Which is better value in the UK — solar PV or solar thermal?

For most UK homes in 2026, solar PV offers better value. A 4kWp PV system costs £5,000-7,000 and generates electricity worth £400-700/year (self-consumption plus Smart Export Guarantee). Solar thermal costs £3,000-5,000 but only offsets hot water costs of £150-300/year. PV is more versatile since electricity can power anything including an immersion heater.

How much roof space does each system need?

A typical 4kWp solar PV system needs about 20 m² (10 panels at 2 m² each). A solar thermal system for a 3-bed house needs just 3-5 m² for flat plates or 2-3 m² for evacuated tubes. Solar thermal is far more space-efficient per kWh of hot water produced, but solar PV can use a larger roof area productively.

Can I have both solar PV and solar thermal?

Yes, and some homes benefit from the combination. Solar thermal provides highly efficient hot water heating on a small roof area, leaving remaining space for PV panels. However, with PV prices falling and heat pump diverters available, many installers now recommend PV with a power diverter (like an iBoost) to heat water with surplus electricity instead of installing separate thermal panels.

What is the payback period for each system?

Solar PV typically pays back in 7-10 years in the UK, depending on self-consumption rate and electricity prices. Solar thermal pays back in 10-15 years. Both systems have 20-25 year lifespans, so both deliver positive returns, but PV delivers the better financial outcome in most scenarios.

Do solar thermal panels work in winter in the UK?

Solar thermal panels produce significantly less hot water in winter — typically 10-20% of summer output. Evacuated tube collectors perform better than flat plates in low light conditions. Most UK solar thermal systems need a backup boiler or immersion heater from October to March. They still provide useful pre-heating that reduces boiler runtime.

Solar PV vs Solar Thermal — UK Compared

Compare solar photovoltaic panels with solar thermal collectors for UK homes, covering costs, output, ROI and when to combine both systems.

Side-by-Side Comparison

Feature	Solar PV	Solar Thermal
Output type	Electricity	Hot water
Typical install cost	£5,000-7,000 (4kWp)	£3,000-5,000
Annual saving	£400-700	£150-300
Roof area needed	~20 m² for 4kWp	3-5 m²
Payback period	7-10 years	10-15 years
Battery storage option	Yes	Hot water cylinder only
Export income	SEG 4-15p/kWh	None
Maintenance	Minimal	Annual glycol check