgent Power Ventures.
As can be seen from the above table, PGCIL dominated with a share of around 58 per cent in terms of transmission lines and project outlay, while it had a higher share of 63.1 per cent with respect to transformation capacity.
Within the private sector, prominent developers with respect to transmission infrastructure under construction through ISTS-TBCB schemes are AESL and Resonia.
ISTS-TBCB market in FY26
In the current fiscal year FY26 so far (April 1, 2025 to May 19, 2025), not a single ISTS-TBCB scheme was formally transferred to its winning developer. However, at least three schemes where bidders have been shortlisted are up for imminent award. Another 15-odd schemes are at various stages of bidding.
Modes of capacity build-up
CEA monitors power transmission infrastructure – lines and substations – of voltage class 220kV or above only. Such infrastructure can come through interstate transmission system (ISTS) or intrastate transmission system (InSTS) schemes. Within each of the two types, the implementation mode can be either TBCB or RTM. Thus, there are four basic modes by which transmission infrastructure is added – ISTS-TBCB, ISTS-RTM, InSTS-TBCB and InSTS-RTM. The present story covers only the ISTS-TBCB type.
Featured photograph (source: Adani Energy Solutions Ltd) showing a 765kV transmission line of AESL in Bikaner, Rajasthan is for representation only
