Plymouth in the PVGIS data
PVGIS models Plymouth at 1,122 kWh per kWp a year. That assumes a south-facing roof at a 35 degree tilt. The figure sits well above the London value of 1,019.
A 4 kWp system therefore comes to about 4,488 kWh a year. The same system makes about 4,076 kWh in London and about 3,572 kWh in Aberdeen. Plymouth lands about 10% above London and 26% above Aberdeen.
Our guide on how much electricity a 4kW solar system generates explains the sums behind these totals. Real systems vary, because shade, roof direction and inverter losses all matter. Treat the city figure as a starting point.
Best and worst months
May is the best month in Plymouth at 138.3 kWh per kWp, with June close behind at 138.0. December is the weakest at 36.1. The best month is therefore about 3.8 times the worst.
May to August supply about 48% of the year. November, December and January supply about 11%. As a result, a December day gives only a small fraction of a May day.
Winter needs its own plan, so read our post on solar panel output in winter. It explains what to expect from short, dull days. Because the grid fills the gap, expect solar to cut your midwinter bills only a little.
What your power is worth
Ofgem’s price cap sets electricity at 26.32p per kWh at the time of writing. Exports typically earn around 12p per kWh. Using a unit at home is therefore worth more than selling it.
Ofgem does not set the export rate, so each supplier chooses its own. Compare the offers before you sign.
Tilt and direction
PVGIS gives an optimal tilt of 39 degrees for Plymouth. At that angle output rises to 1,124 kWh per kWp, only 2 kWh above the baseline. Your roof pitch will usually decide the angle anyway.
Direction matters more. 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 rule one out.
Planning and the council
Plymouth 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, as the Planning Portal sets out.
Listed buildings need planning permission and listed building consent. In a conservation area, you cannot fit panels to a wall, balcony or roof enclosure that fronts a highway. Plymouth City Council is the planning authority, so ask it about Article 4 directions on your street.
National Grid and G98
Plymouth is usually in the National Grid Electricity Distribution area, although your postcode decides it. The Energy Networks Association has a lookup tool. Your installer normally files 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.
Sizing and cost
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 without a battery. Solar installs are currently zero-rated for VAT until 31 March 2027.
How many panels you need depends on your roof and your demand. A planned post on how many solar panels you need covers the sums. Meanwhile, you can read about solar battery storage if evening demand is high.
Getting quotes for Plymouth
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.
You can check any installer on the MCS Find an Installer search. Ask each one to show the kWh per kWp behind their estimate. For comparison, the page on solar panels in Exeter gives a PVGIS figure of 1,052. The page on solar output in Bristol adds another South West view.
Next steps
Use the Solar Yield calculator to test your roof. Then send one enquiry through the get quotes page. Compare each estimate with the PVGIS figures above.