I have a new 2014 Nash 23d Trailer with the same Factory Solar System from Zamp. The Solar Controller is spec'd at 7 Amps.
The 20 Watt Solar Panel handily mounted on top of the A/C Unit out of the way is intended as only a Battery Maintainer.
Because the 23d has a Slide Out, Dual Batteries are supplied. The Zamp Controller does fine at charging them slowly, and keeping them topped off.
Via the Rooftop Plug supplied, I can add another Solar Panel so long as the Zamp Controller Spec is noted.
I 'get' Solar very well, and understand how modest this 2 Stage Controller System is. I'll upgrade for Boondocking fairly soon, and recycle the Zamp Controller & Solar Panel for another non-Trailer function.
- Zamp 7 Amp Solar Controller -