DIY Solar Oven

 

A Do-It-Yourself Solar Oven, is a simple, low cost project that anyone can complete in a couple of hours, once you have collected the materials. We'll start with a very simple design, that gives you a working solar oven.

Materials for a Solar Oven

• Cardboard box, around 20" x 20" x 18", double-walled corrugated cardboard works best.
• A sturdy piece of cardboard, just slightly larger than the opening of the cardboard box. If the cardboard box is 20" x 20", then make this piece around 21" x 21".
• Tape. Duct tape works well.
• 1" thick hardboard insulation - enough to cover the bottom and sides of the box. Not styrofoam.
• Heavy duty aluminum foil - about 10 square feet.
• White glue.
• Flat, black spray paint - used for BBQ or wood stoves works best.
• A big roasting bag or a piece of glass, slightly larger than the opening of the box.
• A BBQ thermometer.

Assemble the Solar Oven

1. Bend the flaps of the cardboard box, OUT and DOWN and tape them down at the corners.
2. Prepare the insulation & aluminum foil & glue into the box.
   • Cut the insulation to size, to fit the bottom & 4 sides of the inside of the box - if you don't have insulation you could use several pieces of cardboard instead. If you double the pieces of insulation, you get even better results.
   • Glue aluminum foil to one side of each piece of insulation and spray with black paint.
   • Glue the pieces of insulation into the box, with the black sides facing the inside of the oven.
3. Prepare the Lid
   • cut a piece of cardboard slightly larger than the opening of the oven. Then cut out a hole the same size as the opening of the oven and tape the roasting bag over this hole (single ply only).
   • if using glass, you don't need the cardboard or roasting bag. Just ensure the glass is slightly larger then the oven opening and makes a good seal when placed on the top.
4. Poke BBQ thermometer through front of oven and seal with tape.

Cooking with your Solar Oven

Aim the oven into the sun by looking at the shadows - don't look at the sun. Periodic repositioning into the sunlight will be required.
Place a drip pan at the bottom of the oven, to catch spills, boil-over's, etc. You need a black pot with a snug lid for cooking. Glass jars, painted black, also work well. Try different pots till you find one that works well. Remember that the pot or jar can get very hot!
This simple oven will work well for warming rolls and keeping cooked items hot. It also works well for items that don't need a set temperature (rice, beans, soup, corn of the cob).

Improving your Solar Oven Design

Materials

You might want to try using plywood rather than cardboard for a longer lasting oven. For sure, you'll want to use a glass window rather than roasting bag. Improve your seal around the glass window and all the joints in the oven to reduce heat loss.

Reflectors

You can boost the heat quite a bit with reflectors. These can be fairly simple as well - cardboard, with aluminum foil glued to them, and taped together and to the oven. Use the shadows to aim everything towards the sun.

Size

Bigger capacity ovens with larger reflectors are capable of getting really hot. They are also easier to work with: getting food in and out.

Source:
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