Home batteries and bidirectional EV charging — known as V2X, or Vehicle-to-Everything — can improve your home's energy efficiency and reduce the cost of running a heat pump. And you do not need solar panels on your roof for either to pay off.
This article covers:
With these in mind you can make an informed decision about whether a battery or a bidirectional charger is worth it alongside your heat pump.
|
The heat pump ready series A nine-part guide to preparing your home, produced with low-carbon homes architect Colin Usher. |
Most domestic batteries hold between 5 kWh and 10 kWh. They are most commonly installed alongside solar panels, storing surplus generated during the day for use later.
In that setup:
With a heat pump you can use stored energy to heat the home in the evening, drawn either from solar or from cheap off-peak electricity. In the darkest winter months there is far less solar available, which is when a time-of-use tariff does the heavy lifting instead.
You do not need solar for a battery to make sense. On a time-of-use tariff you can charge the battery cheaply when demand is low and use it when rates are high — a practice known as peak shaving.
This depends less on the size of your house than on when you are in it.
If someone is home during the day and can use most of the solar generation as it is produced, the financial case for a battery is weaker — you are already consuming what you generate. In the darker months you can still use a time-of-use tariff to store cheap overnight electricity for evening use.
If the house is empty during the day, the panels still generate, and without a battery that electricity is exported at a lower rate than you will pay to buy it back a few hours later. This is the scenario where a battery earns its keep.
Many households use 5 to 10 kWh of electricity a day, with an away-all-day family typically using around 60% of it in the evening. That is consistent with Ofgem's medium benchmark of 2,500 kWh a year, or roughly 6.8 kWh a day.
Before buying anything, monitor your smart meter for a week, noting the reading at 07:00, 12:00, 16:00 and 22:00. That gives you an energy-use curve showing how much you use and when — which tells you what size of battery you actually need rather than what a salesperson suggests.
Do this before installing solar panels too. Fitting both at the same time with a single installer costs less than doing them separately.
Excluding the cost of the car, a bidirectional charging system can be considerably cheaper than a standalone home battery. Fully installed, a bidirectional charger costs around £930 to £1,500, against up to £10,000 for a large home battery.
| Advantages | Drawbacks |
|---|---|
| Far larger capacity than any home battery — enough to run a home through a multi-day power cut | The car needs to be plugged in during most daylight hours to capture solar |
| Stores far more solar generation — some homes run close to off-grid in summer | Not all EVs support bidirectional charging |
| Much lower cost than an equivalent home battery | Compatible cars work with a narrow range of chargers, so you may need a new charger when you change car |
| Can earn from a virtual power plant scheme | Frequent charging and discharging may contribute to battery degradation, though manufacturers are designing systems to limit this |
If you run two EVs — one for commuting, one for family use — the car that stays home can do the V2X job while the other commutes.
Even with a single commuting EV on a dedicated EV tariff, you can still peak-shave: charge overnight at the off-peak rate and power the home from the car during the expensive evening period.
Many energy experts expect time-of-use tariffs to become far more common as the grid becomes more flexible.
The principle is simple: you pay more during peak demand hours and less off-peak. With a battery and no solar, you charge at the cheapest time and discharge at the most expensive, cutting your bill by the difference.
For context, the current price-capped standard rate is 26.11p per kWh. Off-peak rates on time-of-use tariffs are typically a fraction of that, which is where the saving comes from.
Because of the variation in daylight between summer and winter, and the amount of cloud in a British winter, you will lean on a time-of-use tariff most between October and February, and less between March and September.
Be realistic about the numbers. Without solar panels, savings are generally much lower and the payback considerably longer than when a battery is paired with generation. With solar, savings are far greater and payback much shorter.
