Which Direction Should Solar Panels Face?

Solar panels should ideally face due south in the UK, but an east or west facing roof still works and gets around 15 to 20% less energy than one facing directly south. The Energy Saving Trust puts it plainly: "An unshaded, south-facing roof is ideal for maximum performance. East or west facing roofs still work, but we don't recommend installing panels on a north facing roof."

So there is one direction to rule out and a broad middle where solar is still a reasonable buy. What decides it for your house is not the compass point on its own, but the combination of direction, roof pitch and shading. Those are the three things the industry standard actually measures, and this page shows you how to check an installer used your real numbers rather than an optimistic guess. Every figure here comes from the Energy Saving Trust, MCS and Ofgem, fetched on 7 August 2026.

Which direction is best for solar panels in the UK?

Due south, with east and west acceptable, south-east and south-west better than either, and north the one to avoid. MCS, the certification body whose standard your installer has to follow, does not talk in compass points. It measures the azimuth angle, which is how far the roof face is rotated away from due south.

The Solar PV Standard (MIS 3002, Issue 5.0) defines it exactly: "The required value is the azimuth angle of the PV modules relative to due South. Hence, an array facing due south has an azimuth value of 0°; an array facing either SW or SE has an azimuth value of 45°; and an array facing either East or West has an azimuth value of 90°." The value is rounded to the nearest 5 degrees.

Note what that table does not contain: a percentage for south-east and south-west. There is a real number, but it is specific to your postcode zone and roof pitch, and we are not going to invent one. MCS publishes tables of kWh per kWp, called Kk values, for every postcode zone, and the standard says they "provide kWh/kWp values for the zone in question for 1° variations of inclination (pitch) and 5° variations of orientation". Your installer looks yours up. You can ask for it, and further down this page is exactly how.

How much does an east or west facing roof actually cost you?

Around 15 to 20% of annual generation against a due south roof, on the Energy Saving Trust's figure. That is the number worth holding on to, because it is far smaller than the "you need a south-facing roof" folklore implies.

Put it in context. A well-oriented UK roof generates roughly 800 to 900 kWh per kWp per year, higher in southern England and lower in northern Scotland, using the MCS methodology. Losing 15 to 20% of that does not turn a working system into a broken one. It moves a payback that the Energy Saving Trust models at 9 years in London and 11 to 12 years in Stirling, on July 2026 fuel prices and including export payments, somewhat further out. It does not push it past the 25 year life the panels are expected to have. Our guide to how long solar panels last covers that timeline, including the inverter replacement that lands around year 12.

The cost side does not change with orientation. The Energy Saving Trust says domestic systems are "around 4.5 kWp and cost around £7,600", typically about 12 panels across 20 to 30 square metres of roof. An east facing 4.5kWp system costs the same to install as a south facing one. That is the honest trade: same price, somewhat less output, so orientation shows up in your payback rather than in your quote. Our solar panel costs guide breaks the price down, and cost by system size covers 3kW to 6kW.

An east-west roof can suit your household better than the raw percentage suggests

A due south array produces a tall midday peak, while an east-west split spreads generation across the morning and the evening, and if nobody is home at lunchtime the spread version can be worth more to you. This is where the headline percentage stops being the whole answer.

The reason is the gap between what you pay for a unit and what you are paid for one. Under the Ofgem price cap for 1 July to 30 September 2026, a typical direct debit customer in England, Scotland and Wales pays 26.11p per kWh for electricity. Exported units earn a lot less: the Energy Saving Trust says you will "typically get around 12p for every unit that you don't use yourself" through the Smart Export Guarantee, and notes you would normally buy electricity for more than twice that. Export rates are set by each supplier rather than by government and vary widely, so check the rate on the tariff you would actually be on.

So a unit used in the house is worth roughly twice a unit sold to the grid. A south facing array dumps its biggest output into the middle of the day, which is precisely when an out-all-day household is using least, so a larger share of it leaves at the lower rate. An east-west split generates less in total but delivers more of it at breakfast and in the early evening, when the kettle, the oven and the washing machine are actually running. Less generation, more self-consumption.

That does not automatically make east-west better. It means the comparison you care about is annual bill saving, not annual kWh, and the two do not rank roofs identically. Ask every installer what proportion of generation their savings figure assumes you use yourself, because that single assumption moves the answer more than the compass does. Our guide to whether solar panels are worth it in the UK works through the self-consumption maths, and the solar battery storage guide covers the other way of closing the same gap.

Why north facing is the one direction to rule out

The Energy Saving Trust does not recommend installing panels on a north facing roof, and no amount of extra panels fixes the underlying problem. A north facing pitch is angled away from the sun's path for the whole year, so it is not simply a worse version of east or west, it is a different proposition.

Two practical consequences. First, if the only unshaded roof you have faces north, the honest options are a different mounting position rather than a bigger north facing array. The Energy Saving Trust confirms you can put panels on an outbuilding, provided the roof is strong enough, and on a frame in the garden, where they "should be as south-facing as possible". Both are worth pricing before you write solar off.

Second, be alert if a quote proposes a north facing array anyway. That is the point to ask for the MCS performance estimate in writing and check the azimuth figure on it, which the next section explains.

