Want to install solar, questions
We recently got our new 2017 Nexus Ghost and I had it pre wired for solar. Nexus provided (in a box) a Zamp 30 amp Digital Controller with the pre wire. My question is how many 100watt paneles well...
Forum Discussion
KD4UPL wrote:
30 amps would be the total of all the Imp ratings of the solar panels wired in series. This would be around 500 watts total.
Assuming the panel's Vmp is 18v then it would be 18V x 30A = 540 watts.
Probably just a "typo" mistake, but in series you add the voltages, not the amps. PWM controllers have a low max Voc input limit, so are not suitable for panels in series anyway.
PWM controllers do not use Imp or Vmp. That is for controllers with buck converters in them, with MPPT. The MPPT sets/finds the Vmp and the Imp is what you then get on the line from the panel to the MPPT controller. The Imp is used when calculating the line loss on that path. (The higher output current is used for calculating the line loss on the controller to battery path wiring, which has to be fatter gauge when the buck converter is stepping down eg 24-12)
With PWM controllers you get the Isc of the panel when aimed at full sun. When flat you would normally get less than the Isc so it might work to use five 100w panels, but "it depends"
I forgot the Bogart PWM does clip its amps somehow. Most don't.
You can "over-panel" an MPPT controller, since with their buck converters, they do have self-limiting outputs.
From reading the Tracer MPPT manual it appears it limits the input watts as the way to limit its output. So it does not actually "clip the amps" I may be reading that wrong, though--it is not very clear.
