Building A Solar Food Dehydrator In My Backyard.

September 8, 2008

After seeing a diagram of what one might look like in a magazine, this weekend I spent some time building my first solar food dehydrator. And while it was somewhat of a success, there are some changes I will be making on the next version that I will discuss at the end of the article. For those of you interested in following along with the making of this first edition, here are the materials that I used for the entire project:

  • 3 shoeboxes (you really only need 2 if you have something to put the cooking box on. I used a 3rd shoebox)
  • Clear plastic sheeting
  • A screen of some sort, or a roll of screening material
  • Black paint
  • Duct Tape
  • Utility knife

Yep, that’s it. So let’s take a look at what I did and how I did it.

This is shoebox number one, which is going to be used as the solar collector to heat the air prior to going into the second box. As you can see, I cut three holes in each end with the utility knife – one end will pull the outside air into the box, the other end will be attached to the second shoebox.


This is the same shoebox one, but with the insides painted black to absorb the heat of the sun and heat up the air that will be contained inside the box.


This is the second shoebox, and you will note that there are only holes on one end. These 3 holes will match up with 3 of the holes on shoebox one, and this is the box that the food will actually dehydrate in.




This is shoebox number two along with shoebox number three. The third one will act as a base for the second one, but you can use anything you have around the house for this purpose. Just know that shoebox two has to be up higher than “ground” level, whatever that may be.


This is how the three boxes intersect – the base (shoebox three) is on the bottom, shoebox two (the one with holes cut on only one side) is on top of that, and shoebox one is leaning against the base with three of it’s holes aimed at the three holes of shoebox two. I used duct tape to attach them together.





As you can see, you need to close in the space between the two shoeboxes so the air collected in the black box will go into the top box and not just escape. This is where any spare pieces from the shoeboxes comes in, as I cut them up to create what basically amounts to an airlock between the two boxes.


Here are the three shoeboxes assembled together after I wrapped the shoebox painted black with plastic. I attached it to the sides with duct tape once again, and sealed off any possible places the air could leak out of that box other than through the holes at the top leading into shoebox two.


This picture shows the screen I stretched out over the top of shoebox 2, where the food that you want to dehydrate will lay while the heat removes the moisture from it.




These two pictures show the completed solar food dehydrator, other than the top of the “oven” that I fashioned out of the shoebox tops. And while it looks sunny in those pictures, about 15 minutes later the afternoon thunderstorms came along and ruined the fun. Yesterday I set the box out in the sun for an hour before we left for the day, and it got pretty toasty both inside both shoeboxes even without the lid on the cooker. So hopefully in the next week I will be able to A. line the bottom of the cooker with tin foil so the moisture doesn’t ruin the box and B. take some of our fresh tomatoes out of the whiskey barrel they are growing in and test out the ability of my homemade dehydrator to do it’s job. As this is only version number one, there are many things I want to do with the next version. This was the quick and cheap testing version and if it works at all, I will be making a more solid one out of wood. We shall see, and of course I will have a full report once I have a day where the sun stays out long enough to actually dehydrate the food. If anyone has any thoughts/advice/experiences they want to share, please feel free in the comments!

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Comments (8)

  1. Frugal Dad says:

    Now this is a cool project! I’m already imagining the things I could “dry” out for later use. Look forward to a follow up post with some sampling of your results.

  2. question says:

    why did you cover up the top of the black shoebox with duct tape — doesnt that defeat the purpose of painting it black? I thought you are supposed to use a clear plastic screen to cover up the black shoebox

  3. david says:

    Its not duct tape, it is plastic. The sun was just reflecting off of it.

  4. Sheila says:

    Hi,

    Could you tell me what type of black paint you used? We used black tempra paint for a solar oven one year and the smell of the paint transferred to the cookies we baked.

    Did you have this problem using your dehydrator?

  5. David says:

    Just black spray paint. I made sure to leave it in the sun and out for a few days before I used it so the paint smell would go away, so didn’t really have any problems.

  6. Kathryn says:

    What a cool project! I’ve heard of solar dehydrators before but didn’t realize they were such a relatively simple thing to make. Seems like a terrific way to save money on buying one!

  7. Robert says:

    I found that placing small holes in oven at end away from heat source allowed for quicker dry times and a place for excess moisture to escape

  8. Home Improvement Hut says:

    What a simple and cost efficient way to build a solar food dehydrator. Good stuff and good article.