I recently bought a EmonEVSE WiFi Connected EV Charging Station IEC 60947-5 (Type-2) from OpenenergyMonitor shop. It’s worth to mention that I bought the 3-Phase, 22 kW version.
I already have home automation and a PV system and I quickly set up a MQTT topic
homie/inverter-848451/power/available-for-ev-charging I entered the name of the topic in the web GUI --> Services Tab tab --> --> MQTT, Grid (+I/-E) topic: configuration. The payload is an integer showing in watts how much the EV Charger may use. (Negative values means that I have excessive power that I can use for charging my EV) Typically when the PV generates power I have about 14 Kw (-14000) on export.
However using that value caused my EV Charger to rapidly alter between loading 32A and 6A back and forth … Something was obviously wrong. I figured out that I’d need to divide the excess energy by 3 and now my EV Charger is modulating the charging power by available excess power.
I can’t say why it works like that. I have no idea but I thought I’d better share it here in case someone else has the same problem.