Solar Cooking

Ovens, microwaves, and toasters are indispensable tools in the kitchen. Since these appliances run off of electricity, they use energy to cook and are vulnerable to power outages.

Simple no-cook recipes and solar ovens provide opportunities to enjoy home meals—whether the power is out or you just want to enjoy having a no-electricity meal.

Solar ovens harness the sun’s heating energy to cook (imagine the inside of your car on a warm day). They range from professionally built large structures to homemade recycled boxes. Box cookers are well insulated and have reflective, absorptive, and glazed surfaces to collect and intensify heat from the sun’s rays.

Here are two solar cookers you can build, but you can try experimenting with your own design as well.

Building a Box Solar Oven

Pizza Box Oven

Materials needed:

One pizza box
Newspapers
Black construction paper
Clear plastic wrap
Aluminum foil

Make sure the pizza box is assembled and closed. Trace a square on the outside of the box's lid. There should be about an inch between the box's edges and the square outline. Cut three sides of the square, leaving the hinge side uncut. Then, gently lift the cut portion and fold the uncut side to create a flap. Line the underside of the flap with aluminum foil, securing firmly with tape. You now have the reflector for your oven.

Line the inside of the pizza box with black construction paper, which will help absorb the sun’s heat. Stuff the edges of the box with newspaper to create insulation.

With the flap open, line both the underside and the top of the lid's cut opening with plastic wrap. Once you have taped one side of the plastic, pull it tightly, and then tape further to secure. The plastic will let the sun’s light through but keep its heat in the solar cooker.

Seal any cracks to prevent air from escaping (but make sure you can still open the box)—your new solar cooker is ready to use.

If you want a larger cooker to accommodate bigger pots or dishes, try this construction with two cardboard boxes.

Two Box Cooker

Materials Needed:

Two cardboard boxes with lids (e.g. copy paper boxes, cardboard file boxes). One should be slightly smaller than the other
Insulation materials (e.g. rigid foam, fiberglass, newspaper, packing peanuts)
Corrugated cardboard
Aluminum foil or reflective material
Glass, Plexiglas, or clear plastic wrap
Black paint
Prop sticks
String

Paint the inside of the smaller box black, so it absorbs heat, and place the smaller box inside of the larger one. Fill the space between the two boxes with your insulation material.

Cut a hole in the box cover, and seal it with plastic wrap or place glass or Plexiglas in the cut-out portion. Cut a piece of corrugated cardboard to the same size as the box lid, and cover it with foil to create the reflector for the cooker. Attach and hinge the reflector onto the cooking box. Attach props and string to hold up the reflector.

Using a Solar Oven

A solar oven can be used just like a crock pot or a normal oven. Solar cooker temperatures can easily reach between 200°F and 300°F, which means they safely cook dishes, even those containing meat—though cooking times will often be longer.

Remember that solar ovens require sunlight, so make sure you position your cooker in an appropriate place. Cooking times will vary with the amount and intensity of sunlight—between 11:00 am and 3:00 pm are the best times to use a solar cooker.

Generally, allow about double to cooking time than in a conventional oven, and use cooking thermometers to determine food temperatures.

Zucchini Quiche

2 medium zucchini, chopped or shredded
½ cup chopped onion
Diced mushrooms
2 cups Swiss cheese, grated
3 eggs
1 cup biscuit or buttermilk pancake mix
¼ cup oil
¼ teaspoon Italian seasoning
¼ teaspoon nutmeg
Salt and pepper to taste

Lightly oil a dark 9-inch round roaster. Beat eggs, and stir in the biscuit mix and seasonings in the bottom of the pan. Add zucchini, onions, mushrooms, and cheese, and stir lightly with a fork. Cover and bake in preheated solar oven for about 2 hours or until a knife inserted in the center comes out clean.

Pot Roast with Vegetables

2 to 3 pound chuck roast (1 ½ to 2 inches thick)
3 to 4 carrots, but in 3-inch lengths
3 to 4 potatoes, cut in ½-inch lengths
2 tablespoons water
1 package dry onion soup mix

Place vegetables in bottom of dark pan and sprinkle with water. Put the meat on top and sprinkle with soup mix. Cover and bake three to four hours or longer.

Oatmeal Squares

1 egg, beaten
½ cup honey
½ cup melted butter
1 tsp vanilla
½ cup whole wheat flour
½ teaspoon baking soda
½ teaspoon nutmeg
1 cup rolled oats
½ cup chopped walnuts

In a bowl, beat together egg, honey, butter, and vanilla. In another bowl, sift together flour, soda, and nutmeg. Add oats and walnuts to the flour mixture. Stir. Add the egg mixture to the dry ingredients. Mix well. Bake in a covered, greased 9x9 inch pan.

Other Recipes

With solar ovens you can enjoy stews, casseroles, roasted dishes, and baked desserts all by using the natural energy of the sun. Using solar ovens can be a fun and educational activity or needed in time of a disaster.

Adapted and excerpted from:

“Solar Cooking 101" (Material handouts, Presentation, St. John's County Extension, Oct 2, 2010).

Solar Activities for Students (SC125). Published by: NCSU North Carolina Solar Center (09/2001).

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