Under the contract, Iberdrola will buy 50% (or up to 3.8GW) of its turbines from Gamesa between 2013 and 2022. Iberdrola will also acquire and help develop Gamesa's offshore turbines.
A 2.3GW maintenance deal for Iberdrola's 2MW turbines has been extended. Additionally, a 1.7GW three-year deal for 650kW and 850kW Gamesa turbines in Spain and Portugal is also included.
The agreement replaces a similar deal signed in 2008.
Speaking about the agreement, Gamesa CEO Jorge Calvet said: "The agreement establishes a new foundation for cooperation in response to the economic and industry environment of recent years, affords us stability and expands the framework cooperation agreement to Gamesa's key areas of growth for coming years: supplying wind turbines, but also O&M and offshore, all of which the company is firmly committed to developing."
Earlier this year, Gamesa and Iberdrola ended a three-year-old strategic agreement to jointly develop wind projects in Europe.
In a statement, the companies said the decision had been taken on the back of recent "changes in strategies" by the two companies. The economic downturn was also blamed.
In 2010, Iberdrola handed a Alstom supply deal covering the UK and Spain, which included a €200million order from Iberdrola subsidiary Scottish Power for a 217MW extension to the Whitelee wind farm.