Solar Panels on a West-Facing Roof: Worth It?

4kW system comparison by direction:

| Direction | Annual Output | % of South | Annual Savings | Payback | |-----------|-------------|-----------|---------------|----------| | South | 4,000 kWh | 100% | £700–£900 | 8–10 yrs | | South-West | 3,800 kWh | 95% | £660–£850 | 8–11 yrs | | West | 3,300 kWh | 82% | £570–£740 | 9–12 yrs | | North-West | 2,500 kWh | 63% | £430–£560 | 12–16 yrs |

West-facing panels produce almost identical annual output to east-facing (both 80–85%). The only difference is timing: east panels peak in the morning, west panels peak in the afternoon.

Financial return: The 18% reduction in output adds approximately 1–2 years to the payback period. Over 25 years, west-facing panels still deliver £5,000–£10,000 in net savings.

Source: PVGIS UK orientation data; Ofgem Q1 2026.

West-facing panels have a hidden benefit: their peak generation (1pm–5pm) aligns with rising afternoon and early evening electricity demand.

Why this matters: - Many households increase electricity use from 4pm onwards (cooking, home from work/school, heating, lighting) - Electricity tariff peak rates are often 4pm–7pm - West-facing panels generate the most during this transition period - Without a battery, this timing alignment increases self-consumption

For households with these patterns: - Stay-at-home parents with afternoon school runs and evening cooking - Shift workers home in the afternoon - Anyone on a time-of-use tariff where afternoon rates are highest

South-facing panels peak at midday when many households have lower consumption. West-facing panels shift this peak later — sometimes closer to when you actually need the electricity.

Source: Energy Saving Trust UK household consumption patterns.

If you have both east and west roof slopes, installing on both creates an extended generation window:

East-west split (6 panels each side = 12 total): - Morning (east panels): strong generation 7am–12pm - Afternoon (west panels): strong generation 12pm–6pm - Combined: generation across 11+ hours (vs 6–7 hours for south-only) - Total output: approximately 85% per panel, but more panels = potentially more total kWh

Example: - 10 panels south-facing: 4,000 kWh/year - 12 panels east-west split: 4,300 kWh/year (85% × more panels) - The east-west split wins if you can fit more panels total

Use micro-inverters for east-west splits — they allow each panel to operate independently, so morning shade on west panels does not affect east panels.

Source: MCS east-west system design data.

Install now. The same logic applies as east-facing: waiting costs more than the reduced output.

Install today (west-facing): - Year 1 savings: £650 - 25-year savings: £16,250 - Minus cost: £6,750 - Net profit: £9,500

Wait 5 years for a south-facing home: - 5 years of zero savings: £0 - Year 6–25 savings: £14,000 (south) - Minus cost: £8,000 (future price) - Net profit: £6,000

Installing now on a west-facing roof delivers £3,500 MORE over 25 years than waiting 5 years for south-facing. Time in the sun beats perfect orientation.

Source: Calculation using Ofgem Q1 2026 rates, 3% annual price inflation.