Sunsure Energy and Enerica Infra 3 (EnerGrid) won NTPC Vidyut Vyapar Nigam’s (NVVN) auction to set up interstate transmission system (ISTS)-connected 250 MW/1,000 MWh standalone battery energy storage systems (BESS) under the build-own-operate model.

Sunsure won 125 MW/500 MWh at a tariff of ₹6.64 (~$0.0768)/kWh. Enerica also won 125 MW/500 MWh at a tariff of ₹6.65 (~$ 0.076)/kWh.

The tender was floated in February this year.

The BESS will be eligible for Viability Gap Funding (VGF) support of up to ₹2.7 million (~$31,598)/MWh or 30% of the capital cost, whichever is lower.

The project will provide NVVN with energy on an on-demand basis, as required during the peak and off-peak hours.

Bidders must set up the BESS, including its charging power and single-cycle charging/discharging operation, as well as the project’s interconnection with the ISTS. The charging power should preferably come from renewable sources, with other sources meeting any remaining requirements.

The total 1,000 MWh (250 MW × 4 hours) BESS capacity must be distributed and connected to ISTS substations throughout India.

Sunsure and Enerica will also operate and maintain the project, guaranteeing a minimum monthly system availability of 95%. If NVVN is unable to offtake the power, it will be liable to pay 52.88% of the discovered composite energy tariff to the developer for the difference between the energy generated and the energy scheduled monthly.

Bidders must design the BESS to provide a maximum discharge capacity of four hours. The responsibility of getting ISTS connectivity will vest with the developer.

A shortfall in system availability will result in liquidated damages equal to twice the composite discharge value.

In March, the Ministry of Power had directed all states and implementing agencies to award all BESS contracts by June 2025 to enable the VGF program to be completed by May 2027.

Last month, Solar91 Cleantech, Rays Power Experts, Stockwell Solar Services, Oriana Power, and Inox Renewable Solutions won NVVN’s auction to set up 500 MW/1,000 MWh BESS in Rajasthan.