Vattenfall has also awarded Express Reinforcements, based in Neath, the contract to work on the turbine bases.
The developer made the announcement in conjunction with the first of the foundations being installed at the site.
The Swedish utility said it has handed £45 million (EUR 55 million) in contracts for the project to Wales-based businesses since construction operations began last year.
The Pen y Cymoedd site will use 76 Siemens 3MW turbines when it is completed, expected to be in 2016.