Metered, not modelled
Luton vs Chelmsford
Luton and Chelmsford roofs made much the same last year.
836 against 835 kWh per kWp at the median, from 60 and 75 real systems.
Where the two actually overlap
Both areas, grouped by what each system made. The medians differ, but the shapes sit largely on top of one another — a good Chelmsford roof beats a poor Luton one comfortably. Location moves the odds; it does not decide the outcome.
Luton: the middle half of 60 systems made 749–875 kWh per kWp. Chelmsford: the middle half of 75 systems made 734–883 kWh per kWp.
Both figures are what real systems metered last year, so the gap mixes sunlight with system age, roof direction and shading. It is the difference in what people actually got, not a difference in sunshine alone.
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Output figures from openclimatefix/uk_pv (Hugging Face, CC-BY-4.0), collected by Sheffield Solar. How we measure.
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