A Solar Food Dryer from Cardboard Boxes

Putting together a solar food dryer is a simple winter project (for you or your kids) that can help you preserve next summer's produce.

| January/February 1981

067 solar food dryer2

Making your own cardboard box solar food dryer is so easy and cheap, you might have to make two!


It seems that — at long last — a goodly number of people in government and industry are beginning to come around to the notion that, yes, there might be something to this sun-energy concept after all! Unfortunately, whenever the bigwigs begin "talking solar," they invariably speak in terms of multimillion dollar projects, brain-trust technologies, and the all-too-familiar decade-long implementation schedules.

Well, all that may be necessary (although I doubt it) for some solar energy applications, but I've designed a solar food dryer that anyone — and I do mean anyone — can put together for pennies ... and in minutes!

To build your sun-powered unit, choose a long, shallow cardboard box and cut a few holes in each of the narrow ends. That done, paint the inside of the container black or line it with black plastic sheeting — whichever is easier. Cover the box with clear plastic, and your heat catcher is complete.

Now, take another cardboard box and make several holes in one side. Then use some scrap cardboard and masking tape to form an air duct connecting the shallow "solar" unit to the side of the drying box. Set the latter on a table or stand, and lean the solar box against it at the most effective angle to catch the sun's rays. Finally, lay a cloth screen on top of the drying box and deploy the food to be dehydrated on that surface.

If you really splurged on this device, you might be able to spend $1, but I doubt it! Granted, it's not very permanent, and it's certainly not waterproof. But, then, you wouldn't leave your drying comestibles out in the rain or snow anyway, would you?

Note: Run the dryer for a few days without any food, to drive off any fumes that might be released from the paint or plastic.  

6/6/2016 1:40:46 PM

I agree with Sharon....last part of the instructions are too vague. The drawing doesn't look like it includes this step. Step-by-step drawings would help a lot. Could i make a solar dryer with pallets? Any suggestions on how to make a pallet solar dryer would helpful, too. Cindy

6/6/2016 1:40:14 PM

I agree with Sharon....last part of the instructions are too vague. The drawing doesn't look like it includes this step. Step-by-step drawings would help a lot. Could i make a solar dryer with pallets? Any suggestions on how to make a pallet solar dryer would helpful, too. Cindy

barbara brkovich
10/5/2012 6:46:20 PM

Sounds like a great Science Project!

8/19/2010 8:24:43 PM

I have a friend who lives in Michigan and she dehydrates food in her car!!! She has a car with black leather interior. She cracks the windows to release the humidity, and on a warm day she dehydrates apples. She puts them on frames she made with cheese cloth and perches one end of the frames on the dash, the other on the headrest on each seat. She says it works great. She did say, however, that one year she dehydrated thinly sliced onions!!! She said she didn't think about it until going outside to retrieve them! Her car smelled like onions for several weeks!!

lloyd mcdaniel
7/28/2010 7:38:56 PM

Why not just use the heat collector? if you DON'T paint it black it should be OK. I have a 3x5 foot tin box I am going to try with some apples.

laurrie bullock_1
10/30/2008 5:16:43 PM

Each of these methods sounds good. Will certainly try them out this winter (we get a lot of sun here) and use the best one next summer.

8/14/2008 6:36:24 AM

I find the last part of the aticle pretty vague. What is meant by "air dict" and even "connecting". What do you mean "deploy the food on top; is the cloth laid inside the box??? This is not clear.

8/13/2008 10:29:41 PM

Last year I made a 2x2 ft frame out of 1x1 and tacked some cheesecloth type material to one side. I place the items to be dried inside, including herbs, cover with another piece large enough to tuck underneath. The rough wood of the frame snags the cloth helping to hold it. This year I was lucky enough to get several bread racks! place the cloth on the rack, place the food, cover and prop in the sun. Works like a charm. Sliced apples dry in one full day, herbs in the homemade rack slides in under the BBQ grill for shade and also dries in one day. This year I tried corn. 2 days and perfect. We are also trying the car. Today part of the tomatoes actually burnt black in the car and it was vented. Personally I don't have the time to make a box when my method works so well. The cloths can be thrown in the washer. Last week I did have a big japenese beetle dig through the cloth on the peaches, but this is the only bug I ever had get into the food.

adrian comenzind_1
8/13/2008 5:15:21 PM

I would suppose it doesn't get too hot? I like to dehydrate my food below 105 F so I don't lose the enzymes. Maybe it depends on the construction of the boxes?

8/13/2008 10:45:25 AM

What I am concerned about here is the fumes that black paint would give off as it heats up..Also the black plastic. Is this healthy?

b.r. whitfield
8/2/2008 11:31:38 AM

I just tried my hand at drying last summer and fell in love with it! I had purchased a small electrical dryer but just couldn't dry enough fruit to keep up with the apples and pears that were beginning to fall. My wife had changed curtains and the old ones were similar to cheese cloth, so I put together a fairly good sized frame on legs and made a double layer for the bottom and tented the top. As long as the sun shines, it works perfectly. The double bottom, spaced about an inch apart, and the tented top keeps the bugs at bay. This year I have already built two more so that I can keep up, not only with the harvest, but also with the appitites of my six grandsons.

mother earth news fair


Oct. 21-22, 2017
Topeka, KS.

More than 150 workshops, great deals from more than 200 exhibitors, off-stage demos, inspirational keynotes, and great food!