Gamesa will carry out frame reinforcement on five of its 660kW turbines in order to extend their working life for operator Compagnie du Vent, a GDF Suez subsidiary.
It will also upgrade the software 14 of its G97 2MW turbines and make a series of technical changes under its "premium availability" operations and maintenance programme.
Gamesa has been pushing to increase its income from operations and maintenance, which it describes as "a lynchpin of the company's growth potential".
Gamesa said it carries out length-of-life-extension work on its own turbines as well as those from other manufacturers.
Compagnie du Vent has an established relationship with Gamesa, having previously chosen the Spanish manufacturer to supply the turbines for 14 of its projects in France, according to data from Windpower Intelligence.