I am getting confused. Some points-
-The PWM "12v" "600w" system would produce 38a at Isc, not 50a but who's counting? :) that "600w" is defined as Vmp x Imp and Vmp is approx. 17.5v (not 12) so that leaves 600/17.5 = 34.3 amps. Isc is higher than Imp for the "working part" of the IV curve so you get that 38amps max.
-"Headroom"
1. The panel instructions warn that it can go over its ratings at times (such as cloud effect or cold temps, etc) and advises choosing the components (controller size, fuses, etc) to account for that by 20% (at least Sharp does)
2. The US NEC requires a 20% margin above panel amps rating for homes and (not sure if required or advised) RVs
3. Some (all?) PWM controllers will allow amps higher than their amps ratings to go through to the battery. The word is that the controller can then overheat and eventually fry but is ok for short times like cloud effect.
4. Some(all?) MPPT controllers limit their amps output to their ratings. Either:
a. That allows for panels going over their ratings so the controller won't overheat, or
b. It will run warm at rating which will shorten its lifespan, or
c. It will overheat if you strap it to too much panel so the incoming is way over its built-in overhead allowance
5. incoming voltage rating not to be exceeded at all or controller will fry instantly. "Overhead" here is to allow for incoming voltage to be above the panel rating Voc taken at 25C such as in cold temps. Total array Voc (series or parallel )is what counts to the controller when figuring that.
6. Expected max voltage or amps depends on the "voltage" of the system 12/24/36/48
I can't follow what happens to the ratings and their max limits when going from 12 to 24 to 48 and series parallel unless it is spelt out slowly not using any big words.
