How to Build a Solar Oven from a Cardboard Box

Following in the same line of cheap green and my article on a soda can solar collector I decided to build a solar powered cooker or solar oven. I wanted to build it as cheap as possible and get some decent results.

First off I started with a large copy paper case box. I had been collecting boxes like pizza boxes for a few weeks too to use as filler. I also bought a camping kettle with a lid from amazon.com for about $25 and a roll of tinfoil to use in the making of the reflectors. The key however is the turkey bags, and more on that in a second. With a little tape and a little glue hopefully this could turn into a decent slow solar cooker for my next batch of chili.

Next I cut the top of the box up on 3 sides, see photos, so when it was positioned on the base box it would flip up. With the extra boxes I had lying around I cut them up to fit inside the main box to make the walls thicker. They need to be about 3 quarters of an inch think for proper heat retention.

I lined the inside of the box with tinfoil and placed a turkey tray tin in the bottom to catch grease. I used tape on the outside of the box to make sure it was air tight and would not get damaged if the bottom got damp.

To make the reflectors I cut up some more boxes and covered them with tinfoil. I taped and glued them together with a prop stick to get them angled good for sun reflection into the solar oven. I know the description may not be good but the pictures give you the idea.
Now with the opening done and the base box done and the kettle in the base, you place a turkey bag over the base. Then when you put the top on the box it pulls the turkey bag tight and you have a nice window for the reflectors to shoot the solar rays into the box.

Now I tested the cooker. It is springtime here in Iowa so the temps were in the 60's all afternoon. I put an oven thermometer in the new creation to see what I could get. After about 30 minutes out side it had only got to about 160 degrees and you need a little more than that so I painted the inside of the box black with a grill high heat paint that I already had. Then the oven held about 170 -175 degrees for about 4 hours which would have been a good slow cook temp for making stew. And it was a partly cloudy day so maybe it could do even better with full sun.

Not too bad for $30 and a little time you can end up with something to cook with that does not use electricity, just the power of the sun. It could be even less money if you already have a black colored kettle to use. When you make yours make sure you figure out what the best start and end times are for the cook time because if the meat is brought to temp too slow you can create toxins from bacteria. It was a fun project building the solar cooker and now I am off to make my first beef stew while I am camping at my favorite pitbike race track.