I have decided to go 48 volt after all the input from here.

[Jamie.sanders]

Well after several Discussions and listening to several people On here I have decided to go with a 48v system.
The big bonus with this is I will save over $700 on wire from my panels since I hav s 230 foot run and wiring my panels 3S2P will allow me to use 6 gauge wire vs 2 gauge wire.
I will have to buy 8 more LI cells but that saved $700 will go a long way towards purchasing the cells.
I finally made up my mind and just ordered the Schneider 48 volt inverter. Nervous but I think I’m headed in the right direction.

 

[Nobodybusiness]

Well after several Discussions and listening to several people On here I have decided to go with a 48v system.
The big bonus with this is I will save over $700 on wire from my panels since I hav s 230 foot run and wiring my panels 3S2P will allow me to use 6 gauge wire vs 2 gauge wire.
I will have to buy 8 more LI cells but that saved $700 will go a long way towards purchasing the cells.
I finally made up my mind and just ordered the Schneider 48 volt inverter. Nervous but I think I’m headed in the right direction.

I think you will be much happier with the 48v configuration.

 

[iamrich]

What are you using for a solar charge controller? Assuming you are running pretty standard panels, you are looking at 105v at 17a or so. Running 6awg cable I think you will see a 5% drop.

 

[Jamie.sanders]

Charge control is a midnite solar 200, the panels are 440watt panels, according to the calculator my array wired 3S2P will only need 6 gauge wire vs wiring it 2S3P would require 2 gauge to keep loss below 3%

 

[Jamie.sanders]

What are you using for a solar charge controller? Assuming you are running pretty standard panels, you are looking at 105v at 17a or so. Running 6awg cable I think you will see a 5% drop.

If I wire my panels the this way
3S2P
then it would be
3S = 3X Voc/Vmp
2P = 2X Isc/Imp
or
132.9 VMP
21.06 ISC
for a length of 230 feet in plastic PVC

I plug this into the calculator and it says I can use 6 gauge wire with a 2.89% voltage drop. this way will save me around$1,000 vs having to use 2 gauge

 

[iamrich]

Makes sense. I have 250w panels, so my numbers were low. The reason I asked about the controller, is because if you could series all the panels (265v, 11a) you could probably get away with 8awg, maybe even 10awg.

which voltage version of the midnite solar 200 do you have?

 

[Kornbread]

Don't forget to double your footage. 230 feet to and 230 from would be 460 feet.

 

[rmaddy]

I'm confused here. How does the battery voltage have any bearing on the wire size being used between the solar panels and the charge controller? Your panels in your chosen configuration will put out a certain amount of amps and volts. The battery voltage is irrelevant to those values.

The battery voltage certainly affects how much wattage you can use with a given charge controller and of course it affects many other wire sizes but not the wire to the panels.

There are likely lots of good reasons for choosing 48V but the PV wire size is not one of them.

 

[iamrich]

The battery voltage certainly affects how much wattage you can use with a given charge controller

I think you hit it on the head with this...

 

[rmaddy]

I think you hit it on the head with this...

But how does that result in 6AWG versus 2AWG wire?

 

[iamrich]

But how does that result in 6AWG versus 2AWG wire?

The OP would have to answer that, but my guess is that the original plan was using a much lower voltage from the panel array to the controller (or maybe a different array completely). The new plan probably has a higher voltage, so it can use smaller wire. Maybe a limitation based off the equipment being looked at, but again I am guessing...

 

[Jamie.sanders]

The OP would have to answer that, but my guess is that the original plan was using a much lower voltage from the panel array to the controller (or maybe a different array completely). The new plan probably has a higher voltage, so it can use smaller wire. Maybe a limitation based off the equipment being looked at, but again I am guessing...

yes exactly, I was originally going to go 2S3P, this array would require 2 gauge wire.
going to 3S2P will allow me to use 6 gauge wire, but my CC would not handle the nearly 200 amps so I am returning the midnite 150 and
getting the midnite 200.
this saves me over $700. which will buy over half the batteries I need to go 48 Volt. so why not?
I already have 24 cells on order, so I will need 8 more. (around $1200).
I had not bought my inverters until yesterday when I decided to go 48V. I went with the Schneider 48V pure sine wave split phase inverter.

 

[740GLE]

Location of SCC and combiner box weren’t given, the OP enjoys having us guess. ?

 

[rmaddy]

yes exactly, I was originally going to go 2S3P, this array would require 2 gauge wire.
going to 3S2P will allow me to use 6 gauge wire, but my CC would not handle the nearly 200 amps so I am returning the midnite 150 and
getting the midnite 200.
this saves me over $700. which will buy over half the batteries I need to go 48 Volt. so why not?

OK, this confirms that your choice to go with a 48V system had nothing to do with being able to use 6AWG instead of 2AWG. The OP is worded such that it claims the big bonus of choosing 48V is saving lots of money on the PV wiring. But the savings come from using a different SCC that allows for the panels to be in 3S2P instead of 2S3P.

 

[MichaelK]

I am returning the midnite 150 and getting the midnite 200.

I had not bought my inverters until yesterday when I decided to go 48V. I went with the Schneider 48V pure sine wave split phase inverter.

Congratulations! You are assembling a system that closely resembles mine. You'll be very happy with the combination.

 

[HRTKD]

OK, this confirms that your choice to go with a 48V system had nothing to do with being able to use 6AWG instead of 2AWG. The OP is worded such that it claims the big bonus of choosing 48V is saving lots of money on the PV wiring. But the savings come from using a different SCC that allows for the panels to be in 3S2P instead of 2S3P.

That sums it up well. For a fixed installation I would have gone 48 volt from the start.

 

[Jamie.sanders]

Don't forget to double your footage. 230 feet to and 230 from would be 460 feet.

I don’t get this? Why double it?

 

[HRTKD]

I don’t get this? Why double it?

Some wire gauge calculators specifically tell you to provide the round trip distance, not the one-way distance.

 

[rhino]

There are charge controllers and all in ones that could handle all 6 panels in series.. that could save you even more money in wiring if that is your main concern.

 

[dralthi]

It's the best way to do it!