The honest short answer
Yes, panels work all winter in Edmonton. They just produce less when the days are short, and more than enough in summer to make up for it. The trick is sizing for the whole year.
This is the number-one worry I hear at the kitchen table: "won't the snow and the cold kill it?" It is a fair question and the answer is reassuring. Panels keep producing through winter.
Snow does not sit long
Cold weather actually helps efficiency
Daylight hours are what genuinely drops
That last one is exactly what a properly sized Edmonton system plans around. I would not run solar on my own roof through these winters if the annual math did not hold up, and it does.