A spokesman for the Copenhagen-headquartered utility confirmed to Recharge that project had fallen behind its "internal timeline" but stressed it was "still in line with the promise we made at the FID [final investment decision] that we will deliver first power in 2014 and complete the project in the first half of 2015".
A2Sea's Sea Installer installation vessel is moored in Esberg, Denmark awaiting arrival of the 4MW turbines for the North Sea wind project.
Delivery was supposed to be "right about now'", said the Dong spokesman.
"First turbines should be up certainly before year-end."
Foundations at Borkum Riffgrund 1, located 37km north of the island of Borkum, were completed in late July "faster than expected and faster that promised in our internal schedule", he added.
The project will use 78 turbines, including one mounted on a novel suction-bucket jacket.
The wind farm was originally slated to use 3.6MW Siemens machines, but Dong switched to the 4MW turbine to boost total capacity.
Siemens Wind Power said: "The German offshore wind power plant Borkum Riffgrund 1 is the first project to be equipped with the latest generation of Siemens wind turbines of the type SWT-4.0-130.
"During the ramp up of serial production of this new turbine, we experienced some limited delays in the manufacturing process. As a consequence, the start of the installation phase of the turbines at the project site will be delayed by a few weeks."
The statement confirmed Siemens still expects to meet the overall project schedule for Borkum Riffgrund 1.
"In close cooperation with our customer Dong, we are currently looking into all opportunities to mitigate the impact of the delayed start of the turbine installation phase."
