Solar Grounding Question

[addision]

I have a ground mount solar array 200ft from my house, inverter and meter panel. I have pulled the conductors and ground wire for each of the 4 arrays, through the pvc conduit to the house.

Now I am looking at my plans and I am questioning if I need an additional GEC ground inside the conduit to connect the panel frames to the inverter equipment. My plans clearly show the power conductors and ground called out to be in the conduit. However, there is also an earth ground around the outside of the blueprint connecting to each piece of equipment from the solar panels all the way to the main panel. This ground appears to be distinct from the conductors in the conduit.

I https://drive.google.com/file/d/1wKMAELENMmn9lQCvFy3MRLTAw8nzEF4K/view?usp=sharing


According to the image, should I be pulling an additional ground from the solar panels 200' to the equipment? I already have one existing 8' copper grounding rod at my main panel, I plan to add a second near the new equipment (15 ft. from main panel), and I was planning on adding two at my solar panel array, one on each end.

Or do I just ground to the grounding rods I install at the array, and then ground to the rods near my equipment?

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[Steve_S]

The Panel Frames & Rails are NOT Electrical and should NOT be grounded to the Electrical Ground. Remember DC has Positive & Negative - no ground... It's not a car ! Solar Frames & Rails DO however have to be grounded for Lightning Protection, which means linking all the rails & panels frames together and directing that to a grounding rod "through" an SPD (Surge Protection Device).

Your Inverter/Charger -> AC System must be Electrically Grounded at the main demarcation point where it all comes together. These should ALSO have SPD's as surges can & do travel through wires.

See here for Top Quality SPD's for AC & DC. They have Videos & Docs that discuss implementation.

Category Products - MidNite Solar's

MidNite Solar Category Products.

www.midnitesolar.com

 

[ncsolarelectric]

I have a ground mount solar array 200ft from my house, inverter and meter panel. I have pulled the conductors and ground wire for each of the 4 arrays, through the pvc conduit to the house.

Now I am looking at my plans and I am questioning if I need an additional GEC ground inside the conduit to connect the panel frames to the inverter equipment. My plans clearly show the power conductors and ground called out to be in the conduit. However, there is also an earth ground around the outside of the blueprint connecting to each piece of equipment from the solar panels all the way to the main panel. This ground appears to be distinct from the conductors in the conduit.

I https://drive.google.com/file/d/1wKMAELENMmn9lQCvFy3MRLTAw8nzEF4K/view?usp=sharing


According to the image, should I be pulling an additional ground from the solar panels 200' to the equipment? I already have one existing 8' copper grounding rod at my main panel, I plan to add a second near the new equipment (15 ft. from main panel), and I was planning on adding two at my solar panel array, one on each end.

Or do I just ground to the grounding rods I install at the array, and then ground to the rods near my equipment?

Reply
Edit Delete

One is the electrical grounding conductor and the other is the electrical bonding jumper. Per NEC, all bare metal parts shall be bonded together. Yes, they are redundant but serve different purposes per code.

 

[jfharper]

The Panel Frames & Rails are NOT Electrical and should NOT be grounded to the Electrical Ground. Remember DC has Positive & Negative - no ground... It's not a car ! Solar Frames & Rails DO however have to be grounded for Lightning Protection, which means linking all the rails & panels frames together and directing that to a grounding rod "through" an SPD (Surge Protection Device).

I'm currently studying my grounding situation...just to clarify, Panel frames and rails should be grounded for lightning, but not grounded to the systems electrical grounded central point...so lightning grounded at the array with a rod out at the array would do the trick? My array is ironridge UFO's to rails, to metal poles to concrete 3 ft in ground...this provides some grounding, but a rod would also help? Also, how should I ground to the rod...run a ground wire (what size?) on each panel to the rod, or just from 1 pole/frame to the rod? thanks.

 

[zanydroid]

I thought GEC/EGC no longer needed to be separate for a long time (like since early 2010s NEC?), and only EGC is needed now.

Post #2 is dangerous. All metal PV frame components need to be bonded to EGC. Lots of threads on that in the forum.

Also I don't understand the proposed SPD configuration.

Bonding the metal frames to a ground rod will do pretty little for lightning protection. Direct hit, it's dead. Indirect hit, it might help a little bit. But why would the SPD help? You want the frame and earth to be at the same potential. SPD is used to provide clamping of unexpected voltage differences beyond the standard voltage range of the system. It makes sense to put SPD between DC+ to DC-, and DC+ to ground. Since those are at the non-zero operating voltage of the DC circuit. If two things are supposed to be at the same voltage, what better than a wire to help that out.

 

[jfharper]

I thought GEC/EGC no longer needed to be separate for a long time (like since early 2010s NEC?), and only EGC is needed now.

Post #2 is dangerous. All metal PV frame components need to be bonded to EGC. Lots of threads on that in the forum.

Also I don't understand the proposed SPD configuration.

Bonding the metal frames to a ground rod will do pretty little for lightning protection. Direct hit, it's dead. Indirect hit, it might help a little bit. But why would the SPD help? You want the frame and earth to be at the same potential. SPD is used to provide clamping of unexpected voltage differences beyond the standard voltage range of the system. It makes sense to put SPD between DC+ to DC-, and DC+ to ground. Since those are at the non-zero operating voltage of the DC circuit. If two things are supposed to be at the same voltage, what better than a wire to help that out.

OK, will ground panel frames/metal mount back to central grounding point on system, as well as spd to central grounding system, to provide central point for same potential.

 

[zanydroid]

OK, will ground panel frames/metal mount back to central grounding point on system, as well as spd to central grounding system, to provide central point for same potential.

The SPD to central grounding system, I'm not actually sure about.

I was thinking about this and maybe there's an argument to do SPD at the array to a ground rod at the array, that is not bonded to the central grounding system (to avoid clamping the indirect strike directly to the grounding system, and to prevent a gradient pulse from traveling down the EGC).

And then an extra SPD set at the SCC/Inverter.

Although, if there is lightning strike that raises the earth potential at the array but somehow misses the DC lines, that could raise that voltage high enough such that the SPD starts conducting into the DC circuit. Except this does the opposite of what you want -- increases chance for damage.