Riso Low??

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If anybody can help with this one..... 3kw /Aurora PowerOne (ABB) system, 8 years old. One day the error 031 appeared, common relay problem, there was also a burn mark on the board, I replaced the four relays. System then showed a Riso Low error, I left it off for several days, cursed a lot, turned it back on, suddenly it worked, for 2 days, then Riso Low error appeared again. I tried each of the two strands, alternating inputs, and determined that the riso problem was in one of the two strands. Question: is it possible that a fuse was simply blown on one of the two junction switches? Or is there definitely a problem with the panel wiring? Rooftop system with very little head room, very difficult to check the wiring without removing the panels one by one. Any ideas are appreciated!!

 

[brandonoh777]

I am getting the same type of issues low riso values with an ABB PVI 3.0 (basically the exact same inverter) i didnt have the original problem u had though just the low riso....it will eventually start up later in the day and start producing..the riso has to do with current leaking out to earth ground on the DC side

 

[Strangeman24]

Would the low Riso be indicating that there is a problem with the insulation resistance of the circuit or can it be caused some other way?
My inverter has just started to do the same. And I can’t understand what’s changed out on my roof?
An in-sites would be appreciated.

 

[brandonoh777]

I have since got this problem down to a min. i found that running the feed lines underground too close to the main grounding rod for the main breaker panel can also sometimes make this worse.... it IS current leaking to earth ground either form underground feed lines or panel frames etc.(and it doesnt take much) in my case they were older panels (used) and i was getting some current leaking out the metal frames to earth ground ESPECIALLY during wet ground conditions ..but mine is a ground mount you said yours is roof mount? are your panels new or used?

 

[Strangeman24]

Would the low Riso be indicating that there is a problem with the insulation resistance of the circuit or can it be caused some other way?
My inverter has just started to do the same. And I can’t understand what’s changed out on my roof?
An in-sites would be appreciated.

Update: got hold of a seaward pv150 tester, and it turns out that it’s the inverter that’s at fault.
New on ordered as old unit is out of warranty.