EDF FreePhase vs Octopus Agile: which dynamic tariff is better for a heat pump?

EDF FreePhase and Octopus Agile are both dynamic, wholesale-linked electricity tariffs — your unit rate moves with the real cost of electricity rather than sitting at a flat number. Both can deliver periods of free electricity when wholesale prices go negative, both are electricity-only with a standing charge of around 57p a day, and neither has exit fees. On paper they look like rivals doing the same job.

But they're built very differently, and for a heat pump owner that difference decides which one will actually save you money. This guide explains how each works, compares them side by side, and gives a clear verdict on which suits a heat pump — backed by worked examples.

If you'd rather skip the theory and see which tariff wins against your own consumption, you can register for a free account, upload your smart meter data, and compare every tariff against your real usage. For the wider field, our data-driven comparison of the best heat pump tariffs for 2026 covers all the main options.

How EDF FreePhase works

FreePhase is a three-band time-of-use tariff. Instead of a different price every half-hour, it splits the day into three fixed windows, each with its own rate:

• Green (off-peak): 11pm–6am — the cheapest band, overnight
• Amber (mid): 6am–4pm and 7pm–11pm — a medium rate covering most of the day
• Red (peak): 4pm–7pm — the most expensive band

There are two versions. FreePhase Dynamic recalculates those three band prices every day based on the wholesale market, with next-day prices published in advance. FreePhase Static keeps the same three band prices fixed for 12 months. Both cap the unit rate at 75p/kWh no matter what the market does, and both deliver free electricity periods when wholesale prices go negative.

The key feature for planning is that the time windows never move. Peak is always 4–7pm. The cheap window is always overnight. You don't need to check an app every day to know when to avoid using power — you just need to know it's the red band. EDF's own figures showed FreePhase customers averaging around 19.67p/kWh against a price cap of 27.69p over early 2026 — close to a 30% saving — even before actively shifting load.

How Octopus Agile works

Agile is fully half-hourly. Every 30 minutes has its own unit rate, so there are 48 different prices across the day, published by 4pm the day before for the following 24 hours. Rates track the wholesale market in near real time, which means they can fall very low when renewable output is high and demand is low, and spike sharply during evening peaks. There's a safety cap of 100p/kWh to protect against extreme spikes.

The average Agile price across 2026 so far has been around 22p/kWh, comfortably below the Ofgem cap, and from April 2026 Agile rates dropped a further 3.5p/kWh after the government removed certain levies from electricity bills. Like FreePhase, Agile passes through negative wholesale prices — Octopus calls these "plunge pricing" events, where you're effectively paid to use electricity.

The defining difference is granularity. Agile gives you 48 prices a day; FreePhase gives you three bands. That granularity is Agile's strength and its weakness, as we'll see.

Side by side

Which is better for a heat pump?

This is where the structural difference matters most, because a heat pump is a large, shiftable load — exactly the kind of demand these tariffs are designed to reward. But the two tariffs reward different kinds of owner.

FreePhase suits the "set and forget" heat pump owner

A heat pump's biggest lever is running it when electricity is cheap and avoiding the expensive window. FreePhase makes that simple because the windows never move. You can set your heat pump to pre-heat the house and charge the hot water cylinder during the green band (11pm–6am), coast through the morning on stored heat and thermal mass, do any top-up heating in the amber band, and simply avoid running hard during the red 4–7pm peak. That's a heating schedule you set once and leave alone.

For most heat pump owners — who don't have a home battery and don't want to manage energy actively — FreePhase's predictability is a genuine advantage. You always know the rules. The trade-off is that you can't exploit a one-off cheap half-hour, because FreePhase smooths everything into three coarse bands.

Agile suits the automated, storage-equipped heat pump owner

Agile's half-hourly pricing is a bigger prize for anyone who can chase it. With a hot water cylinder, a home battery, or smart heating controls that can target the cheapest individual slots, an Agile heat pump owner can land an effective rate well below FreePhase's overnight band — and capture plunge-pricing events that FreePhase's daily banding partly averages away.

