Hi,
Not sure exactly what you mean.

If you mean that the shutter/collector would fit over the window, then you would really be better off just using the window itself as the collector. As long as the window glass is not the type that absorbers a lot of sunlight, south facing windows make very good and efficient solar collectors.

You could make the inside surface of the shutter reflective and adjust them so that they reflect more sun into the window opening. This is good in that it increases solar gain without increasing heat loss through the glazing at all.

But maybe you had something else in mind?

Gary

That was what I had in mind. To direct more heat inward. The do it yourself solar window collector in the Mother Earth is tilted outward and connects into the window. But if you are in a northern climate and your southern side has eaves, that is where the snow and ice would drop. So I was thinking something tighter to the house that did not extend beyond the eaves to avoid snow and ice fall from the roof, might be an option. Will have to put more thought into it.
Thanks