New Delhi, Dec 21 (AHN) State-owned power producer NHPC on Sunday announced that it will begin commercial operations of the second unit of the 2,000 megawatt Subansiri Lower Hydroelectric Project from Tuesday.

The company announced that Unit-2, with a capacity of 250 MW, will start commercial generation from midnight on December 23, 2025.

In an exchange filing, NHPC said it has declared the commercial operation of the second unit of the Subansiri Lower project, which is being developed at an estimated cost of around Rs 27,000 crore.

The project is being executed under the Ministry of Power. The Subansiri Lower Hydroelectric Project is located at Gerukamukh near North Lakhimpur, along the border of Arunachal Pradesh and Assam.

“It is to inform that after successful completion of trial run, NHPC Limited declares Commercial Operation (CoD) of Unit 2 (250 MW) of Subansiri Lower HE Project, 2000 MW (8 x 250 MW), Assam/Arunachal Pradesh from 00:00 hours on 23.12.2025,” NHPC said in its exchange filing.

“The COD of balance units of Subansiri Lower HE Project will be intimated in due course,” it added.

Once fully commissioned, it will be the largest hydroelectric power station in the country, with an installed capacity of 2,000 MW through eight units of 250 MW each.

The project is a run-of-the-river scheme with water storage on the Subansiri river.

NHPC has said that this design helps harness the river’s natural flow while keeping environmental impact lower compared to large reservoir-based projects.

NHPC Director (Projects) Sanjay Kumar Singh visited the project site to oversee the start of commercial operations of Unit-2.

During his visit, he reviewed key structures such as the main dam, diversion tunnel and spillway, and held discussions with contractors and other stakeholders to assess pending work.

Earlier this month, the first 250 MW unit of the project was successfully test-synchronised with India’s national power grid on December 3, indicating that the project is steadily moving towards full-scale operations.

According to NHPC, the project is expected to generate around 7,421.59 million units of electricity in a year with 90 per cent dependability.