TL;DR
Deye’s EV charger coupled with Deye’s inverter in ‘solar only’ mode of charging is misbehaving when the house battery is full – there are power swings / oscillations that are not normal IMHO.
Sometimes inverter even drops PV production to zero when EV charger is ramping up. The cycle repeats until the afternoon, when the inverter starts to use the battery and the power swings stabilize. Who is chasing who?
Setup and settings:
- 12,5 kWp panels
- Deye’s battery and BMS
- Deye 3 phase hybrid inverter, in “Zero export to CT” mode (set to 20W)
- Deye’s 22kW EV charger connected to inverter’s grid port
- EV charger in ‘solar only’ mode
- EV charger power limit to 8kW
Graph of power oscillations:
It looks like inverter control loop oscillation. It becomes worse when induction cooktop is running.
When charging in ‘plug-and-play’ mode, it the charging power is stable and PV power too.
If anyone knows the solution / which setting should I adjust, please let me know.
**Update 1: I had some success when I set Zero-export-to-CT to 500W and EV charger limit to 8kW. Then oscillations somehow stabilize (until I turn on other major power hungry appliance like cooktop or heatpump).
I think the inverter is quite capable to reduce the oscillations – I can observe it in the afternoon when there is not enough PV power and it starts using the house’s battery. In the afternoon it draws only the missing several hundred of watts from the battery, but the charging power is stable.
Maybe it would be good if inverter used a battery as a dumper also when there is enough PV power available.