Build a Low-Cost Solar Food Dehydrator

Learn how to build a low-cost solar food dehydrator. Here is an easy way to make a solar food dehydrator that you can recycle at the end of the season.

| August/September 2008

Make a low-cost solar food dehydrator to dry your garden produce.

Make a low-cost solar food dehydrator to dry your garden produce.

Diagram by the MOTHER EARTH NEWS staff

Discover how to build a low-cost solar food dehydrator using cardboard and plastic wrap.

Build a Low-Cost Solar Dehydrator

The end of summer is harvest time, and we frequently have no idea how to store the bounty. One way is to dry the fruits and vegetables. There are lots of electric and solar food dehydrators on the market, or you can build your own from free, recycled materials.

To build your sun-powered unit, choose a long, shallow cardboard box and cut a few holes in each of the narrow ends. Then paint the inside of the box black or line it with black plastic sheeting. Cover the box’s top with clear plastic, and the heat catcher portion is complete.

Now, take another cardboard box and make several holes in one side. Set it on a table or stand, and lean the solar box against it at the most effective angle to catch the sun’s rays. Then use some scrap cardboard and tape to form an air duct connecting the shallow “solar” unit to the side of the drying box (as shown in the diagram in the Image Gallery). Finally, lay a screen on top of the drying box and arrange the food to be dehydrated on that surface.

This is not a permanent food dryer, and it’s certainly not waterproof — but you wouldn’t leave your drying produce out in the rain or snow anyway.

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.

tom duchesneau_1
6/3/2009 9:26:13 PM

Bear and Pat have the right ideas. With glass covering the top of the drying box, the hot air is forced to travel the whole distance of the box. An elevated screen off the bottom will help the veggies dry evenly. Screened outlet holes opposite the inlet holes to keep the vermin out. Did anyone mention an old computer fan for air movement? That would be complicating things though, as then you need a power source and transformer (may be available from a junked 'puter). Tom

doug smith
6/3/2009 2:01:53 PM

One could also use an old fish tank with the bottom removed. put it on blacktop (if you have any) or on top of something black and a screen on top!! you get heat from the black bottom, and directly from the sun!!! so it is then truely sun dried!!!

doug smith
6/3/2009 1:51:39 PM

Guys you are missing the point, the hot air goes into the holes on the big box and out the big box through the top thus drying the fruits and vegetables. That is why the screen is on the top. You could further refine it to have the holes close to the bottom, then have a screen half way up for the fruits and veggies, and then of course a screen on top to keep the insects out. I would make a further suggestion to get some cardboard tubes and push them through the big box holes into the long box holes and poke smaller hole along the tubes in the big box to allow more even heat flow throughout the whole big box. This is however just a suggestion and you are free to add or delete whatever you like. I am just glad that someone said here is how to do it on the cheap. Also keeps stuff out of the landfill a little longer. I can tell you that a cotton shirt will not get as hot a say aluminum foil painted black. Sheet metal is also an easy find and that painted black will gather and hold more heat.

6/3/2009 1:38:32 PM

Suggest to line or the shallow solar cardbox with old black T-shirt or old black color clothing. That will not cause smell or fumes. Cover the dryer box with old window/patio door screen, that will prevent flies or any other insects to go inside the solar oven. Glass over will work, but will need to put more holes on opposite side of the air duct, and cover those holes with screen. That way, hot air will pass through the whole solar oven before escaping out.

patricia toler_2
6/3/2009 12:11:28 PM

Great idea but I have a suggestion to add. put some wood blocks inside the drier box and lay a screen on that for the food, then place another screen on top of the box to protect the food from insects.

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