I realize that these controllers are non-isolated units, but would like to know if there is a catastrophic failure of the controller, is it possible that the pv voltage would pass straight through to the battery connection.
Or has it been designed so that this cannot happen at all?
Not seen one do that to date. And some pretty serious mistakes were made on installation by a few guys locally.
For example I have seen what happens when two 550V strings are connected to a 150/70 and not checked before going live. (Nothing happened to the battery in fact no current or voltage was passed down at all.
I have also had the chance to see a few opened post mortem. Once the legs/face of the fets are off and fuses blown there is not likely anything passed down.
Stay with in the short circuit rating of the input of the mppt and you will be fine. If you check out the mppt wrrors page you will see the design is that the charge controller will sacrifice itself. Especially those from 26 onward.
Interesting, thanks for that, I only ask out of curiosity given that the new Australian Standard for off grid (AS 5139) stipulates Ground Fault Protection is required for the majority of installs that have non-isolated MPPT charge controllers.
