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POWERGRID Seeks Bids for 1.5 GWh Standalone Battery Storage Projects in Tamil Nadu

Power Grid Corporation of India (POWERGRID) has issued a tender to identify partners for the development of 375 MW / 1,500 MWh standalone battery energy storage system (BESS) projects across seven locations in Tamil Nadu.

The deadline for submitting bids is January 28, 2026, with bid opening scheduled for the same day. Interested bidders are required to pay a tender fee of Rs 25,000.

Previously, the Tamil Nadu Green Energy Corporation Limited (TNGECL) had invited bids for the installation of seven standalone BESS projects with an aggregate capacity of 375 MW / 1,500 MWh.

POWERGRID has indicated its intention to participate in the tender. If selected, the successful bidders will execute the projects in partnership with POWERGRID. However, the selected entities will not be allowed to participate in the tender independently or through subsidiaries, partnerships, ownership links, individual firms, or consortium arrangements.

The shortlisted bidders will enter into a memorandum of understanding (MoU) with POWERGRID for the implementation of the projects. The scope of work includes complete operation and maintenance for a period of 15 months, and the projects are required to be completed within the same timeframe.

Technical and Operational Requirements

As per the TNGECL tender requirements, the BESS must be designed for 1.5 full operational cycles per day and operate at a C-rate of 0.25. The systems should support grouped charging and discharging configurations ranging from 25 MW / 100 MWh to 50 MW / 200 MWh, up to the total contracted capacity under the battery energy storage supply agreement.

The projects must ensure a minimum annual system availability of 95% and achieve an AC-to-AC round-trip efficiency of at least 85% at the monthly metering point.

Power required for charging the BESS will be supplied by the Tamil Nadu Power Distribution Corporation, subject to compliance with the minimum efficiency norms outlined in the agreement. Meanwhile, the Tamil Nadu Transmission Corporation will provide land on a right-to-use basis at an annual lease fee of Rs 1 per project per year.

The projects will also be eligible for viability gap funding (VGF) of Rs 1.8 million per MWh of the awarded capacity. The VGF will be released in three stages: 20% at financial closure, 50% upon commercial operation date (COD), and the remaining 30% one year after COD, subject to certification.

To mitigate technology risks and ensure timely commissioning, only commercially proven and operational battery storage technologies will be permitted for deployment.

Recently, POWERGRID had also issued two separate tenders for setting up 187.5 MW / 750 MWh standalone BESS projects at the Maheswaram and Choutuppal substations operated by the Transmission Corporation of Telangana.