South-facing vs east-west solar arrays — why the lower-yield option often wins for business

Ask most installers about panel orientation and you'll hear "south-facing is best." For maximising total kilowatt-hours, that's true. But it answers the wrong question for a business. Your goal isn't to generate the most electricity — it's to generate the most electricity you actually use on site, because that's what's worth your full retail rate rather than the much lower export rate. Once you frame it that way, an east-west layout often wins.

What each orientation does

South-facing points all the panels at the midday sun. It produces the highest total annual yield — around 950 kWh per kWp in southern England — concentrated in a tall spike around the middle of the day.

East-west splits the array: half the panels face east, half face west, usually on an A-frame across a flat roof. Total annual yield drops by roughly 15% versus south. But instead of one midday spike, you get a flatter, wider curve — generation ramps up in the morning from the east-facing panels and stays up into the late afternoon from the west-facing ones.

Why the flatter curve is worth more to a business

Picture a typical commercial load: people arrive, equipment switches on, and consumption runs steadily across the working day, often with a morning ramp-up and an afternoon that doesn't fall away until closing.

A south-facing array dumps most of its output in a few midday hours. If that exceeds what you're using at that moment, the surplus is exported — earning you the low SEG rate (a few pence) instead of offsetting your ~28p retail rate. You've generated lots of electricity but captured less of its value.

An east-west array spreads its output to match that working-day shape. More of every kilowatt-hour is consumed on site, at full retail value, across more hours. So even though it generates ~15% fewer total units, it can deliver more financial benefit, because a larger share lands at the high-value retail rate rather than the low export rate.

There's a structural bonus too: on a flat roof, east-west A-frames pack in more panels per square metre (south-facing rows need wide gaps to avoid shading each other), sit at a lower tilt with less wind load and less ballast, and avoid the midday export glut. More capacity, simpler engineering.

When south still wins

East-west isn't always the answer:

• Limited roof area. If you can only fit a small array, you want maximum yield per panel — go south.
• A genuinely midday-peaking load. Some operations really do peak in the middle of the day; south matches them.
• You're adding a battery. A battery can soak up the south-facing midday spike and release it later, which neutralises south's main downside. (See battery storage for commercial solar.)
• Pitched roofs that already face a particular way — you work with the roof you have.

The decision rule

Don't choose orientation on total-yield bragging rights. Match the generation curve to your consumption curve. The way to do that properly is to ask your installer to model self-consumption and financial return for both layouts against your half-hourly consumption data — not just the headline annual kWh. A good installer can do this; if they only quote total generation, push them, because total generation is the number that flatters south while hiding the value question.

Sanity-check

1. What does my load shape look like across the day? Spread across working hours → east-west likely better. Sharp midday peak → south.
2. Is the installer comparing self-consumption, or just total kWh? Insist on the former.
3. Flat roof? East-west usually means more capacity, less ballast, lower wind load — worth pricing.
4. Battery planned? If yes, south's midday spike becomes less of a drawback.

The bottom line

South-facing maximises electricity; east-west often maximises value for a business by matching the working day and capturing more generation at the retail rate. The lower-yield layout can be the higher-return one. Make the installer model self-consumption for both against your real usage — that comparison, not the total-kWh figure, is the one that decides your return.

To see the savings case for your building, run the calculator. For how storage changes the orientation calculus, see battery storage. For payback fundamentals, read commercial solar payback in 2026.

General information. Have your installer model both layouts against your half-hourly data before deciding.