When chargers share a meter with a building, they cannot avoid demand charges on their own: the utility bills one combined peak for the whole site, and the building’s highest moment and the chargers’ load land in the same measurement. What a site can do is work on the combination — keep charging away from the building’s peak moments, and, where the shared peak keeps costing more, separate charging onto its own service.
Key Takeaways
- Behind a shared meter there is one peak: the building’s load and the chargers’ load are billed as a single total.
- The avoidable part is coincidence — charging that lands on the building’s peak interval.
- Read the interval data, then cap and schedule charging against the building’s curve before changing hardware.
- Sub-metering allocates costs internally; only a separate service gives charging its own demand measurement.
One Meter, One Peak
A demand charge prices the highest power, in kilowatts, drawn through the meter in a billing period. Behind a shared meter the utility sees one combined load curve, and the demand line is set by its worst interval.
| Load | Typical pattern | What it does to the shared peak |
|---|---|---|
| The building | Peaks in working hours: cooling, lighting, lifts, kitchens, machinery | Sets the base peak the site already pays for |
| The chargers | Whenever cars plug in — often the same working hours | Adds on top of whatever the building is drawing at that moment |
| The meter total | The sum of both, interval by interval | Its single highest interval sets the demand charge for the period |
So the first question is not how powerful the chargers are, but when they run relative to the building — the hardware and software behind such a site is covered in our overview of how commercial EV charging stations work.
The Avoidable Part Is Coincidence
Chargers only raise the demand charge when their load coincides with the building’s high moments. That gives the site two honest levers, in the order to try them:
- Read the combined pattern first. Interval data from the bill or meter shows when the peak actually happens. Guessing wastes money: if the building peaks at midday and the cars charge overnight, there may be no problem to fix.
- Cap and schedule charging against the building’s curve. Networked chargers can hold a site power cap and shift sessions into quiet hours, filling valleys instead of stacking on the peak — the idea behind smart charging and time-of-use tariffs.
None of this removes the demand charge. It removes the avoidable part — charging that needlessly lands on the building’s worst quarter-hour.
Sub-Meters and Separate Services: What Each Actually Does
Two structural options get confused, and the difference matters:
| Option | What it changes | What it does not change |
|---|---|---|
| Sub-metering the chargers | Shows the chargers’ consumption, so costs can be allocated internally | The utility bill: the site still has one meter and one combined peak |
| A separate meter or service for charging | The chargers get their own account and their own demand measurement, apart from the building’s | Their own peak: simultaneous charging sets it, and it is billed as such |
A separate service is a utility application plus electrical work, designed with a licensed electrician and priced against your tariff — worth it when the shared peak is large, regular and cannot be scheduled away. Which tariff the new service lands on, and how it measures demand, is read from the utility’s own tariff documents, not assumed.
Hardware for Shared-Meter Sites
Capping only works if the chargers can take instructions. The EVDANCE EV-AC03201T dual-connector AC station shares up to 43 kW across its two Type 2 connectors and connects over OCPP 1.6J with RFID authorisation, so a site platform can schedule and limit it against the building’s pattern. For staff and tenant car parks, the EV-ACT3204PE 22 kW wallbox provides RFID and app control per bay. More configurations are on our commercial EV charging page.
Frequently Asked Questions
Does sub-metering the chargers reduce the utility demand charge?
No. A sub-meter only allocates costs internally. The utility still bills through its one revenue meter, on the combined peak. Only changing when or how much the site draws — or separating the service — changes that bill.
Our building peaks at midday but cars charge overnight. Do the chargers add demand charges?
Probably very little. If charging never overlaps the building’s peak interval, the peak stays the building’s own. Confirm it from interval data — one busy daytime event can set the month’s peak.
Is a separate meter for the chargers always the answer?
No. It trades a shared peak for a charging-only peak, plus installation costs. It pays when the combined peak is consistently expensive and scheduling cannot move the load — judge it from your tariff and a year of interval data.
Related Reading
- How Do Commercial EV Charging Stations Work?
- Why Is DC Fast Charging So Expensive?
- Smart Charging and Time-of-Use Tariffs: How Scheduling Cuts EV Charging Costs
