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Solar array grounding question

Roswell Bob

Solar Enthusiast
Joined
Dec 5, 2020
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759
Location
Warner, NH
34503495_2208357669193697_4795314338690760704_n.jpg


I have had some problems with lightning strikes. I'm thinking I may have a grounding problem - that may be difficult to resolve.

My array is a home brew pole mount with the (8" schedule 40) pole sunk about 6' down with a 3'x3'x3' block of concrete to anchor the array. Array is about 100' behind the house. The panels are floating in that I did not make any effort to ground them beyond the mechanicals of the array structure. Panels are bolted to the extrusions with the usual hardware. Extrusions are bolted to some steel channel. Steel channel is riding on a trailer axle which sits atop the 8" pole mount. So electrical connection is very iffy as it travels through the bearings sitting on the axle.

I think from what I have read that the panels should be isolated from ground at the array and a seperate ground wire should be brought to the ground rod where service enterance is. Since system is >50v either positive or negative side of panels should probably be tied to ground at the inverter.

Any Ideas on what I should be doing?
 
34503495_2208357669193697_4795314338690760704_n.jpg


I have had some problems with lightning strikes. I'm thinking I may have a grounding problem - that may be difficult to resolve.

My array is a home brew pole mount with the (8" schedule 40) pole sunk about 6' down with a 3'x3'x3' block of concrete to anchor the array. Array is about 100' behind the house. The panels are floating in that I did not make any effort to ground them beyond the mechanicals of the array structure. Panels are bolted to the extrusions with the usual hardware. Extrusions are bolted to some steel channel. Steel channel is riding on a trailer axle which sits atop the 8" pole mount. So electrical connection is very iffy as it travels through the bearings sitting on the axle.

I think from what I have read that the panels should be isolated from ground at the array and a seperate ground wire should be brought to the ground rod where service enterance is. Since system is >50v either positive or negative side of panels should probably be tied to ground at the inverter.

Any Ideas on what I should be doing?
You are struggling with the same issues that many others with remote arrays wonder about. I am not an expert on the NEC, but I think they require bringing the Panel Frame ground back to the house and allow a supplemental grounding electrode at the panels. In your case, I would be tempted to earth-ground the frames local to the panels but not run the wire back to the house. However, I don't think the NEC allows for this. (Perhaps someone else on the forum can comment).

I will say that if the panel frames are tied back to the house, do not add a supplemental grounding electrode at the array.

You may want to review the set of resources on grounding....but they do not directly answer your question.
 
Thank you. I am tempted to reinforce the panel frames connection to ground at the panels and then ground the negative side of the panels inside by the inverter. As I said, the ground path from panel frames to earth is fairly weak.

I've got some MOVs to sprinkle around the system for whatever they're worth. I thought about adding some air core inductors and sturdy caps to the system too. These lightning strikes (2) are getting expensive.


I read your app note on grounding last week - the complete series thank you. That's what spawned this dialog. I'm watching Mike Holt presentation now.
 
I'm watching Mike Holt presentation now.
Mike is a great resource..... and he is a big influencer with the NEC. I find I have to watch his videos a few time to understand exactly what he is saying. However, once I do understand....it always makes a lot of sense.
 
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