The latest bidding results for various Inter-State Transmission System (ISTS) renewable energy schemes highlight India’s continued focus on expanding solar power, hybrid renewable projects, and battery energy storage systems (BESS). Most of the schemes follow a common framework, with the Solar Energy Corporation of India (SECI) applying a standard trading margin of INR 0.07/kWh over the discovered tariffs. Additionally, the majority of the projects are expected to achieve their Scheduled Commercial Delivery (SCD) or Commercial Operation Date (COD) within 24 months from the effective date of signing the Power Purchase Agreement (PPA).

Among the recent tenders, the ISTS Tranche-XXI Solar+BESS scheme awarded a total capacity of 1,200 MW. NLC India Renewables and Engie Energy India secured projects at a tariff of INR 3.12/kWh, while RPIL Power Three and Oriana Power Limited won capacity at INR 3.13/kWh. The scheme requires developers to supply normal solar power along with 50% of the contracted capacity for six hours during morning and evening peak demand periods.

The larger ISTS Tranche-XX Solar+BESS scheme allocated 1,500 MW. Most developers, including MB Power, Shivalaya Construction, Oswal Cables, Purvah Green Power, LC Infra Projects, and Stockwell Solar Services, discovered a tariff of INR 2.86/kWh. SAEL Industries, GH2 Solar, and Navayuga Green Energy secured projects at INR 2.87/kWh. Developers under this scheme must supply half of the contracted capacity for four hours during evening peak demand. In comparison, the earlier ISTS Tranche-XV Solar+BESS scheme awarded 500 MW entirely to JSW Neo Energy Limited at a tariff of INR 3.42/kWh, with a two-hour peak supply requirement.

Pure solar projects recorded lower tariffs. The ISTS Tranche-XIV scheme awarded 600 MW equally to Avaada Energy and ReNew Solar Power at INR 2.57/kWh. The Manufacturing Linked Solar Power Scheme achieved the lowest tariffs, with Adani Green Energy Four securing 1,799 MW at INR 2.42/kWh. Azure Power India also won capacities at tariffs of INR 2.42/kWh and INR 2.54/kWh. While some projects may face additional costs due to Basic Customs Duty (BCD), these manufacturing-linked projects continue to benefit from waivers on ISTS transmission charges and losses.

Hybrid renewable energy projects also attracted significant interest. The Hybrid Tranche-IX scheme awarded 600 MW to Juniper Green Energy, ACME Solar Holdings, and Sembcorp Green Infra at tariffs between INR 3.25 and INR 3.26/kWh. Hybrid Tranche-VIII allocated 1,200 MW to developers including JSW Neo Energy, Adyant Enersol, AMPIN Energy, Asurari Renewables, Juniper Green Energy, and Avaada Energy, with tariffs ranging from INR 3.43 to INR 3.46/kWh.

Projects with more advanced storage requirements recorded higher tariffs. The Hybrid Tranche-VI Wind-Solar Hybrid plus BESS scheme awarded 410 MW to AMP Energy, ReNew Vikram Shakti, and Hero Solar Energy at tariffs between INR 4.64 and INR 4.72/kWh. Meanwhile, the ISTS FDRE-VI scheme awarded 200 MW to Altra Xergi Power Private Limited at a discounted tariff of INR 8.1/kWh, reflecting the premium associated with providing assured evening peak power supply.

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