Home Heat Pump Guide

Heat Pump and Battery Storage: Is It Worth It?

Home batteries are becoming increasingly popular alongside solar panels in UK homes. But when you add a heat pump into the mix — a system that can use 20 to 30 kWh of electricity per day in winter — does battery storage make financial sense? Or is it an expensive gadget that does not shift the numbers enough?

The answer depends on your specific setup, tariff, and whether you already have solar panels. Let us work through the economics honestly.

How Battery Storage Works With a Heat Pump

A home battery stores electricity for use later. There are two main strategies for using a battery with a heat pump:

Strategy 1: Store Solar Electricity

If you have solar panels, they generate electricity during the day — often more than you need. Without a battery, excess solar is exported to the grid for a modest payment (typically 4p to 15p per kWh under the Smart Export Guarantee). With a battery, you store that surplus and use it in the evening and overnight, when your heat pump might still be running.

This increases your solar self-consumption, meaning more of your free solar electricity displaces expensive grid electricity at 24p per kWh.

Strategy 2: Store Cheap Off-Peak Electricity

Even without solar panels, a battery can save you money if you are on a time-of-use tariff with cheap overnight rates. Charge the battery at 7p to 10p per kWh overnight, then discharge it during peak hours when the grid rate is 25p to 35p per kWh. The battery effectively acts as a price arbitrage tool.

Some tariffs, like Octopus Flux and Intelligent Octopus, are specifically designed for this kind of battery operation.

The Economics: Running the Numbers

Let us look at two realistic scenarios for a UK household with a heat pump.

Scenario 1: Solar Panels + Battery + Heat Pump

Setup: 4 kWp solar system, 10 kWh battery, 8 kW air source heat pump in a 3-bed semi.

  • Annual heat pump electricity: 4,000 kWh
  • Annual solar generation: 3,600 kWh
  • Solar self-consumption without battery: ~30% (1,080 kWh)
  • Solar self-consumption with battery: ~55% (1,980 kWh)
  • Additional kWh used on-site thanks to battery: 900 kWh
  • Value of those kWh (saved at 24p vs exported at 10p): 900 x 14p = £126 per year

Battery cost: £3,000 to £5,000 for a 10 kWh system (e.g., GivEnergy, Tesla Powerwall, Sofar).

Payback from solar shifting alone: 24 to 40 years — which is longer than the battery's expected lifespan of 10 to 15 years.

This does not look great on its own. But the battery also shifts non-heat-pump electricity (lights, cooking, appliances), which adds another £50 to £100 per year in savings. And there are additional benefits we will discuss below.

Scenario 2: Battery + Time-of-Use Tariff + Heat Pump (No Solar)

Setup: 10 kWh battery, 8 kW air source heat pump, Octopus Go tariff (7.5p overnight, 28p daytime).

  • Daily battery cycles: Charge 10 kWh at 7.5p overnight, discharge during peak hours
  • Saving per cycle: 10 kWh x (28p - 7.5p) = £2.05
  • Annual saving (365 days): approximately £750
  • Battery degradation: Expect ~20% capacity loss over 10 years, reducing average savings to ~£650/year

Battery cost: £3,000 to £5,000.

Payback: 4 to 7 years — significantly better than the solar-only scenario.

This is where batteries really shine with heat pumps. The combination of a large daily electricity demand (from the heat pump) and a significant price difference between off-peak and peak rates creates a strong business case.

What Size Battery Do You Need?

Battery sizing depends on your strategy:

For Solar Storage

A battery sized to match your typical daily solar surplus works best. For a 4 kWp system, that is typically 5 to 8 kWh. Going bigger means the extra capacity often sits unused except on the sunniest days, which is poor value for money.

For Tariff Arbitrage

Bigger is generally better, because every additional kWh of cheap overnight electricity you can store and use during peak hours saves you money. A 10 to 13.5 kWh battery (such as the Tesla Powerwall or GivEnergy All-in-One) maximises daily savings. Some households install two batteries for 20+ kWh capacity.

For Both Solar and Tariff Arbitrage

If you have solar panels and a time-of-use tariff, a 10 to 13.5 kWh battery gives you the best of both worlds: store solar by day, charge from cheap grid electricity overnight. This dual-use strategy delivers the strongest financial returns.

Current Battery Costs and Trends

Battery prices have fallen significantly and continue to drop. Here are approximate 2026 UK prices including installation:

  • 5 kWh battery: £2,000 to £3,500
  • 10 kWh battery: £3,000 to £5,000
  • 13.5 kWh battery (Tesla Powerwall): £5,500 to £7,500
  • 20 kWh+ systems: £6,000 to £10,000

Like solar panels, home batteries are VAT-free when installed alongside or on a property with existing solar panels. This has made them significantly more affordable since the VAT exemption was introduced.

