CESC 600 MW Auction: Vismaya, Purvah, Sprng, Hexa Emerge Winners

Introduction to CESC's Renewable Energy Initiative

Calcutta Electric Supply Corporation (CESC) has concluded its auction for the development of 600 MW of Inter-State Transmission System (ISTS)-connected wind-solar hybrid projects. The tender, floated in November 2025, attracted significant interest from major renewable energy players. The auction results name Vismaya Renewables, Hexa Climate Solutions, Purvah Green Power, and Sprng Energy as the successful bidders. These projects will be developed under a build-own-operate model and are a crucial part of CESC's strategy to meet its renewable purchase obligations and expand its green energy portfolio.

Auction Winners and Tariff Details

The competitive bidding process resulted in tariffs ranging from ₹3.74 to ₹3.75 per kWh. Vismaya Renewables India Project, a subsidiary of UPC Renewables, secured 100 MW at the lowest tariff of ₹3.74 per kWh. The remaining capacity was awarded at a tariff of ₹3.75 per kWh. Purvah Green Power, a subsidiary of CESC itself, won the largest share with 300 MW. Hexa Climate Solutions secured 100 MW, and Sprng Energy was awarded 100 MW of its quoted 200 MW capacity through the bucket-filling method.

Project Scope and Technical Specifications

The scope of work for the winning developers is comprehensive. It includes identifying land, setting up the wind-solar hybrid power plants, and establishing the transmission network up to the interconnection point. The projects must be connected to the ISTS network at a voltage level of at least 220 kV. A key technical requirement is that the wind and solar components must be in a capacity ratio of at least 2:1, ensuring a more stable and reliable power output compared to standalone renewable sources. The projects are mandated to be completed within 20 months from the date of signing the Power Purchase Agreement (PPA).

Long-Term Agreements and Quality Standards

CESC will enter into a 25-year PPA with each of the successful bidders, providing long-term revenue visibility and project bankability. To ensure project quality and longevity, developers must use commercially established technologies. The solar modules must be sourced from the Approved List of Models and Manufacturers (ALMM) List I, with cells from ALMM List II. Similarly, wind turbines must be listed under the respective ALMM. The tender also specifies strict performance warranties for the solar modules, requiring them to provide at least 90% of their peak output at the end of 10 years and 80% at the end of 25 years.

Financial Commitments for Developers

Participation in the tender required significant financial assurances. Bidders had to submit an Earnest Money Deposit (EMD) of ₹2 million per MW. Following the award, successful developers are required to furnish a Performance Bank Guarantee (PBG) before signing the PPA. The PBG is set at ₹2.3 million per MW for the solar component and ₹3.2 million per MW for the wind component. These financial instruments are designed to ensure that only serious and capable developers undertake the projects and adhere to the committed timelines and quality standards.

CESC's Broader Push into Renewables

This 600 MW auction is part of a larger strategic push by CESC to significantly increase its renewable energy capacity. The company aims to add 3 GW of renewable assets over the next three years. This strategy is further evidenced by other recent activities. For instance, CESC's subsidiary, Purvah Green Power, recently received a Letter of Award from the Solar Energy Corporation of India (SECI) to develop a 300 MW solar project integrated with an energy storage system. That project was secured at a competitive tariff of ₹2.86 per kWh for a 25-year period, highlighting the company's aggressive expansion in the clean energy sector.

Market Impact and Future Outlook

The successful conclusion of this auction strengthens CESC's position in India's power sector. By securing 600 MW of hybrid power, the company not only diversifies its energy sources but also helps stabilize the grid by integrating less intermittent renewable power. The fixed, long-term tariffs will also help manage power purchase costs effectively. For the winning developers, these projects represent significant additions to their portfolios, backed by a long-term agreement with a reputable utility. As India continues its transition towards clean energy, such large-scale tenders from utilities like CESC will remain critical in driving investment and achieving national renewable energy targets.