How to Ground Solar Array Tracking System

[Joe555]

Hello,
Need a little help here as safety is all our primary concern. I'm trying to develop a dual tracking system that is cost-effective. The Invertors in our test system are transformerless or non-isolated and the PV modules are not grounded except at panel frames and panel support (tracking) frames. Since each panel will move I need a flexible cable and am not clear on NEC code for bonding and splicing using a multistrand cable. Was thinking of using UL-approved WEEB connector washers and crimp lugs with 8 AWG PV Wire but would that violate the permanent splice rule because of so many connections (2 lugs per) which I believe does not apply to EGC? but since there is daily motion is still a concern. What about GEC grounding and the fact that due to motion, steel and aluminum parts conductivity might be an issue and any bonding between parts would still require a flexible cable? I have contacted electrical parts manufacturers but so far no clear answers.

Thank you in advance for your time and any help you can offer,
Joe

 

[petersonra]

I would think such an assembly would need to be UL listed.

 

[electrofelon]

So you plan to have an array of modules, and each module will be mounted to its own 2 axis pivoting mechanism? you also have the issue of the +/- leads...I wonder if you could have a custom cable made that has the power and EGC conductors all in one?

 

[Joe555]

I would think such an assembly would need to be UL listed.

This is not a grid-tied system so it should be exempt. Even our local building department told us since it is ground-mounted not roof-mounted there is no need for a permit (I should have indicated it is a ground-mounted array).

 

[Joe555]

So you plan to have an array of modules, and each module will be mounted to its own 2 axis pivoting mechanism? you also have the issue of the +/- leads...I wonder if you could have a custom cable made that has the power and EGC conductors all in one?

The modules/panels will share the north-south ground mount but each panel with move east-west on its own pivot. The panel frames will need to be bonded as well as the mounts but the module conductors + and - never tie to ground as this system is transformerless AKA non-isolated AKA non-grounded pv panels and thus both conductors of the arrays run directly to the Inverters. Sorry I was not more clear in my original post.

 

[robertd]

What about using Ground Braid. It's designed for exactly this sort of the thing. Put "ground braid" into google or google images and you get thousands of hits. For outdoor use use Tin plated, not bare copper. POCOs use them when they have a pole mounted disconnect or switch with a control rod coming down to ground lever with a lever. They bond the rod and lever to the ground wire going down the pole. I think they are also used to bond fence gates at substations. The braid comes in all sizes, from very small, equivalent to #12 or #14 wire or smaller, to stuff rated at thousands of amps. You can get premade lengths with lugs soldered on that will function fine outside in the weather.

 

[electrofelon]

The panel frames will need to be bonded as well as the mounts but the module conductors + and - never tie to ground as this system is transformerless AKA non-isolated AKA non-grounded pv panels and thus both conductors of the arrays run directly to the Inverters. Sorry I was not more clear in my original post.

I understand. What I was proposing was possibly having a cable that had both +/- and EGC/bonding conductor in one, since you will apparently have the same issue of required movement with the +/-.

 

[Joe555]

What about using Ground Braid. It's designed for exactly this sort of the thing. Put "ground braid" into google or google images and you get thousands of hits. For outdoor use use Tin plated, not bare copper. POCOs use them when they have a pole mounted disconnect or switch with a control rod coming down to ground lever with a lever. They bond the rod and lever to the ground wire going down the pole. I think they are also used to bond fence gates at substations. The braid comes in all sizes, from very small, equivalent to #12 or #14 wire or smaller, to stuff rated at thousands of amps. You can get premade lengths with lugs soldered on that will function fine outside in the weather.

Thanks for the great suggestion, I'll look into it.

 

[Joe555]

I understand. What I was proposing was possibly having a cable that had both +/- and EGC/bonding conductor in one, since you will apparently have the same issue of required movement with the +/-.

Thank you that would be a great product and I will explore it this coming week.

 

[jaggedben]

Hello,
Need a little help here as safety is all our primary concern. I'm trying to develop a dual tracking system that is cost-effective.

Word of advice; change your criteria. That goal has been impossible for a few years since it became more cost effective to add more modules at fixed orientations than to maintain the moving parts of a tracker.

The Invertors in our test system are transformerless or non-isolated and the PV modules are not grounded except at panel frames and panel support (tracking) frames. Since each panel will move I need a flexible cable and am not clear on NEC code for bonding and splicing using a multistrand cable. Was thinking of using UL-approved WEEB connector washers and crimp lugs with 8 AWG PV Wire but would that violate the permanent splice rule because of so many connections (2 lugs per) which I believe does not apply to EGC? but since there is daily motion is still a concern. What about GEC grounding and the fact that due to motion, steel and aluminum parts conductivity might be an issue and any bonding between parts would still require a flexible cable? I have contacted electrical parts manufacturers but so far no clear answers.

Under the 2017 NEC or later all you need is an EGC in your flexible cable. There is no GEC required for the array anymore, and therefore no 'permanent splice' requirement.

 

[jaggedben]

This is not a grid-tied system so it should be exempt.

That is misinformed.

Even our local building department told us since it is ground-mounted not roof-mounted there is no need for a permit (I should have indicated it is a ground-mounted array).

That's bizarre in my experience. Around here the requirements for ground mounts can be more stringent. But anyway, if the local AHJ isn't gonna inspect then why is code an issue?