Workshop at home: one connection, one peak, one bill

Keep one connection, measure what the workshop uses, and spread or cover the moments when the workshop and the house run together. A semi-off-grid system runs the workshop and the house on your own solar power and a battery. The grid only steps in, like a generator, when the battery runs low. For a smaller workshop, a home battery with peak shaving can already cover the evening overlap.

You work where you live. A welding set and a compressor in the garage, a saw in the shed, a van that charges at the door. In the evening the family cooks, the heat pump runs and the dryer turns. "Peaks that last barely five minutes mess everything up," one Belgian wrote on Reddit about the capacity tariff. Another, with a hobby workshop next to the house, lists a 5.5 kW compressor, a lathe, a mill and welders on one three-phase connection.

What most self-employed people do not see: the grid bills the house and the workshop as one site. The monthly peak is set by whatever runs at the same time, whether it is private or business. Nobody knows which share of the bill belongs to the business, so the accountant uses a rough percentage. And the obvious fixes, a heavier connection or a second one for the workshop, add fixed costs every year.

A garden contractor in Zele needed power for a warehouse, offices and the home. The home and the warehouse were still being built. Future use was unknown, so we first monitored the average and peak use for a month. Only then did we match the number of solar panels to the real use: 5 kWp, followed up in an app. In Hamme, a warehouse with a solid solar installation stands empty during the day, while most power is used in the evening. A three-phase battery of 30.8 kWh with back-up now stores the daytime surplus, so the electric car can charge too.

Does the grid see your workshop and your house as one customer?

Yes. Behind one meter, the grid sees one connection, one monthly peak and one bill. It does not know which kilowatt goes to the kitchen and which to the welding set.

In Flanders, the capacity tariff for homes and small businesses works per meter. The grid operator takes the highest quarter-hour of each month as the monthly peak. It then bills the average of the last twelve monthly peaks. In 2026 one kW costs on average about 53.39 euro a year, excluding VAT. Everyone pays for at least 2.5 kW.

For a home workshop this has one consequence: every machine and every household appliance counts towards the same peak. A heat pump, an oven and a car charger in the house weigh as much as the compressor in the workshop. Our guide to calculating the capacity tariff for a business shows how to read your own figures.

Which machines and appliances set the peak on a shared connection?

Not the machine with the biggest start, but the combination that runs for a whole quarter of an hour. The meter averages your use over each quarter-hour.

A start of a few seconds lifts the quarter-hour average only a little. What drives the peak is overlap: the workshop that runs until six while the house starts cooking at half past five. A workshop that stops at noon on Saturday and a household that cooks at seven rarely meet.

Take an example workshop that draws 11 kW and a house that draws 7 kW at its busiest. When both run in the same quarter-hour, the meter sees 18 kW. When the house waits, or the workshop stops earlier, the meter sees 11 kW.

At the 2026 Flemish average, those 7 kW are worth about 370 euro a year, excluding VAT. Spreading the loads costs nothing. Our article on peak demand in a business lists the usual ways to do it.

How do you find out what your workshop really uses?

Look at your quarter-hour data first, then measure the workshop on its own. Without figures, every decision about a battery or a second connection is a guess.

That is exactly how the Zele project started. The warehouse and the home were still being built, so the future use was unknown. A month of monitoring gave the average and the peak, and the solar installation was sized on those figures. The same app now shows the use every day.

For the long term, ask your electrician for a sub-meter on the workshop circuits, behind the main meter. It is not a meter of the grid operator and plays no role in your bill. It only tells you, and your accountant, how many kWh the workshop used.

Who pays for the electricity: you privately or your business?

With one meter, there are two usual routes. You pay the bill privately and charge a share to your business. Or you take a professional contract and settle the private share inside the business.

Energy supplier Luminus describes these two routes for people whose home is also their workplace and who have no separate meter. Social insurance fund Xerius adds the basic rule for mixed costs. Only the part you use professionally counts as a professional cost, and that applies to energy too.

That is where the measured figure pays off. A sub-meter or the monitoring of a battery system gives a share that you can show, month by month. A fixed guess goes stale as soon as you buy a new machine or install a heat pump in the house. Farmers face the same question. Our article on one connection for the farmhouse and the farm goes deeper into the private share, VAT and benefits in kind.

Do you need a second connection for the workshop?

Usually not. A second connection gives two clean bills, but it doubles the fixed costs and cuts the workshop and the house off from each other.

• Two capacity tariffs. In Flanders each meter pays for at least 2.5 kW, about 133 euro a year at the 2026 average, even when it hardly uses power.
• Two contracts and two sets of fixed fees. Each connection has its own supplier contract and network costs.
• No shared solar power. Panels on the workshop roof then only feed the workshop meter, while the house buys power in the evening.

A second connection does make sense when the workshop is rented out, sold or used by another company. Then it becomes another customer, with its own meter. Already have two connections on one site? Our article on two grid connections and one battery explains what you can and cannot combine.

The real limit is sometimes the connection itself. A 3x230 V connection is a limit for many three-phase machines; read why a 3x230 V connection is too weak for a business. Need more power for one heavy machine? See more power without a heavier grid connection.

What can one battery do for the workshop and the house together?

It works for both, because it sits behind the same meter. The battery sees the total and does not care whether the power goes to a machine or to the kitchen.

• A lower joint peak. The battery covers the overlap of the late workshop hours and the evening at home.
• Solar power when you need it. Panels on the workshop roof charge the battery at noon; the house and the car use it in the evening, as in Hamme.
• Back-up for chosen circuits. The main systems and equipment can be connected separately to the battery, so they keep running during a power cut.
• One set of figures. The monitoring shows what the workshop, the house and the panels do, which also helps the split with your accountant.

In our semi-off-grid system the power comes either from the grid or from the off-grid system. A transfer switch separates the two, so the battery is not charged from the grid. After a period of use you can still decide to go fully off-grid. Want to keep the house running in a cut? Read our article on a home battery with back-up power.

Charging a company van at home is its own topic; see charging points for a business without a heavier connection. Who buys the battery matters for the tax deduction too, as our article on tax deductions and subsidies for a business battery explains.

Does the same apply in Wallonia and Brussels?

The shared meter does, the capacity tariff does not. Small connections in Wallonia and Brussels are billed without a measured monthly peak.

So on the Walloon bi-hourly tariff, a battery earns more by moving your use out of the evening than by shaving a peak. Our article on grid tariffs for businesses in Wallonia and Brussels gives the details per grid operator.

When is a battery not worth it for a home workshop?

When the workshop and the house hardly overlap, or when your peak already sits close to the 2.5 kW minimum. Then shifting a few loads is enough.

Three other cases. When the workshop moves within a few years, invest in measuring and habits first. When the connection is simply too small for your machines, the connection question comes before the battery. And when you want the workshop fully independent of the grid, read our article on an off-grid workshop or garage.

How do we look at a workshop on the same connection as the house?

We start with measuring, not with a battery size.

1. Step 1: We read your quarter-hour data and, where needed, monitor the workshop and the house for a period, as in Zele.
2. Step 2: We look for the overlap and propose what to shift before anything is bought.
3. Step 3: Where a battery helps, we choose a home battery or a semi-off-grid system, and the circuits that stay on in a power cut.
4. Step 4: After installation, you follow the use of the workshop, the house and the panels in the app.