Category Archives: How To (How I Did)

I like dehydrating food, sometimes because it makes food storage easier, and sometimes (like in the cases of apples or meat) I like eating dehydrated food.

The devils of food storage are:

• Heat
• Light
• Oxygen
• Moisture.

Dehydrating helps increase shelf life because many organisms (like Botulism) cannot thrive in dry spaces.  If you vacuum seal moist food and botulism is present,the bacteria grow and create enough toxin to kill.

However, if you vacuum seal food with less than a 10% moisture level the bacteria stays dormant.  So it does not produce toxins.  This works well for things that you don’t want to super heat using a pressure cooker.

I have a pretty good electric dehydrator that I use to make jerky and other dried foods.  However, it is small and takes up valuable kitchen space when it’s working.  Besides that, my wife doesn’t sleep very well if I try to leave it running overnight.  She worries about the catching the house on fire.

Research

Build it Solar was first resource I found online, and I went there quite a bit.  The idea of the J R Whipple solar dehydrator is really cool, but I wanted it in wood.  Root Simple also provided some ideas.

A large wooden shipping crate came from the trash and I decided to get to work.

*I later found a PDF entitled How to Build a Solar Crop Dryer that I believe this research was based on, I linked to it in my download section.

Building the Solar Dehydrator

Basically all I did was to cut a shipping crate to a manageable size, add a door, some legs and a few tray supports on the inside to make the drying cabinet.  I will probably add some ventilation later once I know how much I need.  I don’t want to cut a bunch of holes on the front end of the experiment as I don’t want to cut too many.

The next stage was to build the solar collector.  My original idea was to use some glass scrounged from a storm door.  Unfortunately, it was a couple inches too wide.  (BTW you cannot cut storm door glass; it’s tempered and will shatter into thousands of pieces).  But for an unnamed reason I ended up going with a large 24 x 60 piece of Plexiglass as the top of the collector.  The sides and bottom end are 1×6 boards, and the underside is a piece of plywood I had left from my chicken coop shipping box project.

I cut the top end of the 1x6s at an angle (I did not measure the angle, just marked it as the angle it would take to lay flush against the drying cabinet with the bottom end of the collector sitting on the ground.  This allows me to hinge the two pieces together so that the solar collector rests on the ground when in use, but folds up for storage.  The inside of the collector is painted black to help absorb heat.  I painted the outside white because I had white paint.  I also cut some ventilation holes in the bottom end of the solar collector, as there will need to be airflow to remove the moisture out of the drying box.

The drying trays and screens for the air vents are aluminum screen.  I simply made some frames out of strips of molding and stapled the screen tightly to the frames.

I still need to experiment with the correct drying times and amount of airflow needed, but the plan is to set this on the sunny side of my house, fill with vegetables and see how long it takes to turn them nice and dry.

Stay tuned, and I will add to this post as I learn more about my Solar Dehydrator….

My last tenants got direct TV without asking me, that’s not so bad, but they set this big metal post in concrete right at the edge of my house. I don’t like it, but I really did not want to grub out this post. Rather than rip it out, I re-purposed it to make a parabolic solar heater

I am a fan of solar energy, especially when its limitations are accounted for. Through research, I have decided that the heating aspects of solar is easier to utilize than converting it to electricity.  Its also much cheaper.

A man that has done quite a bit of work in this area is Dan Rojas of Green Power Science.  He has done quite a few projects that I admire and plan on emulating.  He also sells some supplies for these projects and that where I bought the solar film I used in this project

Re-purposing a Direct TV Dish

What I did was dismantle the Direct TV dish and sand it smooth, I then painted it with black paint (and should have sanded that smooth also).

I cut strips of the mirror film and attached them to the dish.  Its easiest to just cut straight strips and overlap them slightly.  Early cartographers learned that it is impossible to draw a round earth accurately on a flat sheet of paper, its the same with the film and a parabolic dish.  You cannot just slap the film to the dish, it will bubble up and refuse to form to the shape.  Some try to calculate the curve and cut out “pie” slices, but this works best in theory, the math works, but it does not translate well to the real world.  Strips that are allowed to slightly overlap each other works the easiest.

You will find its impossible to separate the thin strip of film from its backing by hand.  Mr. Rojas suggested to use slap a piece of tape to both sides of the film (at the end of the strip, and don’t let your tape strips touch).  When you do this the film and the backer adhere to the tape so when you pull the tape in opposite directions the film will peel away.

Its a lot like Window Tint

Very carefully install the film on your dish, if you have ever installed window tint, its the exact same process.  I started in the center and worked outward, as this was easiest for me.  I imagine it does not make a big difference.  Just try not to overlap the strips too much, don’t allow bubbles to form, and don’t get two worried about the holes for the mounting bracket.

After the strips filled the dish, I took a very sharp razor knife and cut a cross into the area of the mounting bracket holes.  This allows the screws to be inserted back into the dish.  I also trimmed around the edges of the dish.

For some reason (dust and a bad paint job most likely) the film did not want to stick at the edges.  I had planned on running around the center of the dish with tape for decorative purposes, but I ended up doing it to help hold the film down.

Reinstall the Dish and Focus the sun on the Jar

I then reinstalled the dish on the post (don’t just leave it there, the focused sunlight can be dangerous – so don’t leave it unattended for long periods).  Pointed it a the sun, and rigged a empty glass jar at the focal point.

The sunlight then heats whatever is in the jar.  You can use this to cook.  I have seen this on a large scale to boil water, and even make steam.  In California, Rojas’s dish actually burned a wood board.  I was not patient enough for that, but it did heat the jar uncomfortably hot.  (it was about 4pm in the afternoon, and there are a lot of trees in my neighbor’s yard, so that contributed to the heat difference.)

I plan on working with this a little more, and seeing how effective this can be to cook.  Who knows, I may even come up with some recipes.