Thanx for the replies so far, let me add more info. So the system received new panels and was working fine for 2 years now and then one battery started off gassing and was hot, and the others were hot or very warm as well. The small square TRiMetric device, located above one of the 2 charge controllers stopped working at the same time. So I turned off anything to do with the batteries and let everything cool off, opened windows etc.
I left the solar production on, went upstairs and found some light flickered, opened the fridge and some flickering there...I didn't think it was wise to leave on the solar at all because it looks like the problem runs deeper so it's currently off. I have a feeling that somehow the TRimetric device (even though it just monitors) is wired into the circuit somehow (maybe not completely proper) and since it died the circuit cannot function as before, but that is only a guess.
Honestly, I can perform some tests (probably) but I'm not the best with electrical. I'm not afraid to try, or to pay someone to try haha...
There's no reason it can't be figured out and brought back to working, even if one or more charge controllers needed replacing, which they probably don't.
The batteries are the lead acid kind, like car batteries but double sized, 8 of them and they are kind of old so I wouldn't mind lithium ions if possible.
