The following is an excerpt from The City Homesteader: Self-Sufficiency on Any Square Footage by Scott Meyer (Running Press, 2011). The excerpt is from Chapter 3: Save It For Later.
Using passive solar power to dehydrate food is energy-efficient and lets you dry tomatoes and fruit for which air-drying typically isn’t fast enough. You can make this simple solar food dehydrator with stuff you have around the house or that’s easy to scrounge up. It’s better to try drying on a sunny day, in warmbut not scalding temperatures, rather than in the dead ofwinter.
1. Get a long, shallow cardboard box like a men’s shirt box or gift box. The lid will be the solar panel, and the food will go inside the bottom half of the box.
2. Cut four air holes in each of the narrow ends of the box’s top piece—the holes should be about the size of a bottle cap.
3. Paint the inside of the top black, or line it with a black plastic bag.
4. Cover the topwith clear plastic. This section captures heat fromthe sun, which will be reflected back on the food.
5. Cut matching holes in one end of the bottom piece of the box.
6. Place the two boxes so that one set of holes on the top lines up with the holes on the bottom. Then, using scrap cardboard and masking tape, form an air duct that guides the air flow from the lid (the solar collector side) into the bottom section, where the food is.
7. Set the drying box (the bottom) on a stool or stand and lean the solar box (the top) against the stool at the most effective angle to catch the sun’s rays.
8. Spread a piece of cheesecloth or other thin fabric on top of the drying box. Put the food you want to dehydrate on the cloth or screen. If the sunlight is steady all day, the food should be ready for storage by sundown.