How do find solar string frog round fault using multimeter?

[ppreceipt]

I have a 2010 sunny boy 5000 with ground fault error and blown fuse. This is the only article I have found but I don’t understand exactly what they are saying. Can anyone tell me how to do step 3???? Better explained?

https://manuals.sma.de/SBx1SPUS40/en-US/391466379.html

set up is very simple 14 panels in series going to combo box and then to sma 5000us inverter. Only have one more day to try and fix this. Speedy replies very much appreciated!!

[solarix]

Disconnect the strings one by one and see if the ground fault goes away. Then reconnect the string in question and measure each end to ground. If the ground fault is somewhere on the string, then the end voltages will be proportional. For example if one end of the string measures -100volts and the other end measures +200 volts to ground, then the fault is 1/3 of the way around the string.
However, my experience with the older Sunnyboy inverters is they fail short internally and its the inverter itself that is causing the ground fault. Measure the string voltage when the DC disconnect is off, and if it goes to zero when turned on - then the inverter is shorted. Hope you get in under the 10 year warranty.

[J.P.M.]

Disconnect the strings one by one and see if the ground fault goes away. Then reconnect the string in question and measure each end to ground. If the ground fault is somewhere on the string, then the end voltages will be proportional. For example if one end of the string measures -100volts and the other end measures +200 volts to ground, then the fault is 1/3 of the way around the string.
However, my experience with the older Sunnyboy inverters is they fail short internally and its the inverter itself that is causing the ground fault. Measure the string voltage when the DC disconnect is off, and if it goes to zero when turned on - then the inverter is shorted. Hope you get in under the 10 year warranty.

If the problem is the inverter and it needs replacement, and the panels are the older Sunpowers that are positively grounded, good luck on finding a replacement inverter and more luck getting any help from Sunpower.