Solar - Grounding Concern

[3L3CTRIC]

I notice that my solar system doesn’t have every rail grounded. The ground wire and lug is in both pictures, but I added some colors to highlight as they are difficult to see.

The green line represents the ground wire, the red star represents where it’s secured to the rail with a lug, and the yellow question mark is where it’s only secured to the rail with a zip tie.

Notice in the first picture, the bottom rail on the right side doesn’t even have a ground wire. Is that normal?



The second picture is a close up of how it’s secured to the rails with lugs and zip ties.




The third picture shows how there’s nothing on the bottom rail.



Is there any type of grounding concern here? Is this normal?

 

[cdherman]

The panels have a frame that is aluminum. Only one of the two rails needs to be grounded to ground the entire array, ONCE the panels are in place. As far as I could tell, your pictures seem to indicate that one of the two rails is grounded for each course.

AFAIK, it allowable to use the panel frames as a ground. Perhaps others know more.....

 

[LakeHouse]

Yes, this is normal. The panels provide the ground connection from one rail to the next.

 

[timselectric]

Perfectly normal.

 

[3L3CTRIC]

The panels have a frame that is aluminum. Only one of the two rails needs to be grounded to ground the entire array, ONCE the panels are in place. As far as I could tell, your pictures seem to indicate that one of the two rails is grounded for each course.

AFAIK, it allowable to use the panel frames as a ground. Perhaps others know more.....

Yes, this is normal. The panels provide the ground connection from one rail to the next.

Perfectly normal.

Thanks for the clarification.

Now that I think of it, every other rail did have the ground secured to it (which is good) but the top two rails were an audible, as we had to install them sideways due to vents in the roof.



I didn’t actually get a visual on the ground connected to these two rails.



1. What would happen if these two rails weren’t grounded with the top two panels?
2. What would happen if none of the rails were grounded?

 

[zanydroid]

1) If the rails are not grounded then there is extra surface area of electrical parts that may go hot if there is a ground fault. Rails are electrically irrelevant

2) if the modules frames are not grounded, theoretically voltage could build up on those frames relative to solar cells in excess of what the insulation is meant to handle. That likely has an electrically meaningful consequence. I’ll leave power engineers to answer that.

3) If large swathes of metal chassis are not bonded to ground then safety mechanisms like ground fault detection on AC or DC side will not operate as expected which poses a risk during maintenance or being near the solar panels.

Note that it is actually quite complicated to de energize completely a PV system in all situations (though rapid shutdown helps, esp if it’s interlocked with Arc and ground fault defection… some firmware will likely need to be in the critical path), so Swiss cheese model/calculated risk thinking is needed.

 

[JoeHam]

That looks like Tamarack racking.

Their system is designed to have the panel clamp teeth penetrate the anodized coating and use the racking as a ground conductor. Their rail splices also provide an electrical as well as mechanical bridge.

If that is the case each separate row of panels needs a ground and Tamarack typically sends ground lugs (like the WEEBS) along with each purchase.