I was asked for investigation of problem in one installation (not made by me). 3x MultiPlus-II 48/3000/35-32 (FW v492), 1x SS MPPT 250/10, 1x SS MPPT 250/70, 2x SS MPPT 250/60, 3x Pylontech US3000C, Cerbo GX (FW v3.62).
System sometimes goes into overload and is switched off after some time in case of high energy consumption, especially when induction hob in the kitchen is operating on high power levels. I was not on-site, but have only access to VRM. Two years ago there was also indicated error 24 (switch-over system protection initiated).
Here are data during the problem - measured voltage goes down on AC-in and also AC-out side, frequency goes down only on AC-in side.
I happen to have one installation made by me next to this house, and there is no fluctuations in voltage or frequency from grid during this time, so problem is isolated to this installation.
Is it possible, that controlling of induction hob can influence Multis in this way? Or battery capacity is too low (I have experiences with 3 to 5 US3000C with no problems)? I also see that MK3 driver in Multis is not updated - could it be a problem? Or older FW in Multis or maybe old ESS assistant version could be a problem?
Of course someone must check installation physically on-site, but did anyone have the same problem?
All devices was updated to latest FW, but problem remains.
After Multis are connected to grid by internal relays, then after a while AC-in voltages and frequency together with AC-out voltages goes to low values and system go to Blocked state without any significant load on AC-out. Before Multis there is independent anti-islanding device with contactor, which also disconnect due to low voltages, which is very weird.
When Multi are bypassed (house is powered directly from grid through anti-islanding device, outputs of Multis are disconnected from the house installation), everything is functional properly and Multis can even feed-in PV energy back to grid.
Is it possible that there is some HW issue inside Multi @guystewart which produced this behavior on all phases? It is very weird, that independent anti-islanding device with its own measuring also disconnect the installation from the grid, but in case of bypassed Multis (when outputs of Multis are disconnected from installation and whole house installation is powered from grid through anti-islanding device), everything works without problem and Multis are able to feed-in PV energy to grid…
What I find strange is the input frequency drops along with input volts. This looks like a poor/missing neutral. You can test this by putting a meter between neutral and a known good earth and putting a kettle on. The meter should be close to 0V AC and stay that way with the kettle on. Equally you can put the meter N to P1, the P2, then P3, note the volts and repeat with a kettle on 1 phase. You’ll see one reading drop and the other 2 rise quite a lot.
If the system has been ok for 2 years it doesnt sound like firmware, but do check what battery health reports.
I consulted it with my colleague, who is also intended in making PV systems on Victron components, and he had very similar issue on one installation and problem was in damaged VE.Bus (RS485) interfaces on all Multis.
Is there any way to measure/check interface on all Multis?
Yes, it was probably during thunderstorm after near-lightning strike and surge was coming from DSL cable through Cerbo GX. And the behaviour was very similar like this - when disconnecting from the grid after a while Multis goes to Off or Blocked state… After repair everything works well.
so are we saying that when we see the error for self protection that this is what is causing it. i have a system that worked for months in togo africa and has this issue now with nothing changing and now wont work???
