passive solar
 

I have seen a shop near where we live that has solar hot air panels on the Southwest Wall and the dual gates facing southern have been modified out to dual 36" storm gates...providing lot of light to the inside area and also act as 42 sq ft inactive solar warming panel for the floor and two black plastic water drums which are shifted around a store once warmed to push off heat in other areas at night. Any ideas on how realistic or effective?

I'm sure they are effective. Solar hot air panels are a proven way to produce heat.

I'm not sure about the barrel thing though. Could you explain it a bit more? I'm guessing these are just for thermal mass.