The solar air heating collector uses recycled aluminum soda pop cans for the absorbed. The pop cans have the tops and bottoms drilled out, and are assembled into vertical columns that the air passes through.
In operation, the black painted soda pop cans are heated by the sun, warming the air that is flowing up through the cans.
More Info A manifold at the bottom evenly distributes room air to all the can columns, and a similar manifold at the top of the collector collects the heated air for distribution back to the room.
The combination of uniform air distribution to the whole collector and the large amount of heat transfer area from the cans to the air makes for an efficient collector. Greg's collector also uses Twinwall polycarbonate glazing -- this is a type of double glazing that reduces heat loss and increases the efficiency of the collector Can You Be Creative