If you have solar panels, or you're thinking about them, electric underfloor heating is the cleanest pair on the planet. Solar generates most when you need heat (cool mornings) or storage (winter). UFH takes that power and turns it into a warm house. Here's how to size the stack, what it costs, and what you actually save.
Solar panels produce free electricity. Without a battery, anything you don't use immediately gets sold to the grid for 5–15p/kWh, well below what you pay to buy it back at 24p+/kWh. The real value in solar is using as much as you can on-site.
Heat is the biggest household electricity sink. A typical UK home uses 2,500 kWh/year for lighting and appliances and 12,000+ kWh for heating. If your solar array can divert even a fraction of its output into heat, the self-consumption rate jumps from 30% to 70%+. That's where the payback comes from.
Heat pumps run at a constant low wattage all day whether the sun is out or not, they can't flex with your solar output. Wet underfloor heating systems take hours to respond. EkoBuild electric UFH is different: it ramps from cold to warm in 3–5 minutes, and you can split it across rooms with WiFi thermostats. When the sun comes out at 10am you can crank the kitchen and living room. When it goes behind a cloud, the thermostats hold temperature on a tiny trickle. The system flexes with solar output in a way no other heating system does. (If you're being sold a solar + heat pump bundle, read why most UK homes shouldn't get a heat pump first.)
Four components. Each one earns its place.
4–6 kWp covers most UK homes. South-facing is best, east-west splits also work well for self-consumption. Budget £6k–£9k installed in 2026.
Whole-house or room-by-room. Ribbon from £45/m². WiFi thermostats let you target heat to where solar is feeding right now.
Bank 5–10 kWh of midday excess for evening heating. Pairs with off-peak tariffs for the cheapest possible heating bill. More on batteries →
Octopus Go, Cosy, or Agile. Charge battery overnight at 7–13p/kWh, top up with solar during the day, run heating from stored or live solar.
All figures below assume average UK insulation, south-facing array, and current electricity at 24p/kWh.
| House size | UFH coverage | Solar array | Battery | Annual heat cost |
|---|---|---|---|---|
| Flat / 1-bed | 30m² | 3 kWp | 5 kWh | ~£200 |
| 2-bed terrace | 50m² | 4 kWp | 5 kWh | ~£350 |
| 3-bed semi | 75m² | 5 kWp | 10 kWh | ~£500 |
| 4-bed detached | 110m² | 6 kWp | 13 kWh | ~£750 |
For context: the same 3-bed semi running on UFH alone (no solar/battery) is ~£2,000/year. With gas central heating at 7p/kWh and the boiler standing-charges, it's ~£1,400/year. So solar + UFH halves the gas bill and is two thirds cheaper than running UFH on standard tariff alone.
Modern UK time-of-use tariffs make UFH dramatically cheaper to run. The principle: heating doesn't need to happen at 5pm peak rates if you can preheat the floor at 3am when electricity costs a fifth as much.
7p/kWh off-peak between 00:30–05:30. Charge the battery overnight, run the UFH from that battery during the day. Solar tops up the battery whenever it's sunny. With a 10 kWh battery and a 5 kWp array, most homes pay nothing for heating between April and September.
13p/kWh off-peak during three windows (04:00–07:00, 13:00–16:00, 22:00–24:00). Designed specifically for heat-pump-style heating profiles. Works equally well for UFH with a battery, preheat the floor in cheap windows, coast through peaks.
Anything you don't use from your solar gets sold back at 5–15p/kWh depending on supplier. With UFH paired you're using more on-site, but the surplus still earns. Octopus Outgoing currently pays 15p in some plans.
Here's the maths for a representative project: 1970s 3-bed detached, 95m² heated area, average UK insulation. The numbers below come from EkoBuild's running cost per m² and standard solar/battery industry assumptions for 2026.
These are modelled numbers, not a single customer. For an exact quote on your home, send a floor plan via the contact page or open the Room Designer.
EkoBuild specifies the heating side. We can recommend trusted solar and battery installers for the rest. Free design consultation, no pressure.