Hello guys and possibly ladies, I have a question regarding one of the ESS Victron systems that I recently installed. It is a three phase system with Multiplus-II 48V/5000VA AC coupled on the output with 15kW Fronius Symo. The battery is 16S2P LiFePo4 280Ah (approx 28 kWh) monitored by SmartShunt (and ofcourse by an external bms, but thats not the point). Since it is not yet allowed by the distributor to connect this system to the grid, I choose to run it offgrid for now and Im observing weird behavior of AC output power and DC power values. I attach screenshots from the Remote Console to properly describe it. Both cases are with fronius disconnected to present that the behavior doesnt depent on it. One case is with small ac load and one is with a bit larger ac load.
So, the point is, that the value of DC power is constantly nonzero, and negative around 150-250 W although there are no DC loads present. I know that this value is calculated and not measured directly and I know it can vary and it hardly ever is zero, but in correctly working system this value fluctuates around zero from my experience. I think that the reasonable assumption is that the power value measured by SmartShunt is just correct. That means that the ac output power is not correct and neither is DC power value, but if we sum up those values, the result seems to be correct. Sometimes it even gets to the point where smartshunt shows smaller power value than is the AC output load which is obviously wrong because there is some efficiency loss and the self consumption power, but again, if we subtract the DC power shown by the system, it matches...
If I connect the system to the grid, The DC Power value drops to the expected range of values around zero and the ac output load decreases by those 150-200W and everything works perfectly fine.
Im running newest fw on Cerbo as well as on MP-II.
Does anyone have any suggestions what might be causing this and possibly how to solve it?
Thank you!
