The key is to have exact south facing glazing, whatever the exact method is. Any other direction tends to overheat in summer and autumn, and not give much heat in winter. Is the window or wall south facing? The amount of heat collected is limited by the area of south-facing surface.
I heat my house with a detachable greenhouse. I put up the plastic in October or November and take it down in late April or May. But I designed my house with the long wall facing south, and the rooms that we want to be heated all on that south side.
There are hot air generating collectors that can be roof mounted. But honestly hot air blowing into a room doesn't really give much thermal comfort unless there's really a lot of it, and then there are other comfort issues.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.