Additional electrodes for Array grounding 690.47(D)

[KDK]

We are working on a project that consists of three inverters with two combiner boxes each on a roof top. (2008 NEC)

According to what I've been reading we need to install an additional grounding electrode which our intent is to use the structure of the building.

My question is do we need to connect from each string, combiner box or at each inverter? Does tihis need to be a continuous conductor for the whole array?

 

[jbelectric777]

The rod is only good for 25 ohms, are you refering to the DC side ground rod? I dont have a book in front of me but Im almost positive one rod can be continous through each disconnect. If multiple rods are needed they have to be six feet apart. Don know if this helps but good luck, Im goin on memory here. Also when you say your using the house thats a bond not a ground unless the structure meets certain criteria which a house doesnt, thats more for buildings with structural steel buried in earth. And I also thing there are some exceptions in the book where the same rod can be used for both AC and DC but read all of PV systems first, I been laid off for more than a year, good luck. !!!