My system is an ESS with Cerbo GX, Solar MPPT 450/100, MultiPlus II 48/5000 (internal power measurements) and 2x Pylontech US300C, connected to grid, feed in excess DC PV only, with a limit of 3700 Watts (230V 16 amps). Grid code is Germany (for Switzerland).
I have following wierd bug happening, reproducible:
Starting situation: Battery almost full at 98%, BMS current limit 14 Amps, only one 3400 Watts load on AC out 1 (electric car charger), solar producing 3300-3600 Watts (around 60-65 amps at 52 volts), battery is balancing the remaining or excess part, within BMS current limit.
When the car is charged at 80%, it suddenly interrupts the load.
Then the bug happens:
1. The full current amperage of the Smart Solar MPPT 450/100 drops only slightly to 60 amps, but
2. The MultiPlus II does not feed-in the excess to the grid, but stays at the grid setpoint for a long time, overloading the battery massively with 60 amps while BMS authorizes only 14 Amps with 98% SOC.
It stays so for minutes, before picking up grid feed-in.
This can lead to shortened battery life and could void the Pylontech warranty for those 2 batteries!
I have seen a similar situation when switching on the system: There is a large delay between MPPT 450/100 increasing its amperage and the MultiPlus II feeding-in the excess to the grid. Both are remotely controlled by the Cerbo GX, so not sure if bug is in Venus GX or in MultiPlus.
Interestingly, when I quickly go edit the grid setpoint, the feed-in reacts instantly, within seconds, but the excess PV DC feed-in does not until sometimes a minute of few mintues later. I'm even surprised the Pylontechs don't safety-switch off!
There are no coms errors on the CAN busses for BMS.Can and VE.Can, nothing in the error logs either.
The Cerbo GX firmware and MPPT RS too, the VE.Bus firmware in the MP II is also up-to-date (except for the very latest release of August 1st). Solar MPPT 450/100 has a date-code 2222, from within the range with the extended warranty, but I doubt it is related to that.
This seems to me like a big issue, probably to be taken seriously, I can give VRM access to Victron, please just PM the request.
I searched through the forum but didn't find a similar issue. Thanks in advance for any insight. :-)