Metered, not modelled
Portsmouth vs Bristol
Portsmouth roofs made about 16% more than Bristol roofs last year.
919 against 789 kWh per kWp at the median, from 203 and 468 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 Bristol roof beats a poor Portsmouth one comfortably. Location moves the odds; it does not decide the outcome.
Portsmouth: the middle half of 203 systems made 844–963 kWh per kWp. Bristol: the middle half of 468 systems made 725–848 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.
Is your roof right for solar?
Enter your postcode and we'll estimate your roof's direction, its solar potential, and show certified installers covering your area.
Output figures from openclimatefix/uk_pv (Hugging Face, CC-BY-4.0), collected by Sheffield Solar. How we measure.
Related
Keep going.
Check your roof
Address-based roof check. Postcode in, Solarable Report out.
Open →
How much electricity does a solar panel produce?
What a kWp really generates in Britain, modelled and metered.
Open →
Solar savings calculator
Annual benefit and payback in honest UK ranges.
Open →
How we measure
Our sources, our cross-checks, and what we refuse to publish.
Open →
How much sun does my roof get?
How sunlight falls on a UK roof, month by month.
Open →