The plan is NOT to be in area's where it 32°F or to be there or just a short period of time.. So with that said could you series 2 panels and have the third in parallel so the voltage is lower going to MPPT charge controller.?? not that it really matters..
The amount of time we would spend in freezingish weather would be small in the great scheme of things. If that were the case I would take one panel "off the grid" and go with two. From what I was reading the MPPT can take overvoltage it just does nothing with the extra voltage.
In doing the string calculator and using 19°F as low and 95°F high with a Morningstar Product: TriStar-MPPT-45 controller, it still show 3 strings as "Optimal Configuration" at 570 watts.
PS i have been posting using a MPPT controller way the by.
