Wire Gauge Required Question

BFL13 wrote:
Yes, thanks. I was checking just for changing actual wire sizes.

I think it is starting to make sense (to me---others got there long ago!) how to use the linked calculator in real life to pick the size of wire on either side of the controller for how much change that might mean in charging amps for a particular array wattage size.

Kind of an eye-opener, especially learning that 12v applies to one side and 24v to the other side of the controller. This is not easy, like 12v PWM.

Disregard the voltage, voltage in water terms is like water pressure, the higher the voltage, the higher the pressure.

Amperage is like volume flow, like a dams release measured in cubic feet per second.

It is easy. We do it all the time wiring residental. You are interested in I where I = Amperage.
If the run is 30 feet or less...

15 amps or less, use 14 gauge
20 amps or less, use 12 gauge
30 amps or less, use 10 gauge


Wire gauge size made easy.

Think of amperage as flow of water, and wire gauge as hose diameter, where gauge is number of balls to the pound. 10 gauge is 10 balls to the pound, so it is larger in diameter than 12 gauge which is 12 balls to the pound. Like a shot gun.

Now, if you exceed 30 feet, go up a size in wire from above, get a fatter, lower gauge number wire. More than 60 or 70 feet, go up a size in wire again. But know that copper is an expensive component when you go up a gauge is wire, and is priced accordingly. At some point, adding watts to the panel and allowing for losses in wiring can become more cost effective, depending on all your parameters.

In general, low voltage = 12v = requires fat wire. If you have 180 watts per panel and 18V Vmax, you'll have 10 amps. If you have 180 watts and you double the Vmax to 36V, since you doubled the voltage (pressure), you halved (ie the inverse) the amperage... so you can use skinnier wire on the higher voltage size. Battery side of charger controller is fat wire if with MPPT, it's the same size (fat) on both sides of the controller with PWM.

As the new kid on the block, I would like to thank everyone with their patience the past 4 days as I read, re read, and digested some very heavy material for me, a non EE backrounded guy, with all the myriad of variables that engineers must take into consideration when building and designing power supplies for our RV toys.

I've learned a ton of practical knowledge, I won't feel so dumb or overwhelmed around the the campfire next time with beers in hand when the motorhome guys start up with their electrical charging systems. I'm now beyond the Eu1000 /2000 /3000 or yamaha 2400 hurdles, and going more green each day.