How Much Electricity Do Solar Panels Produce in the UK?
Realistic output figures by system size, season, and orientation — with the assumptions that matter.
Annual Output by System Size
Based on central England (Midlands), 30–35° roof pitch. Southern England adds ~5%; Scotland/Northern England reduces by ~5–10%.
| System Size | Panels (400W) | South-Facing (kWh/yr) | East/West (kWh/yr) |
|---|---|---|---|
| 3 kWp | 7–8 | 2,550–2,850 | 2,150–2,400 |
| 4 kWp | 9–10 | 3,400–3,800 | 2,900–3,200 |
| 5 kWp | 12–13 | 4,250–4,750 | 3,600–4,000 |
| 6 kWp | 15–16 | 5,100–5,700 | 4,300–4,800 |
Assumes no significant shading, modern monocrystalline panels, and string inverter. Microinverters/optimisers may improve output by 5–15% on shaded roofs.
Seasonal Output Split
Spring (Mar–May)
Increasing daylight, moderate temperatures — often the best generation months
Summer (Jun–Aug)
Longest days, highest sun angle. Peak output but also peak self-consumption opportunity
Autumn (Sep–Nov)
Declining daylight but still meaningful. October half-term often surprisingly sunny
Winter (Dec–Feb)
Shortest days, lowest sun. Battery storage maximises value of limited generation
Key Factors Affecting Output
Location
Southern England receives ~10% more solar irradiance than Scotland. Cornwall vs Aberdeen can mean 800–1,100 vs 750–950 kWh per kWp installed.
Orientation & Pitch
Due south at 30–35° is optimal. East or west facing produces ~85% of south. Even north-facing can produce ~60% — though rarely cost-effective.
Shading
Even partial shading (chimney, tree, neighbouring building) can reduce output 10–30% with string inverters. Microinverters mitigate this per-panel.
Panel Technology
Modern monocrystalline panels (400–430W) produce more per m² than older polycrystalline. N-type and HJT panels perform better in low light and high temperatures.
Get a Personalised Output Estimate
Based on your roof, location, and shading — not national averages.
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