The Tamil Nadu Government unveiled the Tamil Nadu Battery Energy Storage Systems (BESS) Policy, 2026, in Chennai on 3 November 2026. Electricity and Law Minister CTR Nirmal Kumar launched the policy and the Renewable Energy Application Portal, which is intended to streamline project approvals.
Capacity targets and requirements
The policy targets at least 2.5 GW/10 GWh of Battery Energy Storage Systems across the state over three years. New solar and solar-hybrid renewable energy projects of 1 MW or more, commissioned from 1 April 2027 or applied for after the policy’s notification, must install storage equal to at least 10% of installed capacity, with a four-hour discharge duration. New renewable energy pooling substations must have standalone storage of at least 10% of sanctioned capacity. Existing substations must add 5% by FY2028 and a further 5% by FY2029. Eligible co-located and standalone projects commissioned during the policy period qualify for a 100% waiver of applicable transmission and wheeling charges for 10 years, if discharged energy is used within Tamil Nadu.
Implementation and ongoing projects
Tamil Nadu Green Energy Corporation Limited will coordinate, facilitate and monitor projects as the State Nodal Agency through a single-window system. Tamil Nadu Power Distribution Corporation is slated to procure 2,500 MW/10,000 MWh in the first phase through competitive bidding. The policy aims to improve grid stability, manage peak demand and use the state’s 29.8 GW of renewable capacity; 3,000–4,000 MW of solar power currently cannot be fully utilised each day. Four storage projects are already under development: a 500 MW/1,000 MWh project and a 375 MW/1,500 MWh project under Viability Gap Funding schemes, plus two 15 MW/45 MWh solar-plus-storage projects.
Important Facts for Exams
- Sodium-ion trade-off: Sodium-ion batteries offer lower cost and better safety characteristics than lithium-ion batteries, but have lower energy density and similar power delivery.
- Grid-forming controls: In grid-forming mode, a battery inverter establishes voltage and frequency references; grid-following controls instead synchronise with an existing grid waveform.
- Power and energy ratings: A BESS’s MW rating describes its power output, whereas its MWh rating measures stored energy; neither alone specifies usable discharge duration.
- Round-trip efficiency: Round-trip efficiency compares electrical energy returned with energy used to charge a storage system; inverter conversion and auxiliary loads cause losses.
