How can a metal workshop lower its peak demand?

By finding the quarter-hour in which the laser cutter, the compressor and the welders overlap, and spreading them. Lower the compressor pressure, fix the leaks and stagger the morning start. A business battery then covers the peak demand above a limit you set. It recharges when the metal workshop is quiet or the roof produces solar power.

You bought a laser cutter to cut faster and to stop sending plates out. Network costs rose with production, and Mijn Fluvius shows a monthly peak nobody recognises.

A Belgian home owner asked a forum what his peak would be "if everything happens to fall together". In a metal workshop, it falls together every morning.

What sets the peak demand of a metal workshop?

The peak of a metal workshop is set by the quarter-hour in which the laser cutter, the compressor and several welders run together. The meter averages every quarter-hour, so a machine counts for the minutes it actually draws power.

That quarter-hour is your normal working rhythm, so it weighs on all twelve monthly peaks. A heavier connection is sized on it.

Another Belgian forum member found that his 11 kW charger had raised his network costs. "Had someone bothered to explain this to me", he wrote, he would have acted sooner. How the peak is measured and billed is in our article on how to read and lower your business peak demand.

Press brakes, saws, drills and grinders are short loads between handling: small in the average, large only at the start. Extraction, heating and lighting add a long, even base under everything else.

A motor start of a few seconds can trip a breaker but barely moves a quarter-hour average. Why it still sizes a connection is in our article on the start-up current of a heavy machine.

How much electricity does a laser cutter use?

A laser cutter uses far more electricity than its laser power suggests, because the source, the chiller, the drives and the extraction all draw power. Bystronic gives an average power consumption of 22 kW for a 6 kW fiber laser machine, and 65 kW for a 6 kW CO2 machine.

The laser power on the brochure is the beam, not what your meter sees. A laser that cuts a full nest runs as a steady block for hours and sets the floor of your peak. Trotec adds that the extraction and the cooling unit, which often run while the operator loads plates, have a direct impact on consumption.

Do welders raise your peak?

Welders (MIG/MAG, TIG) raise your peak by the share of each quarter-hour in which the arc actually burns.

Take the Fronius TransSteel 3500c, a three-phase 3 x 400 V MIG/MAG welder. At full output it draws 15.87 kVA, with a power factor (cos phi) of 0.99. In standby it uses only 36.5 W, so an idle welder costs almost nothing in your peak.

Its duty cycle is 350 A at 40%, 300 A at 60% and 250 A at 100%, over ten minutes at 40 °C. That is a heat limit: at 350 A it may weld four minutes out of ten, then it must cool down. Real welding time depends on the fitting, grinding and handling between the welds.

• Two welders in a quarter-hour, each welding a third of the time, add less than one welder at full power for the whole quarter-hour.
• Six welders who all start after the morning briefing can set a peak that the same six never reach when their work is spread.
• A single-phase welder loads one phase only. On a low-voltage connection that phase reaches its fuse first, even when the total power still fits. A three-phase welder spreads its power over three phases.

What does a compressor do to your peak?

A compressor raises your peak when it fills at full power in the same quarter-hour as the laser and the welders. A fixed-speed screw or piston compressor does that after a pause, or when leaks keep it running. What counts is how long it runs at full power in your busiest quarter-hour.

Atlas Copco writes that electricity is around 76% of the lifecycle cost of a traditional fixed-speed compressor. Its four levers also lower your peak:

How do the machines add up in one quarter-hour?

The peak builds where the laser, the compressor and the welders overlap, usually in the first hours of the shift.

The gap of about 20 kW comes from habits. If that worst quarter-hour happens in every month, it costs about 1,068 euro a year in Flanders. That is 20 kW x 53.39 euro per kW per year (2026 average, excl. VAT).

If it happens once a year, it costs far less, because Fluvius averages the monthly peaks over 12 months. The full calculation is in our article on how to calculate the capacity tariff.

That is the Flemish system. Wallonia and Brussels reward a different habit.

• Wallonia, professional sites with peak metering: ORES charges a capacity term in euro per kW. Two thirds are based on the eleventh highest quarter-hour of the month, one third on the highest monthly peak of the last 12 months. So one bad quarter-hour counts little; a peak that returns on eleven days counts fully.
• Wallonia, low voltage up to 56 kVA: the standard tariff has no capacity term. The time of use matters more there.
• Brussels: Sibelga applies its own tariff structure.

The full comparison is in our article on grid tariffs for businesses in Wallonia and Brussels.

How do you lower a workshop peak without a battery?

Start with the order of the day, then with the compressor, and only then with equipment. Most of the 20 kW in the example can be moved without buying a battery.

• Let the compressor fill before the shift starts, so it rests while the laser and the welders start. A larger air receiver makes that possible without buying anything electrical.
• Start the laser nest and the welding bay a quarter-hour apart instead of at the same minute after the briefing.
• Plan long laser nests for quiet hours, such as late in the day or during breaks, when the welders stop.
• Spread single-phase welders over the three phases when the wiring is designed.
• Put chargers for company vans on load management, so they share the power that is left. Our article on chargers without a heavier connection explains how.
• Let an energy management system switch flexible loads, such as heating, extraction on demand or the compressor, when the site nears a limit. Read what an energy management system does for a business.

First download a year of quarter-hour data from Mijn Fluvius and find the hours where the peaks cluster. You cannot move a peak you have not found. Our monitoring software shows consumption per phase, with reports per minute, hour or day.

When does a business battery make sense for a metal workshop?

A business battery makes sense when the workshop peak is structural and cannot be moved without slowing production.

The battery is sized on two numbers from your quarter-hour data: how many kW to shave, and for how long. Our article on peak shaving with a battery explains how. Solar panels on the hall roof let the same battery store midday power: read whether solar panels on a business roof still pay off.

A site in Beveren uses 350,000 kWh per year. There, a battery of 154 kWh works with 200 solar panels, and a high-voltage cabin provides the missing peak current.

Knowing where a battery stops is part of sizing it. Does a new machine push your connection above 250 kVA? Then read our article on a medium-voltage cabin or a battery, which works out that decision for a metalworking company.