Growatt N-G confusion

[timselectric]

I thought the battery cables needed to be the same length when you use 2 inverters , something about current sharing, I will read the annual again but it says something about keeping all battery cables the same length

Not individual positive and negative.
Total length per inverter, needs to be the same.
The reason is that each inverter needs to see the same voltage, when stacked as a single system. Conductors have resistance. Longer Conductors have higher resistance. Resistance creates voltage drop.
So for both inverters to see the same voltage. The total length (positive and negative added together) for each inverter needs to be the same as the other inverter/s.
For example: inverter #1 could have a positive cable of 6ft and a negative cable of 3ft.
Inverter #2 could have a positive cable of 3ft and a negative cable of 6ft.
The resistance would be the same. Because the total length (round trip) is 9ft, for each inverter. Therefore both inverters would see the same voltage.

 

[MT off grid]

Not individual positive and negative.
Total length per inverter, needs to be the same.
The reason is that each inverter needs to see the same voltage, when stacked as a single system. Conductors have resistance. Longer Conductors have higher resistance. Resistance creates voltage drop.
So for both inverters to see the same voltage. The total length (positive and negative added together) for each inverter needs to be the same as the other inverter/s.
For example: inverter #1 could have a positive cable of 6ft and a negative cable of 3ft.
Inverter #2 could have a positive cable of 3ft and a negative cable of 6ft.
The resistance would be the same. Because the total length (round trip) is 9ft, for each inverter. Therefore both inverters would see the same voltage.

 

[MT off grid]

Well crap, I spent hours calculating lengths to keep everything the same length, if I use the breakers I would need to make the positives About 10 inches longer then they currently are but that means I would need to make the negatives 10 inches longer? I used 2/0 on everything but it won't
fit in the breakers, would it be okay tisus3 4awg to run positives from inverters to breakers? It would be the only wire in the entire system that is 4

 

[timselectric]

Well crap, I spent hours calculating lengths to keep everything the same length, if I use the breakers I would need to make the positives About 10 inches longer then they currently are but that means I would need to make the negatives 10 inches longer?

No, only the positives.

 

[MT off grid]

I think I updated my comment as you were replying to mine, would it be okay to use 4 awg for my new longer positives even though I over build the system wi

 

[MT off grid]

No, only the positives.

 

[MT off grid]

I think I updated my comment as you were replying to mine, would it be okay to use 4 awg for my new longer positives even though I over build the system with 2/0?

 

[timselectric]

That's fine from the bus bars to each inverter.
The breaker can still be 125a.

 

[MT off grid]

That's fine from the bus bars to each inverter.
The breaker can still be 125a.

 

[MT off grid]

So since the smallest wire is still rated for the inverters I'm fine? Wasn't sure if smaller wires on the positive and larger on the negative would cause any issues with resistance

 

[timselectric]

So since the smallest wire is still rated for the inverters I'm fine? Wasn't sure if smaller wires on the positive and larger on the negative would cause any issues with resistance

As long as the lengths are the same. The resistance is the same.
Both positive #4's same length.
Both negative 2/0's same length.

 

[timselectric]

But negative and positive don't have to be the same length. (Or size)

 

[MT off grid]

As long as the lengths are the same. The resistance is the same.
Both positive #4's same length.
Both negative 2/0's same length.

 

[MT off grid]

Sounds good, I will add some 4 awg positives and see how it goes, can't believe I spent hours calculating how to make all of the cables the same length

 

[MT off grid]

But negative and positive don't have to be the same length. (Or size)

 

[MT off grid]

.

 

[MT off grid]

But negative and positive don't have to be the same length. (Or size)

 

[MT off grid]

Is 6 awg still the required size ground wire for solar array? I will be doing a ground mount that is about 100 feet from the house, the NEC I read says that a 6 is required anywhere that damage to the conductor to happen, I will be using conduit and buying it so wasn't sure of o still need that large of a wire

 

[timselectric]

How many amps are you going to have on your solar circuits? Check the chart I posted. (Post #87)
That will tell you what size for in conduit. #6 is only required where it's exposed.

 

[MT off grid]

How many amps are you going to have on your solar circuits? Check the chart I posted. (Post #87)
That will tell you what size for in conduit. #6 is only required where it's exposed.