Which insulation do you use with your solar home?
Passive House. Not sure about temperature range where you are, but you are a long way South of us so will get much more Solar than we do in Winter. Our Winter Solar is 10% of our mid summer (because of our Latitude). For us winter nights are a few degrees minus-C, and daytime < 10C. Night temperatures of -10C or below, and days not rising above 0C, are a once-or-twice-a-decade thing, and only lasts maybe a week. Summer is rare for > 30C, but does happen, and even then nights are usually 16C, rarely >20C, and night-venting lowers the temperature.
Passive House is very high levels of insulation, very very good air tightness, and mechanical-ventilation with heat-recovery (exhause air heat incoming air).
In mid Winter with house unoccupied for the day it will lose 1C. In Summer it gains 1C during a hot sunny day, and we easily lose that overnight by opening the windows. We've been in a heatwave in the UK for some time, next week 30C - 35C forecast. We haven't had rain for months (so hotter / sunnier than "normal"). Max day temperature in the house has been 24C (no air con installed here)
In principle Passive House (here in UK at least) needs no winter heating system installed, so the cost saved on that, fuel, and no maintenance / replace goes towards the insulation. It is reckoned that Passive House costs 7% more than "normal", but then close to zero fuel bills and no maintenance / replace costs for boiler/furnace - for the lifetime of the building.
The mechanical ventilation is also far better for health. A combination of no corners-of-rooms with bad airflow that then cause moulds etc. and the even temperature. We've had passive House for 5 years and wife and I not had a winter cold / cough in hat time. I, in particularly, have spent a good month shaking off a winter cold previous to that, and I cannot remember a single winter when I didn't have one.
Ours is actually an extension (to original house) and we already had a boiler, so we did install underfloor heating downstairs. Since the build we have lowered the thermostat in the main part of the house, as we don't actually "live" in it during the winter, bar a few festive days entertaining, and our total fuel usage has dropped by 50% - even including heat for the new part, so basically Passive House part is using "not much more than nothing". Upstairs has no heating and minimum temperature over winter is maybe 17C, mostly 18C plus.
Windows are triple glazed. Important that inner surface is no more than 4C less than room temperature, so that adjacent air doesn't "fall" which creates convection draughts and the feeling of "cold" (and then you turn up the thermostat to compensate).
Given that we have underfloor downstairs, and if we had used a heat exchanger, then I would have been able to use "cold side" to feed cold water through the floor in Summer. I was more focused on "eco" than I was "comfort", so now I've got over that!!, and we are so much more Green than everyone we know, I might persuade myself to retro fit that
A bit like buying first EV it was a leap of faith, but absolutely hands-down the best decision we ever made