Electricity consumption in the UK in 2021 was 294.4 TWh: https://www.statista.com/statistics/322874/electricity-consumption-from-all-electricity-suppliers-in-t

Electricity consumption in the UK in 2021 was 294.4 TWh: https://www.statista.com/statistics/322874/electricity-consumption-from-all-electricity-suppliers-in-the-united-kingdom/ https://www.statista.com/statistics/322874/electricity-consu... Annualized, that's an average power of 33.5 GW. On http://gridwatch.templar.co.uk/ http://gridwatch.templar.co.uk/ you can see in the yearly demand view that peak demand for the year was under 40 GW. This initial estimate of 150 km^2 of desert solar farms is too small and your later estimate of 13,000 km^2 is too large. A conservative rule of thumb would be 10 megawatts (real power, annualized) per km^2 of solar farm, which would mean 3,350 km^2 of solar farms for 33,500 average megawatts. Note that solar farm area is larger than solar panel area because solar farms need space between racks of panels.