The Tamil Nadu Green Energy Corporation (TNGECL) has invited bids to set up seven standalone battery energy storage systems (BESS) with a total capacity of 375 MW/1,500 MWh.

Bids must be submitted by December 22, 2025. Bids will be opened on the next day.

Bidders must submit a bid processing fee of ₹1.5 million (~$16,930) plus 18% GST.

They must also furnish ₹200,000 (~$2,257)/ MW of the quoted capacity as an earnest money deposit.

Selected bidders must submit a performance bank guarantee for a value equivalent to 40% of the annual payment due to the developer prior to signing of battery energy storage purchase agreement (BESPA) with Tamil Nadu Power Distribution Corporation (TNPDCL).

The minimum bid size must be 25 MW / 100 MWh. The project size should be quoted in multiples of 25 MW. A maximum of 175 MW/ 700 MWh will be allocated to a single bidder.

The BESS must be designed to ensure that it can charge and discharge with a C rate of 0.25. Additionally, the BESS must be capable of being charged or discharged in groups from 25 MW/100 MWh to 50 MW/200 MWh, up to the total rated capacity specified in the BESPA.

The BESS must be available for 1.5 full operational cycles per day, i.e., 1.5 complete charge-discharge cycles per day.

The BESS must guarantee a minimum system availability of 95% on an annual basis.

The BESS should guarantee AC to AC round-trip efficiency of ≥85% for the system on a monthly basis up to the metering point.

TNPDCL will provide the required power for charging the BESS, considering the minimum system efficiency as specified in the agreement.

The scheduled commissioning date for the full project capacity must be 18 months from the effective date of BESPA.

The BESPA will be valid for 15 years from the date of the project’s full commissioning.

The BESPA signing date will be within one month of the letter of award issuance date or within 10 days of the state electricity regulator’s approval for the tariff adoption, whichever is later.

The projects will receive viability gap funding (VGF) of ₹1.8 million (~$20,306.86)/MWh of the awarded capacity. The VGF will be disbursed in three tranches: 20% at financial closure, 50% at commercial operation date (COD), and 30% a year post-COD upon certification.

Land will be provided on a right-to-use basis by the Tamil Nadu Transmission Corporation at an annual lease fee of ₹1 (~$0.011)/project/year.

Only commercially established and operational technologies must be used to minimize technology risk and achieve timely commissioning of the projects.

The net worth of the bidder should be equal to or greater than ₹4 million (~$45,147) /MWh of the quoted capacity as of the last date of the previous financial year or as of the day at least 7 days before the bid submission deadline.

Bidders must have a minimum average annual turnover of ₹5 million (~$56,434)/ MW of the quoted capacity during the three financial years preceding the bid submission deadline.

India’s cumulative installed energy storage capacity reached 490 MWh by the end of June 2025, according to Mercom India Research’s India’s Energy Storage Landscape 1H 2025 Report.