For many homeowners in Redhill and across Surrey, installing an EV charger is only the first step towards lower-cost, more convenient motoring. The next question is whether adding home battery storage could reduce electricity costs further.
A battery can store cheaper electricity overnight, capture surplus solar power during the day and help supply household appliances when electricity prices rise. It can also support EV charging, but it is important to understand what a domestic battery can realistically do.
A typical 7kW home charger and a 5–13.5kWh domestic battery can work well together. However, the battery normally tops up the car rather than fully charging it from empty.
How does a home battery work with a 7kW EV charger?
A domestic EV charger is connected to your property’s electrical installation, not directly to the battery terminals.
In a properly designed system, the battery connects to the home through an inverter. When the battery is programmed to discharge, electricity flows through the inverter and into the property’s AC electrical system. The EV charger can then use that available energy, alongside electricity from the grid if necessary.
In simple terms:
- The battery stores electricity from solar panels or the grid.
- The inverter converts the battery’s stored energy into usable AC electricity.
- The home consumes that electricity first, including appliances and the EV charger.
- If demand is greater than the battery’s output, the grid supplies the difference.
- Smart controls can decide when the battery charges or discharges.
A 7kW charger can draw up to approximately 32 amps on a single-phase supply. If the battery inverter can deliver 3–5kW, it may reduce the amount of electricity imported from the grid while the car is charging. The charger may still be drawing some power from the grid, particularly if household demand is high.
This is known as peak shaving rather than complete off-grid charging.
Can you charge the battery overnight and use it for the house and car?
Yes, provided your tariff, battery system and controls support it.
A common arrangement is to charge the battery during a cheaper overnight period. During the day, the battery can discharge to help run household appliances, lighting and other loads. It may also contribute to EV charging when the car is plugged in.
However, there is an important distinction between using a battery to support EV charging and charging the entire EV from the battery.
Many electric cars have batteries with capacities of around 40–60kWh. Domestic storage systems are commonly much smaller, often between 5kWh and 13.5kWh. After allowing for usable capacity and inverter losses, a 10kWh home battery might provide only a portion of the energy needed for a substantial EV charge.
For example, a battery may:
- Add several miles of range during an evening charging session.
- Reduce the grid demand created by the charger.
- Supply household electricity while the car charges.
- Store daytime solar energy for use later.
- Help avoid importing electricity during more expensive periods.
It is unlikely to fill a 40–60kWh EV battery on its own. For most households, the most cost-effective approach is to use a suitable off-peak EV tariff for the car and allow the home battery to focus on household demand, solar storage and peak reduction.
Is a battery worth installing if you do not have solar panels?
It can be, but the financial case requires careful calculation.
A battery without solar can charge from the grid during a cheaper period and discharge during a more expensive period. This is sometimes called time-of-use arbitrage. Whether it pays depends on:
- The difference between cheap and expensive electricity prices.
- How often the battery can cycle.
- Battery capacity and inverter power.
- Round-trip efficiency losses.
- Standing charges and tariff conditions.
- Battery degradation over time.
- Whether the system can automatically respond to tariff changes.
- How much electricity your home uses outside the off-peak period.
A standalone battery may make sense for a home with high evening demand, a flexible tariff and regular energy usage. It may be less attractive for a low-consumption property or a household that can already charge its EV directly at a very low overnight rate.
In some cases, simply installing a smart 7kW charger and scheduling it to charge overnight will provide most of the available EV charging savings without the cost and complexity of a battery.
That is why a professional assessment is important. A battery should be sized around your actual consumption rather than installed simply because it is technically possible.
The full picture: solar, battery storage and EV charging
Solar panels, battery storage and an EV can complement one another particularly well.
Solar electricity generated during the day can be used to:
- Run appliances while the sun is shining.
- Charge the home battery.
- Export surplus power.
- Contribute to EV charging if the vehicle is at home.
- Reduce electricity imported from the grid.
The battery can then store excess solar generation for use in the evening, when household demand often increases and the car may be plugged in.
This arrangement can increase solar self-consumption. However, the system still needs appropriate controls. Without careful configuration, the battery could discharge into the car when it would be more economical to charge the vehicle directly from an off-peak tariff.
A good design considers your daily routine, solar generation, EV mileage, tariff times and household demand together.
Battery sizing: capacity is not the same as charging power
Two battery specifications are particularly important:
- Capacity, measured in kilowatt-hours, describes how much energy the battery can store.
- Power output, measured in kilowatts, describes how much energy it can supply at one time.
A larger capacity does not automatically mean that the battery can support a 7kW charger at full output. If the battery inverter is limited to 3kW, the grid may still provide the remaining power required by the car and the house.
For a typical domestic installation:
- 5–8kWh may suit modest household use or limited solar storage.
