Metered, not modelled
Solar output in Portsmouth
844–963 kWh per kWp a year
the middle half of 203 real Portsmouth systems, measured over 2024
- Systems measured 203
- Median 919
- Best 10% of roofs 1006
- Rank of 49 areas 1st
- Typical system size 3.2 kWp
A typical 4 kWp system here made roughly 3,380 to 3,850 units of electricity last year.
Not a forecast. 203 solar systems around Portsmouth were metered through 2024, and the middle half made 844 to 963 kWh for every kWp of panels.
The best tenth reached about 1,006 kWh per kWp — some 31% clear of the British median of 766, and among the strongest roofs we can measure anywhere.
That puts Portsmouth 1st of the 49 postcode areas we can measure.
The local roof stock is unusually well pointed: 97% of these systems face south, south-east or south-west, against 86% nationally. Some of the figure above is orientation rather than weather.
Systems here land unusually close together — just 119 kWh per kWp between the lower and upper quarter, against 161 nationally. Results in Portsmouth are more predictable than most of Britain.
What none of it tells you is what your own roof would do. These systems point in every direction and some have been up for fifteen years.
The spread behind that number
Every Portsmouth system, grouped by what it made, against Britain as a whole. The two shapes overlap heavily, which is the honest headline: your postcode nudges the result, your roof decides it.
Portsmouth: the middle half of 203 systems made 844–963 kWh per kWp.
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Areas near Portsmouth
Neighbouring postcode areas we can also measure.
How Portsmouth compares
Looking for someone to fit them? MCS-certified solar installers in Portsmouth are listed in the Solarable directory.
Output figures from openclimatefix/uk_pv (Hugging Face, CC-BY-4.0), collected by Sheffield Solar. The British median is 766 kWh per kWp. How we measure.
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What a kWp really generates in Britain, modelled and metered.
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Annual benefit and payback in honest UK ranges.
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How we measure
Our sources, our cross-checks, and what we refuse to publish.
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How sunlight falls on a UK roof, month by month.
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