I don't know anything about modern fancy
solar windows, but I have lived in passively solar heated houses in a cold climate for over 20 years, and I can say that using thick curtains for winter nights makes a huge difference. We have just single or home-made crappy double glass, not special coatings, nothing. Even if the windows don't have adequate insulating value on their own, you can put up thick curtains made of blanket cloth for the winter, and diligently open and close them every morning and evening during the coldest season. Then in late winter when they seem less necessary, take them down, wash them and store them. I believe this will make your solar windows much more effective.
PS You can add your location in your profile so that it shows on every one of your posts, and it will make it easier for people to respond to your future posts or questions.