I am currently testing a 3-phase system with three Victron MultiPlus-II 48/10000/140-100 units connected to an external AC source.
System setup:
3 × MultiPlus-II 48/10000/140-100 (configured as a 3-phase system)
Controlled via Cerbo GX
External supply: 3-phase CEE 32 A
Cable length from distribution to system: approx. 30 m (5 × 6 mm²)
AC Input Current Limit set to about 33–35 A
Power of every MultiPlus set to about +7500 W
Goal:
I would like to reach roughly 22 kW total AC input power (≈7.5 kW per phase).
During testing I measured the following values at high load:
MultiPlus 1
U = 221.46 V
I = 30.38 A
P ≈ 6.70 kW
MultiPlus 2
U = 222.13 V
I = 31.17 A
P ≈ 6.88 kW
MultiPlus 3
U = 223.61 V
I = 29.33 A
P ≈ 6.52 kW
This results in roughly 20–21.5 kW total power.
At low load the voltage is around 228 V, but under high load it drops to around 222–223 V, which I assume is mainly due to the 30 m cable.
However, even when increasing the AC Input Current Limit on the Cerbo GX, the current per inverter seems to stay around 30–31 A and never approaches the configured limit.
I also verified that battery charge current is not limiting, since during the test a large AC load was connected and the batteries were not being charged significantly.
My question:
Is there an internal limitation in the MultiPlus-II 48/10000 that effectively limits AC input current to around 30–32 A per unit, or is the behavior simply caused by voltage drop and normal control margin?
Or are there additional settings that might limit the AC input power in this scenario?
The battery should not be the limiting factor in this case. I am using 5×6 Pylontech US5000 modules, so there is more than enough battery capacity and charge capability available.
During the test I also had several large AC loads connected, so the power coming from the grid was not mainly used for charging the batteries, but was largely consumed directly by the AC loads.
Because of this, the 140 A charger limit of the MultiPlus should not be the bottleneck in this scenario.
Unfortunately I cannot change the cable cross section in this installation. With the relatively long cable (about 30 m, 5×6 mm²) and currents around 30 A per phase, a voltage drop is expected, which then also reduces the achievable power. So seeing around 222–223 V under load makes sense.
Regarding my statement “AC Input Current Limit set to about 33–35 A”: what I meant is that the AC input current limit configured on the Cerbo GX was set higher than 32 A, sometimes even up to 37 A during testing.
However, even with this higher limit configured, the current per phase never exceeds roughly 30–32 A. That is why I was wondering if there might be an internal limitation per MultiPlus unit or if this behaviour is simply the result of voltage drop and normal control margins.
Hi Hendrik, thanks for your explanation, and I really like it!!
About grid code, my opinion YES, it can help you to achieve your goal.
From my experience (not from documentation!) Victron hardware and firmware works with AC input through grid codes algorithm in very standard way, which is:
If AC voltage drops to undervoltage value, Victron trying to reduce AC power just to keep this voltage value.
If this value is 218 for example, Victron will try to keep it in 217-219V by reducing amperage from AC input.
