Siemens will supply, install and commission 23 3MW turbines at ScottishPower Renewables' 69MW Dersalloch project in South Ayrshire, west Scotland.
Installation is set to begin in spring 2016, with completion expected the following autumn.
The second contract, also with ScottishPower, will see Siemens supply 22 SWT-2.3-93 turbines to the 50.6MW Ewe Hill project.
The site will be built in two phases. Installation of the turbines for phase 1 is scheduled for spring 2016, while phase 2 turbines will be installed in autumn 2016. Siemens will also provide long-term maintenance services.
Ewe Hill is located 15km from Lockerbie, Dumfries and Galloway in southern Scotland, according to Windpower Intelligence, the research and data division of Windpower Monthy.
Finally, Siemens will also supply two SWT-3.2-101 turbines to extend the Millour Hill Community wind farm in North Ayrshire, also in west Scotland.
There are six 3MW turbines already in place at the site installed in 2012. Siemens will maintain the two additional turbines for 20 years.
The extension project is being developed by Community Windpower, which has four operational projects in Scotland, totalling 123MW.
In July, Siemens was contracted to supply 19 3.2MW turbines with a 113-metre rotor to Community Windpower's Aikengall 2 project, also in southern Scotland. It is scheduled to be commissioned in summer 2016 and will be serviced by Siemens for 20 years.