A short circuit in a grid connection cable sidelined the 209 MW wind farm in October.
To repair the problem, the cause of which has not yet been diagnosed, a 3.6 metre section of the cable located 40 km offshore was cut out and replaced.
Jesper Ferloev Greth, head of the Maintain Jutland department at Danish utility Energinet.dk, was quoted as saying that extreme weather conditions and high waves contributed to the extended repair period.
The cable connecting Horns Rev 2’s 91 Siemens SWT 2.3-93 turbines to the onshore grid is 42 km in length.
The wind farm, which is owned by Dong Energy, came online in 2009.