Industry forecasts suggest battery prices will continue falling by 5% to 10% per year, which means waiting a year or two could improve the economics further — but you also miss out on a year or two of savings.

Additional Benefits Beyond Bill Savings

The pure financial payback calculation does not capture the full picture. Batteries offer several additional benefits:

Power Cut Protection

Many batteries (including the Tesla Powerwall and some GivEnergy models) can provide backup power during grid outages. For a heat pump household, this means your heating continues to work during a power cut — particularly valuable in winter. Without a battery, a power cut means no heating.

Grid Services Revenue

Some battery providers allow you to participate in grid balancing services, where you are paid to discharge your battery at times of peak national demand. Octopus Energy's Powerups programme and similar schemes can add £50 to £200 per year in additional income.

Future-Proofing

As the UK electricity grid incorporates more renewable energy, time-of-use pricing is likely to become more extreme — with very cheap periods during high wind/solar output and expensive peaks during calm, dark evenings. A battery positions you to take advantage of these price swings, and the financial benefit is likely to increase over time.

Carbon Reduction

By storing solar electricity or cheap overnight wind power and using it during peak hours, you reduce demand for gas-fired power stations. It is not just about money — it is a genuine contribution to grid decarbonisation.

When Battery Storage Is NOT Worth It

To be balanced, here are situations where a battery may not make financial sense:

  • Flat-rate tariff with no solar: If you do not have solar panels and are on a standard flat-rate tariff, a battery has nothing to arbitrage. There is no price difference to exploit.
  • Very small heat pump usage: If your heat pump uses less than 3,000 kWh per year (small, well-insulated home), the absolute savings from a battery are smaller and the payback period stretches out.
  • Limited budget: If you have to choose between a battery and improving your home's insulation, insulation is almost always the better investment. It reduces demand permanently and has no moving parts or degradation.
  • Short-term ownership: If you are likely to move within 5 years, you may not recoup the battery cost — although batteries do add value to a property.

Popular Battery Systems for UK Heat Pump Homes

GivEnergy

A British company offering modular batteries from 2.6 kWh upwards. Excellent app, local support, and competitive pricing. Popular choice for new installations.

Tesla Powerwall

The best-known name in home batteries. 13.5 kWh capacity, integrated inverter, and backup power capability. Premium price but high quality and strong warranty.

Sofar/Pylontech

Budget-friendly options that still deliver reliable performance. Good for those prioritising payback period over brand prestige.

myenergi Libbi

Designed to integrate with the myenergi ecosystem (zappi EV charger, eddi solar diverter). Good option if you also have an EV charger.

Frequently Asked Questions

Can a battery power a heat pump during a power cut?

Some batteries can, but not all. You need a system with "backup" or "off-grid" capability (like the Tesla Powerwall). Even then, a 10 kWh battery will only power a heat pump for a few hours in winter — it is enough for short outages but not extended ones. Check the battery specification and discuss backup requirements with your installer.

How long does a home battery last?

Most lithium-ion home batteries are warranted for 10 years or a specific number of charge cycles (typically 4,000 to 6,000). In practice, many last 12 to 15 years with gradual capacity degradation. After 10 years, expect 70% to 80% of original capacity.

Should I get solar panels before a battery?

Not necessarily. If you are on a time-of-use tariff, a battery alone can deliver strong savings through tariff arbitrage. However, the combination of solar plus battery typically gives the best overall return. See our guide on solar panels and heat pumps for more detail.

Can I add a battery to an existing solar system?

Yes. Most batteries can be retrofitted to an existing solar installation. An installer may need to add a battery inverter or replace your existing solar inverter with a hybrid model, but it is a straightforward process. For more on solar options, visit Home Solar Guide.

Is a bigger battery always better?

Not always. A battery that is too large for your usage pattern will not cycle fully each day, which means you are paying for capacity you do not use. For most heat pump households, 10 to 13.5 kWh hits the sweet spot for daily cycling and value.

The Bottom Line

Battery storage with a heat pump is increasingly worth it in 2026 — but the economics depend heavily on your tariff and whether you have solar panels. The strongest case is for households on time-of-use tariffs, where daily tariff arbitrage can deliver payback in 4 to 7 years. The case for solar-only households is weaker on pure financial grounds but improving as battery prices fall.

If you are already planning a heat pump and solar panels, adding a battery at the same time is worth serious consideration — particularly if you can access a time-of-use tariff. The combination of solar generation, battery storage, and an efficient heat pump is the closest most UK homes can get to genuinely low-cost, low-carbon heating.