EMS questions and answers: design and operation
Article contents
Starting with one charger or designing an entire site? These answers help identify what to measure and which behaviour to configure.
Do I need a meter on every circuit?
No. A circuit serving only controlled chargers can use a shared fixed or dynamic budget. Where vehicles share a supply with other equipment, EMS needs total measurement, or the BMS must calculate and supply the remaining EV-only budget. See dynamic power management.
Can I use an existing building meter?
Yes, if it provides the required data through an agreed integration. A kW limit needs active power with energy direction; an A limit needs current per phase. MQTT support alone does not guarantee the correct format. Suitable Shelly and SmartMeter configurations are listed in the technical guide.
What if a measured point has several supplies?
Measurements can be summed when they cover the intended total without counting the same consumption twice. Phases must be mapped correctly. Independent supplies retain their own current limits even if their power is assessed together.
How is SmartMeter connected?
The TECO C-EM-0300M measurement module connects over CIB to SmartSystem, which sends data to the cloud. Sensors and auxiliary power depend on the specific configuration. CIB is not Ethernet. A qualified person installs it according to the SmartMeter documentation.
The reading shows negative power or incorrect consumption
Negative active power can represent export to the grid. Incorrect values may also result from sensor orientation, phase assignment or a conversion setting. A technician should compare the quantities and wiring with actual energy flow; readings should not simply be converted to absolute values.
Contracted capacity is at MV but metering is at LV
The design must define how the measurement relates to contractual and technical limits, including transformation and losses. A kW limit in EMS is ongoing power regulation, not a separate optimiser for 15-minute demand peaks.
Why has EMS paused charging?
There may be insufficient power for a functional minimum, a scheduled pause, Surplus only mode, a zero budget or fallback behaviour due to missing metering. An AC vehicle receives zero or at least 6 A. Priorities and rotation govern allocation when capacity is limited.
Solar is generating, but ECO is not charging
Surplus after building consumption and the selected mode determine charging. Surplus only may wait for the vehicle minimum. ECO with minimum can supplement that minimum from the grid if capacity allows. An increase above the minimum needs surplus covering the entire ECO load. See the ECO mode comparison.
The vehicle does not resume after a pause
Distinguish the permitted limit, command acceptance and actual consumption. Resuming also depends on the vehicle and station. The specific combination and its current state must be checked; an API acknowledgement alone is insufficient.
Must every vehicle swap after half an hour?
No. At each full and half hour in local time, the order within a priority is reconsidered using energy delivered and waiting time. It is not a mandatory swap of all vehicles or half an hour from arrival.
What happens if the BMS stops renewing its budget?
After 10 minutes without valid renewal, the stored manual fallback applies. Zero also expires: a positive fallback may resume charging. A fresh valid BMS budget automatically takes precedence. See BMS integration.
What happens if connectivity is lost?
If required measurement is missing while the station connection works, the configured fallback limit applies, with pausing as the default. A cloud or station-connection outage prevents guaranteed delivery of a new command; the last accepted profile may remain. Fresh inputs are required after recovery.
Where to go next
Cloud EMS technical guide · Product guide (PDF, Slovak) · Technical guide (PDF, Slovak).