See the attached picture from VRM.
“PV inverter” is the exact amount solar power generated by the SMA Sunny Boy.
“Grid” is the exact amount of power taken/fed from/to the grid.
So, you see, CerboGX knows everything…
Then maybe it’s time to delve into the Victron OS insides, D-Bus variables and scripts and seek there some answers…
Or maybe to use a DESS (Dynamic ESS), Victron’s or similar.
Hi @moltean
I have the definitive answer from R&D
The system can see the AC PV production, however if the customer had loads on AC input they might unnecessarily import.
Lowest cost solution for the customer is to require AC PV on AC output.
It’s conceptually possible to import the PV reported by an AC input PV-inverter, but it would only work if there are no loads in front of the Multi/Quattro. If there are loads as well, you would have no indication of how much the loads are consuming, no way to estimate how much of the PV is left that can be imported by the Multi.
It also adds complication by having yet another way to regulate loads.
That is a rare setup: All loads are on the output, but PV-inverter on the input. Much easier to then also put the PV-inverter on the output.
If it must stay wired as is, then it will require using a grid meter.
I apologise and agree with you this limitation isn’t clearly documented and I will improve that.
Hi,
Where should I place the grid meter? I can buy one, this is not a problem.
thank you,
@alexpescaru posted the image above
Note that image uses the Carlo Gavazzi meter, but I would strongly recommend using the Victron Energy Meter.
Also depending on how your installation is set up, it might be possible to use the built in energy meter of the MultiPlus, it has an external CT clamp.
But why not just move the AC PV inverter to the AC output side of the MultiPlus?
But why not just move the AC PV inverter to the AC output side of the MultiPlus?
Currently, I have a 3kW Multiplus 2, and 6kW solar installation. So, I will not respect 1:1 rule.
1 Like
I just purchased a single-phase Victron meter. I’ll be back to you after installation.
Thank you so far,
1 Like
Now I have the ET1112 meter…
Is this the exact schema that I have to implement?
The ET112 meter is placed on the AC-IN side of the Multiplus?
I see a fuse there, too. What value (Voltage, Amps) should the fuse have?
1 Like
Schematic is correct, 1or 2A fuse is enough, its only for powering the grid meter
1 Like
I have installed the ET1112 meter.
The role is set to “Grid meter”.
Grid metering inside ESS is set to “External meter” (is this correct?).
Now I see new information on the dashboard (See below).
But, still, the batteries are not charged from surplus!
Edit1: Also, the reported information is not correct: AC loads seem to be equal to PV inverter.
Edit2: Attached is also my electrical implementation.
Edit3. I think that ET112 is not correctly inserted. That was my mistake … will fix it soon.
What to do now?
Now, I think that the connections are correct.
Power values also seem to be correct.
But the batteries are not charged!
You can see that all PV current is sent to the grid, and the batteries are discharging to supply the loads.
Edit 1: The grid setpoint has no effect anymore. Previously, setting it to a positive value charged the batteries.
Please suggest what to do.
After a few more minutes, out of the blue, it started to charge the batteries!
I’ll monitor more and let you know.
Ok, to confirm everything is now working as expected?
It seems to charge the battery as expected. Thank you for helping me with that.
But, now I have a different problem. See the attached image.
Because solar panels provide 6kW and my Multiplus 2 is small (3kW version), not all loads are attached to MP2 AC Out1. Instead, some loads are connected in parallel with the Multiplus.
But, to my surprise, batteries are discharged to supply power not only to loads connected to AC Out 1, but also to the loads connected in parallel.
In the attached images, “AC Loads” are parallel to the MP2. Only the “Critical loads” are the ones connected to MP2 AC Out1. Still, the batteries are discharged for both!
How is this possible?
The only way to do this is by discharging the batteries through AC IN, but I disabled the grid feed in from the ESS.
I do not want power to flow back through AC IN. How can I prevent this?
Edit1. How can I be sure that MP2 will not feed (through AC IN) the grid when the grid is shut down?
I think you have to change setting “Self-consumption from battery” to only critical loads (it’s under ESS).
- OK. This seems to work! Thank you!
- But, still, what happens if I have “All system loads” ? Will I somehow risk the grid feed-in? Power seems to flow back through AC-IN!
That is correct.
There is a chance of some power flowing back to the grid when using ESS mode.
The larger and more sudden the load change, the more likely this is to occur, but it is ‘normal’ and not usually causing any issues.
The purpose of the grid meter is to know where that line is and minimise it.
I turned off the main fuse (from grid input), and the loads installed in parallel with the MP2 were no longer supplied by the battery. Only loads connected to AC-OUT were supplied (from battery). This is great!
That would also disconnect your AC PV inverter as well remember.
Yes, it did that!
It was just a test to be sure that no power is sent to the grid when the grid is off.