I was contacted asking had I made a basic error? Yes I had. But it is still true that wind and solar PV *capacities* are reported on the basis of fantasy load factors defined by legislation in 2010
I have been doing some analysis on the DUKES numbers. Here are some observations.
1) Taking 2021, the capacity factors implied by table 2 (using the end of year capacity not the average) and the stated generation are: Onshore wind - 22.9%; Offshore wind - 36.0% (Combined wind - 28.9%); Solar - 9.9%; Hydro 33.2%. These are pretty close to expected so I think we can presume that the generation values are accurate, although footnote 8 signals that estimates based on the estimated (inaccurate) capacity factors may have been used if actual data were not available.
2) Again using 2021 values, if we apply the stated de-rating factors (Hydro 0.365; Wind 0.43, Solar 0.17) to the stated Installed capacity values, we get a total of 22,234 MW, which is close to the Declared Net Capacity of 22,393 MW.
3) If we substitute the calculated capacity factors in 1) above for Combined wind, Solar and Hydro instead of the 2010 estimates, the total Declared Net Capacity would be 17,610 MW, which is 20% less than the stated DNC. So, the DUKES DNC values overestimate generation from those sources by 25%! If the DNC values are used for planning, that is certainly enough to generate some false optimism.
4) I agree that the average Installed capacity for any year is a better value than the end of year but without knowing when any particular capacity actually came on line, we don't know how much better.
I'd still like to understand why there is such a large gap between the DUKES generation numbers and Gridwatch. It would be useful to know how both sets of numbers are compiled.
To me, the most annoying fact is BEIS's narrative-based comparisons without providing Tables of Data that would enable its audience to easily compare the different variables and over time.
E.g. Year vs Year; Energy sources; Generation mixes etc, etc.
This is especially annoying because DUKES is 'UK', yet doesn't apportion data England / Scotland / Wales / Northern Ireland. (Or even Britain / Northern Ireland)
We in Britain have our grid & our data, and in real time. Northern Ireland has its SONI data. Naturally, they're not easily comparable.
Hello Chris.
[Previous comments deleted]
I have been doing some analysis on the DUKES numbers. Here are some observations.
1) Taking 2021, the capacity factors implied by table 2 (using the end of year capacity not the average) and the stated generation are: Onshore wind - 22.9%; Offshore wind - 36.0% (Combined wind - 28.9%); Solar - 9.9%; Hydro 33.2%. These are pretty close to expected so I think we can presume that the generation values are accurate, although footnote 8 signals that estimates based on the estimated (inaccurate) capacity factors may have been used if actual data were not available.
2) Again using 2021 values, if we apply the stated de-rating factors (Hydro 0.365; Wind 0.43, Solar 0.17) to the stated Installed capacity values, we get a total of 22,234 MW, which is close to the Declared Net Capacity of 22,393 MW.
3) If we substitute the calculated capacity factors in 1) above for Combined wind, Solar and Hydro instead of the 2010 estimates, the total Declared Net Capacity would be 17,610 MW, which is 20% less than the stated DNC. So, the DUKES DNC values overestimate generation from those sources by 25%! If the DNC values are used for planning, that is certainly enough to generate some false optimism.
4) I agree that the average Installed capacity for any year is a better value than the end of year but without knowing when any particular capacity actually came on line, we don't know how much better.
I'd still like to understand why there is such a large gap between the DUKES generation numbers and Gridwatch. It would be useful to know how both sets of numbers are compiled.
Thanks for your efforts, Chris.
In my opinion, DUKES is shambles, and designed to deliberately obfuscate facts about UK energy.
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1130501/DUKES_2022.pdf
To me, the most annoying fact is BEIS's narrative-based comparisons without providing Tables of Data that would enable its audience to easily compare the different variables and over time.
E.g. Year vs Year; Energy sources; Generation mixes etc, etc.
This is especially annoying because DUKES is 'UK', yet doesn't apportion data England / Scotland / Wales / Northern Ireland. (Or even Britain / Northern Ireland)
We in Britain have our grid & our data, and in real time. Northern Ireland has its SONI data. Naturally, they're not easily comparable.
https://www.soni.ltd.uk/how-the-grid-works/system-information/
/Rant over. ;-)
If you want more accurate capacity factors then you should look at the quarterly data published in Energy Trends.
https://www.gov.uk/government/statistics/energy-trends-section-6-renewables
Not sure if they are starting to over-egg capacity by not accounting for capacity that has been closed or re-powered.
Better still is looking at data for individual wind and solar farms via OFGEM's REGO database. The hazard is it is somewhat in arrears.