Any sort of sustainable food plan that involves a garden and/or fruit trees needs a good dehydrator.  This in conjunction with some canning and some animal protein can get you through any low production season.

Here is a solar dehydrator that uses a solar heat collector and dc powered fans to push hot air through the dehydration chamber.   I built without plans and based the size of the solar collector on how the beer cans would fit in when stacked up.   The fans aren’t needed, but can improve the air flow.  They use so little wattage; they can run off of a small 10-15w solar panel.  Or you can plug them in.

Step 1: Sizing the Solar Collector

Gather some aluminum cans of your choice, measure the boards based on the sizing of the cans and the number of rows you'd like.  My box was 117cm x 69cm.   I used a variety of different can sizes. I also used a treated lumber since this will be sitting outside all of the time.   I used 2x4's for the entire construction.
<p>These &quot;Appalachian&quot; solar dryers work OK if you track the collector toward the sun periodically, have a fully sunny day, and don't load in much food. We got tired of spoiled food and designed a radiant solar dryer back in 1985 that is much easier and cheaper to build, leaving cash left over for food-safe stainless steel screens. You can just build the screens and use black polyester cloth over the food to generate heat, placing them in direct sunlight inside a parked car, with the biggest glass area facing the sun. Crack a couple of windows an inch to vent the humidity. The result is a much faster drying time and more uniformly dried food, all without building a dryer. You can read about the physical principles and design options here: </p><p>http://www.geopathfinder.com/Solar-Food-Drying.html</p>
<p>I made one of these years ago but didn't need the fans as hot air rises. You actually want the air to go slow as it won't heat up quickly enough otherwise. I had some of my students make a similar design and they used fans which melted in the heat. </p>
<p>It looks as if your cans are whole. A previous design I saw cut off the can bottoms and snipped and folded the top ends so air would go up the tubes and into the drying chamber. ??</p>
This is one thing I want to change. I might just take the cans out completely. I'll do it next month and report back.
<p>I made a collector with similar design to yours, but with a crappy dehydration chamber (re-purpused chipboard) - it was built just to test if the thing really works. </p><p>If anyone is interested, here is the whole thing described: <a href="http://www.spacepetuniareview.com/2014/11/diy-building-solar-can-air-dehydrator.html" rel="nofollow">http://www.spacepetuniareview.com/2014/11/diy-buil...</a></p><p>Just to remind, this was one of my first wood-building-stuff projects :)</p>
<p>I didn't see any step where you drilled holes in the bottom of the cans. In this type of design isn't the air supposed to flow through the inside of the can? Or did you do it differently?</p>
<p>LOL the aluminium drink cans... that is more an urban myth for solar heat collectors, than fact.</p><p>Any plain surface with a matt black paint applied to it, will work just fine and it will save hours of rooting around with making tubes from cans.</p><p>LOL what a joke.</p><p>The picking up of heat energy has everything to do with absorbtion, thermodynamics and convection and absolutely nothing to do with aluminium tubes.</p>
So, to clarify, the soda-can-fan-array is a source of dry hot air for dehydrating the food?
<p>Correct. In the case of this design the fans would be added to increase airflow and the black cans increase temperature. Technically speaking you don't *need* fans. as the air current would move the air anyway... but sometimes that is not enough flow - as I speculate was the case here.</p>
<p>LOL - not true. The black cans do not increase temperature - there is only so much energy coming in and there is only so much that the temperature that a given flow of air will be heated by, per unit of time.</p><p>More anergy = larger gathering area. Higher temperature = slower rate of air flow.</p>
Simple, effective!
I've seen something similar to this only the ends of the cans are cut out and they are connected so that altho the cans are still painted black, the air goes thru the insides of the cans.The air is pulled by convection from the bottom to where the stuff being dried is by the heat of the sun heating the black cans. You must make sure the bottoms of the can/tubes are screened to keep insects out. This way the air is not passing thru any painted surfaces.
actually i made one like that. works pretty well
CRP, what about sterling engine powered fans? You should have plenty of heat to run them from the looks of things.
Would the spray paint of the roofing and cans not taint or &quot;flavour&quot; the hot air as it bakes in the sun? <br>
