array grounding on flat roof

[brankulo]

i was hoping somebody could clarify a bit how to ground my system.
i am using unirac rm10 rakcks and the diagram shows how to ground but i am not really sure what it means. it looks like there is only one grounding lug ath the end of string. this confuses me as from what i have seen for other systems, the grounding wire runs from panel to panel?

also my one line diagram just shows ground wire from last panel to j box. the kit only came with 5' of grounding wire. so do i just run gound wire from last panel/rack to j box?

also any idea what "ground wire in rail trunk cables, black L1, red L2" means on one line diagram? i always thought there is only one bare copper ground.

 

[DThames]

It would be typical for a rack system to "bond" all panels together that were mounted on the same rail, or in some cases rail to rail bonding is part of the design. In cases where bonding is not part of the design, a ground connected to each panel would be needed.

I am not an experienced roof installer but if it were me, I would run a #6 ground wire from the array to the house ground rod. Your junction box might be grounded okay but it is a weak link (sometimes) to depend on grounding that goes from point to point where mechanical means is your ground path.

 

[brankulo]

i dont really have access to grounding rod, i remember it was set when they poured foundation and now is hidden.
i woul probably have to drive in new rod, which i dont know i want to do.

i also have a sub panel in the garage, that has its separate grounding rod, but the rod is under raised sunroom and i dont have access to it either.
but the grond wire from rod goes ridght into my garage sub panel, which is about 5' away from grounding rod. i could get a grounding wire from array down to my garge (aray is on garage roof) sub panel and attach it to ground wire coming from rod maybe? would that be a better option then just going to junction box on the roof?
thanks

 

[x98myers7]

you need to bond a common ground wire across each of the panels which bonds to the main inverter/SCC ground.

 

[DThames]

i dont really have access to grounding rod, i remember it was set when they poured foundation and now is hidden.
i woul probably have to drive in new rod, which i dont know i want to do.

i also have a sub panel in the garage, that has its separate grounding rod, but the rod is under raised sunroom and i dont have access to it either.
but the grond wire from rod goes ridght into my garage sub panel, which is about 5' away from grounding rod. i could get a grounding wire from array down to my garge (aray is on garage roof) sub panel and attach it to ground wire coming from rod maybe? would that be a better option then just going to junction box on the roof?
thanks

Connecting to the grounding conductor that goes to the ground electrode (ground rod) is one way to do the grounding.

 

[brankulo]

you need to bond a common ground wire across each of the panels which bonds to the main inverter/SCC ground.

looks like the bonding is done via clips that attach each panel to the racks. so i only need to run wire from last rack to my junction box

 

[x98myers7]

looks like the bonding is done via clips that attach each panel to the racks. so i only need to run wire from last rack to my junction box

yep, correct. all of the grounds on the entire system need to be bonded together and then connected to the main service panel ground.

 

[AHTrimble]

looks like the bonding is done via clips that attach each panel to the racks. so i only need to run wire from last rack to my junction box

In our area each panel has to have a grounding lug, and the rack needs to be grounded as well.
I ran a single #6 bare copper wire through each panel ground lug, then through the rack grounding lug.
Then the #6 wire continued to the grounding rod.
In our area we have dry sandy and rocky ground that requires 3 x 8' grounding rods with the #6 ground wire running continuously through each rod ground clamp. The bare copper wire between grounding rods is also buried 12" below grade for additional ground contact.