NHPC Limited has initiated commercial operations of the fourth 250 MW unit at the Subansiri Lower Hydroelectric Power Station, thereby increasing the project's total capacity to 1,000 MW. This is the halfway point for the phased commissioning process of the 2,000 MW project.

The project comprises eight units of 250 MW each and is located on the boundary between Assam and Arunachal Pradesh. Four units have now started their operations, indicating that half the capacity has been commissioned.

According to earlier timelines,1,000 MW was expected to be commissioned by early 2026, and the rest of the remaining capacity is targeted for completion by December 2026.

This project has faced delays due to several issues, including environmental problems. The first commissioning began in December 2025, and up till now, four units have been synchronized and commissioned into commercial operation.

It is estimated that the generation of electricity from the project, once completed, would be about 7,400 million units per year.

Hydro power plants are sources of renewable energy and are mainly utilized in base load power generation. Hydro power plants act as buffer plants to stabilize electricity generation, as opposed to solar and wind plants that depend on the weather.

Subansiri power plant is a run-of-the-river project where electricity is produced from the flow of the river, with no major water storage involved. It is one of the largest hydro power projects in the country and has taken more than ten years to develop.

Completion of the remaining units is set to take place gradually until 2026.