EV load management is control logic that sets how much current each charger may draw, so the combined load of all chargers plus the building's other equipment stays within the capacity of the electrical supply. Instead of every car charging at full power and risking an overloaded main supply, chargers slow down or take turns when capacity is tight and speed up when it frees. Because most cars are parked far longer than they need to recharge, this lets a building install many more chargers than its supply could run at full power at the same time.

The capacity problem

Every building has a limit on the power it can draw, set by the consumer mains, the main switch and service protection, and ultimately the network's local transformer. A simple calculation shows how quickly chargers use it up. Ten 7 kW chargers running together draw 70 kW, which on a three-phase supply is roughly 100 A per phase, on top of lifts, lighting, pumps, ventilation and the apartments themselves.

Increasing supply capacity can be slow and expensive, sometimes requiring larger mains, a new main switchboard or network substation work. Yet the energy cars actually need is often modest. A car driven 40 km a day needs roughly 6-8 kWh, which a 7 kW charger delivers in about an hour, or a 2 kW allocation delivers over three to four hours overnight. Load management exploits that gap between connected capacity and energy needed.

Static load management

Static load management sets a fixed total current for a group of chargers at installation. The controller divides that allowance between active sessions, for example sharing 32 A per phase evenly among whichever cars are plugged in. It does not measure the rest of the building.

Because it cannot see other loads, a static limit must assume the building could be at its own maximum demand at the same moment. That makes it conservative: safe and simple, but chargers stay slow even at 2 am, when the building uses little power.

Dynamic load management

Dynamic load management measures the building's supply in real time, using current transformers or a meter at the main switchboard. Every few seconds the controller works out the available headroom:

1. Start from the supply limit for each phase.
2. Subtract the building's measured load, excluding the chargers.
3. Subtract a safety margin.
4. Share what remains among active chargers according to the priority rules.
5. Send each charger its new current limit, then repeat.

Measuring each phase separately matters, because single-phase chargers and apartment loads can leave one phase much busier than the others. Chargers also have a floor: most cannot charge below about 6 A, so when headroom is too small the controller pauses some sessions rather than running every car below the minimum. A well-designed system also has a fail-safe, so that if communication with the meter or a charger is lost, chargers drop to a safe fallback current or stop. The measurement principle is the same one a household smart meter relies on, as covered in smart meters and solar.

Priority rules: who charges first

When cars want more power than the headroom allows, the controller needs rules. Common approaches include:

• Equal sharing, dividing the available current evenly among connected cars.
• First come, first served, filling earlier arrivals before later ones.
• Minimum share first, giving every car a baseline and then distributing the rest.
• Departure-based priority, favouring cars that leave soonest with the most energy still required.
• Rotation, cycling charging slots when too many cars are connected to run them all above the minimum.
• Solar or tariff awareness, raising charging rates when on-site solar is exporting or off-peak prices apply.

A simple example: at 7 pm, measured load leaves 60 A of headroom on a phase shared by six cars, so each receives 10 A. By midnight, apartment loads have fallen and headroom rises to 120 A, so each car can take 20 A. A car set to leave at 6 am with a nearly empty battery could be allocated more than the others.

In a strata building these rules affect residents directly, so they should be documented and agreed by the owners corporation, together with how each resident's charging is metered and billed.

Why it can avoid or delay a supply upgrade

Without load management, a building's maximum demand calculation has to allow for chargers running at full power alongside everything else, which quickly points to an upgrade. With a controlled limit, the chargers cannot exceed the capacity assigned to them, so the electrical design can be based on that limit where the wiring rules and the network accept it.

This allows a building to install a cable backbone that reaches every parking bay, add chargers as residents buy EVs, and let the controller spread the available capacity as more cars join. Charging slows when many cars need energy at once, but for typical daily driving the overnight parking period usually covers the need. If demand eventually outgrows what software can share, an upgrade can be planned with real usage data rather than worst-case assumptions. Design, maximum demand calculations and installation must be carried out by licensed electricians. Coordinating charging with solar and batteries is explored in solar, EV and the smart home energy ecosystem.

Next steps

The Blue Energy Solar market lists an EV Load-Management System from $1,490 per site, an EV Charging Backbone for Every Parking Bay from $1,190 per bay, and an EV-Ready Building Study from $1,490 per building for owners corporations planning a staged rollout. Prices are indicative and confirmed after a site assessment. To discuss a building or a home, request a free assessment from Blue Energy Solar.

Frequently asked questions

Can load management reduce a building's demand charges?

Yes, if it is configured for that goal. Besides protecting the supply limit, a controller can apply a lower site import cap during the network's demand window, so EV charging does not create the half-hour that sets a demand charge. Charging then catches up after the window closes. This needs the building's tariff details and interval data, so the settings match how the bill is actually calculated.

Is load management useful in a house with a single charger?

It often is. A home charger with a current sensor on the main supply can reduce its output when the oven, air conditioning and hot water run together, keeping the total within the home's capacity. That can allow a faster charger without upgrading the consumer mains. The same sensor frequently enables solar-matched charging, so one device handles both supply protection and solar use.

Can chargers from different suppliers share one load management system?

Sometimes. Many chargers and controllers communicate using open protocols such as OCPP, which can allow mixed hardware to be managed together. In practice, features such as phase switching, fallback behaviour and billing integration vary between models, so compatibility should be confirmed at the design stage. Choosing chargers that support the building's chosen system avoids costly replacements later.