EDF FreePhase vs British Gas Heat Power: the no-peak-rate heat pump tariff showdown
EDF FreePhase and British Gas Heat Power are the two main heat pump tariffs without a punishing peak rate. Both give you cheap overnight electricity; Heat Power adds a midday window that FreePhase doesn't have. FreePhase keeps you with EDF and has a simpler three-band day structure. Heat Power gives more total cheap hours but requires switching to British Gas. Here's the head-to-head.
Why these two tariffs belong in the same conversation
Most heat pump tariff comparisons focus on Cosy Octopus. That makes sense — it's the market leader. But Cosy's 16:00–19:00 peak rate at ~51.7p/kWh is a significant liability for households that can't reliably schedule around it.
EDF FreePhase and British Gas Heat Power are the main alternatives that deliver meaningful cheap-rate windows without a high peak penalty. Neither charges more than the standard cap rate at any time of day. That changes the risk profile entirely — you can't make your bill worse by running the heat pump at the wrong time.
| EDF FreePhase | British Gas Heat Power | |
|---|---|---|
| Supplier | EDF | British Gas |
| Cheap window(s) | Green: 23:00–06:00 (7 hrs) | 00:00–07:00 + 13:00–16:00 (10 hrs) |
| Cheap rate (Apr 2026) | ~10–12p/kWh (green) | ~12–13p/kWh (off-peak) |
| Mid rate | ~24.7p/kWh (amber, standard level) | ~24.7p/kWh (standard) |
| Expensive rate | Red: 16:00–19:00, mild uplift | None — standard rate applies all day |
| Exit fee | None | None |
| Typical saving vs cap | £160–£225 (Cucumber Eco estimate) | £275–£370 (Cucumber Eco estimate) |
EDF FreePhase in detail
FreePhase divides the day into three colour-coded bands:
- Green (cheapest): 23:00–06:00 — ~10–12p/kWh, approximately 7 hours of deep discount
- Amber (standard): 06:00–16:00 and 19:00–23:00 — at or very close to the standard cap rate
- Red (mild premium): 16:00–19:00 — a modest uplift above the standard rate, significantly lower than Cosy Octopus's peak
The red rate is important context: it exists, but it's mild. Unlike Cosy's 51.7p peak, FreePhase's red rate is typically a few pence above the standard cap — enough to notice if your heat pump runs heavily during those hours, but not enough to undo your savings in the way Cosy's peak can.
The main limitation is that all the cheap electricity is concentrated into a 7-hour overnight window. That's the same total cheap hours as Economy 7, though crucially without Economy 7's inflated day rate. The amber rate during the day is simply the standard cap level — you're not being penalised for daytime usage, you're just not getting a discount either.
For hot water, FreePhase's green window is excellent: 7 hours is more than enough to reheat a 200–250 litre cylinder and run a space heating preheat. The challenge is space heating during the day — your heat pump pays the standard rate for all daytime heating, which means the tariff's annual savings are concentrated in the hot water and overnight heating proportion of your consumption.
British Gas Heat Power in detail
Heat Power offers half-price electricity during two daily windows:
- 00:00–07:00: 7 hours overnight — ~12–13p/kWh
- 13:00–16:00: 3 hours midday — ~12–13p/kWh
Outside those windows, the standard cap rate applies. There is no premium rate at any time of day.
The midday window is the defining difference versus FreePhase. Three extra hours of cheap electricity in the early afternoon aligns well with heat pump behaviour: outdoor temperatures are warmer between 1pm and 4pm than overnight, so the heat pump runs more efficiently during those hours. You get the rate discount and the COP bonus simultaneously.
Ten hours of cheap electricity per day compares favourably with most dedicated heat pump tariffs — more total cheap hours than FreePhase (7), Cosy Octopus (8), or EDF Heat Pump Tracker (6). Only E.ON Next Pumped's 21-hour structure covers more of the day at below-cap rates.
The requirement to switch to British Gas is the main practical friction. If you're already a British Gas customer, Heat Power is a straightforward tariff upgrade. If you're switching from another supplier, the admin takes 2–3 weeks and you need to factor in smart meter compatibility.
The numbers compared
Based on a 3-bedroom home, 6,500 kWh annual heat pump consumption, April 2026 rates, moderate load-shifting:
| Usage profile | EDF FreePhase | British Gas Heat Power |
|---|---|---|
| Passive user (no scheduling) | ~£1,600–£1,650 | ~£1,470–£1,560 |
| Active user (cheap windows used) | ~£1,420–£1,500 | ~£1,350–£1,430 |
| Potential saving vs standard cap | ~£160–£225 | ~£275–£370 |
Heat Power's wider cheap-hour coverage gives it an advantage across almost all usage profiles in these estimates. The gap is most pronounced for households that use significant electricity during the 13:00–16:00 window — which most heat pumps do, particularly on cold afternoons.
That said, these are national averages from third-party modelling. Your actual result depends on your DNO region, consumption pattern, and how much you actually shift to the cheap windows. Run your own comparison on Heat Pump Tariffs using real half-hourly data to see which tariff wins for your home.
Practical differences
Midday flexibility: Heat Power's 13:00–16:00 window is a meaningful advantage for heat pump households — it covers the period when heat demand is often building ahead of the evening, and when outdoor temperatures mean the heat pump runs efficiently. FreePhase offers nothing comparable during the day.
No red-rate risk on Heat Power: FreePhase has a mild red uplift at 16:00–19:00. It's not severe, but it means running the heat pump during those hours costs slightly more than the standard cap. Heat Power has no such exposure at any time.
Supplier relationship: FreePhase keeps you with EDF, which some customers prefer for billing simplicity or existing dual-fuel arrangements. Heat Power requires British Gas electricity, though you can keep your gas with a different supplier.
Hive integration: If you use Hive smart controls, Heat Power integrates directly with them for scheduling. FreePhase has no equivalent smart home tie-in.
Exit fees: Neither tariff has exit fees — both are variable tariffs you can leave at any time.
The verdict
Choose EDF FreePhase if:
- You're already with EDF and switching supplier is inconvenient
- Your heat pump's heating demand is mostly overnight and morning
- You want the simplest possible no-peak structure with a single overnight cheap window
Choose British Gas Heat Power if:
- You want maximum cheap-hour coverage without a peak rate
- Your heat pump runs during the early afternoon as well as overnight
- You already use Hive or are open to switching to British Gas
- The modelled saving difference (£100–£150/year) is worth the switching effort for you
Neither is the wrong choice — both remove the peak-rate risk that makes Cosy Octopus unsuitable for some households. The decision comes down to the value of the midday window and whether switching supplier is worth the admin.
Compare EDF FreePhase, British Gas Heat Power and every other UK heat pump tariff against your actual half-hourly usage data on Heat Pump Tariffs.