Ground Mount Earth grounding

[Stryker777]

I have three ground mount arrays 150ft from my home and EG4 Flexboss. I've read multiple things about grounding, and still I'm not sure what to do. I have all of the panels grounded and two 8' ground rods 6 ft apart that are connected to the arrays and disconnect box out there. In the box, I have surge protectors and breakers for each string. On the inverter end, I also have another set of SPDs and breakers for each string. At this point, I do not have a ground wire going from the house ground tying to the ground at the array. Everything stops at the termination boxes. In my buried PVC conduit, I have 6 wires for the DC from the arrays. Should I be adding a ground wire in that conduit to connect the two grounds? Since the grounds are isolated on both ends, with only DC wires between, it seemed odd to do so. I'm not against it, just questioning if that is correct or not? If so, what gauge would you recommend for that additional tie? My biggest concern is lightning and it making it's way through my systems.

 

[timselectric]

I do not have a ground wire going from the house ground tying to the ground at the array.

Then your array isn't grounded, it's just connected to the local earth.
Which provides zero protection against anything but static electricity.

Your array should be grounded (connected to the existing grounding system at the house).
Lighting can create a surge through your system. Because of the earth connection at the array, this is more likely. Which is why we recommend against auxiliary ground rods at the array.
EGC size is determined by the circuit it's protecting, when inside conduit.
If exposed to physical damage, #6 is the minimum allowed.

 

[Stryker777]

Thank you for the reply. So tie to the house ground and get rid of the rods at the array. Got it.

 

[Madcodger]

This knowledge should almost be a requirement for Will allowing continued use of the forum (not really, but there are moments it sounds like a good idea. Want to be an active user? First, understand this one area of knowledge...). I think about 10% of @timselectric posts have been helping others understand this basic point (thanks, Tim). And the sad thing is, some idiots will often still argue.

 

[wonderspark]

Is there a preferred location where you connect the EGC for a ground mount array to:

1. Anywhere on the neutral bus bar, when there is a neutral bonding screw installed, or
2. Directly onto the grounding electrode conductor,

... in order to properly ground the array?

 

[Fisherguy66]

I have three ground mount arrays 150ft from my home and EG4 Flexboss. I've read multiple things about grounding, and still I'm not sure what to do. I have all of the panels grounded and two 8' ground rods 6 ft apart that are connected to the arrays and disconnect box out there. In the box, I have surge protectors and breakers for each string. On the inverter end, I also have another set of SPDs and breakers for each string. At this point, I do not have a ground wire going from the house ground tying to the ground at the array. Everything stops at the termination boxes. In my buried PVC conduit, I have 6 wires for the DC from the arrays. Should I be adding a ground wire in that conduit to connect the two grounds? Since the grounds are isolated on both ends, with only DC wires between, it seemed odd to do so. I'm not against it, just questioning if that is correct or not? If so, what gauge would you recommend for that additional tie? My biggest concern is lightning and it making it's way through my systems.

I used a 4c with ground teck cable back to the house and ran ground to the main electric panel. Should only be one main ground in the system.

 

[Madcodger]

Is there a preferred location where you connect the EGC for a ground mount array to:

1. Anywhere on the neutral bus bar, when there is a neutral bonding screw installed, or
2. Directly onto the grounding electrode conductor,

... in order to properly ground the array?

I can't tell you what is right or preferred - I can only tell you what I did, that worked for me. I have a combiner box that contains a DC breaker for each string (from Midnite), and my Midnite SPDs (sticking out of the box). The EGC for each string runs into that box and along with the current-carrying conductors and connects to the EGC connection of the SPD (one for each string). That box has an EGC running out of it, connected to the EGC bar in the main electrical panel (which is connected to the external ground rods of the electrical system). The only connection in the entire system between neutral and the EGC is in that main panel, through the neutral bonding screw. In my view, if you have any doubt whatsoever, hire an electrician familiar with solar to advise you.

 

[wonderspark]

I have two 200 amp service panels in parallel, because the company that built our house was supposed to install a 320 amp panel and forgot, so they just added in a second 200 amp panel. Anyway, they are parallel, mirror images of each other, except one has most of the breakers.

Since it has two of everything, I metered out the two grounding electrode conductors, all four neutral bus bars, and verified neutral bonding screws, and they all share continuity. So, I'm thinking it's going to be fine to use one of the terminals on one of the neutral bus bars to connect my EGC from the ground mount array. I'll use the terminal directly beside the one with the ground conductor from the transfer switch, in fact.

I was going to clamp it directly to the GEC, but it's all bonded together, so who cares where, right?