The best part about using a solar cooker is that it uses no electricity at all. It creates no heat in your kitchen for your refrigerator and air conditioner to fight against. It is carbon-neutral, green technology that can be cheaply made and acquired, that will pay for itself in savings after a few uses.
I am unclear on why so few people use solar cooking here in Florida and elsewhere around the United States. When the weather is pleasant it is good to just be outside, and most solar cookers require very little tending. Sunlight, is much more plentiful and cheaper than charcoal, firewood, or propane.
The most basic solar cooker that I know of has materials I was able to get at the local W. Mart for under 10 USD. It really has only two necessities, a vehicle sun visor and some self-adhesive Velcro from the craft department.
Wrap the vehicle sun visor into a cone with the reflective side on the inside. Place the Velcro carefully so as to attach the sides to one another. Ready to go, and portable.
When dehydrating, follow the conventional rules for dehydration. There are many great videos online, apparently spearheaded by the Mormon movement. Cut the food as thinly as possible, then into as small of pieces as possible. I placed the apples in between two splatter guards that I got for Christmas. I put the splatter guards on top of a dark bowl, then out in the sun at about 11:00 am. I did end up turning the cooker about every hour to track the sun - about 5 seconds worth of work. After 4 hours, half the apples were completely dry. The rest I put out the next day to finish up. The secret to dehydrating well seems to be all in the cutting. A lot of people recommend using things like lemon juice or soy sauce, and you can if you wish. But the magic is in the slicing.
Windshield Shade Solar Cooker