PV wires and Grounding?

[Superman_006]

I am build an array that has 9 x 320w panels (9.4amps) in parallel it its going to be about 80ft from the inverter (could be less). Would I just buy 80ft of 10awg cables with the MC4 connectors on one end of it and run 1 ground wire all the way back to the panel or inverter? Or are people using a combiner box and using a 3 wire cable to get back to the inverter?

Also in photos that I've see of the ground wires on the racking are solid and not stranded but looking at 2 wire with ground PV ... all 3 are stranded

[foo1bar]

I am build an array that has 9 x 320w panels (9.4amps) in parallel it its going to be about 80ft from the inverter (could be less). Would I just buy 80ft of 10awg cables with the MC4 connectors on one end of it and run 1 ground wire all the way back to the panel or inverter? Or are people using a combiner box and using a 3 wire cable to get back to the inverter?

Also in photos that I've see of the ground wires on the racking are solid and not stranded but looking at 2 wire with ground PV ... all 3 are stranded

Ground mount I'm guessing?

How are the wires being run to the inverter?
If in conduit, the conduit needs to be sized large enough for the wires, and the wires need to be proper type to be inside conduit.
Cheapest option is likely doing a transition from PV wire to THWN2 in a Jbox at the array and running the THWN2 wires inside conduit to the inverter.

[Paul Land]

I am build an array that has 9 x 320w panels (9.4amps) in parallel it its going to be about 80ft from the inverter (could be less). Would I just buy 80ft of 10awg cables with the MC4 connectors on one end of it and run 1 ground wire all the way back to the panel or inverter? Or are people using a combiner box and using a 3 wire cable to get back to the inverter?

Also in photos that I've see of the ground wires on the racking are solid and not stranded but looking at 2 wire with ground PV ... all 3 are stranded

Does this help

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[Superman_006]

Better call Saul, I don't understand the chart at all. At the array... my Voc could be as much as 360v dc. Put % wise.. 1.119576% of 360v is like 4.3v. Is this how I figure it up/ does 4.3v mean a loss of wattage input?

Ive applied with AEP to use a SMA SB3000-US which sounds like has its own DC connect/ fuse combiner combo built on. I haven't bought it yet. However startup voltage is 228v and it will work between 200-400v and lets the smoke out at 500v dc.

When say THWN 2 wire in a conduit.... you're saying a metal conduit for grounding purpose?

i can't seem to find a definitive answer about the ground for lighting protection being stranded or solid. I've read arguments both ways... but I'm thinking 10awg vs dirrect lighting strike probably not going to matter in reality

[Paul Land]

Better call Saul, I don't understand the chart at all. At the array... my Voc could be as much as 360v dc. Put % wise.. 1.119576% of 360v is like 4.3v. Is this how I figure it up/ does 4.3v mean a loss of wattage

Just add your tweaks, I've been using this Calculator for long runs

https://www.rapidtables.com/calc/wir...alculator.html

[NewBostonConst]

I don't think lightening protection is a requirement but shock protection is. The ground gives a place for the current to go and trip the breaker to shut things down if there is a wiring/component problem.

I remember lightening wire is in the 4 awg size.....way bigger then your planned wire sizes...

[Superman_006]

The calculator is showing a loss of -1.49 v dc. I'm assuming that's no big deal? Is that a loss of watts?

also is it acceptable to just buy these, cut 1 end off and run an additional ground wire?

[ButchDeal]

is it acceptable to just buy these, cut 1 end off

This is a very acceptable path. Gets you a manufactured connection for the weather end at a reasonable cost without trying to crimp your own

[Paul Land]

The calculator is showing a loss of -1.49 v dc. I'm assuming that's no big deal? Is that a loss of watts?

also is it acceptable to just buy these, cut 1 end off and run an additional ground wire?

Stick with Brand Name you get what you pay for.
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[Superman_006]

Also if I go with the 3000TL-US which is transformer-less, The manual says that the inverter has no galvanic isolation. Wouldn't that mean that grounding the arrays would be counter-intuitive or does that mean you shouldn't ground it at all or I should ground the array but not thru the inverter

[foo1bar]

Also if I go with the 3000TL-US which is transformer-less, The manual says that the inverter has no galvanic isolation. Wouldn't that mean that grounding the arrays would be counter-intuitive or does that mean you shouldn't ground it at all or I should ground the array but not thru the inverter

There used to be installations where you would tie to ground one of the wires for the array (I think normally the negative wire)
There is still some documentation that talks about that.
But designs now have a ground (bonding wire really) tied to the racking and module frames, but not to the electrical wires of the array. These are called "ungrounded systems".

You'll have to research what the right answer is with a ground mount system for how to properly bond all the structure of the system. (And I think you'll want to have it in your plans that the AHJ approves.)

[Paul Land]

There used to be installations where you would tie to ground one of the wires for the array (I think normally the negative wire)
There is still some documentation that talks about that.
But designs now have a ground (bonding wire really) tied to the racking and module frames, but not to the electrical wires of the array. These are called "ungrounded systems".

You'll have to research what the right answer is with a ground mount system for how to properly bond all the structure of the system. (And I think you'll want to have it in your plans that the AHJ approves.)

If my memory serves me right there's ground and earth-ground. Rack needs bonding/ground
grond.jpg

[Superman_006]

Ok, I think your correct. It means " not grounding the array" means not bonding (neg) or (positive) to your array frames ... it's not saying no equipment ground

[Salience]

I believe it depends on the inverter being "non-isolated" such as MPP Solar - therefore "transformerless" - where the manual for the MPP for example specifies NO GROUNDING of the array power wires. I came across this analysis in Bonding and Grounding PV Systems _ IAEI News magazine.htm:
"a large percentage of new inverters being installed today have non-isolated ac output circuits. What this means is that the ac output of the inverter does not pass through an isolation transformer the way most grounded dc inverters do. PV systems with grounded dc PV arrays must have an isolation transformer to isolate the grounded dc array from the grounded ac service conductors that it is connected to on the output of the inverter. With a non-isolated inverter, the lack of isolation to the grounded ac service conductors requires that the dc PV array be ungrounded for the inverter to work. While this type of system is operating, the dc PV array actually becomes referenced to ground through the ac output conductors. The PV industry often refers to this system configuration as "ungrounded," but in reality the PV array is only ungrounded when the inverter is not operating. As soon as the inverter begins producing power, the whole system becomes referenced to ground through the ac service conductors."

[NewBostonConst]

Ok, I think your correct. It means " not grounding the array" means not bonding (neg) or (positive) to your array frames ... it's not saying no equipment ground

Bonding does not mean connecting a ground wire to the frame of the array...
Bonding is connecting the neutral wire to the ground wire in a main circuit breaker box. It is connected in one place and only one place. This is standard in the US, Europe is different.