Worked examples

Solar system size and output references

Illustrative 2–12 kWp solar-system output ranges. Each page explains why postcode, orientation, pitch and shading matter more than a national average.

All worked examples

2 kWp solar systemIllustrative annual generation range 1,600–2,000 kWh before site-specific modelling

3 kWp solar systemIllustrative annual generation range 2,400–3,000 kWh before site-specific modelling

4 kWp solar systemIllustrative annual generation range 3,200–4,000 kWh before site-specific modelling

5 kWp solar systemIllustrative annual generation range 4,000–5,000 kWh before site-specific modelling

6 kWp solar systemIllustrative annual generation range 4,800–6,000 kWh before site-specific modelling

7 kWp solar systemIllustrative annual generation range 5,600–7,000 kWh before site-specific modelling

8 kWp solar systemIllustrative annual generation range 6,400–8,000 kWh before site-specific modelling

10 kWp solar systemIllustrative annual generation range 8,000–10,000 kWh before site-specific modelling

12 kWp solar systemIllustrative annual generation range 9,600–12,000 kWh before site-specific modelling

Model a solar quote for your postcode

kWp is system capacity, not annual generation

The system-size references above help put common array sizes into context, but a 4 kWp array does not produce 4 kW continuously and does not imply a fixed annual kWh figure. Output changes with location, roof orientation, pitch, shading, system losses and weather.

Two homes with the same installed kWp can therefore have meaningfully different annual generation. System size should also be considered alongside roof area, inverter design and household demand rather than treated as a stand-alone performance guarantee.

Use postcode-based modelling for a real quote

The Solar Quote Checker uses location and system inputs to model expected generation, so it is a better next step than relying on a generic kWh-per-kWp rule. Enter the quoted array size, orientation and pitch, then compare the modelled output with the installer's forecast. The result remains an estimate, but it exposes the assumptions and gives you a consistent basis for comparing quotes.

Inputs on these pages are illustrative. Replace them with your own tariff, product, quote or household figures in the linked calculator before making a decision.