Could leaving the solar panels ungrounded burn out a VICTRON 250/100 charge controller or cause it to shut down completely—twice, even without rain?
Please post detailed information about the setup here! (This isn’t Meta, which knows more about you than you know about yourself! 
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Here are the details. We have a solar installation consisting of 24 620 W panels connected to 3 VICTRON MPPT charge controllers (2 250/100 controllers and one 150/35 controller), 1 Quattro 48/15 kVA inverter and 4 BYD 5.0 kWh lithium batteries.
Twice now, one of the charge controllers has started shutting down and the display goes blank. So my question is: could not connecting the panels to earth be causing this problem?
Illustrative view of the installation
Do you have the technical specifications for the modules, as well as the string plans?
P.S. Unfortunately, it’s not very easy to read or make out much.
No, but I tell you what can…
Your per panel voc is a bit high for 5 in series… Lower temps and cloud edge effect will mean that overshoots the voltage max. An basically breaks one of the two main sizing rules.
Run your panel config through the calculator.
Yes, the series Uoc of the 5s strings is just under 240 V!
Did the failures happen in cold weather or in winter? (Worst case is in spring: the modules are cold in the morning, and irradiance can easily reach or exceed 100% to 120%!)
The panels are 24 x 620W, Gosolar brand,
connected as follows:
- 1st 250/100 charge controller: 3 strings of 3 panels in series (9 panels in total)
- 2nd 250/100 charge controller: 3 strings of 3 panels in series, making 9 panels
- The 3rd 150/35 charge controller has 6 panels across 2 strings (that is, 3 in series for each of the two strings). There has been no rain or anything like that on the connection, and only the first charge controller has already been replaced twice after it stopped working in the middle of the day and/or while charging.
Yet here you said this?
It’s been verified. The first response was an error.
You should not ground PV side cables.
On the regular Victron MPPTs the battery negative is the same as PV negative. So if so grounded the battery negative, automatically also the PV side negative will be grpunded. Additional ground connections will introduce ground loops.
On the RS line of MPPTs the PV side is isolated, including an isolation resistance check.
You can ground the frames and underconstruction. Depending on region/electrical codes its not optional.
So what would be causing the shutdown problem with these regulators?
You got three 48.5Voc panels in series on a 150V MPPT. Id say classic case of overvoltage. I suggest to use a 250V MPPT instead.
Also use the MPPT calculator, its there for a reason.
I’m saying this: it’s a 250/100 regulator that’s causing the problem, not a 150. That’s twice now. The 250 V regulator stops the charging.
Ah, i only saw that you mentioned it in the 150 listing. However, even if that one did not burn out yet, its at risk to be sooner or later.
Now to the 250, is it completely dead, not reachable via VE.direct or bluetooth anymore? Any other symptoms, like a blown fuse?
At the moment, the controller won’t turn on anymore. There’s no way to view the history, which is why we’re trying to find out what could be causing these sudden shutdowns.
Does it still receive battery voltage? Have you checked with a multimeter? Is your cerbo connected to VRM, does it perhaps show something in the advanced graphs? If you say it “shut down” does that mean ir returns to normal operation after some time or its dead for ever?
As there seems to be confusion on as installed configuration and potential design issues such as over voltage PV for given MPPT.
I would go over the design item by item, to ensure compatibility.
For instance 3x of those panels in series into victron mppt calculator give 152v @10c ( highest low temp calculator allows)which indicates clear design issue.
Permanently out of service