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How To Build a Solar Food Dehydrator

Enjoying fresh food from a healthy source is one of the most enjoyable, and important, aspects of living off the grid. Unfortunately, not every food is in season throughout the year. Of course, there are a variety of solutions for this. Canned foods provide great opportunities, but oftentimes, commercial preparations are filled with too many preservatives to be considered fresh. In addition, certain foods do not lend themselves to being canned easily. However, food dehydration is a way you can enjoy your produce in a variety of ways, while knowing the food you are eating has come from a trusted source and is free of preservatives.

What is a Solar Dehydrator?

Food dehydration is not a new concept. From raisins to prunes to jerky, food has been dried for storage and later consumption for years. Solar dehydration simply refers to using the sun’s energy to complete that process. If built correctly, a solar dehydrator will not need any electricity and will be able to dry foods in even the most humid climates.

Learn How To Can And Dehydrate Your Own Food…

Types of Solar Dehydrators

There are literally hundreds of varieties of solar dehydrators. Deciding which one to build will really be a matter of taste and necessity for your family. There are several important elements in selecting a design:

  • It must dry food fairly quickly in your environment.
  • It is easy to use, particularly in terms of loading, unloading, and cleaning.
  • It is easy to maneuver, set up, and put away.
  • Portability is relatively easy.
  • Durability and sturdiness are also extremely important.
  • Venting controls are available to control temperature and airflow.
  • The design should be fairly weather resistant.
  • The design should be pest proof.

In this instance, we will focus on a design created by the Appalachian State University’s Appropriate Technology Program. This is not necessarily a reflection of preference; however, the design meets our need of using no electricity, drying in any climate, and ease of construction. This design uses a creative system to control airflow, which allows air to move with the use of electric fans. The original design article can be found here. Additional schematics can be found posted in a PDF posted by Doug Sharkey, of the Organic Growers School.

Although you can vary your dehydrator as you build it, the basic design is made of plywood and is built in two components: a heat collector and the dehydrator box. The heat collector is built with a clear plastic top that heats up and pushes air into the dehydrator box above it. You can control the amount of air pushed into the dehydrator box with vents at the bottom. The food is stored on screen trays in the dehydrator box with the hot air from the heat collection box constantly moving around the food. In this type of dehydrator, food such as tomatoes can take approximately two days to complete drying.

Additional information and styles of dehydrators can be found at the Build it Solar website.

What Are the Drawbacks to a Solar Dehydrator?

While eating and working with dehydrated foods provides many benefits, there are a few possible drawbacks that must be understood. Dehydrated food weighs less, which can make it easier to store; however, food preparation times need to be increased. Additionally, food that is dehydrated will have a different taste than its fresh counterpart. This may take some getting used to by family members. Finally, solar dehydrators are limited to use only when the sun is out, which will require planning.

How to Build a Dehydrator

Build the Heat Collector Box First

  • The box should lined with a black plastic sheet or painted black; however, petroleum based paints should not be used as the fumes will affect your food.
  • Holes should be made at the bottom front of the collector to allow for air ventilation (filters should be placed on the inside to keep out pests and other debris).
  • The bottom and sides can be covered with Styrofoam or others types of insulation to increase heat efficiency.

(The image to the right shows an excellent example of a heat collector with a smaller, roofless version of the food dehydrator.)

Build Dehydrator Box Second

  • Construct a box out of plywood with vents at the bottom front to receive the heated air from the heat collector.
  • Line the dehydrator box with aluminum foil or other reflective material.
  • Ensure trays are at least five inches shorter than the container so air can circulate completely around the food trays.
  • Each individual tray should be made of plywood pieces and food-safe screens.

(See the photo at the beginning of this article for a visual of the dehydrator box.)

Several videos can be found that provide overviews of how to build a good food dehydrator.

The first video offers an excellent visual of a shorted heat collector and smaller dehydrator box.

The second video was created by a group of engineering students at the University of Wisconsin – Madison.

The final video is a description of a similar dehydrator and heat collector that can be built.

©2012 Off the Grid News

© 2008-2014 Off The Grid News

20 comments

  1. THANKS!!!

  2. What sort of planning do you have to do for lack of sun, like at night?

    • this looks like a very well thought out drier. I have one of a simuller design I use for seeds. One thing that I have added is a UV light to kill off mold and provide heat for drying when the sun is not strong enough. 

    • I always plan on NOT having solar at night. ;-)
      Actually, the linked to article says that most foods dry in one day if they’re prepared correctly ahead of
      time: thinly sliced. Cloudy days will affect the high temperatures that can be achieved, but you may
      just need to let it run a 2nd day.

    • I literally cannot believe you actually said that…….

  3. What sort of planning do you do for lack of sun, like at night.?

    • No solar power at night? Wha? When did that happen? I always have sun even at night, i guess if you don’t then maybe you can stick a candle in there…

  4. What a great idea! Thank you.

  5. Can you get more heat and a faster drying time if you make the sun-collection thing sort of fan shaped, having the heat funnle from a wide area into the dehidration chamber?

  6. You may want to try to find an old patio door or windows at a salvage yard or elsewhere.
    Double panes, impact resistant glass. You’ll need to modify the sizing of your dehydrator
    to fit the salvaged window size, but that would reduce or eliminate the cost for the glazing
    materials needed.
    Being a scrounger at heart, I recently built 2 cold frames from salvaged windows
    that my co-worker was throwing away since they were replacing all the windows
    in their home. My cold frame functions more as a dehydrator!
    I have to water the lettuce every day as it dries out quickly. This article has me rethinking
    the cold frame idea. I may re-build one of the cold frames to make a dehydrator now…

  7. My husband built a dehydrator years ago using a single light bulb (incadescent, of course!) in the bottom of a relatively tall (about 3 feet X 18″ X 18″) wooden box, lined with foil. There is an adjustable intake vent at the bottom and an adjustable vent on center of the top. It worked great, but you have to be careful to rotate the shelves (we only have 2), because the lower one will “cook” if you don’t! The vents just make a ‘draft’, much like a wood stove, pulling air in and moisture and heat up and out the top. No fan required, just a small wattage light bulb.

    Of course, some foods work better than others, but we found that “dryer” fruits and veggies were easier to dry–onions, peppers, apples, etc. Beef jerky does well, also, but the shrimp we tried was too smelly to eat! And of course very thin slices and smaller pieces dry quicker and easier.

  8. great recipes, thnaks for sharing! So, I’ve been making morning smoothies and they don’t come out as vibrant as yours but still very tasty. Didn’t think a Kale smoothie or a mostly veggie smoothie could taste so good but surprisingly they are. Think I’ll try The Glow (cayenne pepper in my smoothie definitely stands out to me) BTW, your calamari looks delish Just a few nights ago, I made the zucchini spaghetti pasta and my tomato sauce didn’t turn out as red wonder what I did wrong?? Between you and your husband’s cooking I’d like to move in

  9. how would you build a solar dehydrator out of just tin foil and wood. and some other supplys that you could find on an island

  10. Thank you

  11. Pirate Carpenter

    I like to use a box fan, some furnace filters and bungees to hold them together. works great for jerky and apples. takes some electricity but it doesn’t cook the food just dehydrates

  12. starting to think about winter projects to build. will this dryer work in a northern Vermont environment?

  13. First, they won’t need a wet storage silo; the barley grain can normally be stored in a dry barn after harvesting.
    Of course the easy way to handle the sauce is just to simply
    go to our site at Jake’s. A solar sun oven has two temperature settings, sunny and shady.

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