Solar cooking is a method that has been growing in popularity and sophistication in recent years, probably due to the emphasis on emergency preparedness.
A solar cooker is basically a box or reflective container that absorbs and magnifies the power of sunlight to produce temperatures hot enough to cook food. It works by converting ultraviolet light rays from the sun to longer infrared rays that cannot escape and have the right energy to make the water, fat and protein molecules in the food vibrate vigorously and heat up. The temperature generally reaches about 200 degrees, although some commercial solar ovens can attain much higher temperatures for roasting and baking. A general rule of thumb is that solar cooking takes approximately twice as long to cook foods as a regular oven. The main drawback is that you can only do it on sunny days. Even a sunny winter day can work, although cold air temperatures will slow down the process. People have even successfully cooked a meal on top of four feet of snow!
There are different types of solar cookers. The solar box cooker has a tilt-able reflective lid that redirects the sun's rays onto the food pot sitting in the box. The solar parabolic cooker looks like a dish-TV receiver with a pot suspended in the middle. A solar panel cooker has reflective panels surrounding the pot of food.
Whatever solar method you use, here are a few tips that will increase your chances of a satisfactory cooking experience:
Try to have food at room temperature when you begin to cook.
Place food in a dark pot such as a cast iron or enameled roasting pan. You can use BBQ paint (available at most barbecue supply stores) to coat the outside of any light, shiny pans you plan to use.
A clear, transparent covering such as a large, clear glass bowl or a turkey roasting bag should be placed over the pot to increase temperatures and prevent heat and steam from escaping.
Small pieces of food cook better than large thick pieces.
Wide, shallow pans work better than deep ones.
Use clean soup cans to bake bread, and for rolls or biscuits, leave an empty space in the middle of the pie tin.
Any material that is shiny and will reflect the sun's rays toward the pot can be used – mirrors, foil panels, or buffed tin or sheet metal. These can be tilted or the whole thing turned from time to time to follow the sun and keep the light directed onto the pot.
Some experts at solar cooking use Fresnel lenses, which are glass structures used to magnify and increase the power of light. They were originally created for lighthouses. These should be about one meter square, and you will need some sort of stand that allows you to raise or lower the lens to keep an ideal cooking distance from your pot. These lenses can cause your cast iron pots to get very hot, so be sure to use hot pads and avoid plastic utensils. Long-handled wooden spoons are ideal. For a single square Fresnel lens, keep the focus of the light about four inches wide on the cooking pot. You can also use these to pre-heat pots so that the cooking process begins more quickly. This method will heat water quickly and even fry fish.
This unique cooking method is a bright option, especially one that may be useful in an emergency!