Solar Food Dehydrator (Dryer)

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Introduction: Solar Food Dehydrator (Dryer)

Dry your fruit, vegetables, and other goods with your own sun powered dehydrator. Electric Food Dehydrators can be expensive and consume unnecessary energy.

This solar dehydrator was made entirely of recovered materials. It was constructed with scrap ply wood, 2x4s from an old ladder, a house window, and other items which could be considered trash. It was created as a project at Maharishi University of Management in Fairfield, Iowa.

Why We Dry: Removal of moisture prevents bacteria from ruining your values fruits and vegetables. Drying is a form of preservation.

Step 1: Learn the Design

Become familiar with the design to minimize mistakes...

There are vents underneath in the front which are hidden in this picture. The darker section is a piece of heat absorbent material, we used painted metal for this particular dehydrator, but other materials will do as long as they are dark. The food itself is placed on the shelf, which will be made out of a cloth screen. Other screen-like materials can be used, but take chemical leeching into consideration to prevent contamination. The back piece of ply wood can be opened to remove the shelf and provide additional ventilation.

Step 2: Find Materials

Thin Ply Wood (Body)

4 2.5' Long 2" x 4"s

10 feet of 2" x 2" wood (Braces and drying shelf support)

A Window (20" x 23 1/8") or a suitable slab of clear plastic.

Screen (For covering vents)

Stretchable Cloth/Material. We used stalkings. (For drying rack)

2 Hinges

Screws

Staples

Thermometer

A Hook & String (To fasten the rear door)

Caulk (For perfectionists)



Step 3: Size Pieces

Here is a checklist for the plywood pieces.

-1' x 23 1/4"' (Top)

- TWO 20" x 12" x 26 1/8" x 14 1/8" (Sides) This has a diagonal cut.

-26 1/8" x 23 1/16" (Bottom) This will be trimmed to fit legs and vents.

-14 1/8" x 23 1/16" (Back) This will be on hinges.

*Careful Cutting

Step 4: Assemble Frame

A. Cut 2" x 4" notches out on the bottom ply wood piece for legs. Cut out 2" x 4" slits for ventilation.

B. Construct base first as pictured.

C. Fasten side pieces of ply wood to legs.

D. Attach rear ply wood piece.

E. Screw 2" x 2" on top of side pieces to anchor the top piece. (This is more clear after viewing the second picture on this step)

*Drill then screw to prevent splitting

Step 5: Additional Components


A. Size and Insert heat absorbent shelf (Approximately 23" x 20") . This rests on the top of the legs.

B. Construct drying screen by stretching and stapling material over a 14" x 22 1/2" frame constructed of 2" x 2" pieces.

C. Cut and attach support piece for drying screen.

D. Attach the window. Caulking the borders is recommended, but if the window is flush against the frame, then caulking is optional.

E. Cover vents with screen material to protect from insects.

F. Place thermometer inside, ideally close to the drying screen rack.

*Clean parts before adding them

Step 6: Dehydration Tips

A. Dehydration will occur between 100 and 140 degrees Fahrenheit. Any lower and bacteria can grow, any higher and it will be cooking. In order to achieve this balance the rear door may need to be left ajar.

B. Different fruits and vegetables have different optimum drying temperature ranges. Research what you are drying to find this out.

C. Remember to store your result in a dry place.

Thank you for reading our directions!

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    43 Comments

    Great Idea and instructable!

    However for use in more northern climes the sun is not enough during the cooler months and we have to resort to electrical methods.

    Rather than using a stand alone dehydrator I've found a single 100W incandescent light bulb placed at the bottom of the oven of my stove works very well, creating sustained 150-160 degree heat.  I've added a light dimmer to vary the bulb intensity ie. a heat control - a little expermentation and I have a cheap and effective dehydrator with relatively low running costs. For more heat add light bulbs or a combination of different wattages.

    Note: CFL bulbs will NOT create the desired heat. 

    16 replies

    just a tip ...try instaling a hairdryer motor on a timer ...we use it for making biltong (jerky) and it really works great.

