ESS Current Oscilations with Multiplus II + Shelly 3EM Pro

[vZEV]

Dear @mkgsch and @ricardocello

@mkgsch

However after big steps in energy consumption the ESS current sometimes starts to oscilate. This happened in the night with no solar power.

I’m seeing the exact same behavior with my 3EM Pro plus three MP2 3000s. Don’t have the oscillations out of nowhere though.

Configured the outbound websocket through LAN, integration in VenusOS was straightforward and simple.

@ricardocello

I would suspect that a delay is the culprit, what the the period of the oscillations in seconds?
That may tell you something.

@ricardocello

OK, can you watch the updates to the grid power on the console (as you did above) and guess at the update rate?

It seems logical to me too that the problem must be connected to this. I’m seeing new values every 5s, far from 1 or 10 Hz of course:

Supporting this thesis is also this guy which is using his utility meter (limited to 1 Hz) and got rid of the oscillation changing parameters in his D-Bus script.

@ricardocello

Do you have ESS Multiphase Regulation setup for “Total of all Phases”?

I do too for reasons of efficiency. We have net phase metering here.

When going from “external meter” to “inverter/charger” the problem is gone. Even better/faster when running off grid. But this does not work for us as one Fronius AC inverter is installed outside ESS due to 1:1 already being overstretched.

@mkgsch

I ordered a VM-3P75CT now. Hope I can squeeze it into my fusebox somehow.

Did this solve your problem? I kind of hesitate to buy every component it’s corresponding meter though as Shelly, Fronius and SolarManager are already present here (we’re running the system for a shared neighborhood battery).