Grounding!

I wish to ground my backyard solar shed, which will have a 130 watt solar panel, 25 amp charge controller, two 12V-126amp hour deep-cycle batteries in parallel, 1750 watt inverter, and AC distribution panel. The system will have a nominal voltage of 12 volts.
First, do all of the metal devices I've mentioned above need to be grounded separately to a single grounding point, or can a grounding wire simply "daisy-chain" all the devices, and then terminate in a single spot? This sounds like a stupid question even to me, but I just need to know.
Second, once a single grounding point is reached, what is the best diameter of copper grounding wire to use as a grounding conductor from that point to the grounding electrode in the earth? And, must the conducting wire be solid, or can it be stranded?
Thirdly, is there a requirement for the distance that the grounding electrode must be away from the shed before I bury it?
Lastly, if I am only able to get the grounding electrode part way into the earth, say 4 feet, can I put another grounding electrode 4 feet in the ground some distance from the first one? If so, how far do I need to separate the two grounding electrodes? Or, am I jst pipe-dreaming?
Thanks, Lou Dalessandro
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So many questions on such an elaborate project! Without doing a lot of homework myself, I can't answer everything. There are, however, many online resources available for you to research. I suggest that you get an electrical code book (NFPA 70) for starters. Look at articles 480, 250, and 690. The solar panel and inverter manufacturers should also have information available.
The main grounding conductor can be solid or stranded and is usually no smaller than #8, but the code book can tell you better in your situation. Two four foot ground rods do not equal one eight foot ground rod in terms of code compliance. Rent a jack hammer and pound those suckers in. You should have two eight footers. As far as distance you can have one right beneath your electrical panel, but the second one must be at least six feet away from the first although the optimum distance is sixteen feet. There are other choices for grounding electrodes which are defined in article 250.
Normally an equipment grounding conductor is daisy chained since it is not usually a current carrying conductor. I would check the code book and with your local inspector on grounding since there will be AC and DC involved.
John Grabowski http://www.mrelectrician.tv
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John Grabowski wrote:

many places are no longer allowing daisy chaining of grounds.
Best to home run ground anyway to be safe.
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arthuritis wrote:

Electrical devices can be daisy chained. Electronic systems benefit from single point grounds.

#6, solid or stranded.

No.
It's not the length of the rod that's important - it's the conductivity of the soil. An 8 ft rod is average for average soil. But in some soils a 4 ft rod may be adequate. Or if the soil is sandy or poor you may need multiple 8 ft. rods. You are looking for 5 ohms or less measured with an earth ground tester (not a standard ohm meter!). If poor ground resistance is encountered, you need multiple rods or treat the soil around the single rod with rock salt to increase conductivity.
Bob S.
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The important thing is to be sure this gets bonded to the grounding system of your electrical service. There is an article in IAEI magazine about this (IAEI.ORG)
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The 12V portion of the system does not require a safety ground as this voltage is considered non lethal. It is advised to use one for the primary reason of lightning protection and or unintentional connection to the 120V side of the system.
There are strandard practices used by PV folks. Do some more research before settling on a solution. The manuals of each piece of equipment should have had something on the subject.

Multiple Grounding electrodes and uthe use of a UFER (rebar in your foundation) as a ground are all covered in NEC. Get a copy of Code Check electrical (or another book) if you are doing any substantial wiring job and want to be familiar with the principals and rules for safe wiring.

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With $$ you are spending be sure to add lightning protection to the system. The solar cells make an inviting target for lightning.

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