Can a construction site battery replace your diesel generator?

Yes, in most cases, as long as it is sized on your real peak and daily energy. A construction site battery is a mobile battery that supplies site power without a diesel generator running all day. It charges from a small site connection, a generator that runs briefly and efficiently, or solar panels. Then it delivers the power and the peaks the site asks for, so a tower crane, hoist or site cabin runs on a connection that is too small on its own. Technically it uses the same building blocks as a fixed business battery: battery cells, a BMS, an inverter and control.

The site connection is not there yet, or it is too small for the crane. So a generator runs from seven in the morning until the last worker leaves, mostly for a few kettles, the lights and a phone charger, and then for the short lifts that really need the power. You pay for the fuel, the refuelling rounds and the noise complaints.

What you do not see on the fuel bill: most of those running hours deliver almost nothing. The generator is sized for the peak and idles the rest of the day. A farm in Saint-Georges-sur-Meuse had the same problem on a permanent site: its street had no grid connection and the farm ran entirely on a generator. After solar panels and a battery system were added, the generator only serves as a backup, and a street connection was never needed.

Why do contractors choose a construction site battery?

A classic generator often runs all day, even when almost nothing is used. That costs fuel, brings noise and exhaust fumes to the site and the neighbourhood, and needs refuelling and maintenance. A battery supplies power quietly and without local emissions, and a generator next to it only runs when the battery needs charging.

There are three more practical reasons:

• The site connection is too small or comes too late. A heavier connection is not always available quickly. What you can do then is explained in our article on a heavier connection that is refused or delayed.
• Working in town or near residents. Some clients and local authorities set their own rules on noise and emissions. Check the specifications and the local conditions of your project.
• The demand is peaky. A crane or hoist asks a lot of power for a short time, and little for the rest of the day. A battery absorbs exactly those peaks.

A construction site battery is not the same as a portable power station. A power station feeds a few tools; a site battery feeds a site distribution board with three-phase loads. How we build battery systems for businesses is explained on our page on business batteries and energy storage.

How does a construction site battery work?

A construction site battery has the same building blocks as a fixed business battery: battery modules with a BMS, an inverter/charger and control. On a site, a rugged enclosure, a site distribution board and movable connections come on top. More about those building blocks is in our article on BESS and battery storage for businesses.

The principle depends on the energy source:

Handling peaks. Victron inverters such as the Quattro have PowerAssist. When a generator or limited connection is about to be overloaded, they first reduce battery charging. Then they add energy from the battery to the power of that source. The Quattro also has two AC inputs and switches automatically to the active source.

Generator as a second line. According to the Victron manual, a GX device can start and stop a generator automatically. It does so based on, among other things, the battery state of charge or the load, with adjustable quiet hours. So the generator only runs when it is needed, not all day.

How big a battery do you need for a construction site?

Two questions decide everything:

• How much power does the site need at its busiest moment? Do not add up all rated powers; look at which loads really run at the same time, with the starting currents of motors on top.
• How much energy does the site use per day? That sets the kWh of the battery and how often it needs recharging.

The power sets the inverter (kW), the daily energy sets the battery (kWh). A large battery with an inverter that is too small will not get a crane moving. If you have measurements from a similar site, use them: quarter-hour values show how short and how frequent the peaks really are.

Worked example (illustrative figures)

A site has a site connection of 3 x 400 V 25 A. That is about 17 kVA (√3 x 400 V x 25 A). Consumption on a working day of 10 hours:

While lifting, the site asks 26 kW on average (6 + 20), while the connection supplies about 17 kW (at a power factor of about 1). So the battery must add 9 kW on average and up to 19 kW at the highest moment (36 kW minus 17 kW). Over 2 hours of lifting that is about 18 kWh.

That gives:

• an inverter that can deliver more than 19 kW continuously, with a margin for starting currents;
• a usable capacity of about 30 kWh, so a busy morning with many lifts in a row is no problem;
• recharging between lifts and at night, from the same connection.

Without a battery, this site would need a connection of at least 36 kW, or a generator running all day to supply short peaks.

Should you rent or buy a construction site battery?

That depends on how often you use one. A contractor with several sites all year round uses its own system more often than a client with one project. Compare the same points for both options: power and capacity, three-phase output and the ability to control a generator. Also look at remote monitoring, and at who takes care of inspection and maintenance. Need power for a festival or event rather than a building site? Read how big a battery must be to run a festival or event without diesel.

If you buy, also look at the use between two sites: site batteries that then stand as a buffer at the depot keep earning. If the battery then stands at your depot, also read whether a battery on your business site is safe and which rules apply.

A battery can also carry a permanent business site, as an example from a related sector shows. Special Renting in Zele, which rents out electric lifting equipment, runs its warehouse and offices fully off-grid on solar panels, a battery and a backup generator. For the generator we assume about 5% of the yearly demand. More about such systems is on our page on off-grid installations.

Buying a battery placed on the market from 18 February 2027? Then an industrial battery above 2 kWh needs a battery passport, according to the European Commission.

Which rules apply to a construction site battery?

AREI (federal, the Belgian electrical code). According to book 1 of the AREI, special rules apply to non-domestic site installations (chapter 7.4). Site installations are characterised among other things by the presence of water (AD2 to AD4) and contact with earth potential (BC3). With protection by automatic disconnection, a voltage limit of 25 V AC applies. Flexible cables must be class II or equivalent. At the origin of each site installation there is a board with a general control device and main protections.

Inspection of mobile installations. The AREI distinguishes two kinds of movable, mobile or temporary installations. An installation with a fixed make-up, such as a generator on a vehicle or a site cabin, is inspected before its first use. An installation put together differently each time from separate parts is in principle inspected before every commissioning. If you have to make an earth connection on site, for example with a generator, that is checked too. A site battery used as one finished unit seems to fit the first category; have that confirmed by your approved inspection body.

Site connection. You request a temporary site connection from your grid operator, with the power you need during the works and for the final connection. In Flanders you apply to Fluvius and provide the site cabinet yourself. In Wallonia you apply online to ORES; neither publishes a typical lead time, so plan a fallback early.

Environment. In Flanders, according to the Department of Environment, movable generators used temporarily for construction or demolition work are not covered by VLAREM heading 12.1, and engines on a building site do not count as stationary installations. In Wallonia, check the class of a generator with the SPW heading tool or your municipality. Either way, a battery mainly cuts the hours an engine runs on site.