MP2 0,5 kW from grid during night despite GridSetPoint -150W

Hi folks, having setup of three MP2 5000VA on-grid system plus BYD LVL 31kWh battery, with AC-coupled SolarEdge invertors.

My issue is that despite I set GridSetPoint to -150W (which I would expect to cause “slight” discharge to the grid, etc) and despite the vrm shows -150W to grid sometimes, at other times there are “plus” oscilations (although the night consumption is rather stable around 500Wh).

Therefor, when seeying it at the morning (like today), I have a balance between 0 and 6 hours “from Grid 0,5kWh” and “to Grid 0,2kWh” (when I would expect “from Grid very low” and "to Grid 0,8kWh or so).

So I am still consuming a bit of grid power (for which I have to pay, obviously). During the day, as long as the AC-coupled PV produces more than 500W, I usualy have nothing from Grid.

So what is the issue? How come a gridsetpoint of -150W results in so high grid consumption?

FAQ 10.6

How is your multiphase regulation set up?

1 Like

I have three-phase with Individual phase regulation (this is necessary as we have an individual phase metering in our oligarchic country)

What kind of grid meter do you use? Are your main loads connected to ACIN or ACOut of the multi?

Because consumption on ACIN can only be accounted for when the grid meter starts to measure and report actual grid2load happening and the inverter can start to react to that.

However that always give some split seconds of energy beeing pulled from grid.

Using ET340 as my meter.
My setup is that everything is hooked at ACOUT1 (including my AC-coupled SolarEdge invertors). So I got no loads at ACIN, there is just GRID->ET340->3xMP2 there.
I understand “some” energy would be pulled from grid nevertheless, but the house is fairly stable thoroughout the night, taking around 400-600Wh, with oscilations up to 800Wh (but no more as water heater is now used thoroughout the day only). So getting oscillations (as to be able to se 400 from grid at vrm at some moments) and to get 0,5kW in the morning is rather frustrating. Also, with GridSetPoint of -150W one would expect “to Grid” in the morning much higher than these 0,2kW.
As said, in this time of the year I have thoroughout the day electricity in spades (and big battery). So I am willing to lose some in the grid, but I really dont know why I should by buying any!

You should generate advanced graphs of all 3 ACIN Values and see if it’s a particular phase that is not balancing well, or if it appears on all phases.

Optionaly - since you have no loads on acin - you could give it a try with switching from “external meter” to meateringmethod “multiplus” and observe for a day or two if that makes a difference.

(Or verify you actually set that to “external meter” at all)

Thanks - yep, I have external meter set on. Do you think I can switch to “multiplus” without any issues, just to try it?
My graphs look like this - and yep, I have GridSetPoint at -150W, which definitely does not look so when looking at the graph:

Yes, you can switch to multiplus-metering anytime. It then will just ignore the external meter for that time.

Is this graph now the values reported by the multiplus for ACIN, or the values reported by the meter?

Maybe you wanna create a graph showing both (:= All 6) values, eventually there is difference visible?

Something like

It seems meters of VE.bus and grid meter are in accordance. This is with the GridSetPoint of -60W, still this is the result - taking around 0.4 to 0.6 kWh thoroughout the night from the grid!

I have step-by-step tried getting the GridSetPoint as low as -250W. However, the only difference with GSP of -250W was that I still took around 0.8 to 1 kWh thoroughout the night but sent also another 1kWh to the grid… So meaningless for me this way!
This seems to be the diagram when GSP was set to -250W.

Whereas this is the “best” result ever - from 0:00 to 6:00 I got from the grid mere 0.1 kWh which is reflected on the graph. But dont know why - GSP was -60W, consumption in the home fairly low (but different days with same consumption end with 0.4kWh from the grid!

I missed the Obvious:

The ET340 is a non-saldating meter. That means, if you have two phases for 10 hours sitting at -200 and 200 Watts, the result of the ET340 will be to log 2kWh taken from grid and 2 kWh beeing send to grid.

If you want this to be considered as “0 Grid” in either way, you need a saldating Grid Meter, the EM540 works quite nice.

You could switch the systems Multi-Phase-Balancing to individual mode temporary, so the MPs try to keep every phase at 0 individual, accounting for having a non-saldating meter.

This however has efficiency drawbacks and limits your available output power before energy is taken from grid to what a single multi can provide on that phase. (It’s kind of running 3 Single-phase systems then, counting-wise)

Thanks, however I need a “non-saldating meter”. We in Czech have a “each phase individual billing” which means that even if you at the same time send energy into one phase and get energy from another phase, it is not offseted, but you need to pay for the one you get - yep, welcome to this idiotic corrupt country - its because or policymakers really want our energy companies to make business any time! We are the only country with this in the world, I am afraid!
Therefor, I need each phase to have ideally 0 on taking on any phase, not just in total.
I believe I have individual mode set on - as I see here. Still I get these amounts of energy from grid every night: