Does my grounding 'plan' seem appropriate?
I am installing a new solar setup at an off-grid cabin in Northern Arizona. Lightning is a real concern in our area. My array will be a ground mount using Ironridge components and will be about 50 feet from the cabin. My plan is to sink four grounding rods basically at each corner of the array. I would tie each of these to the bare 6 ga. copper grounding wire coming off of the array (I'm guessing at the combiner box at the ground busbar). The 6 ga. bare wire would then continue, buried outside of the conduit but in the same trench, all the way to the cabin. At the cabin, the ground wire would go to the ground of the Outback equipment as well as the negative side of the battery bank and the existing ground rod for the cabin itself. Does this sound correct? I greatly appreciate any guidance here.
Northern Arizona...4050 Watt off-grid system - Outback FP1 - Rolls 605 in a 48V bank
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http://forum.solar-electric.com/discussion/comment/84242#Comment_84242
-Bill
That does not bother me for offgrid where it probably will not be inspected.
I would not run any larger than required ground wire into the structure. If your array is #10 wires then that is what I would run into the structure for ground. At the arrary use as big of wire as you can for ground and as Westbrook said bond them and use an SPD.
I like the midnite and delta SPD's and would use one of each.
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As for the grounding wire between the array and cabin, I had read it was best to run it outside the conduit to increase the earth ground. Is that not right? Oh, and we are pretty far off the grid so there will be no inspections. (yay)
and put the pipe and rebar in, you can tie it together electrically and make each hole a small UFER ground point, Spread over 4 holes, you should not get too much current saturation in the soil. Or do a 6" slab underneath, with rebar between it all, and then it's likely to be an absolutely bomb-proof ufer ground for the array chassis. Not sure what code wants for your house wire grounding, but UFER was designed for ammo bunkers in the desert
https://en.wikipedia.org/wiki/Ufer_ground
Just don't use a moisture/vapor barrier under the concrete, like my inspector insisted on !
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
Anyone who reasons with lightning is just going on past experience. The problem with lightning is the experience varies.
If you are in a really prone area, and you are home, disconnect everything coming into the home by many feet if you want to increase your odds.
If you are away, do the best you can and cross your fingers. Many who are part time disconnect everything when they leave.
They often keep a small DC freezer going, shut off / disconnect the inverter, and use a small cheap array to charge leaving their main system offline. Even then, lightning can do alot of damage in a close strike, Alot! Say your prayers and good luck!
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|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,
I am available for custom hardware/firmware development
http://members.sti.net/offgridsolar/
E-mail [email protected]
Hope this helps! Like others have referred to in this thread...it all depends on what your AHJ allows from a permit standpoint, as well as what soil type you have, the repercussions (i.e. loss of $ or time if struck by lightning) of a nearby strike which will help guide you as to how much to protect your equipment.
We looked into the UFER ground thing and it just depends on what you're comfortable with. I had seen some reports that the current actually blew out the concrete near the rebar. However, keep in mind that a direct strike on almost any system will result in damage...it will always be a risk and there is no 100% truly safe system that is reasonably priced.