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Full-load hours


A comparison of the performance of several wind turbines at different locations was achieved by standardising the annual energy output in relation to the rated capacity of the wind turbines. The number of the thus calculated equivalent full load hours depends to a significant degree on the performance curve of the wind turbine in question and the conditions at its location. Significantly more full load hours are achieved offshore than onshore. The first commercial German offshore wind farm Alpha Ventus achieved almost 4,500 full load hours in its first year of operation, almost three times as many full load hours as the average onshore wind turbine.


 Tracking the annual operating results for offshore wind farms is only possible to a limited extent, as operators usually do not disclose the yield data for their assets. However, it is possible to determine reference values indirectly. An approximate calculation will be carried out for a regional differentiation of the 2017 full-load hours in the feed-in regions of the North Sea and Baltic Sea. The input data consists of the monthly installation data according to the register data of the Bundesnetzagentur [10] and the monthly projections of publications on the information platform for the German transmission system operators [124]. The results of the calculations are plausible, but should be viewed as conservative values, as simplifying assumptions are made due to the method: It is assumed that all turbines commissioned in the respective month will be fully included in the monthly balance sheets. This simplification causes the results to be underestimated, errors in which become greater the later the turbines actually went into operation in the respective months. However, random comparisons of published results for the offshore wind farms alpha ventus and Bard Offshore – both located in the North Sea – show good correspondence: The equivalent of 3720 h for 2017 and 3293 h for 2016 can be derived from press releases about Bard Offshore, [125]; alpha ventus reported 503 full-load hours for October 2017 [126]. According to the above approach, this results in 499 full-load hours for North Sea wind farms for this month. As an average value, alpha ventus reports 4038 full-load hours since the start of operation.





Tentative, conservative estimation of full-load hours of use in the North Sea and Baltic Sea.

Data sources: [EEG_Register_2017] , [Netztransparenz]





Similar but somewhat lower values for full-load hours in 2017 arise according to a statement by Fraunhofer ISE [127], which summarises the annual yields of offshore wind farms in terawatt hours on the basis of EEX data. A selection of this recalculated data is shown in Figure 6.33. The average full-load hours for 2017 result from this data as 3554 hours for the selected wind farms in the North Sea and 4252 hours for the two wind farms in the Baltic Sea. 3,500 to 4,500 full-load hours per year for offshore wind farms in the German EEZ are realistic according to the authors' estimates, depending on the respective wind conditions.




Full load hours 2017 of selected OWP calculated according to [Fraunhofer_ISE]