The outlook on long-term rating is 'stable', Icra said in statement.
According to the statement, Icra's AAA rating for NHPC reflects its established position in the hydro power generation industry in India, its significant size of operating projects and strategic importance, which is also reflected in consistent support from the government in terms of low cost subordinated debt for some of its projects.
Icra also notes competitive tariffs of its plants with an average tariff of Rs 3.67/kwh during 2015-16 (adjusted for previous years income) and strong operating efficiencies, as reflected by average plant availability factor (PAF) of 81.6 per cent in 2015-16 (against normative availability of 77.80 per cent).
The rating continues to reflect low business risks arising out of favourable demand outlook in view of the power deficit scenario in states and cost plus tariff mechanism applicable for its hydel based power generating stations.
Further, it said the rating continues to factor in the healthy track record of power generation from operational hydel projects arising out of favourable hydrology and ability to maintain high operating availability.