How a battery complements your heat pump

A battery usually gets pitched as a solar accessory: charge it from the roof by day, use the stored power at night. That's true for solar homes, but it leaves out a much larger group: anyone getting a heat pump, or anyone who already has one.

A heat pump is usually the biggest electricity user in a UK home, which makes it the biggest opportunity to buy that electricity at the right time rather than the wrong one. If you're getting a heat pump installed, there's a practical reason to think about a battery now rather than later: some of the work, and some of the cost, overlaps. If you already have a heat pump, the same logic still applies, just without that overlap.

The short answer

Yes, a battery can be worth adding when you get a heat pump, or afterwards, and solar isn't the point. It isn't really about making money, the way it can get marketed alongside solar; it's about buying less electricity from the grid overall, and making sure that whatever you do buy comes in at the cheapest time of day. A heat pump gives a battery more to work with, because it's usually the biggest single electricity load in a home that has one. Standalone battery installations also carry 0% VAT until 31 March 2027, whichever way the wider decision lands.

Is a battery only worth it if you have solar?

No. Solar changes where the cheap electricity comes from: generated on your own roof instead of bought in. Without solar, it's still bought in, just timed to the cheapest hours on your tariff instead of whenever you happen to need it.

Either way, the mechanism is the same: charge the battery when electricity is cheap, and draw on it instead of buying at a higher rate later. That means the decision hinges on your tariff and how much of your electricity use you can shift, not on your roof. Without a time-of-use tariff, and no plan to move to one, a battery has very little to work with. Already on one, or with a heat pump giving you a reason to switch, the saving is real and needs no solar panel at all.

Why a heat pump gives a battery more to do

Most of a home's space heating happens during the day, because that's when a house loses heat fastest and needs replacing. Hot water works differently: a heat pump usually heats it during a quiet, cheap period and stores it in the cylinder, ready for whenever it's wanted, rather than heating it on demand.

Tariffs built around heat pumps are designed around exactly that pattern. Octopus's Cosy Octopus runs three daily "Cosy Hours" windows (04:00 to 07:00, 13:00 to 16:00, and 22:00 to 00:00), priced 51% below the region's day rate, against one peak window (16:00 to 19:00) priced 50% above it (Octopus Energy, Cosy Octopus tariff page, read 13 September 2026).

A battery adds a way to cover more of the day from electricity bought in those cheap windows. Charge it up during the Cosy Hours, and it can then supply daytime heating and the evening household load — appliances, lighting, cooking — through the peak window, instead of buying at the most expensive rate. It doesn't change how much heat or hot water you use; it changes when the electricity behind it is bought, which is why this case reads differently for a heat pump home than generic battery advice aimed at anyone with a meter.

What does home battery storage cost in the UK, and how long is the payback?

There's no single UK figure worth quoting, because the cost turns on a handful of things specific to your home rather than a national average. What actually moves the price:

Size. A battery's capacity is the main driver of cost — a bigger battery costs more, in roughly the way a bigger radiator does.

Your consumer unit. Fitting a battery sometimes means bringing the consumer unit (the fuse board) up to the required standard. If you're already having a heat pump installed, ask the installer whether the consumer unit is being upgraded as part of that work — it often is, or is already at the standard a battery needs, in which case there's no separate cost for the battery on this point.

Electrician time. The main labour cost is having a qualified electrician on site. A heat pump install already puts one there, so ask whether the battery can be wired in during the same visit — it's usually quicker and cheaper than a separate call-out later.

Location and access. Cost can rise if the cable run to the battery is long or the site is hard to get to. Choosing a sensible spot, close to the consumer unit and easy to reach, usually avoids this.

For an actual number, ask for a battery quote alongside your heat pump quote. The same electrician and the same site visit are often already accounted for, so that's where the price is most likely to come in lowest.

Whichever way the number lands, the installation carries 0% VAT, and that covers more than the unit itself. HMRC's VAT Notice 708/6 zero-rates electrical storage batteries directly, including standalone installations with no solar involved (section 2.19), and its "ancillary supply" rule brings the work needed to fit a qualifying material — not only the material itself — into the same zero-rated supply. The notice illustrates that rule with a different example (cutting a loft hatch to fit insulation, section 2.5.1), but the same principle applies to a battery: a consumer unit upgrade or the electrician's time done to fit it is ancillary to the installation, not a separate, standard-rated job. The zero rate is due to revert to 5% from 1 April 2027.

