Peninsula solar map: how much panels make across the Wirral

The six areas side by side

Each area takes its yearly and monthly figures from one PVGIS point inside it, and its range from the map squares whose centres fall on land in that area. The difference between the best and worst areas is about 30 kWh per kW a year, or about 120 kWh for a typical 4 kW system: worth knowing, but much smaller than the effect of shade or a poor roof direction.

PVGIS 5.3 (SARAH3 satellite data, 2005–2023), 1 kW of crystalline panels, 14% system losses, terrain shading included. Read 3 November 2026.

Two things stand out. First, the split runs west to east rather than coast to inland: New Brighton sits on the sea but reads about 959, the same as central Birkenhead, because it is on the Mersey side of the cloud pattern, while inland Greasby is the highest point we sampled. Second, the best tilt everywhere is 40 to 41°, a little steeper than most roofs, so the ordinary 35° to 45° pitch of a Victorian or 1930s Wirral roof is already close to ideal.

Roof direction and pitch

Where your house sits on the peninsula moves output by a few per cent. Which way the roof faces moves it by tens of per cent. The table shows the yearly output for every direction and pitch at a mid-peninsula point (Upton and Greasby); for the west add about 1%, for the Birkenhead side take off about 2%.

PVGIS 5.3 at 53.384° N, 3.095° W, same settings as above. Read 3 November 2026.

Three practical points follow from the table:

• East–west splits work. Many Wirral semis have a gable roof with one slope facing roughly east and one roughly west. Panels on both slopes make about 80% as much per panel as a south roof, but spread the output over the morning and evening.
• Shallow pitches flatten the differences. At 10°, a south roof gives about 91% of its 30° output and a north roof about three quarters of a south roof at 30°, which is why panels on flat-roofed extensions are usually tilted on frames.
• Steep north slopes are poor. A north roof at 40° or 50° gives under half of a south roof. Most installers will not recommend panels there.

What the numbers mean for a household

Ofgem, the energy regulator, treats 2,500 kWh a year as typical electricity use for a home on a single-rate tariff (its "medium" value from July 2026). A 4 kW south-facing system on the Wirral makes about 3,800 to 3,950 kWh a year, more than that typical use. But the two do not line up in time: the panels make most in summer middays, and a household uses most on winter evenings. In practice a home without a battery uses only part of what its panels make and exports the rest. Is it worth it works through what that split is worth in pounds, with the tariffs stated.

How the map was made

The outline is the Office for National Statistics' boundary for the borough of Wirral (December 2024, generalised to 20 m and clipped to the coastline), published under the Open Government Licence. The squares are a regular grid of points 0.025° apart, about 2.8 km by 1.7 km at this latitude, for each of which we asked PVGIS for the yearly output of 1 kW of panels facing south at 35°. PVGIS is run by the European Commission's Joint Research Centre and draws its sunlight figures from satellite images for 2005 to 2023 and its temperatures from the ERA5 weather record. We used its standard 14% allowance for losses in cables, the inverter and dirt, and its terrain model for shading by hills such as Bidston Hill and the Heswall Dales.

The satellite data comes in cells roughly 3 to 5 km across, so neighbouring squares often share a value, and the boundary between the higher west and lower east is sharper on the map than it is on the ground. Treat each square as the neighbourhood's figure, not your house's. The Met Office's nearest station with a sunshine record, Hawarden Airport across the Dee, averaged 1,572 hours of bright sunshine a year in 1991–2020; there is no sunshine station on the Wirral itself.

What the map cannot tell you

• Shade. A tree, a chimney stack or a taller house to the south can cost more output than the whole west–east difference. An installer should model it from your roof.
• Your roof's real direction and pitch. Few roofs face exactly south. Use the table above with your own compass reading.
• Hot panels. Panels lose a little output in heat. PVGIS allows for it, but not for a roof that traps heat behind the panels.
• Future weather. The figures are averages of past years. In a typical year output lands within about 3% of the average (PVGIS reports a year-to-year spread of about 30 kWh per kW for these points), and a poor summer can fall further.