60 amps is the output. I imagine wire size is the issue, among other things.
Input wattage (and voltage) are the other two factors.
Morningstar claims their controllers can just ignore any extra input (within reason).
I've always based input wattage on output amps X voltage, so the sixty amp can possibly tolerate 800 watts.
My Blue Sky, on the other hand, wants a 25% cushion so that 30 amps becomes only 22.5 amps (X 12.8 = 288 watts). As I have 256 I'm unable to add more panels.
I'm possibly going to throw caution to the winds this next summer and do a rack on the roof with 1600 watts of panels. I'll probably go with the 40 amp Grape controller(s).
