[Abstract] We show that Swedish wind turbines constructed before 2007 lose 0.15 capacity factor percentage points per year, corresponding to a lifetime energy loss of 6%. A gradual increase of downtime accounts for around one third of the deterioration and worsened efficiency for the remaining. Although the performance loss in Sweden is considerably smaller than previously reported in the UK, it is statistically significant and calls for a revision of the industry practice for wind energy calculations. The study is based on two partly overlapping datasets, comprising 1,100 monthly and 1,300 hourly time series spanning 5–25 years each.
Jon Olauson, Division of Electricity, Department of Engineering Sciences, Uppsala University, Uppsala, Sweden
Per Edström, Sweco Energuide, Gothenburg, Sweden
Jesper Rydén, Department of Mathematics, Uppsala University, Uppsala, Sweden
Wind Energy 2017; 20(12):2049–2053. DOI: 10.1002/we.2132
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