The Solar Dryer

marco

As part of our Appropriate Technology course we made a solar dryer to harness the sun’s energy for  drying and preserving some of our excess fruit and vegetables so we can eat them throughout the year.
The basic design is a radiant heat solar dryer. It is a really easy design, but works really effectively.
Basically there is a layer of glass that is propped up on a timber frame, and two layers of corrugate iron.  The sun shines through the clear glass at the top of the dryer which then hits the black painted corrugate iron that heats up the metal.

drid toms

The heat from the underside of the metal then heats the food below in a stainless mesh tray, causing  it to lose moisture and dry.  The moisture leaving the food flows out under the screen and up the sloped air channels. The cool air comes through the corrugate troughs and draws the hot air and moisture out leaving behind tasty dried food.
You can dry all sorts of fruit and vegetables. Depending on the size of the fruit and amount of sun, the drying process can happen in a day or two.  It would be advised to put the produce in on a sunny day and to cut it quite thinly.  As you can see in the photo above, we have wild blackberries, alma tomatoes (which are specific for drying), elderberries and peaches.

solar group

We have made a large solar dryer to suit the community, but you could build a much smaller one for home use out of pallets, for example.

Here is our design draft:

Solar drier sketch