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Here are the average capacity factors for offshore wind farms in UK waters, newly updated to include data to the end of 2019 (though there are still some figures to come through for the last couple of months of last year, for the smaller windfarms). There are 37 operational windfarms presented here, and two closed demonstration sites.

2019 set a new record for the highest annual average capacity factor for a UK offshore windfarm: Hywind Scotland achieved 55.3% in the calendar year 2019.

Hywind Scotland has a median output of 59.1%. The next-closest to this was Walney phases 3&4, which has a median output of 48.4%. The lowest is Rampion: median 19.3%. Median aggregate output for the fleet of 25 windfarms that have detailed data is 36.3%. Hywind, the floating windfarm, has behaved differently to any windfarm we’ve seen before.

At the other extreme, Rampion has had several prolonged faults, harming output. The load-duration curves at the bottom of this page show the differences in distribution of outputs: click on the individual farm names in the legend, to toggle the display of individual curves.

You might be interested in comparing these with the capacity factors and load-duration curves for Belgium, Denmark and Germany.

Load duration curves

I’ve constructed for each of the offshore windfarms for which there is half-hourly metered data. Use the pause and play buttons to stop and start the sequential display of curves. Click on the windfarm name in the legend to toggle the display of that farm’s curve.

Note that for each individual windfarm, its curve is based on data starting from either January 2009, or from the date that the windfarm was fully commissioned, whichever is more recent. The curve for all windfarms is for the last five years.

Capacity factor calculation method

Just as with the Danish offshore windfarm capacity factors, the capacity factors are calculated by calculating, for each wind farm, the number of hours since it was commissioned. This is then multiplied by its capacity, to give the number of peak-MW-hours. This is divided into the total energy generated by that wind farm, to give its capacity factor. The input energy data is from Elexon, and goes back to 2009; and from Ofgem, which goes back to 2000. There are some UK offshore windfarms for which Elexon does not have metered data: for those, I’ve used the REGO data from Ofgem.

To cite this page:

https://energynumbers.info/uk-offshore-wind-capacity-factors by Andrew ZP Smith, ORCID 0000-0002-8215-4526