I am currently testing a 2-phase Multi RS system. While I understand that a 2-phase setup is not officially supported, the system is performing quite well overall, with one notable issue regarding grid setpoints.
System Configuration:
2x Multi RS (FW v1.29) — one connected to L1, one to L3
The Issue: I use MQTT to update the general AcPowerSetpoint of my system every 45 seconds (topic: venus-home/W/.../acsystem/0/Ess/AcPowerSetpoint). This works perfectly with a single Multi RS, but the 2-phase setup exhibits unexpected behavior:
Example 1: Setpoint at 0W (with a 2000W load) The system successfully matches the 0W grid setpoint. However, instead of an expected even distribution (1000W per Multi), the two units output the 2000W completely randomly (e.g., Multi 1 provides 1800W, Multi 2 provides 200W). Furthermore, this distribution does not correlate with the load on the corresponding phase. For instance, a 2000W load on L3 might be entirely covered by Multi 1 on L1, rather than by Multi 2 on L3.
Example 2: Setpoint at -2000W (Feed-in) The system fails to match the -2000W setpoint and only feeds in 1000W. It appears that whenever the setpoint is non-zero, the system only attempts to match exactly half of the requested AcPowerSetpoint.
Observations: Monitoring the ESS MQTT topics reveals that the system is correctly allocating half of the general AcPowerSetpoint to each individual Multi (see attached screenshot). However, the device-specific setpoints (e.g., venus-home/N/.../multi/0/Ess/AcPowerSetpoint) do not seem to be processed correctly by the inverters themselves.
Question: Does someone know how the AcPowerSetpoint handling works in a 3-phase system? I am trying to understand if this issue is related to my 2-phase configuration or a broader logic issue with the device-specific setpoint processing.
My grid connection doesn’t support more than 30 kVA and because of a running contract with 100% feed-in for one of my systems, I can’t switch to a 3-phase system before 2029.
So they are on a three phase connection but configured as stand alone units?
Try setting the can instance of one of them on the gx to a different number i.e. 0 and 1. I read the other day a different thread where this worked for a slightly different issue but possibly has the same addrssing issue.
That didn’t work. Changing the instance of the second Multi to 1 switched it to Float mode and caused a “No BMS” error in the Grid settings section of this device in Victron Connect.
