Solar with Battery storage is a very useful source for heating energy, even in the coldest climates in CA. Even in the mountains where it drops below freezing at night, most places it's still sunny a lot more than the US average during the day. Most Battery setups I know of target a 4 day stretch of cloud cover for storage capacity, so it is certainly an option.

Where I live at 7000 feet, we have so much sunshine, even in winter, solar is a very viable option. Legislation removing people's ability to recoup the costs is the only reason it's not in every house in the city. The only option left is a much more costly battery setup.