Off Grid Grounding

Hi,
Sorry if this topic has already been discussed. I need help understanding grounding in my Off Grid System.
I have all my AC side grounded and no problem there. The problem is the DC side. The panels and the DC surge arrest are about grounded to a separate grounding rod.
I question is, Should I ground the Battery and the charge controller to the same grounding rod as the AC or to the panels?
System Setup
Nine 310W panels. Three in series and all three sets in parallel.
Breaker for each series set and all combined through a bus bar and to another breaker.
Citel DS240S-130DC Surge protection device connected in the combiner box with grounding.
Midnite Surge arrest for the AC side
Schneider MPPT 60-150 charge controller
Schneider SW4048 inverter
48V L16 US Battery
Sorry if this topic has already been discussed. I need help understanding grounding in my Off Grid System.
I have all my AC side grounded and no problem there. The problem is the DC side. The panels and the DC surge arrest are about grounded to a separate grounding rod.
I question is, Should I ground the Battery and the charge controller to the same grounding rod as the AC or to the panels?
System Setup
Nine 310W panels. Three in series and all three sets in parallel.
Breaker for each series set and all combined through a bus bar and to another breaker.
Citel DS240S-130DC Surge protection device connected in the combiner box with grounding.
Midnite Surge arrest for the AC side
Schneider MPPT 60-150 charge controller
Schneider SW4048 inverter
48V L16 US Battery
Comments
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
From some earlier European research (that I have not since been able to fine)--I think much of it was looking at the lightning ground on old German churches (as I recall), and they found "fused" (burned open) 8 AWG and smaller cable from lightning hits, and no fused 6 AWG and heavier cables.
Note that "real lightning" ground protection is a complex subject that requires lots of reading/research (and use of experts for larger installations).
NEC (US national electric code) mostly aBddresses 60 Hz grounding for safety. Lightning is actually a low frequency radio current (with lots of voltage and current)--The physics of "radio frequency energy" is quite different from DC or 60 Hz AC.
-Bill
How to ground the propane tank connected via a 50 foot copper pipe buried inside a poly pipe conduit in a trench that will be backfilled? I have a wire run in the trench to the tank, but am not sure of where to route the wire from the tank.
Our electrician told us that we should ground the propane tank legs to the AC panel ground. Our panel ground goes to a standard AC ground plate on the other side of the house via the typical large bare Cu ground wire.
Since the tank is bolted to concrete foundations set in the ground it is "slightly grounded" already. I gather that it probably won't create too much of a problem to have these two routes to earth and there isn't much that could be done to isolate the tank from the earth.
The only other option would be to connect the tank to the AC ground plate directly with another wire run to the plate.
LIkely, the object of grounding the tank to the panel ground or ground plate is so that the propane piping does not carry all of the induced current and currents resulting from differences in ground potential in the event of a nearby strike. Since we have have plastic water pipes there is no other interconnection between plumbing or gas pipes and the electrical ground. Our propane appliances are all connected via copper pipe. The gas kitchen range has no electrical ground as it is a battery powered Unique spark ignition range.
Does anyone know the proper way to do this?
Thanks!
Offgrid in cloudy PNW
MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install ....
BB. said: Add prayer as even the professional lightning folks will tell you that. Good advice that will only go so far.
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E-mail [email protected]
Probably best to run tank ground to panel ground which goes to earth plate as that keeps area between copper pipe and ground wire small in my case, reducing induced potentials from circulating currents.
My understanding though is that generally you want to have the straightest, shortest path to ground to have the lowest inductance and best chance of current following grounding conductor as the leading edge of the strike is a high frequency component that reacts strongly to conductor self inductance. Larger flatter conductors are better than small wires as this component of the current doesn't have much surface area to travel on in a small wire.
Offgrid in cloudy PNW
MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install ....
I would be more concerned with an unneeded ground bringing the lightning into your ground system.
Just adding another way to get in trouble offgrid.
http://members.sti.net/offgridsolar/
E-mail [email protected]
convey LP-Gas from a gas storage container shall be provided
with dielectric fittings installed above ground and outdoors at
the building to electrically isolate it from the aboveground
portion of the fixed piping system that enters a building.
|| 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 ,
http://members.sti.net/offgridsolar/
E-mail [email protected]
Offgrid in cloudy PNW
MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install ....