# Quick electrical question



## Meinecke (Jun 30, 2017)

Hello...

I am gathering the needed equipment right now to build my Solar array...
And for the transport of the DC to the House (approx. 80-90 ft) i want to put down thick cable.
But 4 or 8 gauge as i was reading here is not on the for free list right now...
BUT i can have as much 10 Gauge strained cable as i want...
Now i was thinking if 2 runs of them per pol (4 in total) would be working or not to recommend?
Would result in best case gauge 7...according to calc that i found...
Would you use that idea for a underground in PVC conduit on that distance or wait to find better cable?
And what would be the max wattage you would send through it without to much loss?!

Thx for a few thoughts


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## farmrbrown (Jun 25, 2012)

I don't know, I'll let others weigh in, but my instinct says, "No, it don't work that way."
It's the ampacity of the individual wire.
Now if you split up the arrays into lesser amps per wire run, then that would work.


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## Meinecke (Jun 30, 2017)

It is just that i want to dig just one time...so place over provisioned capacity in the ground...and be done with it...
Right now it will be just 20 Panels with a peak of 3500 watt...
But as soon that is up, i assume it will be either added on or replaced piece by piece


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## Bellyman (Jul 6, 2013)

There are a couple of ways to minimize losses. Heavier conductors are one way. I wouldn't see how multiple conductors would be a problem considering that many wire cables are made up of multiple individual strands. I'd be reluctant to mix and match different sizes of wire for individual runs, or lengths, but I don't think that would mean much in your application.

Another thing you could consider is running a higher voltage through your conductors. 12volts vs 48volts makes a considerable difference in power losses. If you are running the DC voltage into a charge controller, there may be options for even higher voltages. Some charge controllers can handle somewhere in the 200v to 250v range from what I read. 

Yet another option is to put your power house out with your panels and run everything from there at 120v or 220v AC. 

Just the thoughts that come to mind, but others will have more experience. Best of luck!


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## wy_white_wolf (Oct 14, 2004)

Not allowed by any code that I know of. Should 1 wire break or gets disconnected all the current would be carried by the remaining wire that is too small.

If you spilt your array so each pair is only connected to 1/2 the array it would be legal if the wire is large enough. That way if one wire break or gets disconnected it doesn't affect the other.

WWW


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## Meinecke (Jun 30, 2017)

Ok...thx...then i gues i let this cable offer pass...and look further...
Thx for your thoughts...


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## Steve_S (Feb 25, 2015)

Two thoughts here.
1) If your running 80/90 feet from Panels to Demarcation Point (entry to building) there would be wisdom in running a conduit, such as a 4" O-Pipe along with a pull string (thin nylon rope) inside it, therefore if you ever need to pull more wire, change something etc, you have the ability in place with least amount of fuss... You did say you intended on future upgrades & changes, so accommodate such in your planning ahead.
REF: https://www.homedepot.ca/en/home/p.4-inch-x-100-foot-solid-tubing.1000124225.html
just ensure you use Non-Perforated pipe... BTW: TSC (Tractor Supply in USA) like ours sells this for the best price on average.

2) You can use 10 AWG *(NMWU)* "Non Metallic Wet Underground" for each panel "set" (4 or 8 pending on panel capacity, max combined volts & amps) from the panels to the controller point at which time you would need to connect them via a Combiner Box, providing a breaker for each incoming wire. You do need the ability to shut off / disconnect the panels before the controller - safety first !

3500 Watts / 20 panels = 175 watt panels. ?
Would be better if you included the specifics about the panels you are using, a photo of the Data Tag on the back would be best. Also if they are different versions / generations.


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## melli (May 7, 2016)

Meinecke said:


> Ok...thx...then i gues i let this cable offer pass...and look further...
> Thx for your thoughts...


