Yes, east- and west-facing solar panels can be worth installing in the UK. You don’t need a south-facing roof to generate useful electricity. What matters is how much unshaded roof space you have, what the proposed system will produce, and how that generation fits your electricity use.
The trade-off is usually lower annual output per panel than an equivalent south-facing installation, with more of the generation shifted towards the morning or afternoon. That can suit some households, but it isn’t a guarantee of better savings. Here’s how to judge your roof without getting distracted by a single percentage.
How much output do east- and west-facing panels lose?
The Energy Saving Trust’s solar panel guide says an east- or west-facing system tends to generate around 15–20% less energy than one facing directly south. Treat that as a broad guide, not a prediction for your house. Roof pitch, shade and location all affect the result.
South, east, west, south-east and south-west compared
Here’s what the European Commission’s PVGIS model estimates for a 35° roof in Nuneaton. It’s per kWp of panels, with typical system losses.
| Roof faces | Yearly output per kWp | Compared with south |
|---|---|---|
| South | about 980 kWh | 100% |
| South-east | about 930 kWh | 95% |
| South-west | about 920 kWh | 93% |
| East | about 790 kWh | 80% |
| West | about 770 kWh | 78% |
A south-east or south-west roof is close to ideal. East and west give up around a fifth. That’s in line with the Energy Saving Trust’s 15–20%. Your own roof could be higher or lower. Pitch and shade matter as much as direction.
Compare like with like. Twelve panels facing west should be compared with twelve equivalent panels facing south under comparable conditions. Comparing a large east–west array with a small south-facing array answers a different question: how much electricity can each available layout produce?
A percentage reduction in annual generation also isn’t automatically the same percentage reduction in bill savings. Electricity used in the home and electricity exported can have different values under your tariff. The installation price matters too, particularly if using two slopes requires more scaffolding or a more involved cable route.
East in the morning, west in the afternoon
East-facing panels favour the earlier part of the day; west-facing panels favour the later part. Splitting panels across both slopes can spread generation over a longer daily window. It doesn’t double the daylight hours or mean each side produces its rated power continuously.
Manufacturer SMA explains that east and west arrays peak at different times, which can give a more level combined output. The exact shape still changes with the season and weather.
Think about when you’re actually at home. Morning generation may help with daytime household demand; afternoon generation may overlap with your return from work in the lighter months. But a west-facing roof won’t power dinner directly from solar after sunset in December.
If you have an electric car, its availability matters as much as roof direction. A car parked at work can’t use solar from the house directly. Our guide to charging an electric car with solar panels explains how surplus charging fits around your routine.
The gap is biggest in winter
East and west roofs keep up well in summer. In winter, with the sun low in the south, they fall further behind.
On the same PVGIS figures, an east or west roof in Nuneaton makes about 95% of a south roof’s output in June, but only about 40% in December.
So plan on a sunny summer and a quieter winter. See how solar panel output in winter compares with summer.
Should you put panels on one roof slope or both?
It’s worth asking for both options when the roof allows it. The Centre for Sustainable Energy’s solar PV advice identifies an east–west roof as a candidate for panels on both sides and highlights the importance of shade and roof strength.
Consider a simple layout example, not a generation forecast: twelve 470 W panels total 5.64 kWp of rated panel capacity. Six on the east slope and six on the west give 2.82 kWp on each side. The combined array is still 5.64 kWp. kWp describes rated peak capacity; kWh is the electricity generated over time.
A split layout may let you use roof area that would otherwise sit empty. On another property, one slope might be heavily shaded by a neighbouring building, making a smaller layout on the clearer slope more sensible. Neither an equal split nor filling every available space should be the default.
Ask for the expected output and extra installed cost of the second slope. You’re deciding whether the additional generation is worth the additional work, rather than choosing a direction in isolation. Already have panels on one slope? Here’s how adding more solar panels to an existing system works.
Check the shade and inverter design
A compass reading is only a starting point. Chimneys, dormers, nearby trees and surrounding buildings can cast moving shadows. A roof that looks clear at lunchtime may be shaded during the very morning or afternoon hours you hoped to use. If your quote includes extra equipment to manage those shadows, our guide to whether solar panel optimisers are worth it explains what to compare.
The electrical design must suit the layout too. Installers often separate differently facing groups using independent maximum power point trackers, or MPPTs, within the inverter. These help the inverter manage groups operating under different sunlight conditions. Two roof slopes do not automatically require two separate inverters.
The correct arrangement depends on the equipment. For example, SMA’s polystring guidance permits certain differently oriented strings to share a tracker subject to specific conditions. Ask your installer to confirm the panel grouping and inverter limits for the proposed design, rather than assuming any mix of panels will work.
What a useful solar quote should show
A proposal for solar panel installation should show the actual panel layout and a generation estimate based on your property. Request the capacity on each slope, the roof direction and pitch used in the calculation, and the allowance for shading.
Ask for monthly output as well as the annual total. The European Commission’s PVGIS guidance explains how generation modelling uses location, orientation, slope and system losses. A model is an estimate, and local obstacles still need assessing.
The savings estimate should then separate electricity used directly, any electricity stored in a battery, and exports. It should state the import and export prices assumed. If battery storage is included, allow for charging and discharging losses instead of counting every unit put into storage as a unit available later.
Be cautious about a quotation that shows only a panel count and an annual saving. Without the generation and usage assumptions, you can’t tell whether the estimate reflects your roof and routine.
East and west-facing solar panels: your questions
Is a west-facing roof better than an east-facing roof?
Not automatically. A west-facing roof may fit afternoon demand better, while an east-facing roof may suit earlier demand. Shade, usable area and pitch can outweigh that timing difference. Compare the proposed designs for your home rather than treating one direction as universally better.
Are south-west facing solar panels worth it?
Usually, yes. A south-west roof gets close to the output of a south-facing one. That’s about 93% on the figures above. It also tilts generation towards the afternoon, when many homes start using more.
Do east–west panels need a battery?
No. Solar can supply household appliances directly without storage. A battery is an optional way to keep surplus for later, with its own cost, usable capacity and losses. If you’re considering adding battery storage, ask for solar-only and solar-plus-battery estimates so you can see what the battery contributes.
Will an east–west roof make solar worthwhile for my home?
It makes solar worth assessing, but it doesn’t settle the financial decision. You need a realistic generation forecast, an installed quote and an estimate of how you’ll use the electricity. There is no single payback period that applies to every east–west roof.
Get your roof assessed
Sunergy Renewables is based in Nuneaton and helps homeowners across Warwickshire, Leicester, Leicestershire and the wider Midlands. Send us your postcode and a recent electricity bill, along with any roof photos you already have. We can assess the available slopes and explain a layout that fits your home. There’s no need to climb onto the roof to get started.
