A solar dryer is a low cost, simple mechanism that traps light energy and uses that energy to dry fruits, vegetables, and meat. Solar dryers are usually very simply designed, highly effective and incurre virtually no operation cost. 
Food dehydration has proven to be an efficient form of long term food preservation that reaches far back in the history of food storage. Minimal food nutrients are lost through solar preservation. Some measure need to be take to preserve the Vitamin C. The design of our dehydrator preserves the Vitamin C content from being effected, by shielding the UV rays and only allowing the food to have contact with radiated heat.
University Display Garden staff worked with University of WI – Freshmen, Engineering students, to designed and built a solar food dehydrator, for the display gardens. The garden staff is now using this dehydrator to preserve fruits and vegetables being trialing in the garden.
We are recording the temperatures attained within the dehydrator on throughout several drying periods. Temperatures over 160 degrees, or higher, have been attained on most sunny days. In a few days we will know how long it takes to dehydrate a large selection of fruits and vegetables.
If you wish to find out more about the dehydrator, please visit the gardens or come to our Urban Horticulture Day on August 21 – 10:00 to 3:00. We will be demonstrating how the dehydrator works and have plans available for this style and plans for small, simpler systems. We will also have hand-outs available on the basic drying guidelines and samples of dried fruits and vegetables will be available for tasting. Join us and have fun learning a new way to use old methods of preserving your garden produce.
For more information see the following link:
Very interesting. We are wondering if you keep the metal panel open during the day or close it to get to the temperature noted on your article. I guess yes! Do you think it is drying the fruit faster than a regular solar dryer? We are planning one for africa.
THanks for replying
Is there a way to make it so you can control the temperature even on hot days? We are raw foodists so we would like to maintain under 110 degrees if possible. Thanks!
No way to control temperatures other than cracking open the drier a little.
It rarely seems to get hotter than 120 even on the hottest days, due to the convection cooling in the system.
Judy
This seems like a good idea to try. I would like to know how big is the unit, how many lbs of product you have in it at one time and how long it took to finish drying
Mike,
Thanks for your interest in this project. It was a real nice experiment. We had a fairly easy time getting this unit up to the proper temp but drying time was highly dependent on humidity, especially overnight. I will send you a copy of the report that the creators of the unit came up with. As far as amount of product, it was all dependent on slicing width. We often cut the veggies thinner to get them to dry quicker. Onions worked well and so did thin walled hot peppers such as cayenne or serrano. In the case of cayennes we could maybe fit a couple hundred in the unit at a time.
Brian Emerson
Could I get a copy of the report too? I’m doing some research on solar food dryers for the Leopold Neighborhood Community Garden.
thanks!
–bill