Battery container or technical room: what fits your site?

Put the battery inside when you have a dry, frost-free room with a strong floor, easy access and space to grow. Choose a container or an outdoor cabinet when no such room exists. The same goes for a large battery, or one you want away from the building. A business battery is designed around that spot: the right location keeps cables short, cooling simple and the next expansion cheap.

Maybe the battery is decided, and now someone asks: "Where do we put it?" The store room is full. The only free corner is next to the compressor. The ideal spot is 40 metres from the main board, as one forum user found, with only one 5-core cable in between. Another owner plans a small shed for an inverter of 40 kg and a battery of 600 kg. His worry: the noise next to the neighbours.

What most buyers do not see yet: the spot decides the cable, the cooling, the crane and the next expansion. Together, those can cost more than the battery cabinet itself. A battery 40 metres away on the wrong side needs trenching and thick cables. A container in full sun needs cooling all summer. A room with no free wall means a second installation when you add capacity.

Placement is a design choice, not a leftover. At Special Renting Van Zele in Zele, the generator was put in the basement on purpose. Its heat is not lost: it warms the floor of the warehouse, as the owner explained to HLN. In Beveren the battery holds 154 kWh with 45 kVA of charging power. At that size, every metre of cable and every degree of heat counts.

What is the difference between a battery container, an outdoor cabinet and a technical room?

A technical room is an indoor space for battery racks and inverters. An outdoor cabinet is a closed, weatherproof box. A container is a walk-in steel box with its own cooling. The battery inside can be the same. What changes is the shell around it.

Where is the tipping point? A UK installer names indoor cabinets of about 60 to 500 kWh as typical. It sees containers as practical from about 500 kWh up to several MWh. Treat that as a rule of thumb: your site decides.

Want to know what a battery system contains before choosing its home? Then read our guide to battery storage for businesses.

Can battery modules and inverters stand outside without a container?

Usually not: most rack battery modules and inverters are built for indoor use only. Their datasheets say IP20, which means protected against fingers but not against water.

The IP code (IEC 60529) has two digits. The first is protection against objects and dust, the second against water. A Pylontech US3000C battery module and a Victron Quattro inverter are both IP20: the "0" means no protection against water at all. Outside, such equipment needs a room, a container or a cabinet around it.

For an outdoor cabinet, look for a first digit of 5 (dust protected). The second digit should be at least 4 (splashing water) or 5 (water jets). Then check what the cabinet does with heat and frost, because a closed box in the sun gets hot.

How much space and floor strength does a business battery need?

Count the weight first, then the floor space. A business battery is heavy: a common LFP module weighs about 9 kg per kWh, and the inverters hang on a wall.

Take one common module as an example. The Pylontech US3000C stores 3.55 kWh and weighs 32 kg. A battery of 100 kWh built from these modules needs about 29 of them: roughly 930 kg before racks and cables. A battery the size of the one in Beveren would weigh about 1.4 tonnes in the same modules.

The inverters add their own weight and space. A Victron Quattro of 15 kVA weighs 72 kg and measures 572 x 488 x 344 mm. On a 3 x 400 V connection you need at least three: one per phase, as in our off-grid case. That is more than 200 kg on one wall, with at least 10 cm of free space around each unit for cooling.

The battery location itself needs:

• A stable, level floor that carries the racks. On a mezzanine or an old wooden floor, ask a structural engineer first.
• A watertight room with minimal dust and no flammable materials nearby.
• At least 2 m from a heat source and at least 0.5 m from the ventilation of the inverter.
• Free space around the battery: never cover it.
• No inverter directly above the batteries, as the Victron manual states.

Designing a new building with the architect? Then read our guide on designing a building with a battery: it covers the technical room from the drawing board.

How is a battery container delivered, and what does it stand on?

A container arrives on a truck and is lifted onto a prepared, level base: a concrete slab or foundation that can carry its full weight. Plan that base and the route before you order.

A standard 20-foot container measures about 6.06 by 2.44 metres, about 15 m² of ground, and weighs about 2,200 kg empty. Add the batteries, racks, inverters and cooling, and the total weight runs to several tonnes. That weight needs a firm base, and the crane truck needs firm ground and free space to set up.

Walk the route on your site before the order:

• Access: can a truck with a crane reach the spot? Look at gates, overhead lines, trees and soft ground.
• Base: who designs and pours the slab, and how long must it cure before the container can stand on it?
• Service access: can a technician open the doors and reach every rack, also in winter?
• Vehicles: near a road or a yard where forklifts drive, the container needs protection against collisions.

Indoors, the route is different but just as real. Modules of 32 kg go through a normal door and up stairs by hand. A pre-assembled cabinet of several hundred kilos does not. Check doors, corridors, lifts and floor thresholds.

How hot or cold may a battery room or container get?

