An advisory that CTUIL issued on 20 October 2026 has fixed the minimum storage that a BESS project in India must offer in order to connect to the inter-state transmission system (ISTS). New applicants will have to offer 4 hours of discharge, whereas those in the right of first refusal (RoFR) category will have to offer 2 hours.
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The Central Transmission Utility of India Limited (CTUIL), an India-based transmission utility, has set the minimum storage that a BESS project must offer when it applies for connectivity to the inter-state transmission system (ISTS). Under an advisory dated 20 October 2026, an applicant in the right of first refusal (RoFR) category must offer 2 hours of discharge, and all other applicants must offer 4 hours.
The shorter duration applies to connectivity grantees, and to entities whose applications were in process on 9 September 2025, provided that they were eligible under the Connectivity and General Network Access (GNA) Regulations and applied by 21 February 2026. The longer duration applies to applications received on or after 22 February 2026, to those received earlier from ineligible entities, and to standalone BESS at renewable energy pooling stations and substations.
Rules have also been set on the renewable energy generating stations (REGS) that are to charge the batteries. An RoFR applicant may install co-located REGS, or it may charge the battery from the REGS of an earlier connectivity or through the ISTS. A standalone BESS at a pooling station must apply under Regulation 5.2 for commensurate co-located REGS, whereas a non-RoFR applicant under Regulation 5.11(a) is not required to do so.
For these last two groups, CTUIL has described such REGS as desirable for the optimal use of the grid, and it has sized them to the MWh capacity of the battery. The stations may be commissioned with the start of connectivity, or within 36 months of the in-principle grant or the firm start date, whichever is later. The battery may also draw power from the ISTS for charging, provided that transmission margins are available.
Pending applications have been given a way to meet the longer duration. A standalone or non-RoFR applicant that offers less than 4 hours, and that had not received an in-principle grant when the advisory was published, may raise its energy capacity (MWh) without changing its installed capacity (MW) during the Consultation Meeting for Evolving Transmission Schemes (CMETS). The applicant must then furnish the eligibility documents under Regulation 5.2(h) within 2 months, and its land, financial closure and commissioning timelines will follow the larger capacity.
The charging provision differs from an earlier proposal at CMETS. The 44th meeting for the Western Region had sought a 2-hour minimum without any withdrawal from the ISTS, according to JMK Research, which estimated in July 2026 that dedicated REGS could raise project capital expenditure by at least 60-80%. The Central Electricity Authority has separately proposed that new solar and wind plants should carry co-located storage at 10% of their capacity, for 2 hours from July 2027 and for 4 hours from July 2029.