But Agile's granularity cuts both ways. A heat pump running on demand through a cold evening can hit several expensive half-hours in a row, and without automation to dodge them, the savings erode fast. Agile rewards engagement and punishes inattention. It has the lowest floor of the two — and the highest ceiling.

The verdict

For a typical heat pump owner who wants predictability and will shift heating around fixed windows, FreePhase is usually the better default. Its fixed bands map cleanly onto how a heat pump actually runs, and you get most of the dynamic-tariff savings without the daily management.

For the technically engaged owner with a battery, smart controls, or willingness to automate, Agile has the higher savings ceiling and is the better choice — provided you'll actually optimise it. Run a heat pump passively on Agile and you may do worse than on FreePhase.

→ See EDF's FreePhase tariff (referral link — supports this site)

→ See Octopus Agile (referral link)

Worked examples

Three heat pump households, showing estimated annual electricity cost (heat pump portion plus standing charge) on the Ofgem cap baseline versus each dynamic tariff. The dynamic figures assume a realistic share of heating load shifted into cheap windows — more achievable on FreePhase's fixed bands without automation, and assumed higher on Agile only where automation is present.

National-average estimates based on published 2026 rates and typical load-shift assumptions. Agile figures assume active automation; without it, Agile can cost more than FreePhase. Your real cost depends on your DNO region, your consumption pattern, and how much you can actually shift — which is why modelling against your own data matters.

The pattern is consistent: both dynamic tariffs comfortably beat the standard cap for a heat pump owner who shifts load. Agile edges ahead when automated, but the margin over FreePhase is modest — often £30–£90 a year — and it depends entirely on the automation being there. For most households, the gap is small enough that FreePhase's simplicity wins.

Free electricity and negative pricing

Both tariffs pass through negative wholesale prices, which are becoming more common as UK renewable capacity grows. On Agile, negative half-hours show up directly as plunge-pricing windows. On FreePhase, free electricity periods are declared when wholesale goes negative, with the unit rate falling to zero (standing charges still apply).

For a heat pump owner, these events are a bonus rather than a strategy — they're unpredictable and can't be scheduled around in advance. Agile's finer granularity captures more of them in full; FreePhase's daily banding partly averages them into the green-band price. Neither should be the deciding factor, but if you have storage to soak up free electricity when it appears, Agile extracts slightly more value from it.

Frequently asked questions

Can I run a heat pump on either tariff? Yes. Both require a working smart meter sending 30-minute readings, which any heat pump household on a smart tariff will already have. Both are electricity-only, so you'd pair either with a separate gas tariff if you still use gas.

Which is cheaper for a heat pump, FreePhase or Agile? For a passively run heat pump on a fixed schedule, FreePhase usually wins on simplicity and predictable savings. For an automated setup with battery or smart controls, Agile has a higher savings ceiling. The real answer depends on your consumption pattern — modelling both against your own smart meter data is the only way to know for sure.

Do I need a battery to benefit? No — both tariffs save money for a heat pump owner who simply shifts heating into cheaper windows. A battery amplifies the benefit, especially on Agile, but it isn't required.

What about the peak window? FreePhase's peak is fixed at 4–7pm, so you plan around it once. Agile's expensive periods move, usually clustering in the late afternoon and evening, so avoiding them needs more attention or automation.

The bottom line

FreePhase and Agile are both strong dynamic tariffs for a heat pump, and both beat the standard price cap if you shift load. The choice comes down to how hands-on you want to be: FreePhase for predictable, schedule-based savings with no daily management; Agile for a higher ceiling if you'll automate and optimise.

The surest way to know which wins for your home is to create a free account and upload your smart meter data — we'll run your real consumption against both tariffs, region included, and show you the actual numbers rather than averages.