Grounding a Ground-Mounted Array

It looks like the final location of the ground-mounted array will be about 200ft from the equipment room. I'm installing a Ufer grounding system (#4 bare connected to the rebar) in the foundation and will stub it up in the slab in the electrical equipment room.
My question is should I provide for a grounding connection to the array at the "main" grounding point in order to have a single earth ground, or install a ground system at the array?
My question is should I provide for a grounding connection to the array at the "main" grounding point in order to have a single earth ground, or install a ground system at the array?
Paul
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
Comments
The grounding of the panels is different from the neutral-bonded ground of the AC systems in the house. You don't risk a ground loop by having a ground for the panels and a ground for the 120VAC circuits in the house.
Steve
If I'm understanding correctly, the array frame, combiner box, and panels are grounded separately from the "main" equipment and terminates at the array. There should be no ground wire in the trench from the array to the equipment?
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
At 200 feet you are also at a length that there is conflicting opinions but the above has worked well for me in over 100 offgrid homes.
We had the most nasty lighting here Tuesday night that I have ever seen on land.
http://members.sti.net/offgridsolar/
E-mail [email protected]
Please see the following link for some ideas and additional guidance in terms of grounding a ground-mounted array that is 100+ feet away from the main structure's ground: http://forum.solar-electric.com/discussion/comment/288232#Comment_288232
We are off-grid in central Texas and it sounds like our situation/setup is very similar to yours. However, please keep in mind that I did not have to obtain approval from an inspector to build this ground system.
Dave, thanks for the tip on the light gauge "ground to the house". When you do this, do you run the "house" ground from the grounding bus in the combiner to the ground bus at the "main?
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
I have favorite prayers from doing this out on the ocean in my boat.
I also do not use combiners anymore with high voltage MPPT's. It is the same concept though. Good Luck!
http://members.sti.net/offgridsolar/
E-mail [email protected]
Dave has a lot more experience than I with lighting--In general, I would suggest using 6 AWG minimum (copper) if you can justify the cost for the ground rod to ground rod connection. 8 AWG and thinner copper wire has been known to "fuse" when hit by direct strike (on occasion). 6 AWG will (almost?) never fuse (from what I have read) from lightning induced current, and is heavy enough for direct burial insulated (which is good for lightning grounding). But 12 AWG appears to keep the inspector happy. NEC/Code does not always reflect "best practices" regarding lightning vs safety.
In general, due to the physics of high frequency current (i.e., lightning pulse current), the lightning will not follow the ground wire more than 10-20 feet before it finds its own path to "earth". In general, I think I prefer ground rod to ground rod grounding for lightning grounding (as well as safety bonding for AC/DC short circuits to trip breakers).
-Bill
Some thoughts. If the #12 is only to satisfy the inspector and doesn't really seem to account for very much except maybe to trip the main breakers in the very unlikely event of a short at the uninhabited array, I'm not sure it's worth the install.
Just sayin....
in Georgia
System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
Having everything at the same potential is not just about safety, or code, but also some prevention of the strike hitting your array.
This becomes more relevant with multiple arrays, metal roofs, antennas, telephone, large trees, etc.
http://members.sti.net/offgridsolar/
E-mail [email protected]
As Dave says--Off grid, it is your choice.
With safety, I suggest playing conservative. Random electrocutions out in the middle of "nowhere" do happen (cattle are very sensitive to stray voltage/current next to a "hot metal structure"--Legs at the four corners pretty much guaranty that electrocution current flows through the heart).
Radio Station Grounding:
https://www.copper.org/applications/electrical/pq/casestudy/nebraska.html
Here is a four year old, longer thread (discussion in our "new" software) asking pretty similar questions about lightning:
http://forum.solar-electric.com/discussion/17973/how-concerned-are-you-about-lightning/p1
Just trying to be educational regarding safety and lightning--Not being argumentative or pedantic.
-Bill
The #12 back to the GFI from the array is also there on the XW inverter/chargers I use because their network senses escalating faults from the Mppts and can shut down the Inverter when things get bad. Once you have seen this happen and also seen the opposite it can open eyes if you are in a lightning prone area. We get a couple nasties a year here but I have systems that get that stuff for months at a time. YUK !
I am not sure of the value of running large bonding wire to the various ground stakes on the large distances many of my systems run.
I think it is fine below 200 feet but above that I just want the #12 there for the above reasons we laid out in this thread.
I had to look up Pedantic
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Yea--Life has interfered with intentions... Still want to do that.
-Bill
Counted about 50 of these cracks in the granite that were shooting streams of water out sideways a thousand feet or more.
Little old Mariposa has rain over 85 inches in some of the wet places.
http://members.sti.net/offgridsolar/
E-mail [email protected]
Do you have left to right bracing to prevent racking? (I see the front to rear brace).
-Bill
One benefit of the big array is that it's given me a great shady place to park the quads.
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
KID #51B 4s 140W to 24V 900Ah C&D AGM
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Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
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