Solar cookers – DIY, cheap and efficient

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Photo: Flikr, Erik Burton CC2
Photo: Flikr, Erik Burton CC2 https://www.flickr.com/photos/[email protected]/5647636987

On hot summer days, there is no real need to blow out your gas bill by using a stove.  Solar cookers are back!

You will need:

  • A large rectangular piece of glass, such as a discarded storm window
  • A large rectangular wooden or cardboard box
  • A smaller box, about 18 by 22 inches, that will fit easily into the larger box
  • Six small spacer blocks (available at the hardware store)
  • Wadded insulation such as crumpled newspaper or construction paper.(Do not use Styrofoam peanuts as they emit toxic fumes)
  • Aluminum foil such as Reynolds Wrap
  • String, such as used in packaging
  • Non-toxic glue or tape other than duct tape (also toxic when heated)
  • Cover the bottom of the large box with the insulation, placing the spacer blocks next to each other on the bottom, in order to balance the smaller box. Place the smaller box inside,filling all space between the sides of the two boxes with more insulation.

If the larger box is cardboard, and has flaps, fold these over to cover the insulated space, if the box is wooden, find folded cardboard nad cover the insulated space, as well the inside of the inside box, and tie it with string at the corners.

Line the inner box and inside of the cardboard sides wth aluminum foil adhered with non-toxic glue so that the entire inside of the cooker is foil lined. Set a piece of square glass over the top, which will reflect the sun.Make a cardboard lid with a foil lined reflector flap cut out of it that can be adjusted to catch the sun.

When cooking with pots, use those with thin metal, and if you can, paint the pots black, and set them on a black-painted tray to absorb more heat. Use black latex paint. After the sun goes down, preserve heat with bricks on top of a blanket over the mirror lid.

Tiny SquirrelSquirrel Tip: Generally, you can count on good cooking time if you place the solar heater directly under the sun, preheating it half an hour before baking  cakes or pastries.