Can you charge an electric car from a home battery?
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Charging an electric vehicle with a home battery is technically possible, but in most cases the battery is too small to fully charge the car.
A typical EV battery is much larger than a home battery, so home storage is usually better suited to adding some extra range rather than providing a full charge. How useful it is also depends on the capacity of your home battery, its power output and the size of the battery inside your electric car.
A home battery can charge your EV, but usually only partly
An electric car typically needs around 40 to 80 kWh for a full charge, while an average home battery may have around 5 to 15 kWh of storage capacity. This means a home battery can add useful driving range, but a full EV charge is usually not realistic for the average household.
Why a home battery cannot fully charge most electric cars
The main reason is the large difference between the capacity of an electric car battery and the capacity of a typical home battery. An electric car usually needs much more stored energy than an average household battery can provide.
Electric car
40–80 kWh
Home battery
5–15 kWh
An electric car can require around 40 to 80 kWh of electricity for a complete charge, depending on the model and battery size, while a typical residential home battery of around 10 kWh only contains a fraction of that. This is why a home battery is usually better used to add some extra EV range rather than trying to provide an entire charge.
A full 10 kWh home battery could theoretically provide around 12.5% to 25% of the capacity of an EV battery between 40 and 80 kWh. In practice, the amount that reaches the vehicle will be slightly lower because some energy is lost during charging and conversion. A home battery can therefore still help you charge your car and reduce how much expensive grid electricity you need, but relying on it alone for a full EV charge is unlikely for most households.
How much can you charge your EV with different battery capacities?
A larger home battery can provide more energy to your electric car and therefore add more driving range. The table below gives an indication of how much different home battery capacities could contribute to EV charging.
| Battery capacity | EV charging % | Driving range |
|---|---|---|
| 5 kWh | 7.5% | 25–32 km |
| 10 kWh | 15% | 50–65 km |
| 15 kWh | 20% | 75–100 km |
| 20 kWh | 30% | 100–135 km |
| 30 kWh | 45% | 150–200 km |
| 40 kWh | 60% | 200–275 km |
| 60 kWh | 85% | 300–400 km |
| 80 kWh | 100% | 400+ km |
The percentages and driving ranges are indicative. The actual result depends on the battery capacity and efficiency of both the home battery and the electric vehicle, as well as the vehicle’s energy consumption.
Does the power output of your home battery matter?
Capacity is not the only thing that matters when choosing a home battery for EV charging. The power output is also very important. These two figures are related, but they tell you something completely different about the battery.
Capacity (kWh): tells you how much electricity the battery can store in total. A 10 kWh home battery can therefore store roughly twice as much electricity as a 5 kWh system, and capacity determines how much energy is potentially available to transfer to the vehicle.
Power (kW): determines how quickly the electricity stored inside the battery can be supplied to your home or electric car. A battery may have plenty of storage capacity, but if its power output is relatively low, transferring that energy to an EV can still take a long time.
80 kWh ÷ 2 kW = 40 hours
If an electric car needs 80 kWh for a full charge and the battery can supply 2 kW continuously, it would take around 40 hours to deliver that amount of energy. A system that can deliver 5 kW would transfer the same energy much faster. Looking only at the number of kWh can give an incomplete picture. If EV charging matters to you, compare both the storage capacity and the maximum power output of the home battery.
Is it better to charge your EV directly from solar panels?
Charging your electric car directly from solar panels is usually more efficient than first storing the solar electricity in a home battery and then transferring it to the EV.
Direct to your EV: if your solar panels are producing enough electricity during the day and your car is at home, it usually makes sense to send as much of that solar electricity as possible directly to the EV. This avoids an additional charging cycle, so less energy is lost along the way.
Via your home battery: when solar power is stored in a home battery first, the electricity has to go through an extra charging and discharging cycle before it reaches your car. Every time electricity is stored and converted, a small amount is lost, so direct solar charging is more efficient whenever your EV is available during sunny hours.
A home battery is useful when your car is not at home
Direct solar charging is not always possible. If your car is away from home during the day, your solar panels may generate their highest output when there is no EV available to use it. A home battery can store part of that surplus electricity so it can be used later when you return home.
Is a larger home battery worth it if you own an electric car?
A larger home battery can be worth considering if you own an electric car, but it depends on how much electricity your household uses, how much solar power you generate and how often you charge your EV at home. An electric car can add a significant amount to your annual household electricity consumption, so a battery that would normally be large enough for your household appliances may become relatively small once regular EV charging is added.
More solar panels: a larger battery can be useful if your solar panels regularly generate more electricity than your household can use during the day, giving you more storage space to keep the surplus for later instead of exporting it.
Higher electricity use: regular EV charging can significantly increase your total electricity use, so a small home battery may only cover part of your normal household demand before you even start charging the car.
Charging from home: if you regularly charge your electric car at home, more storage capacity means more electricity can be saved during the day and used later for either your household or your EV, which is especially useful when your car arrives home after your solar panels have stopped generating.
A larger battery makes the most sense when your electricity demand is also higher
A larger home battery is particularly interesting if you have many solar panels, high household electricity use and regularly charge your electric car at home. But buying the largest battery available is not always the best option: the system should still be matched to your actual electricity use and solar generation. You can compare different home battery capacities or use our home battery configurator to estimate which size is most suitable for your household.
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