Is my roof suitable for solar panels?
Most UK pitched roofs suit solar perfectly well, which is why the honest answer to this question is usually "yes, and here's how well." Suitability isn't a pass-or-fail test; it's a set of six factors that each nudge your likely output up or down. Knowing where your roof lands on each one tells you whether solar is a strong fit, a workable one, or a case for waiting. Here's the checklist an installer runs, so you can run it first yourself.
1. Orientation: which way the roof faces
This is the biggest single factor. A south-facing roof captures the most sun over a day and gives the highest annual output. East and west roofs are very workable, generating perhaps 10 to 20% less in total while often matching your morning and evening use better. A north-only roof is the one case that's usually marginal. Orientation deserves its own treatment, in south vs east-west facing solar panels.
2. Pitch: the angle of the roof
In the UK, a pitch of around 30 to 40 degrees is close to ideal, and most house roofs fall in that range. Shallower or steeper still works, with a small output trade-off. A flat roof is fine too: panels go on angled frames to tilt them toward the sun, which is a standard job rather than a problem.
3. Shading: what blocks the light
Shade from a chimney, aerial, tree or neighbouring building costs more output than its size suggests, because of how panels are wired together. It's the factor people most often underestimate, and it's worth assessing across the day and the seasons, as solar panels and shading explains. The good news is that panel-level electronics can recover much of the loss.
4. Space: how many panels fit
A modern panel is roughly 1.7 square metres, and a typical 4 kWp system uses about 10 panels, so you want somewhere around 20 square metres of clear roof. Here's a rough guide:
| System size | Panels (approx) | Roof area needed |
|---|---|---|
| 3 kWp | ~8 panels | ~14 m² |
| 4 kWp | ~10 panels | ~20 m² |
| 5 kWp | ~13 panels | ~25 m² |
| 6 kWp | ~15 panels | ~30 m² |
Dormers, vents and the chimney eat into the usable area, so the headline roof size is always larger than what you can actually fill. How system size maps to cost is in how much solar panels cost.
5. Roof condition and age
Panels are typically warranted for 25 years and the mounting stays on the roof that whole time, so the roof underneath needs to be sound. If your covering is near the end of its life, it's far cheaper to re-roof before fitting panels than to remove and refit them later. A roof in good order with 10-plus years left in it is no obstacle. Standard tile and slate are straightforward; a competent installer will flag anything unusual on survey.
6. Structure and permissions
Most roofs comfortably carry the modest extra weight of a solar array, and the installer checks this as part of the design. Two specific cases need a closer look: listed buildings and conservation areas, where panels may need permission, and any roof with existing structural issues. For the vast majority of homes, solar is "permitted development" and needs no planning application, a topic worth its own guide. (Guide on planning permission for solar coming soon.)
The detail most people miss
Roof suitability and financial sense are two different questions, and people conflate them. A technically perfect south roof on a home that's empty all day and exports most of its generation can pay back more slowly than an east-west roof on a home that uses power all day. Orientation, shading and space tell you what the roof can produce; your usage pattern decides what that production is worth, which is the heart of is solar worth it.
Frequently asked questions
A south-facing roof pitched at around 30 to 40 degrees with little shading and about 20 square metres of clear space is ideal, but east and west roofs work well too.
Roughly 20 square metres for a typical 4 kWp system of about 10 panels. Allow more if dormers, vents or a chimney break up the roof.
You can, but a north-only roof generates noticeably less and is usually the one orientation where the maths is marginal. East or west faces are far better if available.
No specific age, but it should have plenty of life left, ideally 10-plus years. If it's near replacement, re-roof first to avoid removing and refitting panels later.
Yes. Panels are mounted on angled frames to tilt them toward the sun. It's a routine installation rather than a barrier.