That cost sits on top of what the heat pump itself costs to run day to day, covered in our guide to why heat pump running costs vary [pending live], and separately from what a heat pump costs to install [pending live].

Which tariffs actually make this work?

The tariff does the work, so it's worth naming what "the right tariff" means in practice. Octopus's Cosy Octopus is built specifically around heat pump use, with the three-window structure above. Other suppliers run comparable heat-pump or time-of-use tariffs with their own cheap and peak windows, and the mechanism is the same whichever one you're on: a meaningful gap between your cheapest and most expensive hours, and enough load you can genuinely move into the cheap ones.

If you don't know your current tariff's cheap and peak hours, or whether it has any, that's the first thing to check, before pricing a battery.

Is a home battery right for your home?

Three questions get most heat pump households to an answer.

Are you already on, or willing to move to, a time-of-use tariff? Without one, a battery has nothing to work with, since the whole saving comes from the gap between cheap and expensive hours. Revisit this once you are.

How much of your heat pump's demand can genuinely shift? A well-insulated home with a hot water cylinder can pre-heat and coast further than one that needs to run closer to continuously. [FLAG for Alex, keep or cut: Ample is developing battery support alongside its heat pump systems, expected later in 2026.] Bought and fitted independently today, on a heat-pump tariff, a battery is a decision you can make on its own economics regardless.

Does the rest of your household load move as well? Appliances, EV charging and cooking all count towards what a battery can cover through a peak window, on top of whatever pre-heating already handles.

Where will it actually go? Batteries are heavy, so they're usually sited on the ground floor. Worth raising early if your home doesn't have an obvious ground-floor spot near the consumer unit.

A heat pump already changes how much of a day's electricity use can be timed. Whether a battery is worth adding on top is a question about your tariff and your load, not about your roof.

Get your heat pump numbers first

Battery economics sit on top of what the heat pump itself costs to run, so those numbers come first. If you're getting a heat pump, get an instant estimate to see what it would look like for your home, or read how heat pumps work if you're still deciding whether one is right for you. Already have a heat pump? The cost drivers above are what to raise with an installer when you're ready to price a battery.

Frequently asked questions

Is a home battery worth it without solar?
Yes, if you're on a time-of-use electricity tariff. The saving comes from charging in the cheap hours and using that instead of buying at the expensive ones, which needs a price gap on your tariff, not a solar panel.

Should I add a battery when I get a heat pump?
It's worth considering. A heat pump is usually the largest and most shiftable electricity load in a house, which gives a battery more to work with. Ask your installer whether a battery can be quoted and fitted at the same time.

Is there still 0% VAT on home batteries?
Yes, for now, and it covers the installation as a whole, not just the battery unit. HMRC's VAT Notice 708/6 zero-rates electrical storage batteries directly (section 2.19) and treats the work needed to fit one, such as a consumer unit upgrade, as part of the same zero-rated supply under its ancillary-supply rule (section 2.5.1). The rate is due to rise to 5% from 1 April 2027.

What tariff do I need for a battery to pay off without solar?
A time-of-use tariff with a meaningful gap between its cheapest and most expensive hours. Octopus's Cosy Octopus, built around heat pump use, prices its cheapest hours 51% below the region's day rate and its one peak window 50% above it.

How much does a home battery cost, and how long is the payback?
There's no single UK figure. What actually moves the cost is the battery's size, whether your consumer unit needs upgrading, how much electrician time it takes, and how easy the site is to access — see "What does home battery storage cost" above for how each one plays out, especially if you're already having a heat pump installed.

Can I add a battery after my heat pump is already installed?
Yes. It's a separate job at that point, with its own electrician visit and, if needed, its own consumer-unit work, so it typically costs more than doing it at the same time as the heat pump. The saving from the tariff and the load-timing described above works the same way either way.

Can a battery help in summer as well as winter?
If a heat pump is set up to cool a home, the same principle applies in reverse: a battery can offset the cooling load's peak-hour electricity use just as it offsets heating demand in winter. See can a heat pump cool your home for what that setup involves.