Best Direction and Angle for Solar Panels in the UK

In the UK, solar panels produce the most electricity over a year when they face south at a tilt of roughly 35 to 45 degrees. But the drop-off either side is gentle. A typical east or west-facing roof still produces most of what a south-facing one would, and flat roofs work well with panels on low frames. Shading usually matters more than direction. Here is how each factor affects your roof.

Key points

• South-facing panels produce the most over a year.

• East and west-facing panels produce less in total, but spread generation across the morning or the afternoon and evening.

• An east-west split, with panels on both sides of the roof, is common in London and works well.

• The best tilt is roughly 35 to 45 degrees, but most pitched roofs are close enough that panels are fitted flat to the slope.

• North-facing roofs are generally not recommended, although a very shallow north slope behaves more like a flat roof.

• Shade from chimneys, dormers, trees and neighbouring buildings often affects output more than direction does.

Which direction is best?

South. Panels facing south see the sun for the most hours, so they produce the most over a year. The Energy Saving Trust says south-facing panels generate the most electricity because they capture the most sunlight.

Our guide to how much electricity solar panels generate in the UK explains what else affects output.

East and west. Panels facing east or west produce less in total. On the MCS yield chart for London below, a roof facing due east or west at a typical pitch produces roughly 10 to 20 per cent less over a year than the same panels facing south. What you get in return is a different shape to the day: east-facing panels generate more in the morning, west-facing panels more in the afternoon and early evening.

South-east and south-west. These sit between the two and lose very little compared with due south.

North. The Energy Saving Trust doesn’t recommend panels on north-facing roofs, and on a typical pitch they produce much less. The exception is a very shallow north slope: the flatter the panels, the less their direction matters, so it may still be worth modelling.

The chart shows output as a share of the best possible for London, by direction (up the side) and tilt (along the bottom). The broad dark band shows how forgiving it is: a wide range of directions and angles all land within a few per cent of the maximum.

East-west roofs

A lot of London houses have roofs that face east and west, especially terraces running north to south. Putting panels on both slopes is a common, sensible design.

• Generation is spread out. The east side starts producing early, the west side carries on later, and the midday peak is lower than on a south roof.

• That can suit how you use electricity. A household that uses more in the morning and evening can use more of its own generation directly.

• The design has to allow for it. Panels on different slopes get sun at different times, so they’re usually wired as separate strings to separate inputs on the inverter, or fitted with optimisers. A single string across both slopes would be held back by whichever side is in shade.

If you’re thinking about a battery, the timing of your generation matters less, because the battery shifts it into the evening anyway. Our guide to whether solar batteries are worth it explains how that works.

What angle should solar panels be?

The sun is high in summer and low in winter. For a fixed array in London, the tilt that gives the most over a whole year is roughly 35 to 45 degrees, and output falls away only gently either side of that.

In practice, panels on a pitched roof are fitted close to the existing slope rather than propped up at a different angle. It looks better, keeps wind loading down, and avoids planning problems: permitted development rules limit how far panels can stand out from a roof. Our guide to planning permission for solar in London covers the limits.

Steep roofs. Very steep slopes and dormer faces lose more, particularly in summer when the sun is high.

Flat roofs. Panels on a flat roof go on frames at a low tilt. A low angle gives up a little output per panel compared with the ideal, but panels can sit closer together without shading each other, so more fit on the roof, and they catch less wind. On a flat roof the frames can also face south, or east and west in pairs. Our guide to whether your London roof is suitable for solar covers roof condition and structure.

Our guide to solar panels on flat roofs explains the mounting options and layouts in more detail.

Shading matters more than you might think

The Energy Saving Trust notes that shading can have an even bigger impact than direction. Shade from a chimney, a dormer, a tree or a taller building next door can cut output by more than the shaded area suggests, because panels are wired together in strings and, on a conventional string system, a shaded panel can hold back the others in its string.

There are ways to manage it:

• placing panels away from the worst shade, even if it means fewer panels

• careful string design, so shaded and unshaded panels are kept apart

• optimisers or microinverters on the panels that are affected

Which is right depends on how much shade there is and when it falls during the day and year. That is what a survey is for. If an older system is producing less than it used to, new shade from a growing tree is a common reason. Our guide to solar generating less than it used to covers that and the other causes.

Our guide to string inverters, optimisers and microinverters explains the options for shaded roofs in more detail.

How we work out what your roof will produce

MCS-certified installers give you a standard generation estimate based on the size of the system, a figure for your postcode region, the direction and pitch of each roof face, and a shading factor. It is an estimate, not a guarantee, but it means two quotes for the same roof can be compared on the same basis.

At the survey we measure the roof, note every source of shade, and check the structure and the electrics. The design then puts the panels where they will do the most, which isn’t always the face that looks best from the street. Our guide to what happens at a solar survey explains the visit.

Frequently asked questions

Is east or west better for solar panels?

Over a year they produce similar amounts. West suits households that use more electricity in the late afternoon and evening; east suits those that use more in the morning. Panels on both sides of the roof spread generation across the day.

Can solar panels face north?

On a typical pitch, north-facing panels produce much less and generally aren’t recommended. A very shallow north slope behaves more like a flat roof, so it may be worth modelling.

What is the best angle for solar panels in the UK?

Roughly 35 to 45 degrees for the most over a year. Most pitched roofs are close enough that panels are fitted flat to the slope.

What angle are panels on a flat roof?

Lower than the ideal, on mounting frames. That trades a little output per panel for more panels, less shading between rows and less wind exposure.

Do I need a south-facing roof for solar to be worth it?

No. East, west and flat roofs all work well. Shade, roof condition and how you use electricity usually matter as much as direction.

Request a solar and battery quotation. We’ll survey your roof, model what each face can produce, and design the system around it.