The first energy from wave device at Cornwall's Wave Hub is expected to be connected this weekend.
The device is due to be towed to the site 10 miles off Hayle.
But sea tests could continue for another 12 months before it starts producing electricity said developer Seatricity.
The £30m Wave Hub consists of a giant "socket" on the sea bed, which connects wave energy machines to the power grid by an underwater cable.
The Wave Hub was installed in 2010.
Seatricity said it eventually wanted 60 devices connected to the hub in a plan to create power for the national grid.
Wave Hub managing director Claire Gibson said: "We have been working closely with Seatricity on their first deployment at Wave Hub.
"The mooring system has been installed over the last few weeks and we look forward to them taking up their berth as our first customer."
Seatricity's experimental device, which will be towed from Falmouth, uses octagonal aluminium floats to capture wave energy by pressurising seawater. In turn this drives a turbine which produces electricity.
The Wave Hub - which is publicly-owned by the Department for Business, Innovation and Skills - aims to allow companies to test their devices.