The company was awarded the contract to design and construct the mast in June 2013 by developers Dong Energy and Iberdrola-owned Scottish Power Renewables.
RES developed the foundation design in-house while working with lattice-mast subcontractor Carl C to produce the mast.
GeoSea was brought in to install the structure, using its jack-up vessel Innovation, while RES's engineers designed and installed the instrumentation and communication systems.
The 108 Siemens 3.6MW turbines started operating at the 389MW Duddon Sands project earlier this year. The met mast is designed as a performance management tool that should help improve the performance of the wind project, RES said.