East-west and flat roofs can both work well for solar panels. For a 4 kWp system near Birmingham, EU modelling gives about 3,100 kWh a year on an east roof and 3,030 kWh on a west roof. A south roof gives about 3,870 kWh, so you lose roughly 20%.

Flat roofs lose less than you might expect, because the panels sit on frames at a tilt you choose. This guide covers the figures, the planning rules and the questions to ask. It sits within our wider look at roof and property suitability.

Why south is best, and why it is not essential

In the UK, the sun is highest in the south. A south-facing roof at about 35 degrees gets the most light across the year. That is the classic layout, so it sets the benchmark.

However, you do not need a perfect roof. MCS says an unshaded roof that faces east, south or west gives a good chance of suiting solar. The best choice for your home depends on shade, roof space and when you use power.

Because the basics help here, see how solar panels work.

What the numbers say

We ran PVGIS, the free tool from the European Commission’s Joint Research Centre. It uses satellite data for 2005 to 2023. We used a 4 kWp system, 14% system losses and a Birmingham location. Here are the yearly results:

  • South, 35 degree tilt: about 3,870 kWh
  • South-east, 35 degrees: about 3,670 kWh
  • East, 35 degrees: about 3,100 kWh
  • West, 35 degrees: about 3,030 kWh
  • North, 35 degrees: about 2,100 kWh
  • Flat roof, south, 10 degrees: about 3,500 kWh
  • Flat roof, east, 10 degrees: about 3,215 kWh
  • Flat roof, west, 10 degrees: about 3,190 kWh

Results will differ in other places. For example, in London the south figure rises to about 4,090 kWh, and in Glasgow it falls to about 3,430 kWh. Use the tool with your own postcode, or ask your installer for the same data.

What a split roof gives you

Say you put half your panels on an east face and half on a west face. The average of the two is about 3,060 kWh for a 4 kWp system, which is about 79% of the south result.

You also get an earlier start and a later finish. East panels catch the morning sun, while west panels catch the afternoon and evening sun. As a result, your output curve is flatter and you may use more of it yourself. Our guide to how many solar panels you need explains how to size a split system.

Winter matters more on east and west roofs

The yearly total hides a bigger gap in winter. In December, the Birmingham south system makes about 133 kWh, but an east or west one makes about 55 kWh. So east-west roofs do give up more in the dark months.

That is worth knowing if you use a lot of power in winter. However, a larger array, a battery or a time-of-use tariff can help. Even so, expect lower winter savings than on a south roof.

Flat roof solar

A flat roof gives you freedom. Installers fit frames that hold the panels at a low angle, often facing south or in an east-west pair. However, the results above show a 10 degree south tilt keeps about 90% of the best south-roof output.

East-west pairs are another common flat roof layout. Ask your installer for a layout drawing and a yield estimate for each option. Always compare quotes on yield per pound, not just panel count. Our solar panel costs and savings guide explains how to do that.

Check the roof itself

A flat roof is a waterproof surface, so it needs care. Ask who checks its condition before fitting, how the frames are fixed or weighted, and who repairs a leak. Make sure the warranty covers the roof, not just the panels.

You may also need to leave room for access and cleaning, since you should not step onto the roof yourself. Our post on cleaning and maintaining solar panels covers safe methods. Never climb up there without proper safety kit.

Planning rules for flat and split roofs

In England, most home solar installations fall under permitted development. For a house, Planning Portal sets out the limits for a house. On a flat roof, the highest part of the equipment cannot be more than 600mm above the highest part of the roof. On a pitched roof, panels cannot project more than 200mm from the roof slope.

Although flat roofs are allowed, a flat roof on designated land needs prior approval from the local planning authority. That land includes national parks, the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites. Panels are also not allowed in the grounds of a listed building, or on a scheduled monument site.

The rules were updated on 27 August 2026. Planning Portal says a 12-month transition runs until 27 August 2027, so you can follow the old or new rules until then. Its guidance covers England only, and Wales may differ. Our longer guide, do solar panels need planning permission, goes into more detail. For wider project steps, see our hub on planning your installation.

Costs and export

Layout changes the price, because frames, extra cabling and access can all add cost. Ask each installer to itemise them. Home Energy Scotland gives a wide installation range of £1,500 to £10,000, so quotes vary a lot. Read how much solar panels cost for the wider picture.

HMRC’s rules put a 0% VAT rate on installing solar panels in residential buildings until 31 March 2027. After that, the rate is 5%. Ofgem says Smart Export Guarantee rates are set by each supplier and must be above zero. Our Smart Export Guarantee guide shows how to compare them.

Be careful with offers that sound too good, because some are not what they seem. Our post on free solar panel schemes explains what is genuine.

Questions for your installer

  • What yield do you expect for my roof, in kWh a year, and which tool did you use?
  • How much shade is allowed for, and in which months?
  • Does my roof need prior approval, and who applies?
  • How are flat roof frames fixed, and what is the roof warranty?
  • Would a split east-west layout beat south-only for how I use power?

Our guide to questions to ask a solar installer has a longer list.

Sources

Common questions

Do east-west solar panels work as well as south-facing ones?

They make less over a year, but not by a huge margin. For a 4 kWp system near Birmingham, PVGIS estimates about 3,100 kWh on an east roof and 3,030 kWh on a west roof. A south roof at the same tilt gives about 3,870 kWh.

Can you put solar panels on a flat roof?

Yes. Panels sit on frames, usually at a low tilt. In England, the highest part of the equipment cannot be more than 600mm above the highest part of the roof under permitted development.

Do I need planning permission for solar panels on a flat roof?

Often not in England. Flat roof panels on designated land, such as a conservation area or national park, need prior approval from the local planning authority. Check with your council.

Is a north-facing roof worth using?

Usually not. PVGIS estimates about 2,095 kWh a year for a 4 kWp system facing north near Birmingham. That is around 54% of the south figure.

Which is better for evening use, east or west?

A west roof makes more of its power later in the day, so it suits evening use. An east roof starts earlier. Many homes with both faces get a flatter curve across the day.