http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm

This guy has a nice step by step blog style of what he did.
http://www.arttec.net/Solar/BarnHeat.html

-Jim

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.