Can you charge an electric car from a home battery?

Yes, partly: a home battery with EV support can charge part of an electric car and keep the charging peak low. It cannot fill the car every night at full power: it is too small and the house needs it. Charge from the sun when the car is home, and keep the car off the battery in a power cut.

You drive an electric car, often a company car, and charge it at home on an 11 kW charger. Then the bill arrives. As one driver put it: "my employer reimburses the volume but not anything related to the capacity tariff".

How much of an electric car can a home battery charge?

Only part of it, and only as fast as the battery inverter allows. An electric car holds far more energy than a home battery, and a charger draws more power than most home batteries deliver.

So the battery shares the load with the grid, which suits the capacity tariff. It takes the top off the charging power, the grid delivers a steady base.

On a weak 3x230 V connection that matters even more: read what to do when your 3x230 V connection is too weak.

When should you charge the electric car from the sun, and when from the home battery?

Every kWh that goes into the battery and out again loses a little on the way. So the sun goes into the car when it is home, and the battery supports the car only for a reason.

That is how a site in Hamme works. A warehouse carries a large solar array, nobody is there during the day and most power is used in the evening. A three-phase battery with back-up (9 kVA, 30.8 kWh) stores much of the day's sun, among other things to charge the electric car later.

The Kontich project shows the classic case: an electric car and plenty of solar panels. With the digital meter, that surplus could no longer be used efficiently. The home battery (5 kVA, 15.4 kWh) makes sure the house uses as much of its own power as possible.

What does an 11 kW charger do to your capacity tariff?

In Flanders the grid cost depends on your highest quarter-hour each month, averaged over twelve months, with a minimum of 2.5 kW. An 11 kW charger that runs at full power while you cook sets a new monthly peak in one evening.

One driver saw his monthly peak go from 4 to 5 kW before the car to 10 to 11 kW after it. One careless evening counts for a year, and one careful month barely lowers the average.

Fluvius names electric cars and large heat generators as the heaviest loads. It advises spreading the charging instead of charging at full power as fast as possible. In full sun, full power is fine again: you then charge on your own solar power.

The rate is roughly 49 to 57 euro per kW per year excluding VAT in 2026, depending on the grid area.

Running a business from home? The rules for companies are in our guide to calculating the capacity tariff.

And in Wallonia and Brussels? The Flemish capacity tariff does not exist there in the same form. In Wallonia a standard low-voltage household pays no capacity term for 2026 to 2029.

On a dual-rate (bihoraire) tariff, all Walloon grid operators use off-peak hours from 11:00 to 17:00 and from 22:00 to 07:00 from 2026. Charge the car then: at midday on your own sun, at night on the grid. In Brussels, Brugel sets the network tariffs with its own structure: check the time bands on your bill before you set the charger.

How do you keep the charging peak down: slower charging, load balancing or the battery?

Three tools, and they work best together. The first two cost almost nothing; the battery adds power and back-up.

• Slower charging at night. 20 kWh takes about 1.8 hours at 11 kW and about 5.4 hours at 3.7 kW. A car that stands still from eleven at night to six in the morning does not need 11 kW.
• Load balancing. A smart charger measures the whole house and lowers its power when the oven, the dryer or the heat pump starts. The peak stays at the limit you set.
• Battery support. The energy system caps what the house takes from the grid. When the car and the house ask for more, the battery delivers the difference, within the power of its inverter.

Who pays when a company car is charged at home?

The employer reimburses the kWh that go into the car; the peak on your bill is your problem unless your car policy says otherwise.

For home charging of electric and plug-in hybrid company cars, the FOD Financiën sets a fixed maximum amount per kWh every quarter. It is based on the all-in household price the CREG calculates per region, and employers use it to reimburse the electricity used. For the fourth quarter of 2026 it is 32.25 eurocent per kWh in Flanders, 36.88 in Brussels and 37.79 in Wallonia.

• The charger counts every kWh that goes into the car, whatever the source: grid, solar panels or battery. Ask your employer or accountant how your car policy treats kWh from your own panels.
• The capacity tariff is not a kWh: slower charging and battery support keep your peak where it was before the car arrived.
• Who owns the charger (employer or you) decides who may change its settings. Make sure the charger can be steered by your energy system before you sign.

Charging company cars at the office instead? That is a different puzzle, covered in charging points without a heavier connection.

Should the charger sit on the back-up circuit?

Usually not. During a power cut the battery has one job: keep the house running. A car charging at 7 or 11 kW empties a home battery within hours.

The usual choice is the grid side, so the charger simply stops when the grid fails. In a large home with a big battery and a generator input, a small planned charge can be allowed during a long outage.

In Sint-Niklaas the house runs on full back-up on a single-phase connection (5 kVA, 15.4 kWh). When the street fails, it keeps running on solar panels and battery. That only works when large loads like a charger do not drain the reserve.

The three levels of back-up are explained in home battery with backup power. What a three-phase house needs per phase is in three-phase home battery back-up.

What should you ask before combining a charger and a home battery?