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rv112 avatar image
rv112 asked

Multiplus-II shut down with PV inverter

Hallo!


My setup is as follows:


MultiPlus-II with 2,4kWh Pylontech LiFePO4 battery module. AC-1 out is connected to the loads AND the PV inverter (Zeversolar). See here:


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I turned on the MultiPlus-II with the switch to I (what is II?) and the battery is getting charges fine. Also the PV inverter is charging the battery. After battery is full the MultiPlus-II shuts down and "battery low" and "overload" LED's are on. If I disconnect the PV inverter the same thing happens but without the two red LED's.

Is there anything I have to setup in software? I'm using this system pretty much out of the box and only setup the correct battery type (LiFePO4).


Thanks in advance!

Multiplus-IIVRMPylontech
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2 Answers
marekp avatar image
marekp answered ·

One position of the switch is for charging/inverting and the second just for charging only.

When you have your PV inverter on the AC-out and load is lower than the PV production, the battery is getting charged up to full and at that point ecess PV should go to the grid. But if there is no grid PV inverter have to lover it power production.

Normally MP is controlling PV inverter by frequency shift but you need to load a assistant for it.

Assuming that your Zeversolar will understand the frequency shift as a signal to lower its production.

If not, the battery will be overcharged and the system will shut down.

Battery will not get overcharged if you connect PV inverter on the AC-in side of the MultiPlus.

Assuming that you can feed the grid with your excess PV power.

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rv112 avatar image rv112 commented ·

Thanks for that. Do I need to enable frequency shift at the MultiPlus-II?

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marekp avatar image marekp rv112 commented ·

You need to install assistant for frequency shift to work.

https://www.victronenergy.com/live/assistants:pv-inverter-support

Also ESS assistant adds that functionality.

https://www.victronenergy.com/live/ess:start

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rv112 avatar image rv112 marekp commented ·
Thank you. Isn't it possible that the power from PV inverter is routed back to the grid? Right now it feeds the grid. All I want is that the MultiPlus is between the grid and the PV inverter. PV inverter first should charge the batteries and if they are full feed the the energy back to the grid over the MultiPlus.
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marekp avatar image marekp rv112 commented ·

It should feed the grid, but if grid is not there and battery is full it will overcharge the battery.

Your battery (Matthias noticed that) has different max voltage than the regular 16 cell LFP because it has only 15 cells.

If battery gets overcharged it will disconnect. (battery low error)

You have situation when grid is off battery is off so your system turns off.

Do you have 1:1 ratio between MP-II and PV inverter?


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rv112 avatar image rv112 marekp commented ·

No. My PV is 2000VA and the MultiPlus II is 3000VA. I think this should be fine.


Is there a way to setup the MultiPlus without the GX device? I'm using the MK3-USB adapter.

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marekp avatar image marekp rv112 commented ·
Yes it is fine.

Yes MP-II can be set up with MK3-USB. Without GX device you will not see what is happening with the system and you will not have VRM service to look back in time for troubleshooting.


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rv112 avatar image rv112 marekp commented ·
Thank you, Sir. Right now it is just a test system. Not much space for install. Later if everything works as expected the system will get bigger with full installation and so on...


So I have to install assistent to enable ESS and that is possible with MK3-USB? Sorry, I'm not at the location atm.

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marekp avatar image marekp rv112 commented ·
You will have to download VEconfigure3 software to perform the setup.

Some reading is required. :)

For this test setup you should select the GX version of MP-II.

Final ESS setting are done in the GX device.

Without GX device you can load "PV inverter assistant" to get that frequency shift.

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rv112 avatar image rv112 marekp commented ·

I loaded the assistant and set start to 50.2Hz and End to 51.8Hz. Disconnect is set to 52Hz. At the zeversolar I enabled frequency shift and set that:

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With that I worked fine for 1 minute if I unplug the MultiPlus from grid. The output power of PV inverter was going down from 600W to around 20W and the MultiPlus showed only "Inverter on" and "Absorption". There was no current to the batteries. After 1 minute the Zeversolar turned off with E33 error (Check the grid frequency and observe how often major fluctuations occur. If this fault is caused by frequent fluctuations, try to modify the operating parameters after informing the grid operator first)


Any idea?


EDIT:


OK I restarted the whole system again and now there is no error from Zeversolar. Everything seems to work fine:


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EDIT 2:

After running fine without grid I replugged the grid connection. After couple of seconds the MultiPlus turned off with "Battery low" and "Overload" LED turned on. Waited for it to restart, after that everything was fine and the PV inverter feeded the grid again.

What could be the issue here? I think it's MultiPlus related and not from PV inverter.

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marekp avatar image marekp rv112 commented ·
Did you set the proper voltages for Bulk, Absorption and Float required by your battery? Standard lithium setting are not correct for you battery.

What was the load at that time?

Your PV inverter reacted properly if there was no load and battery was fully loaded (no current to the battery).

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rv112 avatar image rv112 marekp commented ·

Yes. I set the absorption to 52V, float 51V and absorption time to 1 hour for my Pylontech batteries.

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marekp avatar image marekp rv112 commented ·
Ok, thanks to that your battery did not shut itself off.

Was there a load on the AC-out?


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marekp avatar image marekp rv112 commented ·
Ad Edit2.

It is hard to say without GX device.


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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

I think you have much to read now:
https://www.victronenergy.com/live/ess:start

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom

With the default charging parameters you can kill your batteries.
Default is 57.6V but maximum for Pylontech is 52V.

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rv112 avatar image rv112 commented ·

Hallo Matthias, danke. Ich habe aus diesem Grund den Batterietyp auf LiFePO4 angepasst, in der Hoffnung die korrekten Ladeparameter zu erhalten.

Ich habe zudem das CAN auf VE.Bus Kabel, welches mitgeliefert wurde verbunden. An der Batterie am A/CAN und am MultiPlus-II am VE.Bus Port.

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