Introduction: Baggy Solar Cooker

Picture of Baggy Solar Cooker
Introduction. The insight for this project came from two community members: Mintyhippo and pepi. Special thanks to them. I became interested in solar cooking a few months ago. Having surfed several solar cooking sites, I decided to make a solar cooker. This one turned out to be rather efficient. It won’t take you long to build it. You may use materials scattered around the household. The cooker can be easily built by a junior school student (with exception of metal work, it should be done by an adult). So you are welcome to give it a try.
 
 

Step 1: Motivation

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Motivation. I spent a couple of weeks in the countryside in summer. So I needed a portable and cheap solar cooker. This cooker met all my requirements. Being in the countryside, we (my wife and I) left it in the sun and went to the woods to pick up berries. When we were back (in 3 or 4 hours) we could enjoy delicious fruit dessert. We also were able to cook rice, boil eggs and brew tea and coffee.

Step 2:

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Materials and Tools. 1 sheet of drawing paper (size A0), a window shade (as reflective material), 1 glass jar with a metallic screw-on lid (0,5L), 1 aluminum beer can (0,33L), 1 water dispenser bottle(5L) cap, 2 lengths of ribbon, adhesive tape, black paint (preferably flat)
You need few tools: a scissors, a cutter (for metal work), a paint brush (if you don’t use a spray).
 

Step 3: Make a Bag

Picture of Make a Bag
Make a Bag. Go to How To Make An  Origami Cup posted by Mintyhippo. Using a sheet of drawing paper, make a BIG cup. Attach lengths of ribbon on its sides with adhesive tape and you have a bag. Place the bag on a folded (2 layers) window shade and cut out the lining. Insert the lining into the bag and fix it with adhesive tape.

Step 4:

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Some metal work to do. Take a beer can and cut out the upper lid with a cutter. You have a food container now. Take a glass jar lid and cut out a hole in the center. The diameter should be the same like the diameter of the top of the beer can. It should go through the hole with friction. Now press the beer can against the hole and the top of the can goes through it. It’s time to paint the can in black.

Step 5:

Prepare a glass jar. Remove a label from the jar and wash it clean. Insert the beer can into the jar and screw on the lid. Your solar cooker is ready.
 

Step 6: Time to Test

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Time to test. On a sunny day pour 200 mL of water into the beer can and plug it with a water bottle cap. Place the bag on the ground and point it to the sun. Place the jar inside the bag. Tilt the apparatus a bit to get more solar energy. On a hot sunny day temperature change exceeds 30C in an hour. You may pull a woolen sock (preferably black) on the top of the jar to retain heat.

Comments

kostya (author)2013-03-22

To my regret I don't have more photos as this ible was published 4 years ago. The glass jar is 0.5L. The aluminium can (Coke) is 0.25L. The plastic cap is from water dispenser bottle (6L). This summer I'm going to publish a solar cooker made of Tetra Pak bricks if you are interested in solar cooking keep in touch.

siouxsun (author)2013-03-21

You must have very skinny tubular bear cans where you are from. We dont have any here that would be small enough to use a milk jug cap as a cork. We could cut the opening smaller but it would be extremely sharp. I think it is a wonderful idea but I wish you would show more photos of the pieces together and what it looks like before it is placed in the bag. Also where did you purchase that type of shade?

twighahn (author)2011-01-20

gives me some ideas

kostya (author)twighahn2011-01-21

What kind of ideas are you interested in?

twighahn (author)kostya2011-01-21

survival ideas.this will help me build water heaters for taking showers and help me cook when im without fuel.i think i know where i can get some wrapping paper that is silver on one side and white on the other

kostya (author)twighahn2011-01-22

You can find loads of ideas at www.builditsolar.com.

twighahn (author)kostya2011-01-22

ty

bruc33ef (author)2009-10-11

A really great idea and an evolution in solar cookers -- light weight, flexible, very packable, and it looks like it's effective.

 

kostya (author)bruc33ef2009-10-11

Thanks for your comment! Is there anybody around here living in the Southern Hemisphere with lots of sunshine, who wants to test the apparatus?

azrkpntr (author)kostya2010-05-13

 I live in Mexico, just south of Guadalajara. If I can find something to use as the reflector I am going to try your cooker.  I will report the results.

gaiatechnician (author)2009-11-11

I think your cooker will work good but it is a little small.  I like the idea that it isn't round. I think the long axis has to point east west for best results.
I am looking into designing reflectors by using 2 laser levels or laser pointers to model the sun. One pointer shines for the start of your cooking time and one for the end of your cooking time. You adjust your reflector so that all the light from both lasers hits your target.  I started an instructable and as soon as I find cheap long lasting laser pointers, I will do it.
Brian



kostya (author)gaiatechnician2009-11-12

It was nice to get a comment from YOU. Judging by this site, you have made a number of contributions in solar cookers' building. Your trackers impressed me a lot. I agree that  a small food container is a BIG drawback. Last summer I built the cooker with a bigger container(0,5L). It is still small, but my priority was portability. Another cooker which I built is of air-evacuated type.
As for the cooker's orientation, I will follow your advice as soon as the weather is permitable. It's not a solar cooking season here :(
I like your devotion to simple (low-tech) solutions in design and wish you success in your experiments.

gaiatechnician (author)kostya2009-11-12

Thank you, Most people think that scientists have already  looked at solar cooking in depth.
So people think everything has been done.    
  Many things have not been done at all!
Cook offs are hardly ever done.
(Tests of different solar cookers under similar conditions). 
We poor amateur designers cannot afford to test  4 or 5 models and nobody would trust our numbers if we did.
If the system was truely working, your design, and a couple of mine should have been officially evaluated by now.    Yours was on instructables for 10 months and some of mine are well over a year old.
I mean, they invest hundreds of thousands of dollars into giving solar cookers to poor people.  Why not invest a couple of thousand into checking to see if new designs give better results? Or are easier to make or easier to use?
There are constraints about size and speed of cooking and options that people have not looked into.  It becomes an engineering problem where you have a bunch of parameters and you have to find a sweet spot.
And we do not know half of the parameters!   Size and surface area for instance. Volume increases faster than surface area as you use bigger pots.  Your little containers will get hot much quicker but may not be ideal for unattended cooking (because the hot spot might quickly move off the container or the reflector might have to be much smaller).  And what happens to heat transfer if your pot is really hot. Does the heat go quickly in, or does more of it just reflect away? We do not know.
It is a complex game.  I wish more people would play and we could get better answers and ask better  questions.

kostya (author)gaiatechnician2009-11-13

I see your point. I used to work as an engineer and must say there are no ultimate solutions in engineering. High-tech cookers are available at the market. They are expensive and the poor cannot afford them. Unless you don't want to create a state-of-art construction(and such cooker will be inevitably expensive), you needn't consider ALL the parameters you mentioned , just pick out a few of them and build a row of cookers. After testing them(ideally in different geographical zones), let the people know the results. I believe this task is worth of our(hobbyists') efforts.

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