Tamil Nadu Green Energy Corporation Limited (TNGECL) has announced its auction results for 500 MW/1,000 MWh of standalone battery energy storage systems (BESS) across six locations in Tamil Nadu. Bondada Engineering and Oriana Power secured 200 MW/400 MWh and 50 MW/100 MWh respectively, each at a tariff of Rs 246,000 per MW per month. NLC India Renewables won 250 MW/500 MWh at a tariff of Rs 248,000 per MW per month. The tender was floated in March 2025. Viability gap funding support of up to Rs 2.7 million per MWh or 30 per cent of the capital cost, whichever is lower, will be provided.
The developers will set up the projects on a build-own-operate basis. The awarded projects must be completed within 18 months. The Tamil Nadu Transmission Corporation Limited will provide land to developers at an annual lease rate of Rs 1 per project. NLC India Renewables will implement its projects at the Ottapidaram, Anuppankulam, and Kayathar substations. Bondada Engineering will develop projects at Vellalaviduthi and Thennampatty, while Oriana Power will implement one project at Karaikudi. Each BESS must support full charge and discharge in blocks of 50 MW/100 MWh and 100 MW/200 MWh. The systems must be designed to interconnect with the state transmission utility network and maintain a C-rate of 0.5. Additionally, developers must ensure that the BESS project is available for two full operation cycles daily. They must guarantee a 95 per cent minimum annual availability, 100 per cent of minimum despatchable capacity being met, and a minimum round-trip AC-to-AC efficiency of 85 per cent each month.
The BESS technology is required to be technologically agnostic. Additionally, they must be commercially established and operational to minimise risks and ensure timely commissioning. Furthermore, the Tamil Nadu Generation and Distribution Corporation Limited will manage charging operations by drawing and injecting power as per state load despatch centre instructions, under a minimum system efficiency agreement.
