New Ground Rod for Solar Array?

[NEOH]

We checked with local inspector and he stated that we must have add new Ground Rod at the base of the Solar Panel Ground Mount.
I have attached our new 1-wire diagram for our first Solar Project - 2500 Watts, 12 Panels, Ground Mounted.
This new Ground Rod has us confused about the "DC GEC" connection.

The Green dotted line (in the wire diagram) is the 10 AWG Green THWN (EGC) conductor ...
"a" - It starts at the Ground Bar inside the 200 Amp Main Service Panel and connects to the Ground Bar inside the "Outside AC Disconnect Switch".
"b" - Starts at the Ground Bar inside the AC Disconnect Switch and connects to the "AC EGC" Terminal inside the Inverter.
This Equipment Ground Conductor (EGC) is not continuous.

One of the Orange dotted lines (in the wire diagram) is the 6 AWG Bare (GEC) conductor ...
"c" - It starts at the "DC GEC" Terminal inside the Inverter and connects to the Ground Bar inside the DC Disconnect at the Array
"e" - The same wire (continuous) exits the DC Disconnect and is irreversibly bonded to the new underground 6 AWG.
This Grounding Electrode Conductor (GEC) is continuous.

Then we considered this at Wiring Location "e" ...
* Irreversibly Bond the 6 AWG from the Solar Panels to the new underground 6 AWG, too.
* Irreversibly Bond the 6 AWG from the Frame / Rack to the new underground 6 AWG, too.

And we need to dig a trench to lay in the underground ground-to-ground 6 AWG bond wire.

Does this "2nd Ground Rod" design comply with NEC ?

 

[pv_n00b]

I assume this is to comply with 690.47(D) in the 2014 NEC?

I think you are confusing the DC EGC with the DC GEC. The DC EGC connects together all the exposed metal parts of the equipment on the DC side. The DC GEC connects the DC system bonding point, the GFDI in a grounded inverter, to the premises grounding electrode system. Most of what you have marked as DC GEC I would say is DC EGC.

The 690.47(D) grounding electrode is an auxiliary grounding electrode and those do not have to be connected to the premises grounding electrode system, but it does not hurt to do it. It is connected to the DC EGC system.

NEC 690.47(C)(3) allows the AC EGC and DC GEC to be combined and that is what most people do in these smaller systems.

 

[NEOH]

We were told by the Inspector that the New Ground Rod must be installed and must be bonded to the existing Well Casing.
This is now the Red dotted line in the new Wire Diagram #3 (6 AWG Solid)

The Inverter has two terminal strips with labels as follows ...

AC Terminal Strip
============
Line 1
Line 2
AC Ground

DC Terminal Strip
============
POS (+)
NEG (-)
DC Grounding Electrode Conductor from PV

I have attached Revision #3 of my wire diagram, which is now very similar to what we had before the new Ground Rod was added.

Here is my description ...

The Combined AC/DC Grounding Electrode Conductor (GEC) is the Orange dotted line in the new diagram (6 AWG Bare) ...
Wire Set "a" - Starting at the Ground Bar inside the 200 Amp Main Service Panel and continuously passing through Ground Clamp of the "AC Disconnect".
Wire Set "b" - Continues from the Ground Clamp of the "AC Disconnect" and terminates at the "DC GEC" Terminal inside the Inverter.
This combined AC/DC Grounding Electrode Conductor (GEC) is continuous.
Also, connect a 10 AWG Green wire from the "AC EGC" Terminal to the "DC GEC" Terminal, inside the Inverter.


The DC Equipment Grounding Conductor (DC EGC) are the BROWN dotted lines in the new wire diagram (6 AWG Bare)
Wire Set "c" - Starts at the "DC GEC" Terminal inside the Inverter and terminates at the Ground Bar of the "DC Disconnect" at the Array
Wire Set "e" - Starts at the Ground Bar of the "DC Disconnect" and is EGC for the Rack & the PV Panels
Wire Set "f" - (Purple) Starts at the Ground Bar of the "DC Disconnect" and terminates at the new Ground Rod ???

We have discussed the Purple Wire Set "f" and my co-workers say it is a GEC - a Grounding Electrode Conductor.
Is it NEC compliant to connect a GEC between the new Ground Rod and the DC Disconnect?
If it should not be connected there, then where?

 

[pv_n00b]

There is nothing in the NEC that supports that requirement. So you can either ask them to show you where in the NEC that is required or just do whatever they want and be done with it. Connecting the new grounding electrode to the existing grounding electrode extends the existing system.

What you show labeled as the DC GEC terminal is actually the DC GEC / DC EGC terminal so you terminate both here. Your drawing looks fine except f needs to connect the inverter DC ground terminal to the new ground rod.

 

[NEOH]

OK, Thank You.

We found this drawing that fits your explanation ...

It shows that a 2nd Ground Rod is connected directly the Inverter's DC System Grounding Point, which is our "DC GEC" Terminal.
OK, it is very clear now.
Thank You.

 

[pv_n00b]

That's the standard system I see. Keep in mind that the new grounding electrode you are installing does not take the place of anything else, it's just a little extra item tossed in. In the 2017 NEC it's been made optional.

That means that the AC EGC is also the DC GEC going to the AC grounding electrode. So all the normal GEC requirements have to be met for the run from the inverter to the AC panel ground bus. It has to be continuous, the conduit has to be bonded, etc..