I have 2 mppts for different arrays on an unshaded roof. One array always reduced to zero when the battery approached 100% SOC. But in the past few days this behaviour has been happening apparently randomly at lower SOCs. See below.
Same roof one above the other, no shading..
Thanks.
Are you using DVCC?
Yes
The PV voltages are quite far apart on both chargers, do they have the same amount of panels connected?
No Mac, the first array was 4 380w panels to prove that a NNW array would work..its now 5 years old and is the one causing the problem. The second is a 6 x 420w array filling up the rest if the roof.
If the MPPT’s are the same model i would try to switch them out to see if the problem is with the MPPT or the panels.
You could connect the smaller array to the 250/60 temporary to make sure it’s the MPPT and not the panels.
Ideally to make a diagnosis we need to see a screenshot from Victron connect or the device page for both MPPTs when this is happening so we can see the measured PV and battery voltages.
I will attempt to catch it as its happening, its fairly random for the moment.
Ill get some screenshots from the PC where they’re all visible together.
Thanks
Maybe I have the same problem.
Two MPPTs, one charges constantly, one drops to 0 and then starts charging again. It goes on like this all the time.
Now I’ve replaced the faulty one with an identical model, and it works fine. The replacement unit was for a flexible panel, which I don’t need at the moment. Well, two years after the warranty expired, I’ll probably buy a new one.
Screenshot for the past 7 days. You can clearly see 278 randomly zeroing whilst 277 continues to produce.
This is July before the latest problem happened
And this is demonstrating what was happening since installation? (highlighted point) at 99% SOC and above 278 zeros output.
Hope this helps you understand.
That is very useful. The large images ate not easy to read but it looks like 278 took a dip in production towards the right of the graph st 12:00 hrs.
Mostly your high rate charging occurs at night when the solar is off, so I assume that this is ac charging from the grid at cheap overnight rate.
However, when 278 stops charging at 12:00 mid day, you can see that the battery was taking in a full rate charge from the grid. If the battery is limiting charge by CCL, charge current limit through DVCC to around 120A, then when you have grid charge it has to back off something.
I do not know how your overall system is controlled, ESS, DESS but you need to look into why you had a period of grid charge during the day.
That’s easy Octopus free electricity 12 to 1400 yesterday.
ESS control
But still there’s the discrepancy between the 2 mppts, one charging fully, the other at zero.
I’m fairly sure its an impending failure of the mppt.
Sorry about the screenshots , trying to get as much information on thevscreen as possible?
But if the max charge limit is reached, the GX device has to back off some charging. Unluckily I do not know the exact protocol, does it back off the charging sequentially, one MPPT at a time or synchronous, I.e. keep them both producing.
Above, bottom picture 13th July 25. SOC is 100% all morning till past middday, 278 produces nothing whilst 277 produces normally. This is its “usual” behavior I don’t know why.
Again 24th Sept the new different behavior. 278 stops producing for no reason whilst 277 is normal. battery SOC is 70 to 80% exporting about 3kw. Theres no import.
I don’t feed into the grid and I have no AC in but some points to consider:
Thanks for your reply. Do they all switch off? My system is continuously exporting in daylight even when the batteries are at 100%. My smaller display used to only shut down when the batteries approached 100%SOC with the larger continuing to produce and export. But now it seems that whenever the batteries are charging i.e. the SOC is increasing it shuts down and will only start again when the SOC levels off or starts decreasing. This has changed since June and no one has accessed the system apart from me in the past 6 months, I haven’t changed any settings. My grid provider has no dynamic control of my system the limits were set when the system was initiated.
It seems something has changed on the grid side. Are you sure that your system still exports under certain circumstances? It sounds like your system is now not exporting but simply changing your batteries to keep them full?
Yes, in my case, all the chargers shut down when I hit 100% SOC but then, I don’t export to the grid.
