Grid-India issues draft rules for ISTS-connected ESS

Grid-India has released a draft procedure to govern scheduling, metering, accounting, deviation settlement, transmission charge waivers, and Renewable Energy Certificate mechanisms for Energy Storage Systems, including battery storage and pumped storage projects. The draft, dated August 6, 2025, seeks to create a standard operational framework for projects linked to the Interstate Transmission System.

Under the proposal, Regional Load Despatch Centres will handle scheduling for charging and discharging. No ISTS losses will be applied when charging from co-located renewable plants, while applicable losses will apply to other ISTS transactions. All ESS and associated generators will require Special Energy Meters to record injections and drawals.

Deviation settlement will use case-specific calculations for ESS operations, including co-located renewable scenarios. Deviation Settlement Mechanism charges will follow existing rules, with net settlement allowed if a Qualified Coordinating Agency is appointed.

The draft outlines transmission charge waivers. Battery storage projects will receive a full waiver for 12 years if commissioned by June 30, 2028, and charged at least 51 per cent from renewable sources. Reduced waivers will apply to projects commissioned between 2025 and 2028, with no waiver after June 30, 2028. Pumped storage projects will receive a 25-year waiver if awarded by June 30, 2028, and meet the same renewable charging threshold.

For the REC framework, charging energy from renewable generators will be classified as a green transaction and will not be eligible for RECs. Additional provisions include separate scheduling for ESS storing captive energy, data sharing by RLDCs with Regional Power Committees for compliance, and submission of revised technical data by renewable plants three months before ESS integration.

Comments on the draft are open until August 21, 2025.