Solar Panel Roof Orientation: East, West or South?

One of the first questions we get on a survey call is some version of “my roof doesn’t face south, is it even worth it?” It’s a fair question — orientation genuinely affects how much a system generates — but it rules out far fewer homes than people expect. Here’s how the different aspects actually compare, and what it means for sizing your system.

South-facing: the benchmark

A due-south roof with a reasonable pitch (30–40°) is the reference point everyone else gets compared against, because it captures the most sunlight across the whole day and gives the strongest single-face output per panel. If you’ve got a clear south-facing roof with no shading, it’s the simplest case to design for and usually the best generation-per-panel you’ll get.

But “south or nothing” isn’t how most UK housing stock works, and it isn’t how we design systems.

East-west: spread out, not lost

A split east/west array — panels on both faces of a roof rather than one — typically generates around 80–85% of an equivalent south-facing system’s total annual output. That sounds like a compromise, but the shape of that generation is often more useful in practice: east-facing panels catch the morning sun, west-facing panels catch the afternoon and evening, so output is spread across more of the day instead of peaking hard around midday.

For households that are out at work during the midday peak and home in the evening, that spread can mean more of the generation lines up with when electricity is actually being used — which matters more than the total kWh figure on its own once a battery is added, since a battery can bank the midday surplus a south roof produces and use it later regardless of aspect.

Single east or single west roofs

A single east-facing or west-facing roof (no south option at all) will generate somewhat less than a south roof — typically in the region of 15–20% less — but it’s very much still a viable install, and one we design and quote regularly. The panels simply get orientated to make the best of whichever single aspect is available, and the system is sized accordingly.

What about north-facing roofs?

North-facing alone is the one aspect where we’d usually recommend against it, or only proceed with a clear-eyed view of reduced output — direct sun exposure is limited for a large part of the day. In practice, north-facing roofs are more often used as a secondary face in a mixed-aspect design (say, east-west with a small north contribution) rather than the sole aspect for a system.

Flat roofs: orientation becomes a choice, not a constraint

On a flat roof, panels sit on tilted mounting frames rather than following the roof pitch — which means orientation is something we choose during design rather than something the building dictates. That opens up the option of angling every panel toward true south regardless of which way the building itself faces, or splitting the array east-west to spread generation across the day, whichever suits the household’s usage pattern better.

Why this matters for sizing, not just siting

Orientation and system size are decided together, not separately. A south-facing roof might comfortably support a smaller system for a given usage target; an east-west roof aiming for the same annual generation may need a few more panels to close the gap. Our systems typically run from 6 panels up to 20 panels (460W each), and part of a proper survey is working out the right number for your specific roof, not just your usage.

This is also why satellite imagery and postcode estimates only get you so far. Shading from chimneys, neighbouring trees, dormers and roof valleys all interact with orientation in ways that are hard to judge without a physical survey — which is exactly what ours are for.

The short version

South is the benchmark, east-west is a strong and often more practical alternative, single east or west roofs are still very workable, and flat roofs give you the freedom to choose. Very few roofs are genuinely unsuitable for solar — the real question is how big a system your particular aspect needs to hit your goals.

If you’re not sure how your roof stacks up, our free, no-obligation survey will tell you exactly what your aspect means for output, system size and payback — no guesswork required.