GFP vs. grounding PV and battery negatives

[Gordon]

Hi Folks,

I'm upgrading my off-grid solar set-up and have recently purchased the Classic 150. This GFP stuff is new to me, since around here all we've ever done is directly ground the PV and battery negatives. Now the owner's manual is talking about lifting those grounds and letting the whole thing go through that little jumper on the board and a built-in PTC fuse in the 150. I did a little research on the pertinent NEC and it looks like the GFP thing doesn't apply to me since I'm completely off grid and have a small, pole mounted array that is not near any buildings. Am I missing something here? Like some safety related reason why I would want to use the GFP and not directly ground the battery and PV panels? I realize that if a ground fault developed that the GFP would notify me of that and shut everything down. But, is that ample reason to not have those things grounded like before.

I would appreciate any help in clarifying my thoughts on the subject. Thanks. 

[Matrix]

I also have to wonder,  on a UL 1741 off grid inverter,  if that inverter is grounded as equipment to the whole house ground and the neutral of that inverter on the AC side is going to the same bus bar as the EGC,  Is this bonded inside the inverter to the DC negative,  effectively ground the battery negative?  (I can see what I mean in my head, but not sure I am explaining it correctly)

And would this grounding cause either the GFP or the Arc Fault Protection not to work properly?

[FNG]

Solar equipment like an inverter or charge controller does not bond AC neutral to ground or DC - to ground as standard. A charge controller may have a reference to ground for its built-in ground fault protection like the Classic offers.

Now note that no other bond from negative to the ground can or should be made if you use a ground fault device similar to the one int he Classic.
Also note that on the AC side only one bond between AC neutral and ground, This can be made sort of where it is convenient in a new off-grid system but in a grid-connected system will generally already be made int he Main AC panel.

Do note that some balance of system like The E-Panel or other panels like Magnums panels may have bonds made internally that you need to remove and should be labeled as such

[KyleM]

Solar equipment like an inverter or charge controller does not bond AC neutral to ground or DC - to ground as standard. A charge controller may have a reference to ground for its built-in ground fault protection like the Classic offers.

Now note that no other bond from negative to the ground can or should be made if you use a ground fault device similar to the one int he Classic.
Also note that on the AC side only one bond between AC neutral and ground, This can be made sort of where it is convenient in a new off-grid system but in a grid-connected system will generally already be made int he Main AC panel.

Do note that some balance of system like The E-Panel or other panels like Magnums panels may have bonds made internally that you need to remove and should be labeled as such

What he said. ^^^

Kyle M

[Matrix]

Do note that some balance of system like The E-Panel or other panels like Magnums panels may have bonds made internally that you need to remove and should be labeled as such

Well in the E-Panel the ground bus is bonded to the E-Panel casing,  But the Neutral is not bonded at the E-Panel Neutral Bus.  But then I have both the Ground Conductor and the Neutral running back to the main load panel and both bonded and grounded at the main  load panel (and only there).    My concern was that somehow, by grounding the case of the Schneider SW to this same grounding conductor,  that somehow this might also ground the battery negative as it does pass thru the inverter - From the SW case ground and the AC neutral.

Thanks
Mike

[ClassicCrazy]

Grounding  is rather confusing . ( if you look it up there are lots of strong opinions on which way is proper)
Correct me if I am wrong but on my system I have ground wire going from PV combiner box to inverter and controlller . That is grounded to same ground rod as AC  panel from inverter which has neutral also tied to ground.  I found out when connecting a SPSD surgre protector at the combiner  that the LED did not come on until I grounded it . Before I ran that ground line the LED came on when I touched the metal screw on the combiner box so I was part of the circuit.  I am not sure now if I have the DC negative  and ground tied together somewhere in the system or not. Guess I will have to take a look.

Larry

[FNG]

Do note that some balance of system like The E-Panel or other panels like Magnums panels may have bonds made internally that you need to remove and should be labeled as such

Well in the E-Panel the ground bus is bonded to the E-Panel casing,  But the Neutral is not bonded at the E-Panel Neutral Bus.  But then I have both the Ground Conductor and the Neutral running back to the main load panel and both bonded and grounded at the main  load panel (and only there).    My concern was that somehow, by grounding the case of the Schneider SW to this same grounding conductor,  that somehow this might also ground the battery negative as it does pass thru the inverter - From the SW case ground and the AC neutral.

Thanks
Mike

Mike,
The Schneider inverter has no connection internally between Ground, DC negative or AC neutral

[Matrix]

Thanks,  that is what I needed to know

[Gordon]

Thanks everyone for your comments. My panel rack just arrived this past week and I was able to get the system installed over the weekend. I went ahead and grounded the battery negative and PV negative as well, thus defeating the GFP. I removed the jumper from the Classic 150's board and turned off the GFP function in the Tweaks menu too. That's the direction I was leaning on this topic. I decided that it wasn't worth sacrificing proper grounding to get the GFP feature.