What gauge wire?
I'm going to be adding a second solar panel and need to know what gauge wire I need for 2/140w panels on a 35' run. Thanks Keith
Forum Discussion
The $102 Eco-Worthy 20amp MPPT is the lowest cost "real" MPPT but it can only do about 42-45 Voc input limit, so it can do one big panel (250w max?) but not two 12v panels in series. (22 +22=44)
So that forces you to pay kazillions of dollars for MPPT just to run a couple of 12v panels and BTW you don't get any more amps with the MPPT unless you are at the North Pole. The MPPT method requires voltage and the panel loses voltage as soon as the sun gets on it, costing you amps. (you can't get anything with no sun and you lose when the sun is out!)
So the money does not work out for going MPPT in this case just to be able to use some skinnier wire.
Go parallel and PWM. You can wire it all sorts of ways, even use two PWM controllers (eBay $20 each) one for each panel and parallel them to the battery, or several other ways, doesn't matter, you will get your "expected amps" (two times the Isc of one panel)
My 130w panel got its expected amps (its Isc of 8.2a) even on hot days (which badly degraded the MPPT set but had no effect on the PWM set)), on 45 ft one way of #8 as an example.
IMO first try it on the existing wiring and if not satisfied, then get into improving the wiring.
So that forces you to pay kazillions of dollars for MPPT just to run a couple of 12v panels and BTW you don't get any more amps with the MPPT unless you are at the North Pole. The MPPT method requires voltage and the panel loses voltage as soon as the sun gets on it, costing you amps. (you can't get anything with no sun and you lose when the sun is out!)
So the money does not work out for going MPPT in this case just to be able to use some skinnier wire.
Go parallel and PWM. You can wire it all sorts of ways, even use two PWM controllers (eBay $20 each) one for each panel and parallel them to the battery, or several other ways, doesn't matter, you will get your "expected amps" (two times the Isc of one panel)
My 130w panel got its expected amps (its Isc of 8.2a) even on hot days (which badly degraded the MPPT set but had no effect on the PWM set)), on 45 ft one way of #8 as an example.
IMO first try it on the existing wiring and if not satisfied, then get into improving the wiring.
