A spokesperson from Senvion confirmed a "blade loss" from a 6.2M126 turbine occurred on 19 June.
The spokesperson said nobody was injured in the incident and the relevant authorities have been informed.
The cause of the break is still unknown and a full investigation is underway. Early indications suggest it is an isolated incident, said Senvion.
All 48 turbines were shut down following the blade failure at turbine number 17. Approximately half of the turbines are back in operation.
RWE completed the project in January 2015, following the start of turbine installation in July 2014. The project is located 35 kilometres off the German coast in the North Sea.