In a major step toward advancing dispatchable renewable energy in India, the Solar Energy Corporation of India (SECI) has concluded its Tranche XXI auction, awarding contracts for 1,200 MW of interstate transmission system (ISTS)-connected solar photovoltaic capacity integrated with 600 MW / 3,600 MWh of battery energy storage systems (BESS).
The tender represents one of India’s largest solar-plus-storage allocations to date and reinforces the government’s push to integrate long-duration energy storage with renewable generation to address peak demand, grid stability, and renewable intermittency.
Auction Overview
- Total solar capacity awarded: 1,200 MW
- Total BESS capacity: 600 MW / 3,600 MWh
- Storage duration: 6 hours
- Tariff range discovered: ₹3.12–₹3.13 per kWh
- Power Purchase Agreement (PPA) tenure: 25 years
- Project execution model: Build-Own-Operate (BOO)
- Commissioning timeline:C 24 months from PPA effective date, with an additional 6-month grace period
The auction was floated in June 2025 under a competitive reverse bidding mechanism and saw strong participation from both domestic and international renewable energy developers.
Winning Developers & Capacity Allocation
| Developer | Solar Capacity Won (MW) | Tariff (₹/kWh) | Remarks |
| NLC India Renewables Ltd | 600 | 3.12 | Largest allocation |
| Engie Energy India | 200 | 3.12 | Matched lowest tariff |
| Rays Power Infra | 300 | 3.13 | Awarded through competitive bidding |
| Oriana Power | 100 | 3.13 | Allocated under bucket-filling method |
Technical & Compliance Requirements
Under the tender conditions:
- Each solar project must be co-located with its battery energy storage system.
- The BESS must be charged exclusively using solar generation, ensuring clean energy-linked storage.
- Developers are responsible for land acquisition, project development, storage deployment, and grid connectivity.
- Projects must comply with Approved List of Models and Manufacturers (ALMM) norms for both solar modules and cells, supporting domestic manufacturing.
The six-hour storage configuration is designed to enable evening and peak-hour power supply, a critical requirement as India’s renewable share continues to grow.
Strategic Significance for India’s Energy Transition
The successful outcome of this auction highlights the rapid maturation of India’s solar-plus-storage market, with tariffs reaching levels that demonstrate the improving economics of integrated renewable and battery systems.
With 3.6 GWh of storage capacity tied to solar generation, the awarded projects are expected to:
- Improve grid reliability and flexibility
- Reduce dependence on fossil-fuel-based peaking power
- Support large-scale renewable integration
- Strengthen India’s pathway toward round-the-clock clean energy
This tender further cements SECI’s role in shaping the next phase of India’s clean energy transition—where energy storage is no longer optional, but foundational.
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