Southampton in the PVGIS data
PVGIS models Southampton at 1,064 kWh per kWp a year. That assumes a south-facing roof at a 35 degree tilt. It places the city above the UK middle ground, although it is not the top of the range.
To build a household estimate, multiply by system size. Because systems vary, a 4 kWp example is a handy yardstick. A 4 kWp system comes to about 4,256 kWh a year. The same system makes about 4,076 kWh in London and about 3,572 kWh in Aberdeen.
Southampton therefore sits about 4% above London and 19% above Aberdeen. That gap is real but modest, so a well-placed roof matters as much as the city. The calculator lets you test both factors together.
Best and worst months
June is the strongest month in Southampton at 129.6 kWh per kWp, with July close behind at 129.3. December is the weakest at 36.3. The best month therefore makes about 3.6 times the worst.
May to August supply about 47% of the year. November, December and January supply about 12%. As a result, any plan that relies on winter generation needs a careful look.
This spread affects how you value the system. You will export more in summer, because daytime demand is lower. Ofgem’s price cap sets electricity at 26.32p per kWh at the time of writing, while exports typically earn around 12p per kWh. Self-use is therefore worth more.
Tilt and direction
The optimal tilt for Southampton is 39 degrees. Our post on the best tilt angle for solar panels in the UK explains how angle changes output. However, your roof pitch usually sets the angle, so PVGIS shows only a gain of 2 kWh per kWp.
Direction costs more than tilt. Energy Saving Trust says east or west-facing systems tend to get 15% to 20% less than a south-facing one. Test each roof face before you choose.
Planning and the council
Southampton is in England, so the national rules apply. Roof panels on a house are normally permitted development. They must project no more than 200mm and stay below the highest part of the roof. The Planning Portal sets out the full rules.
Listed buildings need planning permission and listed building consent. Conservation areas restrict panels on any wall, balcony or roof enclosure that fronts a highway. Southampton City Council is the planning authority, so confirm whether an Article 4 direction applies to your street.
SSEN and the G98 rule
Southampton is usually in the SSEN Distribution area, though your postcode decides it. The Energy Networks Association has a lookup tool. Your installer handles the notification.
Under G98, a type-tested system up to 16A per phase, about 3.68kW on a single phase, connects first. The installer notifies the operator within 28 days. A larger system needs G99 approval before installation, and the operator may limit export.
Checking a quote
DESNZ puts the median cost for systems up to 4kW at £1,595 per kW for 2025 to 2026. A 4 kWp system therefore costs about £6,400. Compare that with your quotes, because a large gap needs an explanation.
Our guide on how to check a solar quote covers what to ask. MCS rules require the output estimate to use kWp, a regional kWh per kWp value and a shade factor. That estimate is guidance, not a guarantee.
Inverters wear out sooner than panels. Energy Saving Trust says an inverter needs replacing after around 12 years. A planned post on reading your solar inverter app will help you spot problems early.
Getting quotes for Southampton
Solar Yield is an independent estimator and referral service, and we do not install anything. We pass enquiries to MCS-certified installers. Our page on solar panel installation describes the service, and solar battery storage covers batteries.
You can check any installer on the MCS Find an Installer search. For comparison, the data for solar panels in Brighton shows a higher PVGIS figure of 1,156 kWh per kWp. The page on solar output in Oxford gives another view of the South East.
Next steps
Use the Solar Yield calculator to test your roof. Then send one enquiry through the get quotes page. Compare each installer’s estimate with the PVGIS figures above.