A hub is sized by making three numbers agree: the ports, the total power the supply can deliver, and the queue your busiest hour creates. Ports come from the arrival pattern; power per port from the energy a stop must deliver inside its dwell; the supply is a confirmed figure from the utility, not an assumption. Where the three disagree, the smallest one is your real capacity.
Key Takeaways
- Size from the busiest evidenced hour: arrivals times session time gives the ports busy at once.
- Queue behaviour is read from your own arrival pattern and session records, never from a standard table.
- Phase the ports; build the supply works once. Corridor-class 150 kW ports sit outside EVDANCE’s compact DC range.
The Demand Side: Count the Busiest Hour You Can Evidence
Averages hide queues: a hub comfortable on a daily average can fail every Friday evening, because arrivals bunch and dwell shrinks at the same hours. Start from evidence: counted arrivals at a comparable site, the host’s peak hours, or your first-phase records. Session time is then arithmetic, not opinion: the energy each stop must deliver, divided by the power the port actually delivers. The U.S. DOT’s bands frame the choice: Level 2 at 7–19 kW suits long dwells, DC fast at 50–350 kW suits short ones.
The Sizing Worksheet
| Worksheet line | Your input | Where it comes from |
|---|---|---|
| Peak arrivals per hour | Vehicles wanting a charge in the busiest recurring hour | Site counts, host trading peaks, or first-phase records |
| Energy per session | The kWh a typical stop must add before the driver leaves | Your vehicle mix and stop purpose |
| Session time | Energy per session divided by delivered power per port | Your arithmetic; allow for taper on DC sessions |
| Ports needed | Peak arrivals multiplied by session time in hours, rounded up | Ports busy at once at the peak |
| Total power check | Ports multiplied by per-port power, set against the site supply | The utility’s written connection offer |
| Queue test | What happens at the peak with one port out of service | Your decision: more ports, more power per port, or an accepted short wait |
The total power check is the line most often skipped. Ten ports at full rating can exceed what the connection offers; then either per-port power falls or the port count does. The worksheet, not the brochure, must say which one your site picked. If supply binds, the full plan’s civil works can still be built once, with ports phased in as records justify them.
Queue Times Are Read From Your Pattern, Not a Formula
Your wait time cannot be read from a table: it depends on how sharply your arrivals bunch, how long drivers stay plugged in after charging ends, and whether a queue is visible enough to send drivers elsewhere. Queues that form at the same hours each week are sizing evidence — the worksheet inputs were too kind. Queues that form twice a year may be an accepted design choice. Once the first phase runs, platform records replace estimates with your site’s own pattern — that, not a formula, releases the next phase of ports. Choosing the site itself comes first: a hub cannot be sized out of a location problem.
The Hardware Mix, and EVDANCE’s Place in It
This worksheet sizes the site; pricing it from quotes is a separate exercise. On hardware, hubs mix classes by dwell: DC for short stops, AC for long ones. EVDANCE supplies the compact end of that mix. The EV-RHDC30K-L compact DC charger (22 kW DC, OCPP 1.6J, IP54) serves short-dwell light-duty stops at compact sites, below the 50–350 kW corridor class. The EV-AC03201T dual-connector AC station (two Type 2 connectors, up to 43 kW shared, OCPP 1.6J, RFID, IP54) covers longer dwells, two ports per unit. Be plain about the top end: a corridor hub specified around DC ports of at least 150 kW — the NEVI level for funded corridor stations — is beyond EVDANCE’s DC class. Hub plans can be discussed with our commercial charging team via contact us.
Frequently Asked Questions
How many ports should a hub open with?
The number your busiest-hour worksheet produces, with the groundworks sized for the full plan. Opening with every planned port strands capital in idle hardware; too few teaches drivers that your site queues.
Is more power per port better than more ports?
It depends which constraint binds. If sessions are long because each stop needs much energy, power per port shortens them and frees ports. If many drivers arrive at once needing little each, ports are the constraint and power buys nothing.
Does a queue at peak times mean the hub is undersized?
Only if it recurs. A queue at the same hours in your session records is evidence the inputs were optimistic. A rare queue on an exceptional day can be a deliberate, documented design tolerance.
Related Reading
- Where to Install an EV Charging Station: Site Selection Guide
- Is an EV Charging Station Business Profitable?
- How Do Commercial EV Charging Stations Work?
