Is solar PV better than solar thermal?

For most UK homes, yes. PV is more versatile (powers everything, not just hot water), has better financial returns (8–12 year payback vs 15–25 for thermal), requires less maintenance, and can still heat water via an immersion diverter.

Can solar PV heat water?

Yes. A solar PV system with an immersion diverter (£200–£400) automatically uses surplus solar electricity to heat your hot water cylinder. This eliminates the need for separate solar thermal panels.

How much does solar thermal save?

Solar thermal saves approximately £50–£100 per year on hot water heating costs. This is significantly less than PV (£600–£1,100/year) because hot water is only a small portion of total energy costs, and gas/electricity prices for water heating are relatively low.

Is solar thermal still worth installing?

In most cases, no. PV offers better financial returns, more versatility, and lower maintenance. Solar thermal may still make sense for properties with very high hot water demand (swimming pools, B&Bs) or very limited roof space where thermal's higher per-panel water heating efficiency matters.

Solar PV vs Solar Thermal: Which Is Right for You?

Last updated: 18 March 2026

Independently written

Solar PV panels on UK home — the most common solar technology — Solar PV (electricity) vs solar thermal (hot water) — two different technologies for different needs.

Is solar PV or solar thermal better?

Solar PV generates electricity that can power any appliance, charge batteries, and earn export income. Solar thermal heats water directly, reducing your hot water heating bill. For most UK homes, PV is the better choice — it is more versatile, has a better financial return, costs less to install, and can power an immersion heater to heat water anyway. Solar thermal only makes sense if you have very high hot water demand and limited roof space.

The Key Differences

Solar PV (Photovoltaic): - What it does: Converts sunlight into electricity - Output: Electricity (AC) that powers any appliance - Cost: £5,000–£8,000 for a 4kW system - Annual saving: £600–£1,100 (electricity bills + SEG) - Payback: 8–12 years - Lifespan: 25–30+ years - Maintenance: Very low — occasional cleaning, inverter replacement at 10–15 years - Versatility: Powers lights, appliances, EV charging, heat pumps, AND can heat water via immersion heater

Solar Thermal: - What it does: Heats water directly using sunlight - Output: Hot water only - Cost: £3,000–£5,000 for a typical system - Annual saving: £50–£100 (hot water heating costs only) - Payback: 15–25+ years - Lifespan: 20–25 years - Maintenance: Higher — annual fluid checks, pump maintenance, glycol replacement every 5 years - Versatility: Hot water only — cannot power appliances or earn export income

Source: Energy Saving Trust technology comparison; MCS installer data.

Solar PV system diagram showing electricity generation for UK home — Solar PV converts sunlight to electricity — versatile enough to power anything in your home.

Why PV Wins for Most UK Homes

Better financial return — PV saves £600–£1,100/year vs thermal's £50–£100/year. PV pays back in 8–12 years; thermal takes 15–25+ years.
More versatile — PV electricity powers everything. Thermal only heats water.
PV can heat water too — a PV system with an immersion heater diverter (£200–£400) uses surplus solar electricity to heat your hot water cylinder. You get both electricity AND hot water from one system.
Export income — PV earns SEG payments for surplus electricity. Thermal generates no income.
Battery compatible — PV pairs with batteries for evening use. Thermal cannot store energy beyond the hot water cylinder.
EV charging — PV can charge an electric vehicle. Thermal cannot.
Lower maintenance — PV has no moving parts, no fluids, no pumps. Thermal requires annual fluid checks and pump maintenance.
Better technology trajectory — PV costs have fallen 90% in 15 years. Thermal costs have barely changed.

Solar PV energy flow showing versatility — home, battery, and grid — PV electricity flows to your home, battery, and grid — thermal only heats water.

When Solar Thermal Might Make Sense

Solar thermal is not dead — there are a few scenarios where it can work:

High hot water demand: - Large families (5+ people) using 150+ litres of hot water daily - Properties with hot water cylinders already in place - Businesses with high hot water needs (B&Bs, care homes, swimming pools)

Limited roof space: - Thermal panels are more efficient per square metre at heating water than PV + immersion diverter - If you only have space for 2 panels, thermal may heat more water than 2 PV panels

No electricity need: - If you already generate enough electricity through other means (e.g., wind turbine) - Properties that are already very electricity-efficient

In practice: These scenarios are rare. For the vast majority of UK homeowners, PV is the better investment.

Source: Energy Saving Trust; MCS installer recommendations.

Solar PV cost vs savings over 25 years — far better than thermal returns — PV delivers dramatically better financial returns than thermal over 25 years.

Can You Have Both PV and Thermal?

Yes, but it is rarely cost-effective. The roof space used for thermal panels would usually generate more value as additional PV panels. And since PV + immersion diverter can heat water anyway, adding thermal panels is redundant for most homes.

The better approach: Install a larger PV system and use a solar immersion diverter (like the iBoost+ at £200–£400) to automatically heat your hot water cylinder with surplus solar electricity. This gives you: - Electricity for everything - Hot water from surplus solar - Export income from any remaining surplus - Battery compatibility

This is now the standard recommendation from most UK solar installers.

Source: MCS best practice guidance.

UK home with PV panels — the modern standard over thermal — PV + immersion diverter = electricity + hot water from one system. No need for thermal.

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