PV array pole grounding

[Smart $]

Someone needs to ask the PV array manufacturer for the purpose of the insulating bushings. It certainly would be less expensive to have a bolted or welded connection between the array and the poles, either of which would negate the requirement for bonding. There must be at least a perceived purpose to isolate the array and bonding the poles would remove the isolation.

If you are referring to the OP, the isolation is a result of the array tracking system. The array, as depicted in the OP picture, tracks the sun's elevation (angle of deviation from directly overhead, or as some others see it, the angle up from the south horizon in the northern hemisphere) through seasonal changes. So the array has to be able to pivot on an east-west axis.

 

[hurk27]

If lightning can flow through thousands of feet of air to reach this array, it will jump these last few inches across the bushings in this pivot mount to get to the poles if it so chooses that path.

Bonding across these pivots will accomplish nothing in the case of lightning, other then to add electrodes to the system which may or may not help.

Lightning is a very high frequency event, and does not always follow the the path that would be a low impedance path @ 60 hz. with a mean center frequency of around 10 mhz, but can go as low as 20khz to as high as 100 mhz, we can see these paths can look as an open circuit to lightning, this is one of the reasons we see some weird things that lightning may strike even when a path to earth we think is good is right next to the point of attachment, and can even be connected to it, I have had this happen, lightning struck a telephone demark, bonded to a well grounded meter can less then 6" away, but the lightning current followed the 22 awg wire around the building for 60' and jumped to a chain link fence, in another case which I used to have photos of, was a 300' tower with all kinds of grounding electrodes, was missed by less then 15' to a 15' high tree, well the tree made a good broad band antenna. trees are struck more then any other structure in the world, and that is a fact.