question

@mallkuss

The Phoenix has no way of connecting to Grid, so it is best to use a Multiplus.

I was unable to view the plans for your system.

You can set the multiplus internal charger off completely so it does not charge at all from grid but does have the capability of switching the loads to grid at a lower SOC as set in the ESS menu.

@Alexandra : I was planning to go with this unit:

https://greenakku.de/Wechselrichter/Offgridwechselrichter/Victron-Phoenix-Wechselrichter/Phoenix-Wechselrichter-48-5000-230V-VE-Bus::824.html

48V / 5000VA

But taking your reply into account I think a Multiplus als would do the job.

And I do have an additional charge just in case I need it.

That results in the following setup:

https://abload.de/img/plan-xaver-issue2ibkph.jpg

@Alexandra: I couldn't find approval in the documentation what happens is the battery is depleted and grid is availible. What you say makes perfect sense, but how can I be sure?

Thanks for your replies so far :)

short update: in the mean while my equipment was delivered and installed.

Basic functionality is given: currently the system has no connection to mains, so just the power delivered by the solar modules is availible. I'm currently on a business trip, and as soon as I return I will try to get it running with switchover to mains if the battery is empty.

Thanks so far for your help!

any update mallkuss about your system?

Thanks @Nicola for asking :-)
The system now is running for almost a year now, and in general I'm very happy. The Switch-over to mains is working fine, I can adjust the voltage / battery SoC where it happens. Also charging my car during night runs smooth. So I can recommend the setup linked above for a similar job.

But I have a problem that - I think - has become worse in the last few months, this is obviously why I'm here again.

Short system summary: three MPPTs connect to 8 Pylontech Batteries and to a Multiplus 48V/5000W unit, controlled and monitored by a Cerbro Unit. Mode set to DVCC with 125A charge limit and 52.5V EoC Voltage.

The Problem:

If no AC load is active all the sun power goes directly to the battery pack. That's OK.

If I start charging during full sun, the power splits between car and battery as expected.

BUT: sooner or later the system switches off one or even two mppts, and charges the car partly from the battery during full sunlight. That looks like this:

[url=https://abload.de/image.php?img=screenshot_20230311-1nqfkq.png][img]https://abload.de/img/screenshot_20230311-1nqfkq.png[/img][/url]

You can see one mppt is cloase to V_oc, two are running on full throttle.

If I stop charging the car the mppts are re-enabled again, and dropped a few minutes later.

I did so far:

- update Cerbro FW to 2.93

- disconnect the data link between Cerbro and Multiplus as charging seems to have an impact on the situation.

- added some additional cooling to the MPPTs as they are running close to their maximum ouput current (wasn't expecting the solar panles to provide that much power).

Everything looks nominal, the MPPTs have no error, the battery modukes allow charging,...

I have access to the logfiles via ssh, but they were filled with IPV6 error message, that should be fixed now. the next time it happens I should have a logfile...

Does anyone have an idea what is wrong here, or where I can start searching in the logfiles?

Update: went close to the MPPTs, two of them with BT (Smart solar 150/45) and one without (blue solar 150/35).

The two featuring BT did several updates, so let's wait and see if that already fixed it. Updates for the MPPT 150/35 and the Multiplus can be seen in the VRM portal. Will do that and report back here...

Hi Mallkuss, thanks for the answer: considering your reports, I did a test with almost half max load and I was surprised to see the same behavior: even if P load < P panels, the system put in discharge batteries for a few watts.

All my items are updates to the last firmware:

take a look: