A home battery on Octopus Go (or similar smart tariff) lets you charge overnight at 7p/kWh and run your underfloor heating from that stored cheap power during the day. No solar required to get started, just a battery and the right tariff. Here is the maths.
Standard UK electricity costs around 24p/kWh in 2026. Octopus Go drops that to 7p/kWh between 00:30 and 05:30, a 70% discount. The catch: that cheap window is at night, and you need heat during the day. A battery bridges the gap.
The result is that most of your heating runs at the 7p off-peak rate even though heat is delivered during peak hours. The bigger the battery, the more of the day you stay off the expensive grid rate.
Same property, same UFH, same heat demand. Three different tariff setups. Watch what happens to the annual bill.
| Setup | Tariff | Effective rate | Annual heating cost (75m² home) |
|---|---|---|---|
| UFH on standard tariff | Octopus Tracker / fixed | 24p/kWh | ~£2,000 |
| UFH + 10 kWh battery, no solar | Octopus Go | ~10p/kWh (avg) | ~£800 |
| UFH + 10 kWh battery + 5 kWp solar | Octopus Go | ~5p/kWh (avg) | ~£500 |
A 10 kWh battery alone, no solar, cuts the heating bill by 60% just by shifting consumption to the off-peak window. Add solar and you're at 75% savings. The battery is doing more work than the panels in terms of pound-for-pound bill reduction.
Battery capacity is the bottleneck. Too small and you drain it by lunch; too big and you've overspent. Here is a sensible starting point.
| Property | UFH heated area | Recommended battery | Why |
|---|---|---|---|
| Flat / 1-bed | 30m² | 5 kWh | Light heat demand, can refill in one off-peak window |
| 2-bed terrace | 50m² | 5–8 kWh | Covers full day on mild days, peak grid backup needed in cold snaps |
| 3-bed semi | 75m² | 10 kWh | Two-day buffer in mild weather, single-day in cold |
| 4-bed detached | 110m² | 13–16 kWh | Needs split-charge over two off-peak windows or solar top-up |
A 5 kWh battery costs around £2,500 installed in 2026. 10 kWh is roughly £4,500. 13 kWh £6,000. Industry kit, GivEnergy, Tesla Powerwall, Pylontech, Enphase, are all proven options. EkoBuild does not sell batteries; we recommend talking to your solar installer or a battery specialist who works with smart tariffs.
Each room has its own WiFi thermostat. When the battery is full and electricity is cheap, you can crank multiple rooms. When the battery is running low, you can coast on a single room. No central system to over-commit.
UFH only uses power when actively heating. There is no pilot light, no pump, no fluid loop to maintain. When the thermostat is satisfied, the system uses 0W.
3–5 minutes to warm a carpeted floor. The system responds to thermostat changes inside a minute, which means it can take advantage of half-hour electricity price dips you'd never catch with a slow-response wet system.
Schedule the floor to preheat between 03:00 and 05:00 on 7p Go rate. Tile and screed hold heat for hours afterwards. You arrive at breakfast to a warm kitchen at off-peak prices.
For a typical 3-bed semi on a 10 kWh battery:
Battery lifespan is typically 10 years with full performance, 15+ years on degraded capacity. Add SEG (Smart Export Guarantee) revenue if you also have solar, many UK customers earn £200–£500/year selling surplus back to the grid.
Worth noting: battery + UFH on Octopus Go delivers a cheaper effective heating cost than a heat pump for most UK homes, with none of the install complexity. If you're being quoted for a heat pump, read why most UK homes shouldn't get one before committing.
If you don't yet have any of this kit, the right sequence matters. Done in this order, each step makes the next one cheaper. (Notice what's NOT on the list: a heat pump.)
Each step pays its own way. You don't need to do all four at once, and you don't need solar to make UFH economic.
EkoBuild specs and supplies the heating side. We can refer you to trusted battery installers afterwards. Use the Room Designer to get an exact UFH price in 5 minutes.