Wire Gauge Required Question

Salvo wrote:
That's exactly what I attempted to do in my example; use Imp current rating. You started talking about dynamic currents. The history of this discussion is all there. Move on.

Sal

ken white wrote:
That's what I said, install to the manufacturers recommendations and quit worrying about trying to tie down the values.

ken white wrote:
A solar system consists of dynamic variables, not static variables, so some assumptions about power, voltage, current, losses, etc... in this thread may be a bit off.

First, a solar panel behaves as basically a constant current device that will have its voltage, and hence power, controlled by both the Sun (whats available) and MPPT Controller (whats used).

What this means is maximum power transfer between the two devices under normal operation rarely occurs unless batteries are old/weak, and/or the battery bank is under sized for the loads supported.

So, losses between the panel and controller wiring may have little to no real effect on the system performance if the design is sized correctly - without going to extremes. (NOTE: If you are running your system on the edge trying to minimize losses just to keep up with load demand, then there will be energy demand issues, and you will never be happy...)

With that said, we should be concerned with losses and they should be kept reasonable.

For example, wire resistance increases with increased temperature, which increases power losses, which can create a spiraling loss effect when unreasonable installation standards are followed.

Couple these power/heat losses with wiring insulation ratings/properties, and safety becomes a concern - possible melted insulation and fire.

My advice is to follow standard installation guidelines, and upgrade slightly if you so desire, but not to go overboard on wire size, ampacity, losses, etc unless money and time and space are plentiful...

Just my $0.02