Keep the battery room between 0 and 50 °C, and as constant as you can. Outside that range the battery switches itself off. Inverters also lose power long before they stop.

Look at the Victron Quattro 48/15000 datasheet. It delivers 12,000 W continuously at 25 °C, 10,000 W at 40 °C and only 7,000 W at 65 °C. A room or container that gets hot in summer quietly takes away a sixth of your inverter power, and more on the hottest days.

The equipment also makes its own heat. The same inverter has a maximum efficiency of 96%, so at 12,000 W it loses at least about 500 W as heat. Three of them on 3 x 400 V give off about 1.5 kW at full load. That is a small electric heater, running for hours. That heat has to leave the room.

Cold is the other side. Many lithium modules charge only above 0 °C: the US3000C discharges from -10 °C but charges only from 0 °C. In an unheated shed, a frosty morning can stop the battery from storing your solar power. Our article on which battery chemistry to choose explains how chemistries handle the cold.

Heat can also be put to work. That is what the owner in Zele did with his generator in the basement. Next to a heated workshop or office, the waste heat of the inverters is a small bonus in winter. In summer it is a load for the ventilation.

Does a battery make noise, and where do you put it next to offices or neighbours?

The battery cells are silent; the fans of the inverters and the cooling of a container are not. They run when the system works hard, and a container cooler can run at night too.

Remember the owner who wanted a shed against the neighbour's garage wall. His first worry was that the inverter would bother the neighbours with its noise. On a business site the question is the same, only bigger.

• Point the cooling unit away from offices, bedrooms of a farmhouse and the site boundary with houses.
• Do not put a technical room with inverters against a meeting room or an open office without sound insulation.
• Ask the supplier for the sound level of the inverters and of the container cooling, at full power and at night.

Noise is rarely a reason to say no to a battery. It is a reason to choose the spot and the side of the container with care.

How far may the battery be from the inverters and the main board?

Keep the battery within a few metres of its inverters, and bridge any longer distance with the AC cable to the main board. The reason is current: at 48 V, the same power needs far more amperes than at 400 V.

Three 15 kVA inverters deliver 36 kW together. On the 48 V battery side that is about 750 A; on the 3 x 400 V side it is about 52 A per phase. Thick DC cables are expensive and hard to lay, so distance belongs on the AC side.

The Victron manual makes it concrete. For a 10 kVA Quattro on a 48 V battery, it asks for two 50 mm² cables per pole up to 5 metres. From 5 to 10 metres, it asks for two of 95 mm². Beyond 10 metres the table gives no size at all.

That is why a container usually holds the inverters too, and only an AC cable runs to the building. It is also why the spot matters for cost. On the dairy farm in Londerzeel, the semi off-grid system avoided a medium voltage cabin and the need to lay heavy cables on the property.

Can the battery grow later in the same room or container?

Yes, if you plan it on day one: leave free space, and size cables and inverters for the next step. From the start of each project we take a later extension into account, so that inverters, cables and devices are sized for the future.

Why it matters: a battery that grows piece by piece in a room that was never meant for it ends badly. One off-grid workshop owner described four battery packs of three brands side by side. Their battery management systems "fight each other constantly", and the wiring "looks like spaghetti".

• In a technical room: keep wall space for one more inverter and floor space for extra racks.
• In a container: ask how many kWh the same container can hold when full, and whether cooling is sized for that.
• Outside: reserve a second pad next to the first one, with a spare duct for cables.

Our battery systems for businesses are modular up to 1 MW. On the farm in Londerzeel, the solar panels and batteries simply grow along when the farm expands. Room to grow is cheapest when it is planned before the first cable is laid.

Which rules can rule out a spot: fire, distance and permits?

Fire and permit rules can rule out a spot before space or cost do, so check them early. From about 10 kWh environmental rules apply, and above 20 kWh fire zones and the AREI (the Belgian electrical safety code) ask for more.

Fire-rated rooms, container distances and permits are covered in our guide on whether a business battery is safe and which rules apply. Read it before you mark a spot on the site plan. In a rented building, the landlord also has a say: see our article on a battery in a rented business building.

Container or technical room: which one fits your site?

Choose the technical room when a suitable room exists; choose a container when it does not, or when the battery is too large for it. An outdoor cabinet sits in between for smaller systems.

How do we decide where your battery goes?

We start with your site and your consumption, and choose the spot together with the design. Each installation is engineered and tailored to your consumption, your production and your future plans.

1. Step 1: Analysis and sizing: we measure your actual and peak consumption, so we know how many kWh and kW the battery needs.
2. Step 2: Technical design: the spot, the cable route, cooling and room to grow, on your site plan.
3. Step 3: Installation and commissioning.
4. Step 4: Monitoring and ongoing support. Our monitoring software shows in real time what the battery does.

Room, cabinet or container: that choice is made in the design stage, before anything is installed.