NTPC Green Energy Limited (NGEL), an India-based renewable energy company and a subsidiary of NTPC Limited, has invited bids for the balance-of-system (BOS) package of a 250 MW/1 GWh BESS at NTPC Kayamkulam in Kerala, India. The invitation for bids, IFB No. NGEL-CS-5831-004(BESS BOS)-9, is dated 9 November 2026. It has been issued under domestic competitive bidding on a single-stage, two-envelope basis, which will be followed by a reverse auction.

Under the package, the contractor will design, supply, build, test and commission the BESS on a turnkey basis, except for the battery containers and the grid-forming PCS. Those two items are to be supplied by NGEL as free issue, and NGEL will supervise their erection and commissioning. The contractor must, however, engage a customs house agent to clear them at the port, and it must carry them from the Indian port to the site. Because the rated capacity is measured as AC discharge at the point of injection, the nameplate capacity of the batteries and PCS that NGEL supplies is to be 15% higher.

The scope also covers a new 220 kV air-insulated switchyard with 220/33 kV power transformers, pooling switchgear and the evacuation system up to the take-off gantry. The switchyard is to have two 220 kV line bays for a loop-in loop-out (LILO) connection to the existing Kundra line, although the LILO work on that line will be awarded under a separate package. The contractor will also handle the grid compliance study, reactive power compensation, the EMS and SCADA, fire fighting and the auxiliary power for the whole plant, and the metering will follow the requirements of the Kerala State Electricity Board Limited (KSEBL).

The plant is to be built as a single block of 250 MW/1 GWh, integrated at the 220 kV level, with a design life of at least 15 years from the completion of its trial run. The contractor will operate and maintain it for five years from the commissioning of its full capacity, while the batteries and PCS will be maintained under a separate annual contract that NGEL is to arrange.

The bidding documents will be on sale from 16 November to 27 November 2026. Bids are to be submitted by 14:00 on 11 December 2026, and they will be opened at 14:30 on the same day.

The project was first reported in July, when a proposal by NTPC to build a 250 MW/1 GWh BESS at Kayamkulam was under the consideration of KSEBL. That proposal had been submitted in December 2025. In September, NGEL tendered a 1.1 GW/3.3 GWh BESS at the NTPC REL Khavda Solar Plant as a single EPC package, with the BESS containers inside the contractor's scope.