Is bigger always better?

Almost — extra panels generate more total electricity and surplus earns SEG income. The only exception: very small consumption (under 2,000 kWh) where a large system exports most at low value.

How do I know my consumption?

Check your electricity bill or supplier app. Average UK household: ~3,700 kWh/year. High-use home: 5,000+. Low-use: 2,500.

What Size Solar System Do I Need?

By Home Solar Guide Team|Updated 20 March 2026|guide

Independently written | Plain-English guide

Solar system sizing by home type — System size should match your home — but bigger is almost always better.

Find the right system size for your roof

Panel count depends on your electricity use, roof space and direction — not on a rule of thumb. Get a recommended size and what it should cost.

Size My System

Free calculator. No contact details required to see your result.

Find the right system size for your roof

Panel count depends on your electricity use, roof space and direction — not on a rule of thumb. Get a recommended size and what it should cost.

Size My System

What size solar system do I need?

Size your solar system to match your electricity consumption: 1-2 bed (2,500-3,500 kWh/year) = 2-3kW. 3 bed (3,500-4,500 kWh/year) = 4kW. 4 bed (4,500-5,500 kWh/year) = 5kW. 5+ bed (5,500+ kWh/year) = 6-8kW. With EV: add 3-4kW. With heat pump: add 3-4kW. Rule of thumb: install the LARGEST system your roof and budget allow. Extra panels cost only £200-£350 each and pay back in 3-6 years.

Frequently Asked Questions

Related: Home Heating Systems

Solar panels are most powerful when combined with an efficient heating system. Heat pumps use solar-generated electricity to heat your home at 300-400% efficiency — making them the ideal partner for solar.

air source heat pump guide

Learn more about how air source heat pumps work alongside solar panels.

From our sister site Home Heat Pump Guide