Technology developer Tidal Energy's 400kV DeltaStream device weighs 150 tonnes and will stand 16 metres long and 20 metres tall on the seabed.
It will be deployed in Ramsey Sound, off Pembrokeshire, southwest Wales, for 12 months' testing as the first installation in a planned 10MW commercial array at the site.
The demonstrator, built on a triangular gravity foundation designed to be fitted with up to three turbines, is the first private marine project to be fully developed in Wales.
"This
