Roof Orientation and Solar Panels

One of the first questions any UK homeowner asks before getting solar quotes is: does my roof face the right way? It is a fair concern — orientation does affect how much electricity your panels generate. But the relationship is more forgiving than many people expect, and a well-designed system on an east- or west-facing roof can still be a very sound investment.

Why orientation matters in the UK

The UK sits between 50°N and 60°N latitude, which means the sun tracks across the southern sky throughout the year. A roof that faces due south is therefore exposed to the most sunlight — it catches the morning rise, the midday peak, and the afternoon descent. Every degree you rotate away from south reduces the total solar radiation hitting your panels over the course of a year.

The European Commission's PVGIS tool — the industry-standard solar irradiance database used by MCS installers and researchers across Europe — allows you to model any location, orientation, and tilt angle with data from multi-year satellite records. It is worth bookmarking if you want to model your own roof before getting quotes.

South-facing: the benchmark

A south-facing roof at an angle of around 30–35° is treated as 100% yield by convention. For a typical 4 kWp system in England, the Energy Saving Trust's solar calculator indicates annual generation of roughly 3,400–4,200 kWh depending on location, shading, and system losses. Scotland and the north of England will sit towards the lower end of that range; Cornwall and Kent towards the higher end.

The optimal tilt in the UK is approximately 35° — matching the average latitude of central England. Panels closer to 30° or 40° lose less than 2% of annual output, so the pitch of a standard UK roof (typically 30–40°) is conveniently close to ideal. You do not need a perfectly angled roof to make solar work well.

Southeast and southwest: barely any penalty

Roofs facing southeast or southwest — within 45° of due south — typically yield 85–95% of a true south-facing equivalent. On a 4 kWp system generating 3,800 kWh south-facing, that translates to roughly 3,230–3,610 kWh per year. The financial difference at current rates is small enough that southeast and southwest roofs are considered near-equivalent for most installation decisions.

There is an added benefit to southwest orientation in particular: generation is skewed towards the afternoon, which aligns better with typical household consumption patterns when occupants return from work. Self-consumption — using the electricity as it is generated rather than exporting it — can increase as a result, improving overall return without changing the headline kWh figure.

East- and west-facing roofs

A roof facing due east or due west generates roughly 80–85% of the annual output of a south-facing roof, according to the Energy Saving Trust. On our 4 kWp benchmark, that is approximately 2,720–3,230 kWh per year — a meaningful reduction, but still well within the range that makes solar financially viable given current electricity prices and Smart Export Guarantee rates.

Many UK detached and semi-detached homes have a ridge running east–west, leaving one slope facing east and one facing west. Rather than treating this as a compromise, some installers recommend an east–west split array — panels on both slopes using a combined capacity of, say, 4 kWp total. The combined generation of an east–west split system is typically 80–85% of a same-capacity south-facing array, but the generation profile is notably flatter: the east slope peaks in the morning, the west slope in the afternoon, reducing the sharp midday spike you get from south-facing panels. This can improve self-consumption and reduce reliance on battery storage for households that use power in the morning and evening.

For more on how panel count and system design interact with roof layout, see our guide on how many solar panels you need.

North-facing roofs: the exception

North-facing roofs are not recommended for solar in the UK. Generation falls to roughly 50–60% of a south-facing system in summer, and in winter — when the sun barely clears the horizon — output can be negligible for weeks at a time. The Energy Saving Trust explicitly advises against north-facing installations in standard domestic guidance. If the only available roof slope faces north, ground-mounted panels or a solar carport are usually a better solution than a rooftop installation.

Tilt angle and flat roofs

Flat roofs offer full flexibility on orientation and tilt, since panels are mounted on adjustable frames. The standard recommendation for UK latitudes is a 30–35° tilt facing south. Even a modest 10–15° tilt makes a significant difference to annual yield compared to truly horizontal panels, which suffer from poor performance in winter when the sun is low and from soiling as rain cannot wash panels clean as effectively.

Ballasted tilt frames (no roof penetration) are the most common solution for flat roofs and add minimal structural load. Our dedicated guide on flat roof solar panels in the UK covers the structural, planning, and mounting options in detail.

How shading interacts with orientation

Shading can outweigh orientation as a performance factor. A south-facing roof with a chimney casting a shadow across two panels for three hours each morning may generate less than an unshaded west-facing roof of the same capacity. Before finalising any system design, your installer should carry out a shading analysis — most use tools such as PVGIS, PVSyst, or a physical Solmetric SunEye survey.

On roofs with unavoidable partial shading or where panels span multiple orientations, microinverters or DC power optimisers are worth considering. With a standard string inverter, the weakest panel in the string limits the output of all panels connected to it — a well-documented effect sometimes called the "Christmas lights problem." Microinverters eliminate this by converting each panel's DC output to AC independently. On mixed-orientation or partially shaded roofs, this can recover 5–15% of annual generation that would otherwise be lost. See our explainer on solar inverter types for a fuller comparison of string inverters, microinverters, and optimisers.

What the kWh difference means in practice

To put orientation in perspective, here is a simplified comparison for a 4 kWp system at an average UK location (central England, 35° pitch, no shading):

South-facing: ~3,800 kWh/year (benchmark)
Southeast or southwest: ~3,230–3,610 kWh/year (85–95%)
East or west only: ~3,040–3,230 kWh/year (80–85%)
East–west split (2 kWp each slope): ~3,040–3,230 kWh/year combined (80–85%)
North-facing: ~1,900–2,280 kWh/year (50–60%) — not recommended

These are indicative figures based on PVGIS modelling benchmarks and Energy Saving Trust guidance. Your actual yield will depend on your postcode, system losses, and shading. An MCS-accredited installer is required to carry out a detailed site survey and provide a system-specific output estimate before installation.

The takeaway is that south-facing is ideal, but only north-facing is genuinely problematic. If you have an east-, west-, southeast-, or southwest-facing roof, solar panels can still deliver a strong return — especially at current electricity prices.