The sun shines through the window into the lower box, heating air that rises through the upper box, dehydrating fruits and vegetables on the racks. That's the theory; we'll see if it works. Idea shamelessly stolen from Raven Waters; I figure it's his fault if it doesn't work. :-)
Gretchen Quarterman placing racks in the solar dehydrator Pictures by John S. Quarterman for Okra Paradise Farms, Lowndes County, Georgia, 3 August 2012.