Central London sits in the upper half of the UK output table. PVGIS, the European Commission’s solar model, gives about 1,019 kWh per kWp a year for a south-facing roof at 35 degrees. That is an estimate for a clear, unshaded roof. Your own result will differ, so treat it as a starting point.
What a London roof can produce
A 4 kWp system is a common size for a house. At 1,019 kWh per kWp, it would make about 4,076 kWh a year. Aberdeen gets about 893 kWh per kWp, which gives roughly 3,572 kWh from the same system. Aberdeen therefore produces about 12% less than London.
Our full table of 24 cities runs from 853 kWh per kWp in Glasgow to 1,156 in Brighton. The south of England has the edge, yet the gap is modest. Manchester sits at 886 kWh per kWp, so a London roof out-produces it by about 15%. A shaded London roof can lose more than that spread, because the roof matters more than the postcode.
Summer against winter
London’s best month is July, at 123.2 kWh per kWp. Its worst is December, at 36.3 kWh per kWp. That makes July about 3.4 times stronger than December.
For a 4 kWp system, that means roughly 493 kWh in July and 145 kWh in December. Most homes use more power in winter, so a London system will export in summer and fall short in winter. Our post on how much a 4kW system generates shows the swing between summer and winter. The winter output guide explains why December is so weak.
Tilt and direction
PVGIS puts the best fixed tilt for London at 40 degrees. That gives 1,023 kWh per kWp, only a little above the 1,019 you get at 35 degrees. Most pitched roofs sit close to that range already. You rarely gain by building a frame to change the angle.
Direction costs more than tilt. For example, PVGIS shows that a London roof facing west at 35 degrees loses about 23% against south. The calculator lets you test your own roof angle and compass direction.
Planning in London
In England, panels on a house roof are normally permitted development. Their limit is 200mm out from the roof slope, and they must 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. In a conservation area, however, panels cannot go on a wall or roof section that fronts a highway. Some boroughs also hold Article 4 directions that remove these rights. Your borough council sets the rules for your street, so ask it first.
The grid connection
Most of London takes its power from UK Power Networks. A western strip falls under SSEN instead, so your postcode decides. The Energy Networks Association runs a lookup if you are unsure.
A system up to 16A per phase, about 3.68kW on a single-phase supply, falls under rule G98. Your installer tells the network operator within 28 days of commissioning. Larger systems fall under G99, which needs approval before installation, as MCS explains.
A battery can push a 4 kWp home into G99, so ask how your installer plans to handle it. Our page on solar battery storage covers the sizing.
Getting quotes
Solar Yield is an independent estimator and referral service. It does not install panels. It passes your enquiry to MCS-certified installers, and you can check any installer on the MCS register.
Read our guide to solar panel installation before you compare offers. Treat any quote that promises a fixed output with care, because MCS rules say an estimate is guidance, not a guarantee.
You may want a second opinion on a similar area. Compare solar panel output in Oxford with the Brighton estimate. While a few percent of difference is within normal error, the roof details matter more than the city name.
Next steps
Use the Solar Yield calculator to estimate output for your own roof. Then send your details through our quote form to receive offers from MCS-certified installers. Our guide on how many panels you need helps you choose a size first. Estimate openly, then check it against the installer’s figures.