Eagle Construction (Eagle Infra India) and OPG Power (OPG Power Ventures) have won Tamil Nadu Green Energy Corporation’s (TNGECL) auction to set up seven standalone battery energy storage systems with a total capacity of 375 MW/1,500 MWh.

Out of the 375 MW/1,500 MWh tendered capacity, only 350 MW/1,400 MWh was auctioned.

Eagle Construction won 175 MW/700 MWh at a tariff of ₹315,000 (~$3,471.07)/MW/month, and OPG Power won 175 MW/700 MWh at a tariff of ₹316,000 (~$3,482.09)/MW/month.

The tender was floated in November 2025.

The scope of work covers the setup of battery storage projects, ensuring their availability to TNPDCL for on-demand charging and discharging.

The projects must be interconnected with the state transmission utility’s network.

The battery storage projects will be charged by drawing power from the Tamil Nadu Transmission Corporation (TANTRANSCO)/Tamil Nadu Power Distribution Corporation (TNPDCL) and inject power into the TANTRANSCO/TNPDCL network on state load dispatch center’s instructions.

Winners must design the battery storage projects to charge and discharge at a C rate of 0.25.  They must ensure the battery storage projects are capable of charging or discharging in groups ranging from 25 MW/100 MWh to 50 MW/200 MWh, up to the total rated capacity specified in the battery energy storage power sale agreement (BESPA).

The battery storage projects must be available for 1.5 full operational cycles per day and guarantee a minimum annual system availability of 95%.

The battery storage projects must guarantee AC-to-AC round-trip efficiency of ≥85% for the system, up to the metering point, on a monthly basis.

TNPDCL will provide the required power for charging the battery storage projects, in accordance with the minimum system efficiency specified in the agreement.

The projects must be completed within 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 projects will receive viability gap funding of ₹1.8 million (~$20,306.86)/MWh of the awarded capacity.

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

Projects must use only commercially established and operational technologies to minimize technology risk and achieve timely commissioning.

Last year, TNGECL invited bids to select developers to set up a 15 MW solar project, along with a 15 MW/45 MWh battery storage project, in Thiruvarur.