Any sort of sustainable food plan that involves a garden and/or fruit trees needs a good dehydrator. This in conjunction with some canning and some animal protein can get you through any low production season.
Here is a solar dehydrator that uses a solar heat collector and dc powered fans to push hot air through the dehydration chamber. I built without plans and based the size of the solar collector on how the beer cans would fit in when stacked up. The fans aren’t needed, but can improve the air flow. They use so little wattage; they can run off of a small 10-15w solar panel. Or you can plug them in.
Step 1: Sizing the Solar Collector
Gather some aluminum cans of your choice, measure the boards based on the sizing of the cans and the number of rows you'd like. My box was 117cm x 69cm. I used a variety of different can sizes. I also used a treated lumber since this will be sitting outside all of the time. I used 2x4's for the entire construction.