The local council granted planning permission for the 56 Danish-built turbines on an upland moor near the village of Carno last year, and there was no public inquiry.
Even so, it is facing resistance from countryside campaigners and some local residents, who say it is one wind farm too many in the principality.
The pounds 26m farm, owned and built by Britain's biggest electricity generator, National Power, will generate up to 33 mega- watts, enough for 25,000 homes.
It covers more than two square miles and each turbine is more than 160 feet tall from its base to the tip of its uppermost blade.
Project chief, Peter Musgrove, said: ``Wind power is clean, safe and natural and is cheaper than electricity from nuclear sources. We need it to secure our children's future.''
Penny Smith, deputy director of the Campaign for the Protection of Rural Wales, said: ``We objected because there has been so much wind power development already in this part of Wales."
The National Power development is the fourth wind farm in Powys, while all of Britain has only 31. It is prime wind farm country because, being at high altitude and without trees, the wind blows fast and free. There are planning applications for two further farms in Powys and an extension to one that has already been built.Reuse content