Alternative Energy Sources

You can make a good solar oven for under $40, and it works even if you do a messy job of construction. In fact, they’re so cheap, building a sloppy test oven to learn the ropes is a good strategy. Then you can build yourself a quality unit that’s more convenient and lasts a long time.

Here’s a parts list for the oven:

• Plain old cardboard box, around 20″ x 20″ x 18″ deep; double-walled corrugated cardboard walls are best. 
•  A sturdy piece of flat cardboard that matches the top of your oven; if the oven is 20″ x 20″, that’s the size lid you need, with a little overlap. 
•  Tape, with good old duct tape working just fine. Masking tape also works, but not the kind for painting because the adhesive is too weak. 
•  Standard household insulation (not white styrofoam, but hardboard style), 1″ thick; this stuff is around $11 for a 4′ x 8′ piece. 
•  Aluminum foil, heavy duty with one shiny side at least, about 10 square feet. 
•  White glue. 
•  Flat, black spray paint designed for barbecue pits or woodstoves. 
•  Turkey bags or big roasting bags.

Assembly instructions:

1. Bend the flaps of the cardboard box out and down, and tape them down at the corners.
2. Prepare the insulation and aluminum foil and glue them in the box. Cut the insulation to size to fit the bottom of the box, then the front and back, left and right sides of the cardboard box. For even better results, use two layers of insulation. Glue aluminum foil on one side of each piece of insulation, and spray paint the foil black. Glue the pieces of insulation into the box with the black facing the inside of the oven. If you’re using fiberglass-based insulation, use gloves and eyewear; the insulation should indicate when these precautions are necessary.
3. Make sure that the cardboard lid is a little larger than the top of your oven. Then cut an opening in the lid to match the interior size of the oven. Cut the roasting bag and tape it over the opening in the lid.
4. Poke the barbecue thermometer through the front of the oven.

  
Cooking with a solar oven

The first time, just set the oven into direct sunlight and watch the temperature climb. Play around and see how the temperature varies with different conditions. Ovens that get the hottest are the ones that get the most amount of periodic positioning into direct sunlight.

You can use your solar oven in the winter, but it won’t get as hot because the outside air is cooler, plus you get less sunlight in the winter. To do the actual cooking, you need a good drip pan to facilitate both cooking and cleaning. Use a shallow cookie sheet or pan, that fits inside your oven (because of the added insulation, its length and width need to be at least 2″ smaller than the bottom of your cardboard box). You also need a black, aluminum baking pot with a snug lid, everything that’s cooked will go into this pot, so this will limit your food options. You can make an oven as big as you want, however, so that you’re not really limited. Some people have cooked Thanks giving turkeys in a solar oven, to very good effect. The pot will get hotter than the temperature of the oven cavity itself (unlike a conventional oven), so be extra careful. You’ll be pulling the heated pot up and out of the oven, so get handles that facilitate this upward and downward motion. Certain pots work better than others, so try some different candidates and see what happens.

Solar ovens can get real hot, over 400°F. Not only can you get burned, but if you put napkins or other flammables onto them, you can start a fire. (The cardboard box is well insulated from the heat, so it won’t catch on fire.) Treat a solar oven with the same level of respect that you treat your conventional oven.

already been cooked. This method is especially convenient next to a barbecue pit. As you finish burgers or brats, put them into the solar oven, they stay nice and hot. You may be able to cook corn on the cob. Put each ear into a roaster bag with some butter, seal it, and wait. The precise amount of time isn’t important, and neither is the temperature. You can cook half a dozen ears next to your
barbecue, and they taste better than the boiled variety. Likewise, you can heat pots of beans, chili, and other canned goods such
as vegetables and soups, depending on the sun. Solar ovens aren’t ideal for foods with specific times and temperatures.

For example, a cake may not be a good idea. Your solar oven already has a built-in timer. In the morning, just put something in and then aim the oven at whatever point in the sky you want it to cook. For example, aim where the sun is at 5 p.m., and when you get home from work, your dinner’s ready!