Is a south-facing roof always best for solar panels in the UK?

For total annual generation, yes. For earnings it depends, because output only decides earnings if every unit is worth the same, and it is not: units you consume are worth the retail price you avoid while units you export are worth your export rate.

Why might an east–west roof earn more than a south-facing one?

East–west arrays spread generation across morning and late afternoon rather than concentrating it around midday. For a household out during the middle of the day, that shape overlaps better with actual consumption, so more of the output is worth retail price rather than the low export rate.

How much less does an east–west array generate than a south-facing one?

Less in total, because neither slope faces the sun square-on and the midday peak is lower. Whether that reduction matters depends on how much of a south-facing array's peak you could actually have consumed. For a household out during the day, much of it would have been exported at the low rate anyway.

Are north-facing solar panels worth it in the UK?

Generally no. North-facing aspects receive substantially less direct sunlight at UK latitudes, and no tariff arrangement or consumption pattern compensates for the shortfall in generation.

Why an east–west roof can beat a south-facing one

South-facing solar panels produce the most electricity over a year. East–west arrays produce less but spread generation across morning and afternoon, which can be worth more once exported units are paid at a fraction of retail price.

Roofs6 min read

Photograph to accompany: Why an east–west roof can beat a south-facing one

The short answer

A south-facing array produces the most electricity over a year. An east–west array produces less in total but spreads it across morning and late afternoon, which can be worth more once exported units are paid at a fraction of retail price.

Ask which roof direction is best for solar panels in the UK and you will be told south, confidently, by almost everyone. It is the right answer to the wrong question.

South-facing wins on output

A south-facing array at a sensible pitch captures the most sunlight across a year. That is straightforward geometry and it is not in dispute. If your only goal is maximum kilowatt-hours generated, south is the answer.

For years that was also the answer to "which roof earns most", because under the Feed-in Tariff every generated unit was paid for at the same rate regardless of when it appeared. Timing was irrelevant. Total output was everything.

Why output stopped being the whole answer

Total output only decides your earnings if every unit is worth the same amount. Under the Smart Export Guarantee they are not. A unit you consume is worth the retail price you avoid; a unit you export is worth your export rate, typically a fraction of it.

That changes the question from "how much do you generate" to "how much do you generate while you are using electricity".

A south-facing array concentrates its generation into a tall peak around the middle of the day. For a household that is out at work, that peak lands in an empty house and most of it goes to the grid at the low rate.

An east–west array splits the same panels across two slopes. It produces less in total, since the peak is lower and the array never faces the sun square-on, but it generates earlier in the morning and later into the afternoon. The curve is flatter and wider.

When the flatter curve is worth more

For a household using electricity at breakfast and again from late afternoon, an east–west spread overlaps with real demand at both ends of the day. More of the output is worth retail price rather than the export rate, and a lower total can produce higher earnings.

There is a practical advantage too. East–west arrays often fit more panels onto a roof, because the two slopes can be filled without the row-to-row shading spacing that a single south-facing plane needs on a flat roof.

What about east-only, west-only, and north?

West-only tends to suit households that are out during the day and home in the late afternoon, since the generation curve leans towards the evening peak.
East-only front-loads generation into the morning, which suits early risers and anyone whose heavy loads run before work.
North-facing is genuinely poor in the UK and no framing rescues it. If that is the only aspect available, the arithmetic is unlikely to work.

The point

Roof direction is not a ranking, it is a match. The right question is not "which aspect is best" but "which aspect best overlaps with when this household actually uses electricity", and that is a question about you rather than about your roof.

Common questions

Is a south-facing roof always best for solar panels in the UK?: For total annual generation, yes. For earnings it depends, because output only decides earnings if every unit is worth the same, and it is not: units you consume are worth the retail price you avoid while units you export are worth your export rate.
Why might an east–west roof earn more than a south-facing one?: East–west arrays spread generation across morning and late afternoon rather than concentrating it around midday. For a household out during the middle of the day, that shape overlaps better with actual consumption, so more of the output is worth retail price rather than the low export rate.
How much less does an east–west array generate than a south-facing one?: Less in total, because neither slope faces the sun square-on and the midday peak is lower. Whether that reduction matters depends on how much of a south-facing array's peak you could actually have consumed. For a household out during the day, much of it would have been exported at the low rate anyway.
Are north-facing solar panels worth it in the UK?: Generally no. North-facing aspects receive substantially less direct sunlight at UK latitudes, and no tariff arrangement or consumption pattern compensates for the shortfall in generation.