Roughly 421MW of new capacity was commissioned in the six-month period, down from 1,035MW in the same two quarters last year.
Much of this installed capacity appears to be projects that were close to completion at end of the last financial year.
In that period, from April 2016 to March 2017, a record 5.3GW of wind was installed.
The market slowdown was triggered by the country's first federal wind power auction in February, which saw tariffs plunging to INR 3.43/kWh ($0.052/kWh), much lower than the prevalent feed-in-tariffs (FIT) across the states, prompting nearly all utilities to stop wind power procurement on a FIT basis.
Industry observers do not expect the capacity additions to cross 1.2GW this financial year.