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diy solar

Wire gauge to use for a 150 foot run

10 AWG at 2.4% drop per the calculator below.
You can play with the numbers.

But 2 of those 200w Renogy panels in Series are 90.8Voc so cold weather would put you right at 100V

Thanks for the info. I assume it is OK to have it up at 90 voc if the controller rating is 100V?
 
Thanks for the info. I assume it is OK to have it up at 90 voc if the controller rating is 100V?
How cold does it get at that location?
Voltage goes up on cold clear mornings.
32°F x 1.1 so right at 100Voc.
 
Oh no! You lost all of 4% out of 400W (STC) of PV!
That's 16W.
With 10 awg instead of 12 awg, you'll reduce the loss to only 10W.
So you can save 6W (at peak production), about $1 to $3 worth of PV panel capacity ... for how much copper wire cost? I'm guessing $25?
Yeah, I will probably spend the extra for the 10 awg so I have some room if I decide I need more watts eventually. Running the wire through conduit in the ground is going to be a pain, so would like to avoid doing it twice.
 
How cold does it get at that location?
Voltage goes up on cold clear mornings.
32°F x 1.1 so right at 100Voc.
Probably -5F or so is about as cold as it will get here. It is Southern Ohio though, so most winters won't drop below zero.
 
Yeah, I will probably spend the extra for the 10 awg so I have some room if I decide I need more watts eventually. Running the wire through conduit in the ground is going to be a pain, so would like to avoid doing it twice.
Found three to compare:


12 awg $70
10 awg $95
8 awg $162

So 10 awg is good, may break-even with panels for two strings in parallel, depending on your panel cost.

Probably -5F or so is about as cold as it will get here. It is Southern Ohio though, so most winters won't drop below zero.

When it comes to Voc, don't go by "most winters", or "about as cold" - use "the coldest it ever gets".
So consider a different panel or different charge controller, in order to never kill the charge controller.

There is a 327w Sunpower panel 75 Voc, another 427w 86Voc, examples that should stay below 100Voc on a cold day.
 
10 gauge commonly used for solar is rated for outdoors and UV. My MC4 connectors are made to crimp to 10 gauge.

24v panels can be used to charge 24v batteries. 300w 24v Renogy: Optimum 32.2v, open circuit 38.8v
 
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