The German manufacturer will install 64 of its newly enhanced 113-3.2MW turbines, based on its 3MW machine, on the fourth phase of the Bison wind farm.
A 113-metre rotor and 92.5-metre hub height mean that it has been possible to upgrade the direct-drive turbine from 3MW to 3.2MW.
Installation of the turbines is set to begin in December, with commissioning lined up for 2015. A three-year service and maintenance agreement is included in the deal.
The blades for the turbines will be manufactured at Siemens' facility in Fort Madison, Iowa. The first three phases of the project, with a combined capacity of 255MW, also feature Siemens turbines.