"my knowledge and experience with thermo Dynamics tells me that 100W over a 1.6 Sq Meter area in sub zero conditions is going to be about as effective as urinating on a bush fire."
Eskimos insulate with snow. Bigger heat loss may be underside of panel that doesn't have any, as you say. At least if there's any breeze. It is plastic, though. You might be right that wattage similar to STC of panel won't make it shed snow, but then again it might.
"one of those 16 Hour nights or whatever it is in those horrible frozen places"
No, I meant those 28 day nights.
https://en.wikipedia.org/wiki/Polar_night
Maybe ground water source heat pump would help you. Cost of a well, though.
For AC, making ice at night (as you mention). (Either cooler air to dump to, or lower electric rates.) Or that ground water source again.
Those tubes running through ice/water ought to chill their contents to zero C. I would expect the ice to melt as fast as you heat the water above zero.
My panels from 15 ... 17 years ago cost me $5, then $4 per watt. A few years later picked up some more Sharp, used, for $2/watt.
Recently was looking for more to add. After realizing the SunPower put out 50% more per unit area I bought enough to replace 100% of area and paid $0.35/watt. I've seen panels from $0.15 to $0.50 and sometimes more, but selected these as a good price for premium quality. 1/15 the the price I originally paid! And I picked up grid tie inverters for $0.08 to $0.12
My bike is '64 (Super Hawk). Our daily cars/truck are all 2000 and older. And then I have some from the 50's and before. I've pulled and/or overhauled a few engines and transmissions. Maybe that's why I saved enough to be able to go overboard on PV.
My recent appliance acquisitions have been other people's hand-me-downs. A Kitchen Aid fridge for $50, mostly because I was scared by the bad reviews for all new models. A mid-range gas stove to replace the cheapie. My sister had bought a stove with electronic ignition during Enron scam, then had the $500 ignition unit fail twice. I'd rather just have a pilot light, but my "new" stove like the fridge had already proved their reliability with the previous owner. I've bought higher end appliances too, but that was for a rental unit.
As for your air conditioning needs, probably sun load on the house is a lot of it. There was a push for reflective shingles for a while. You said your South roof is clear of panels for cosmetic reasons, which means it gets full sun?
My exposed beam ceiling lets in a lot of heat. Hope to put insulation, maybe reflective layer under the shingles when I re-roof.