- 8–13.5kWh may suit a larger home with higher evening demand.
- A greater capacity may be appropriate where there is substantial solar generation, high consumption or a need for longer backup.
- A battery designed mainly for EV support also needs sufficient inverter output, not just more storage capacity.
The correct size for a Redhill property will depend on the home’s electricity usage, available space, solar system, EV mileage and existing electrical installation.
Older consumer units and single-phase supplies in Redhill
Many homes across Redhill, Reigate, Merstham, Earlswood, Nutfield, Salfords and Horley have older consumer units or single-phase supplies. This does not automatically prevent battery or EV charger installation, but it does make a proper site survey essential.
An electrician should assess:
- The main service fuse and available supply capacity.
- The condition and age of the consumer unit.
- Spare ways and circuit protection.
- Earthing arrangements.
- Cable routes and installation distances.
- The battery inverter’s maximum output.
- Existing loads such as electric showers, ovens and heat pumps.
- Whether dynamic load balancing is required.
- Whether the Distribution Network Operator needs to be notified.
Dynamic load balancing monitors the property’s total demand and reduces EV charging power when the home is using more electricity. This helps prevent overloads, nuisance tripping and unnecessary supply upgrades.
ADS Electrical handles the relevant DNO notification process as part of its EV charger installation service. Where an older fuse board is unsuitable, an 18th Edition consumer unit upgrade may be recommended before connecting new equipment.
What about businesses using several EV chargers?
Battery storage can have a different role in a commercial property.
An office, gym, warehouse, restaurant or industrial unit may have several vehicles charging at the same time, alongside refrigeration, lighting, heating, machinery or kitchen equipment. A battery can help reduce short periods of high demand, while charge management can distribute available capacity between vehicles.
Commercial projects may require:
- Three-phase supply checks.
- Multiple-charge-point load management.
- Battery power and capacity modelling.
- DNO discussions or approvals.
- Metering and tariff analysis.
- Fire safety and equipment location planning.
- Integration with solar PV or building management systems.
A battery is not automatically the cheapest way to manage demand, but it can be useful where peak capacity is constrained or where the business wants to make better use of on-site generation.
0% VAT on residential battery installations until 31 March 2027
Under current HMRC guidance, the supply and installation of qualifying electrical storage batteries in residential accommodation in Great Britain is zero-rated for VAT until 31 March 2027. This can include standalone batteries and batteries installed with solar, subject to the applicable conditions.
The relief applies to the battery installation, not automatically to every part of a wider electrical project. Commercial premises are treated differently, and VAT rules can change, so your installer or accountant should confirm the position for your property.
You can read the current rules in HMRC VAT Notice 708/6.
What payback should you realistically expect?
Battery payback is not guaranteed. In 2026, a sensible assessment should account for:
- The installed system cost.
- The usable battery capacity.
- The expected number of cycles.
- Electricity price differences.
- Solar generation and export rates.
- Maintenance and warranty terms.
- Efficiency losses.
- Future tariff changes.
- The value of reduced peak demand.
A battery used with solar may offer a stronger case than a battery installed only to charge an EV. A battery without solar can still work through off-peak arbitrage, but the payback may be longer and more dependent on tariff spreads.
For some properties, the best solution may be a smart EV charger alone. For others, a charger, solar and battery system can provide greater flexibility over many years.
Is battery storage right for your Surrey property?
If you are considering EV charger installation Surrey, start with a whole-property assessment rather than choosing a battery size from a brochure.
ADS Electrical is a NICEIC Approved Contractor and OZEV-approved EV charger installer serving Redhill, RH1 postcodes and surrounding areas including Caterham, Godstone, Dorking, Leatherhead and Epsom. We provide free site surveys, fixed-price quotes within 24 hours and chargers supplied and fitted from approximately £895–£1,250, depending on the installation and equipment selected.
We assess the consumer unit, supply capacity, cable route, load-balancing requirements and any battery or solar plans before work begins. DNO notification is handled as part of the installation process.
For a professional assessment and practical advice on a home charging point Surrey, contact ADS Electrical. We can help you compare a charger-only installation with a battery-supported system and choose the most sensible option for your home or business.
Key takeaway
A home battery can support a 7kW EV charger, reduce grid demand and store cheap or solar-generated electricity. However, a typical 5–13.5kWh battery is much smaller than a 40–60kWh EV battery, so it will usually top up the car rather than charge it completely.
For many Surrey households, the best result comes from combining:
- A smart 7kW charger.
- An appropriate off-peak tariff.
- Dynamic load balancing.
- A correctly sized battery.
- Solar generation where suitable.
- A professional assessment of the existing electrical supply.
The right answer depends on how your property uses electricity, not simply on how much battery capacity you can install.