Conventional wisdom says solar needs a south-facing roof. That was true in the Feed-in Tariff era, when total kWh generated was all that mattered. It isn't any more.
What the textbooks say
On paper, a south-facing array in southern England generates around 1,000 kWh per kW of capacity per year. East and west-facing arrays generate about 80–85% of that: call it 850 kWh per kW. So south still wins on raw output, by a clear margin.
Why raw output isn't the whole story
What matters financially is the kWh you self-consume, not the kWh you generate. Self-consumed solar saves you 28p/kWh off your bill. Exported solar earns you 5–15p/kWh via SEG. That's roughly a 2–5× gap.
A south-facing array peaks sharply at midday, when most households are out and not using electricity. Most of that generation gets exported at SEG rates. An east-west split generates a flatter morning-and-afternoon curve that better matches households with kids, home working or evening cooking.
The numbers
For a typical household using 3,500 kWh/year with a 4kW system:
- South-facing array: generates 3,800 kWh, self-consumes ~35% = 1,330 kWh saved at 28p = £372/yr from bills
- East-west array: generates 3,200 kWh, self-consumes ~50% = 1,600 kWh saved at 28p = £448/yr from bills
Add export income at a 15p SEG rate and the south-facing array edges back ahead, because it exports more. Add a battery to either and the numbers shift again. The point: don't rule your house out because it doesn't face south. Get a proper design before deciding solar is off the table.
