IsolationFault

[Harry Pay]

Hi can anyone help please. I have installed a 1.75 kW system with a Solar river 1600 TL inverter. It worked fine until a recent SSE cable failure in road. Since then I get an isolation fault on inverter. I have tested each panel which give ICS and voltage as you would expect and carried out Insulation resistance tests on panels which proved ok. Solar River have replaced the inverter but I still get Isolation fault on new inverter. Is there anywhere on AC side that could cause this fault
Happy days Bob

 

[SolarCity]

Do you mean insulation fault?

 

[SibertSolar]

Are there varistors (MOV's) on the AC output of those units? Unlikely to have gone short-circuit but sometimes the software within the inverter will flag up a blown MOV by calling it something else within the GUI. Long shot but.....

 

[Harry Pay]

Hi Thanks for reply, it is Isolation fault though, which assumes a ground fault
Happy days Bob

 

[SolarCity]

What on Earth is an isolation fault?

 

[Harry Pay]

Hi and many thanks for reply. I have now tested the inverter on my own working system and it works fine. This suggests a panel(s) fault, but each panel tested individually appears to work as it should re voltage and ISC. I wondered if there could be anything on AC side causing problem as originally the RCBO had tripped
Happy days Bob

 

[Harry Pay]

Isolation fault according to inverter manual is a panel ground fault

 

[Worcester]

Sometimes it's one of the MC4 connectors... At the Inverter have you measured the voltage between +ve and Ground and -ve and Ground and between the string +ve and -ve (all whilst isolated from the inverter) Based on what the string vaoltage should be that will tell you if and where the fault is (voltage division prinicple) - Remember to use the proper tools for the job (Potentially up to 600V or 16A... depending upon panels and string config)

 

[Harry Pay]

Sometimes it's one of the MC4 connectors... At the Inverter have you measured the voltage between +ve and Ground and -ve and Ground and between the string +ve and -ve (all whilst isolated from the inverter) Based on what the string vaoltage should be that will tell you if and where the fault is (voltage division prinicple) - Remember to use the proper tools for the job (Potentially up to 600V or 16A... depending upon panels and string config)

Hi Worcester, thanks yes I have carried out voltage test and a resistance test which all appear fine. Krannich tell me that Luxfor panels are not the problem and it is either too much voltage for the Solar River 1600TL or a RCBO fault. The voltage tests on between strings gave 390V which is below max of 450V for inverter, so I am back to suare 1
Happy days Bob

 

[Gavin A]

download an SMA manual, then follow the guidance for fault checking on this fault in there as it's pretty good guidance - check the varistors (check continuity on them), and the circuit involved for connection to earth.

I had this once on a job where we'd used metal capping and nicked the cable with the capping pin.