While the performance and the efficiency of wind turbines and their energy yields have been improved with time, their reliability still needs improvement, particularly when considering their deployment offshore.
IWES has been gathering operational experience from wind turbines since 1989, being involved in different projects dealing with the topic of availability and reliability. This paper draws statistical data from Germany's ‘250 MW Wind’ programme, evaluated by IWES. The prime objective of the survey was to extract information about the reliability characteristics of wind turbines. The main purpose of this paper is to discuss the frequency of failures and duration of downtimes for different wind turbine subassemblies based on existing onshore experience and point out the likely outcomes when turbines are deployed offshore. Copyright © 2010 John Wiley & Sons, Ltd.