I don't think so. Not any more than any painted surface in dehydrator. If I see issues I can easily sway out the solar heating media. This was the first prototype. I'll be posting tweaks in the coming months.
Some temperature insulation between the corrugated and the bottom board, may result in higher yield.
I see one not so good thing, using pressure treated lumber in the part that heat up then feeds the drying chamber. If it outgasses toxic things you eat them. <br> <br>Other than that add a light bulb or two to the drying chamber so if it is over cast or after sun down, it keeps going, no fungus will grow that way. <br> <br>The Mother Earth News has reprints on how to make these, (see there website) here is one of their articles, but they have older ones that are built like yours, (or your is like theirs) <br> <br>h ttp://w ww.motherea rthnews.com/diy/build-a-solar-food-dehydrator.aspx#axzz2fBoCO9tN <br> <br>An Amerian university also has a set of plans like yours you must google plans to find it. Measured drawings actually. <br> <br>Yours is great truly, but add the light bulbs if electricity is available.
You are right,pressure treated,heat and items for consumption is not good,plus non pressure treated dose not cost as much. A good coat of non-toxic paint on the outside,and your good to go,Im gonna use a small ceramic heater for the days that the sun is not doing the job,good catch on that one.
You could have also put the fans on the &quot;cool&quot; side of the solar collector and blown the cool air in rather than pull the hot air out. That way, you could use fans that didn't need to handle high temperatures. <br> <br>But other than that, awesome design. I have been looking at options for my own dehydrator and this one seems like a winner.
So, you're saying the cans are empty? Would having full cans/bottles hold more heat?
Yes they're empty. I figure more surface area to heat the air the better. Plus they resting on a piece on galvanized roofing.
How long does it take on average to dehydrate fruit with your dehydrator? Thanks!
I ahven't used it for fruit yet because of the high humidity right now. In one month when dry season comes I'll start doing fruit so there's no hassle with overcast days and what not. But with good sun, it should have no issue drying thinly cut fruit in one day.
Nice job. I like this. <br> I had a close look at your finished pics and spotted a small problem. For better air flow cut the top and bottom off the cans and aline cans so air is sucked or pushed up thew the middle of the cans. If you put fans on the air in end, the air coming in will keep fans cooler. Hop this helps good job. <br> JIM
Your can idea is a good one.
Thanks for this Instructible! Very nice inspiration but the idea of air flowing through and over sprayed aluminium cans to dehydrate herbs seems gross to me. Gonna try and come up with a closed circuit when I start building mine next summer.
You can use what ever you want in the solar chamber.
hot air is moving up itself, the fans move air quicker but it's not as hot then, fans makes the process quicker but theres no limit of cans you can use for heating, another idea a long chimney, the higher the more wind, and the more distance the hot air passes the more cold air it sucks in the hearers.
Also I added the fans because I thought that the speed of the air from just the heat rising.would not be ideal for dehydration....functional.....but not ideal.
as usual, the real thing proves to be different in reality. but I'm a thinker so I like to think of more efficient and green ways. and by the way what are you planing to dehydrate? sorry I haven't read the instructable the pics just say it all and I know the principles, Im thinking of making some dehydrator for herbs in the future.
I built it so big so that i could do a massive ammount of herbs and teas at one time(9 big trays) I grow a lot of herbs like stevia, oregano, basil and tarragon. Also, I grow a tea called &quot;Juanilama&quot; that's magnificent. Veggies, hot peppers and fruits too. <br><br>I haven't used it for jerky yet, but if I can get up around 140ish i will. (It's been overcast during rainy season). I'll use it for beef.<br><br>.
I would 100% agree, if this were a solar oven. However, with dehydrators air movement is key. The more you have going by the food the more efficient dehydration. The temp doesn't need to be anything ridiculous. As long as you can get the temp up to around 130' F. <br><br>I also installed the variable speed electric fans as an alternate means to control temp and air speed. I may install chimney later if it looks like air movement could be improved significantly. That's a great idea and thank you for the input.
Hot idea!
Cool idea!

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Bio: I hang out in Costa Rica and build fun sustainable, eco, survival related projects.....My main goal is to be able to feed the family ... More »
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