Wallowa said:
Hey,
thanks for all the feed back...like I keep saying, I have a lot to learn!
Rando: Forgot about the Zamp 30 PWM controller dumping extra volts, that controller is not the choke point as I understand it, but amperage potentially was excessive for the 10 gauge with the length of wire, and the 15 amp fuse is of course the ultimate limiter in my circuit....However, it does seem that as I currently have my solar system configured it should stay on line even if I lose a percentage of the amps and volts; nor should it blow that 15 amp fuse....no idea the problem I could generate by putting in a 20amp to replace the 15 amp fuse, but I doubt if that will be necessary ...will carry extra bag of 15 amp fuses
just in case..
Phil
I think we are on slightly different frequencies - my point was that the ZAMP PWM
is the choke point, and thus you won't loose any power (voltage or current) from using thinner wire. Your amperage is well below the limits for 10 AWG wiring (>30 amps, se below) and again the fuse is unnecessary so putting a larger fuse in there is a good idea if you will be near 15A output from your panels.
I think Vic is better at explaining this stuff, but I can try - your solar panels have two current specifications Isc (Short circuit current - which is the maximum current the panel can produce into a dead short) and Imp (maximum power current - which is the current at which you get the maximum power from the panel). The absolute maximum current the panel can produce (unless the sun goes super nova) is Isc, so as long as your wire is rated for that current, there is no need to fuse as there is no circumstance where the fuse will be needed. One caveat to note though - you
should to have a fuse between the charge controller and battery, or built into the charge controller. The battery
is capable or producing much more current than the wire can handle.
This question comes up a lot so as a general rule,
up sizing the wire to your solar panels is not going to significantly increase solar panel performance, particularly for the effort involved. The time/money would be better spent on more panels (in series if necessary) and/or an MPPT charge controller.
As for the power loss - 50' of 10AWG wire has a resistance of 0.05 ohms. Assuming two 160W panels in parallel with an Imp of 15A at Vmp of 21V, this is a voltage drop of 0.75V, which reduces the power output by 0.75/21 = 3.5%. This is the maximum 'extra power' you could get by upgrading the wire to (super conducting?) wire with no resistance with your panels at peak performance into an MPPT controller. In reality, the upgraded wire still has some resistance, and the current is actually much lower than Imp for a flat mounted panel so the power loss is around 2%.
PKYS has nice table of
wire ampacity based on ABYC specifications:
Seeing we don't know the exact specs of the wire FWC uses (unfortunately in mine they seem to have used residential wiring) or the connectors they use, I would stay a bit below these limits, but 30A should be fine.
