Load balancing shares a site's available electrical capacity across multiple EV chargers so sockets can be added without assuming every bay draws full power at once. In UK workplaces, residential blocks and retail parks it is often the difference between a viable phase-one install and a stalled grid upgrade. Specifying static diversity on paper is not the same as dynamic control with monitoring and fail-safe behaviour. Ask installers to document the maximum site budget in amps, per-charger ceilings, and what happens if the controller fails. Grants do not replace a proper capacity design; check any OZEV support separately on GOV.UK.
Why simultaneous full power is a fiction
Cars arrive with different states of charge, some finish early, and building loads vary through the day. Designing as if every socket is at maximum forever forces unnecessary reinforcement.
Dynamic systems measure and throttle in real time within a safe envelope set by the electrician and, where relevant, the DNO.
What to put in the specification
Require a stated site capacity budget, metering points, controller redundancy expectations, and user-facing behaviour when power is scarce. Prefer open protocols where they help future hardware swaps.
Demand a commissioning test that proves throttling under simulated load, not only a screenshot of an app.
- Maximum import limit and how it is measured
- Minimum power per active session, if any
- Alarm path when communications fail
Fairness between users
Algorithms can prioritise first-plugged, equal share, tariff windows or fleet VINs. Publish the rule so staff or residents understand why their session slowed at 18:00.
Accessible or operationally critical vehicles may need priority flags.
When load balancing is not enough
If utilisation stays high and sessions routinely crawl, you still need more capacity, more bays elsewhere, or DC for short dwell fleets. Load management buys time and efficiency; it is not magic.
Keep DNO application packs ready so phase two is not improvisation.
Commercial documentation
Record the load-management strategy in O&M manuals and service contracts. When a vendor changes, the amp budget and safety envelope must survive the handover.
Insurers and facilities managers should know how to isolate the charger group safely.
Frequently asked questions
Is load balancing the same as a smart charger?
Smart features can include scheduling and cloud apps. Site load balancing specifically coordinates multiple chargers against a shared supply limit.
Can we add balancing later?
Sometimes, if hardware and cabling were chosen for it. Retrofits are harder when each bay was installed as an island.
Will drivers notice throttling?
They may see lower kW on the screen. Good signage and apps that show shared capacity reduce complaints.
Does the DNO need to know?
Notification or application duties still follow ENA processes for the installed load. Explain diversity assumptions clearly in submissions.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local EV Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.