How to Build A Solar Oven

While studying thermodynamics, we decided to build a solar oven, so see how solar energy, light reflection and household items can combine to help you cook (and survive) in an emergency situation.

Step 1:  Gather supplies:
- one small box
- one slightly larger box
- a cook pan or glass jar with a lid that is either black, or that can be painted black
- old newspapers
- aluminum foil
- plastic wrap
- scissors, glue/tape

Step 2:  Line the inside of the smaller box with aluminum foil, with the shiny side showing.   The smoother you keep the aluminum foil, the better. Tape/glue loose sides/edges to the box.

Step 3:   Place pot/jar in smaller box, and then place smaller box into larger one.  There should be a couple of inches of space between the sides of the two boxes.

Step 4:  Crumple up old newspapers and fill in the gap between the two box sides, and also fill in the open areas in the smaller box, surrounding the pot.

Step 5:  Cut one of the top panels from the side of the box and tape it to the other top side panel.  Cover this two part panel in aluminum foil (shiny side showing).  This will be your sun reflector.

Step 6:  On a sunny day, sit your solar oven outside.  Place it so that the sun is directly hitting the reflector.   Allow time for the oven to “warm”.

Day #1:   It was a bright, sunny day with temperatures in the mid 70’s.   We put a raw egg in the pot around 10:30 am.  We checked the egg every 30 minutes; and saw no change for the first 2 hours, although I did burn the dickens out of myself when I grabbed the lid bare handed around 1pm.   By 1:30 the egg had turned into a rubbery thing with a funny smell.   We called it a fail.

Day #2:

We got rid of the cast iron dutch oven and replaced it with a black, teflon coated sauce pan, and a glass lid.  We set the oven outside in the sun for an hour to “pre-heat” while we went on our morning walk.

When we returned, Olivia did the honors of putting the test egg into the oven.

At 20 minutes, the egg had cooked to a poached egg consistency.

It took about 45 minutes to cook the egg to a “hard egg stage” (the white and yellow were fully cooked).

The temperature on this particular day was around 74 degrees.  A hotter day would of course produce a hotter oven and quicker cooking.   Admittedly, we did not consume this egg…however in an apocalyptic situation this knowledge may come in handy.