If your system is installed by an MCS or Flexi-Orb certified installer, you can be paid for electricity you export under the Smart Export Guarantee (SEG), currently paying roughly 5p to 20p per kWh.
|
An important point about batteries and SEG The Smart Export Guarantee pays for electricity generated by an eligible renewable installation. Where your battery has been charged from your own solar panels, that stored energy can be exported and paid for. Electricity imported from the grid and then re-exported is generally not eligible, and most suppliers' SEG terms prohibit it. Check the specific terms before assuming a battery alone will earn export payments. |
You can sometimes earn more than the SEG rate through a virtual power plant (VPP). These are app-based schemes that aggregate large numbers of home batteries and draw on their stored energy to support the grid at peak times.
The idea is that thousands of small batteries, acting together, can do the job a gas peaking plant would otherwise do — and the operator pays participating households for the energy released.
Schemes are often regional. Solarus, for example, operates across Stockport, Tameside, Cheshire and Greater Manchester in the North West.
The appeal is that a large EV battery can release a meaningful amount of energy during a single peak event — enough, in some schemes, to cover the cost of a takeaway while you watch the football.
VPPs may well be here to stay, but it is worth remembering what happened to the Feed-in Tariff. It was closed to new applicants in 2019 and replaced by the SEG, which pays considerably less. Early adopters of any grid-support scheme tend to be paid best.
Distributed energy storage will play an important role at grid level as more homes install batteries and V2X, and it can genuinely cut carbon emissions by reducing the number of gas-fired power stations needed. But as millions of homes come online, rates are likely to fall.
If you are investing in solar, a battery or V2X, it is worth checking whether a suitable VPP operates in your area — but treat the income as a bonus rather than the basis of your financial case.
It can be. Charging overnight on a time-of-use tariff and using that electricity during expensive peak periods reduces bills through peak shaving. The financial return is usually greater when a battery is paired with solar panels, and payback without generation is considerably longer.
It depends on how much electricity you use and when. Monitor your smart meter for a week, noting readings at 07:00, 12:00, 16:00 and 22:00, to build a usage curve. Most households use 5 to 10 kWh a day, and most domestic batteries hold between 5 kWh and 10 kWh.
Potentially. Some EVs support bidirectional charging, letting stored electricity power your home or export to the grid. A bidirectional charger costs around £930 to £1,500 against up to £10,000 for a large home battery. Compatibility depends on both the vehicle and the charger.
Some systems can, but not all installations include backup functionality. If resilience matters to you, raise it with your installer before purchasing. A bidirectional EV setup has an advantage here, since a car battery can run a home for a couple of days.
Yes, through the Smart Export Guarantee, currently paying around 5p to 20p per kWh for electricity from an eligible renewable installation. Some areas also have virtual power plant schemes paying more. Grid electricity stored and re-exported is generally not eligible.
Frequent charging and discharging may contribute to battery degradation, though manufacturers are designing systems specifically to limit this. Check what your vehicle's warranty says about bidirectional use before committing, as terms vary between manufacturers.
Home batteries and bidirectional EV charging complement a heat pump by cutting electricity costs, making better use of renewable generation, and giving you control over when you buy electricity.
The financial case depends on your usage, your tariff, whether you have solar, and the cost of the equipment. The single most useful thing you can do before committing is monitor your own smart meter for a week — your usage curve will tell you more than any sales pitch.
These technologies are becoming increasingly important as the UK moves towards a smarter, more flexible grid. For most households, considering batteries, solar panels and time-of-use tariffs together will deliver the best long-term value.
|
Next in this series 9. Solar Panels and Heat Pumps: A Natural Partnership — how generation and low-temperature heating work together, and what the pairing is worth. Previously: 7. Energy-saving technologies |
Produced with Colin Usher, low-carbon homes architect. Last updated: 3 August 2026.
Want to be amongst the first to be notified when more competitive energy tariffs become available? Enter your email address here...
The Energy Shop is a free, independent and impartial energy price comparison service. We can help you compare and switch energy suppliers to help you save money. Our service is accredited by the Ofgem Confidence Code.
