It is nearly impossible to heat your home with solar thermal only (no back up heating source) unless a few measures or sacrifices are taken. On one end, if you had enough solar hot water storage to guarantee home heating during prolonged cloudy periods it would be possible. On the other end, without abundant storage if you are willing to sacrifice consistent home temperatures it might be possible. Easier with garage or shop that doesn’t have same requirement for consistent temperature. We almost always recommend having at least some form of back up heating source that can take over the home heating load if solar thermal system cannot keep up.