I agree with posters who suggested upping the voltage (could run solar array in series, have batteries/controller/inverter at array???). To limit turning the cable (any size) into a light bulb (resistive load), one has to increase voltage. You increase voltage, you decrease amperage. 
The only other way, as you were thinking, is to increase cable size or use X number of 10g cables. Using this calc, I am getting a need for super sized cable like 1/0 AWG (5% loss). Depends on voltage 12/24/48V from solar array. 
http://www.nooutage.com/vdrop.htm
BTW - I would be looking at ACWU, as it is direct bury, armored, and cheap. The only issue as someone noted is whether boxes at either end are ok with aluminum conductors (and they can handle the cable size). I went this route for long (350ft) AC run (2 - 250MCM ACWU). PIA. I had to get two splitter boxes rated for 400 amps! I probably would have been fine with one cable...overboard.


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## MichaelK! (Oct 22, 2010)

Which charge controller are you going to use? If you purchase a MPPT controller you can reasonably wire the panels in series to get them in the 100VDC+ range. For my own system, I have arrays of three 300W Renogy panels wired in series to give me ~115VDC. Right now the longest array run to the combiner breaker box is ~50feet, and I see no voltage drop with stranded 10AWG solar wire. The combiner then feeds the 115VDC into a Midnight 200V charge controller which then feeds my 48VDC battery bank at 59.3VDC.
Here's what my arrays look like.







I'm glad that Melli suggested the voltage drop calculator. Here's another one that I like to use.
http://www.calculator.net/voltage-drop-calculator.html Using this calculator and a run of 100 feet, you'd expect to lose less than 2 volts (running at 120VDC) with 10AWG wire.

I am running mine through plastic conduit (can you see it there?) that will be buried soon.

Getting back to you panels, which panels are you using, as Steve asks? Have you already purchased them? The reason is, the best bang for you buck right now is with the larger grid-tie style panels in the 250-275-300-325 watt range. Those can now be had for less than 1$ a watt now. Calling them grid-tie doesn't mean their application is limited to that. They make excellent off-grid arrays. That's what I'm using in my off-grid system pictured above.

My suggestion is to draft up a complete plan here first before start purchasing random components and let solar experienced members give you some feedback into your selected options.
Good luck!


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## Murby (May 24, 2016)

In order to help you design your system, we need to know specifics, circumstances, budget, equipment, etc.... 

If the world collapsed, I wouldn't hesitate to bundle a bunch of 10ga wires up to make a single conductor.. but the world hasn't collapsed and there's no need to takes risks that way.

List some specifics and it will make this all go much easier...


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## Meinecke (Jun 30, 2017)

Ok...it will be my cheaply acquired set of 175 watt panels...they have a 600 volt max voltage...
I want to go with Murby's suggested Grid tie inverter that was stating 3800 watts max...and have 2 ports input
The correct name of it, i have in notes at home, so sorry for being incomplete...
And i already skipped the 10 ga cable...is now money in my pocket from salvage place...
My plan is to dig a pipe into ground...about 4 inch pvc...LAN cable, wires, rope etc...
So i was just curious if i could use combined cables...but i get that it would be no good idea...so i will go with 4 or even thicker...lets see what i come across.
Already thought of inverters per panel, but since they would cost to much...

so far i have: 
20 175 panels ~ 175 watt
40 yards of 1 inch galvanized pipe
so inverter, cable, mounting and "some" concrete is still missing...smile
Thx for being here when questions arise...
@Murby...how is the setup running so far? Any improvements/sagging/mistakes done?


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## Murby (May 24, 2016)

Meinecke said:


> Ok...it will be my cheaply acquired set of 175 watt panels...they have a 600 volt max voltage...
> I want to go with Murby's suggested Grid tie inverter that was stating 3800 watts max...and have 2 ports input
> The correct name of it, i have in notes at home, so sorry for being incomplete...
> And i already skipped the 10 ga cable...is now money in my pocket from salvage place...
> ...


Do not run your ethernet cables with your power cables. Separate them by at least 6 inches per 50-100 feet of parallel run.

My setup is working better then I expected. We are generating about 110% of our calculated output. Not sure if its weather related or the fact that I laid in over-sized wire and people generally don't do that.

As for sagging, none yet but I wouldn't expect any of that this soon even if it was going to happen. It takes a year or two or at least one freeze/thaw cycle to see those kinds of effects.

What's the 1 inch galvanized pipe for??


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## Meinecke (Jun 30, 2017)

The pipe is for the frame...


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