Energy giant SSE has sought permission to add 16 more turbines to its Gordonbush Wind Farm near Brora in Sutherland.
Thirty-five turbines already on the site, which was built at a cost of more than £100m, have been operational since June 2012.
Thirteen of the new turbines would be up to 426ft (130m) in height and the other three 377ft (115m).
They would be taller than the existing 360ft (110m) turbines.
Highland Council’s north planning applications committee will be asked to consider the proposal on 12 January.
Planning officers have recommended that councillors raise no objection, subject to several amendments including the removal of one of the planned turbines and reducing the height of another to 377ft.
The Scottish Wildlife Trust and John Muir Trust have objected to the extension. They say the project would affect blanket bog and wild land.