A search for solar walls in google or Youtube will yield lots of examples.

The cans came from Eastman Recycling.

A jig was needed to punch the cans.

The cas were arranged to allow free air movement.

After the cans were in place, they were painted a mat black by a commercial spray painter.

When the air is heated up, a fan sucks the hot air from the top of the wall down under the garage floor and heats the floor.

The windows are arranged so there is minimal space between the end of the can and the window.

The windows were destined for the land fill -- but were rescued.

This arrangement has kept frost out of Ron's garage.