The Transmission Corporation of Andhra Pradesh (APTRANSCO) has invited bids for the development of 1,000 MW/2,000 MWh battery energy storage systems (BESS) across seven substations in the state. The project, with an estimated viability gap funding of up to Rs 34.9 billion, will be executed under a build, own, and operate (BOO) model through tariff-based competitive bidding.Bid Timeline and StructureBids must be submitted by 29 September 2025 and will be opened on 6 October. The VGF support per project is capped at Rs 1.8 million per MWh and will be released in three instalments—20 per cent upon financial closure, 50 per cent at commercial operation date, and the remaining 30 per cent after one year of operations.Financial and Technical CriteriaEach bidder must submit an earnest money deposit of Rs 480,000 per MW and a document fee of Rs 50,000 plus 18 per cent GST. The successful bidder must also provide a performance bank guarantee of Rs 1.2 million per MW. Bid processing fees range from Rs 100,000 to Rs 750,000, depending on project size.Bidders are required to have a net worth of at least Rs 3 million per MWh and an annual turnover of Rs 6 million per MWh for FY 2024–25, excluding other income.Project RequirementsEach project must interconnect at the 33 kV level with the state transmission utility network. Developers must ensure a minimum of two charge-discharge cycles per day and 95 per cent annual system availability. A round-trip efficiency of at least 85 per cent is required, with penalties imposed for shortfalls and incentives for exceeding targets.Commissioning is expected within 18 months from the signing of the storage purchase agreement, with a grace period of six months allowed. Delays beyond this will invite liquidated damages and forfeiture of performance guarantees.Sector ContextThe move follows a similar tender issued by the Solar Energy Corporation of India (SECI) for 600 MW/1,200 MWh of standalone BESS in Kolimigundla, Andhra Pradesh, signalling the state’s growing focus on grid-balancing renewable solutions.The APTRANSCO initiative marks a significant step towards large-scale battery storage adoption, essential for ensuring stability and efficiency in India’s evolving renewable power landscape.