I actually live on the same latitude as Ontario so -40F/C is not unusual. Add in windchill, and it gets even more common, given my windy location.

Yeah, I understand I'm probably an outlier at 66F. I was using the numbers more to point out how little a house temperature will drop with good windows and insulation.

What? They store the surplus in their batteries during the day and use it at night.

I genuinely do not understand why people are so afraid of solar. It's baffling.

I live in a northern climate and I know multiple people who are net zero with solar+basic battery.

Proper insulation and good windows go a very long way. For instance, I set my heat to 66F during the day and 60F at night. When I wake up in the morning, the register is usually still above 60F.