I have a Victron MultiPlus inverter/charger in a three-phase setup, and I’m trying to optimize my energy usage. My system includes a 15kW solar inverter that is AC coupled on the Victron AC out, with AC loads of around 2kW being powered. Any excess solar power is used to charge the batteries or exported to the grid. During certain times, the MultiPlus units are neither charging the batteries nor inverting (essentially in standby mode).
I’m curious about the energy consumption of the MultiPlus under these conditions:
What is the typical power draw or energy consumption of the MultiPlus when it’s just sitting idle, not actively charging or inverting, even though solar power is being produced, loads are active, and excess power is being exported to the grid in a three-phase system?
Are there any settings or configurations that can reduce this standby consumption?
Thank you, that was a provocative question!
The real question, given your answer, is how it is possible that about 500 Wh is lost each hour when the battery is fully charged and there is excess solar energy?
The interesting fact is that this happens only when energy is exported to grid.
Energy loss is computed as:
imported energy + solar energy + discharged energy - exported energy - energy used by AC loads - charged energy
For measuring solar, grid and AC loads energy VM-3P75CT metters are used.
DC energy is measured by Lynx Shunt.
This kind of question is coming back from time to time over the net.
In order to have a zero or a certain energy value feed-in the inverter has to permanently adapt its frequency AND voltage to the grid voltage.
Leaving aside the complex way of computing the above, what is to be kept in mind is that the grid voltage can vary up and down independent of our will.
This because the grid is shared between consumers and you can’t control others loads, loads that will influence the grid voltage.
This is what your inverter is facing when feed-in is enabled. A lot of adaption that could favor some loses.
As an example, consider that at some point, the MPPT and inverter could produce a certain amount of energy, but the grid voltage could suddenly increase.
This mean you should hold back on the grid injection and add to that the fact that the battery is full, that energy will be lost.
When the grid voltage increases, the solar inverter doesn’t “lose” energy. Instead, it adjusts the PWM signal to slightly increase its output voltage, maintaining normal operation without significant losses. This behavior is typical for ensuring power flow into the grid but doesn’t imply any unusual power loss mechanisms. Since I’m measuring power at the inverter output, the grid voltage change doesn’t account for unexplained power consumption or losses. It’s part of normal inverter operation and not the root of my concern.
The zero-load power consumption mentioned by @nickdb is 18W for my inverter, making it 54W for a three-phase system. However, in my setup, the power consumption is approximately ten times higher. This discrepancy cannot be explained by normal inverter operation adjustments like handling grid voltage changes or maintaining PWM signals, as these actions do not typically lead to such significant increases in power usage.
You can’t increase the output voltage indefinitively in order to keep feed into grid. Otherwise we’ll end up with voltages over 250V on the grid.
You need to define a limit over which the voltage will not increase anymore and that’s what I’ve talked about.
0W consumption doesn’t exactly apply when the system is pumping out power, as your charts show it is for most of the day (peaks above 10kWh). That is an idle consumption only.
A system under load will consume more, we know this as the efficiency curve also deteriorates as load increases and temperature climbs.
At idle fans aren’t even running, at peak they will be at full rpm (not that these are high power, just an example).
You didn’t mention which model inverter you are using.
@nickdb take a look at 13:00 – from the MP perspective, there is no load because the loads are being powered by solar. The battery is charged, so the charger isn’t working either. So why can’t we assume that MP is at zero load?
Energy pumped to the grid comes from the solar inverter, not the MPs.
No measuring device is perfect. Most of the time their precision is measured at their full range. So if youve got a 50A meter with 1% precision, thats 0.5A. It can happen that this meter is already 0.5A off when only 1A flows trough it. The precision even could be worse down low in its range.
Have you actually checked if the measured values are correct?
Right!
If the meter precision is 1%, then the error difference for 10KW would be at most about 100W. So, where is the remaining 400W coming from?
Unfortunatelly Victron hasn’t specified the accuracy of their metters
But you got several meters, inaccuracies compound. Its possible that 250W are measurement errors, another say 150W is lost in the inverters, remains 100W to be lost in cable resistance, connections, fuses, the battery (BMS itself needs a bit to run, then it might be balancing trough resistors, losses in the cells themselves)
