Carl
a string is those panels wired in series plus minus plus minus
how many in the string depends on the peak voltage and the max safe input volts for the controller
yes
they said the BEST configuration is to put those three panels in parallel
(3)in series is probably to high a voltage to be controller safe 'all the time'
now IF you had four panels, you could do (2) sets of two panels
just like wiring up (4) golf cart batteries
two in series , parallel to a second pair in series
MPPT takes high voltage and steps in down to lower 14+ volts charging and increases the amps, the WATTS stay nearly the same (minus slight conversion use losses)
easy example 60v at 2 amps 120w, becomes 14.x at 8 amps 120w
you always need big wire from controller to batteries
but wire size between panels and controller can be smaller
weight and CCC of RV.. the wire changes don't make enough difference to matter
the cheaper price of the small wire , doesn't count much because the controller cost more that the $$ saved on wire cost
its about operational efficiency
this matters a lot more to a full timer, who dry camps most of the time, than it does to the occasional weekend / vacation use
if the install is 'RIGHT' series panels will start producing a little sooner in the morning and keep producing a little later in the evening
but were talking minutes here, i would say less than an hour gain on each end at very low amps
i have had both MPPT and PWM controllers
and currently have over 600w on the roof with a 40amp PWM controller
