Subansiri Hydropower Project begins wet commissioning, India’s largest hydro project nears power generation

NHPC Limited announced that the 250 MW Unit–I of the project underwent a test run on October 24, 2025. Wet commissioning involves running the turbine with water to check operational parameters without generating electricity. The process is expected to last four to five days, officials said.

The project comprises eight units of 250 MW each. NHPC said four of the units are ready for test runs, and the next step will involve synchronising at least two units with the national grid to start power generation.

In a statement issued on Facebook, NHPC said: "In a landmark moment for India’s hydropower sector, Wet Commissioning of Unit–I (250 MW) of NHPC’s 2000 MW Subansiri Lower Hydroelectric Project commenced on 24.10.2025 with successful mechanical run of the machine, marking the beginning of commissioning of the first unit of the nation’s largest hydropower project. Standing tall as NHPC’s largest-ever unit capacity, this milestone celebrates engineering mastery, teamwork and a shared vision of powering a greener tomorrow."

With Unit–I successfully wet-commissioned, synchronization with the national grid is expected soon, followed by three more 250 MW units this year, adding 1,000 MW of electricity.

Upon completion, the Subansiri Lower HEP (8×250 MW) will be India’s largest hydroelectric power station, significantly contributing to the nation’s energy security and sustainable development.