Solar PV vs solar thermal: which one actually saves you more in 2026?

Ten years ago a homeowner weighing solar PV against solar thermal had a genuinely close call on their hands. Today the decision is much clearer — but the two technologies still come up in the same conversation, and we get asked weekly which one to fit. Here is the honest 2026 comparison, with pounds-per-pound numbers rather than brochure claims.

Solar PV vs solar thermal — what each one actually does

Solar PV (photovoltaic) panels convert sunlight into direct current electricity, which an inverter turns into AC your home can use. Any surplus exports to the grid through the Smart Export Guarantee. Solar thermal panels (or evacuated tubes) heat a glycol-water mix that runs through a coil in your hot-water cylinder, pre-heating it so your boiler or immersion does less work. Two different jobs, two very different economics.

Why PV has essentially won the UK rooftop race

1. PV panel costs fell roughly 70% between 2015 and 2025. Solar thermal panel costs barely budged in the same decade.
2. Electricity has become the universal energy currency. PV runs every appliance you already own — plus any EV, heat pump or smart device you might add later.
3. The Smart Export Guarantee puts a cash value on surplus PV. Solar thermal has no equivalent income stream — any surplus heat just dumps into the cylinder coil or is wasted.
4. Heat pumps and hybrid heating have changed the hot-water picture. A heat pump runs on electricity — which PV provides — so PV indirectly pre-heats your water better than thermal ever did.

When solar thermal still makes sense for a UK home

Solar thermal has a narrow remaining niche — and it is real, just small. If any of the situations below describe your home, it's genuinely worth a conversation.

• High-volume domestic hot water — four or more occupants, daily baths, heavy laundry, or a hot tub in regular use.
• Existing oil or LPG heating where hot water is expensive to produce and mains gas isn't available.
• Off-grid properties where exporting PV to a grid isn't possible, so every unit generated needs to be used on-site.
• Homes with no more room on the roof for PV, but a small south-facing patch that could take a two-panel thermal array.

What about evacuated tubes?

Evacuated-tube collectors are the more efficient variant of solar thermal — they hold their performance better through a UK winter than flat-plate panels, but they're more fragile and more expensive to fit. They don't change the underlying economics. For a UK home in 2026, the answer is still overwhelmingly PV.

Our honest recommendation

For almost every household we survey, the right answer is simple — fit PV, size it correctly for your roof and usage, and pair it with either a battery or a PV-diverter that puts surplus into your hot-water cylinder. In pounds saved per pound spent, this beats thermal by a factor of four to six. If your home is one of the rare cases where thermal still earns its place, our surveyors will tell you honestly.

Want a clear-headed answer for your house? Book a free home energy survey online or ring 0800 229 4094 — Monday to Saturday, freephone from any UK number. No cost. No obligation. No pressure.