    Now THAT I like. I might be able to wing that in my little brooklyn apartment.

    Isn't it a bit loud?

    YIP its a bit loud but mine is outside in a shed.Just run it when your not around to hear it.All its doing is speeding up the drying by evacuating the warm air with the moisture in it. It works well with just with A 100W globe but takes longer.Do not try to run a hairdryer on the hot setting as you want to dry not cook and i assume you do not wanna burn the building down.I run it 15min in the hour so as not to burn out the motor.

    I like your idea but as a real guy I would be using a 2000Watt hot air gun that is used to bend pipes and strip paint :-)
    Nothing like having yr jerky done in 5 minutes :-)

    (Sorry, the idea is stolen from 'Tool Time' in which Tim Allen builds 'a manś kitchen', using an acetylene blow torch to roast turkey. Could not resist :-) )

    I have seen people braaing meat with a blowtorch...

    Now I know you are from South Africa :-) 'braaing'

    indeed....we braai regularly...superb way to socialize on a sunny sunday afternoon...chops, wors ,steak, ribs, pap en sous, beer...what else could you wish for?

    well I could mention a couple of things to still wish for :-)

    'braai' no doubt related to dutch (verb) 'braden' or (colloq) 'braaien'

    indeed.....we also do something on a fire which we call a pootjie...it is basically a dutch oven type stew....pootjie means little feet....a poot being a foot...this is derived from the tripod feet on a popular form of cast iron pot...some people take great care and pride and are infact experts at the pootjie cooking...very tasty

    interesting. Maybe not from the tripod but directly from 'potje' (a [small] pot). Often used in food relation: potje koken, wat de pot schaft,etc

    you may be right....not sure why the feet idea is stuck in my head...I think its because i have heard the pot described as a driepootjie...

    I myself am english born and speaking but have lived is south africa all my life...afrikaans is my second language...i could however maintain a decent conversation with a dutch speaking person and it would not take long for me to speak almost fluent dutch..

    I can top that :-) seen someone fry a Turky with dynamite: He fried and sliced it at the same time

    That's from the show home improvement right

    yes 'tool time' was the show IN the home improvement sitcom. Pamela Anderson made her debut there :-)

    If the climate is too cold for a solar dehydrator you can make this wood fired one that will also be adaptable to  your amount of dehydrating crops. Also most of the materials can be picked up for relatively inexpensive.
    www.backwoodshome.com/articles/hooker41.html

    After building nearly every type of solar food dehydrator more than 30 years ago, and using them in a partly sunny, humid climate every year since, I have a few comments about solar dryers of this type: A) they are too small to do much, B) as you load more food it obstructs more of the heat-generating black material, C) you have to rotate it periodically to track the sun, D) they rely on moving warmed air around the food, which is inherently inefficient, and E) the food is exposed to UV-A, bleaching out color and destroying some nutrients. For a design the relies on radiant solar drying, doesn't require tracking, doesn't bleach the food, can be modified for any climate or food, and can be made using local, recycled, and otherwise unused resources already on site, check this link:

    http://www.geopathfinder.com/Solar-Food-Drying.htm...

    Dehydrators of this time-tested design are in use worldwide, in sizes from 2 by 4 feet up to 4 feet by 36 feet.

    Bob Dahse

    2 replies

    basically that is a reference to a book for sale that even in its appraisal doesnt give any indication that it would be different from a regular Solar food dehydrator, other than that is done with a 'veganistic and gluten free' ideology

    Basically you're incorrect, bloke. While the page referenced does contain mention of a book we wrote, after over 30 years of dryer experimentation and teaching solar drying workshops, there is also a great deal of entirely free, pertinent information including comparisons of different designs, building materials, and specialized solar drying techniques. Perhaps you didn't scroll down far enough to get to the design section. And if you wish to dry meat, fish, or wheat crackers that's up to you; the design is entirely "diet agnostic". Just be aware that what's on the surface of some "foods" is quite a bit more dangerous than what's found on others, and the weather variables of solar drying must be taken into account.