Mega-Ohm testing PV array

[GavinA]

removing the panels from the circuit before testing definitely sounds a lot more like my interpretation, but I'm glad that's not what you've been advising, I thought it was a bit odd. Obviously the circuit has to be isolated from the inverter.

[eabadger]

Hello again,
   Not sure how you guys install these to, with mcs, we are nic.
First off do you earth bond each panel? Or is each panel floating? I assume the latter or you would have to have lightening protection, no?
So if each panel is not earth bonded, you are testing what? From good earth to conductor or to frame of pv?
If to earth then no current will flow and no damage occur, if to the panel frame, then you need to test each isolated panel, surely?
In my job I have been doing high voltage insulation tests for many years, and have never destroyed an item, but common sense must prevail on how you do test, I suggest that testing from house earth to conductors (both disconnected and floating) will not cause issues, especially as the latest insulation testers ramp up the HV, so a fault it shown before full test voltage, also dont forget the current produced by tester is very low, i have zapped myself a few times, afetr all voltage is produced by a pp3.
I have installed 8kv 6a electric fences at high security installations, which on the decay side of the voltage spike, software monitor for tampering, these units are mega bucks, but by testing properly we never have had an issue.

The water on the panels or cables will show up faults better when on test, road loops for parking barriers and gates are buried in road surface, and to do a proper test we throw a bucket of water over road surface pre test, the cable we use is very similar to PV cable, and does fail after about 8 to 10 years, has the testing council MCS? Suggested regular retests?

steve