Pitch matters, and flat roofs are not a problem

Roof pitch is measured and priced into the estimate just as precisely as direction, and a flat roof is fine because the panels get tilted up. MCS defines inclination as degrees from horizontal, where "0° represents a horizontal array; 90° represents a vertical array", rounded to the nearest 1 degree. The Kk tables vary by single degrees of pitch, so this is not a rounding detail.

On flat roofs the Energy Saving Trust says panels "are normally tilted up to help maximise energy production", and flags the thing that actually costs money: the mounting must not disturb the roof covering, so systems are often weighted down rather than fixed through it, which means the roof has to carry the added weight. A tilted flat-roof array also gives you a free choice of direction, which a pitched roof does not.

Direction and pitch are not usually a planning issue in themselves, but the rules around solar do differ by nation and there are real conditions on projection and on conservation areas. Our guide to permitted development for solar panels covers England, Wales, Scotland and Northern Ireland separately.

Shading can cost you more than being 45 degrees off south

MCS treats shading as one of the three main site factors alongside orientation and pitch, and it is the one that most often needs someone to visit your house. Appendix B of MIS 3002 says it directly: "Inclination, orientation and shading are the three main site factors that influence the performance of a PV system. While drawings, maps or photos are a suitable means to determine inclination and orientation, an accurate estimation of any shade effects will typically require a site visit."

Shading enters the calculation as a Shade Factor. The standard is clear about when it can be skipped: "Where there is an obvious clear horizon and no near or far shading, the assessment of SF can be omitted and an SF value of 1.00 used in all related calculations." Otherwise the installer works out the likely loss using a method such as the MCS shade evaluation procedure, and the shade factor becomes 1 minus that loss. An estimated 11% shading loss gives a shade factor of 0.89.

That matters when you are weighing up roof faces. A clear east facing roof with a shade factor of 1.00 can beat a south facing roof with a chimney and a neighbour's tree on it. Direction is only one of three inputs, and it is the one you cannot change.

Where shading is unavoidable, the Energy Saving Trust points to optimisers, which mean that "if one panel is shaded, it doesn't impact how much electricity the other panels can generate". It also makes an honest point sellers rarely volunteer: "If your roof doesn't have shading, optimisers won't help you generate more electricity", though they do add monitoring.

How to check the quote used your real roof

Every MCS-certified installer must give you a performance estimate in a set format before you sign, and it has to show your orientation, your pitch and your shade factor. This is the single most useful thing on this page, because it turns "is my roof any good" from a sales conversation into a document you can read.

MIS 3002 clause 4.1.6 prescribes the table. Under installation data it must state the installed capacity in kWp, the "Orientation of the PV system - degrees from South", the "Inclination of system - degrees from horizontal" and your postcode region. Under performance calculations it must state the "kWh/kWp (Kk) from table", the "Shade Factor (SF)" and the estimated annual output, calculated as kWp x Kk x SF. It also has to state the occupancy archetype the self-consumption assumes, offered as home all day, home half day, or out all day.

Four things to look for on that document:

• Does the orientation match your roof? If your roof faces west and the estimate says 45 degrees from south, the generation figure is too high and so is every saving built on it.
• Was the site actually visited? Where the site was assessed remotely, clause 4.1.5 requires this wording: "This system performance calculation has been undertaken using estimated values for array orientation, inclination or shading. Actual performance may be significantly lower or higher if the characteristics of the installed system vary from the estimated values." If you see that sentence, nobody has been on your roof.
• Is the shade factor 1.00, and is that plausible? A shade factor of exactly 1.00 is a claim that you have a clear horizon with no near or far shading. If you can see a tree from the roof, ask how it was assessed. Where the shade factor is below 1, MCS also requires the installer to give you the sunpath diagram used to calculate it.
• Is the headline number the standard MCS estimate? Installers may present an alternative calculation, but MIS 3002 says such estimates "shall not be given greater prominence than the standard MCS estimate" and "shall be accompanied by warning text stating that it should be treated with caution if it is significantly better than the result given by the standard method". A flattering figure with no MCS estimate beside it is a red flag.

Where shading is present, the standard also puts a floor under the promise. If the installer used the MCS shading methodology, the quote must say the result should "yield results within 10% of the actual energy estimate stated for most systems". If they used another method, it must confirm the system "will deliver at least 90% of the energy (in kWh) as set out in this performance estimate".

Get more than one of these and compare them side by side. Where two installers give the same roof very different annual kWh, the difference is almost always in the orientation, pitch or shade factor rather than in the panels. Our guide to choosing an MCS-certified installer covers what else should be in writing before you sign.

What if you have more than one usable roof face?

Splitting an array across two faces is normal and often the right answer, and it changes how the estimate is built. Only the faces getting decent sun count towards the system you can fit, so a mid-terrace with one usable pitch is working with less roof than a detached house with two.

If you are at the stage of working out how much roof you need, start with how many solar panels you need, which sizes the system against your actual electricity consumption rather than against the available roof. A smaller, well-oriented array that you mostly use yourself frequently beats a larger one exporting a big midday surplus at 12p.