Build a Solar Food Dehydrator
(Page 2 of 4)
August/September 2006
By Eben Fodor
Got Sun?
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If you’re wondering whether solar drying could be right for your location, consider that I live in Eugene, Ore., at a latitude equivalent to Bangor, Maine. We receive lots of rain, but fortunately, we also receive enough sunshine during the summer and fall harvest seasons to successfully dry all our crops with solar energy. If you can get two days of sunshine in a row with some regularity, solar food drying will work for you.
But for those times when the sun is hiding, a backup heating system still can help. I added 200-watt light bulbs as heating elements so I could finish drying my produce any time the weather turned cloudy.
Good Designs
A solar food dehydrator can be made in many designs, ranging from the simple to the complex, and from small to large. For the home gardener, a good solar food dehydrator has these qualities:
- It dries food quickly — on par with a good electric food dryer.
- It has venting controls that allow for easy adjustment of drying temperature and airflow.
- It’s easy to load, unload and clean.
- It’s easy to set up and put away, with little or no assembly.
- It’s relatively compact and lightweight for portability.
- It’s weather-resistant and keeps your food dry in the event of rain.
- It has sturdy and durable construction for a long life of outdoor operation.
- It’s pest-proof, and all vent openings are screened.
- The food trays are made from durable, nonstick and food-safe materials.
Now that you know the basics about solar food dryers, where do you go for designs? Surprisingly, you won’t find much useful information on the Internet. If you search, you will find plans for solar dryers made from cardboard and duct tape. Skip these and stick with the handful of high quality dehydrators that meet my criteria. My book The Solar Food Dryer provides information on some of the better designs and includes complete plans for building the SunWorks dehydrator I designed.
The easiest solar food dryer to build is a “hot box,” a design in which the food is enclosed and protected in a box with a clear covering on top. Screened holes should be in the bottom and sides, so warm, moist air can exit the dryer.
To increase airflow and efficiency, you’ll have to modify the simple hot-box design. Many high-performance designs are based on the strategy of separating the two functions of a solar food dryer: gathering heat and drying the food. The New Mexico dehydrator shown below illustrates this approach.
