A FEW SIMPLE SCIENCE FACTS, AFFECTING THE DESIGN & USE OF BOX-STYLE SOLAR OVENS:
- Latitude: Nearer the equator, the sun shines more directly on the earth, and less of it bounces off the atmosphere, back into space. At higher latitudes, more of the sun’s rays (50% or more) are reflected off the atmosphere and less penetrates, hence the cooler climate and less radiation entering your solar oven.
- Seasons: Except in the tropics, the winter sun reaches the earth at more of an angle than in the summer, so more of its rays bounce off the atmosphere and back into space. Cooking may be limited to mid-day (10-2), whereas summer cooking can begin as early as 8:30 a.m. some places, and continue until sunset.
- Time of Day: In the morning and late afternoon, it’s similar to winter time or higher latitudes; the sun reaches us at a greater angle, so we receive less radiation than we will at mid-day.
- Outside temperature: It will affect your oven less than you think. The amount of insulation is the deciding factor. The Sun Oven TM is well enough insulated to cook on very cold days if the sky is clear.
- Orienting your oven: It’s more or less important, depending on what you’re cooking. If you don’t orient your oven often, food will take longer to cook. Some people put in food in the morning, aim it toward the expected mid-morning sun, and come home at 5 to a hot dinner, kept warm all day, but no longer cooking. Aiming it toward the earlier sun is very important, so that it doesn’t sit at bacteria-growing temperatures too long before beginning to cook!
- Color of cooking vessels: Go for dark. White or shiny will reflect the sun’s heat away from your food.
- Weight of cooking vessels: Time to learn about thermal mass. Thermal mass is what holds and conducts heat. Water, food, and cast iron have significant thermal mass. Lighter containers will have less. If you start your food inside in the winter, to give your oven a kick-start, definitely use cast iron! It’ll hold a lot of heat. If you’re cooking in the summer, without starting on the stove, you don’t want to waste your oven’s time getting the cast iron heated before it can get to cooking the food, so then you’ll want to use a lighter-weight pot.
One of my favorite
“do-it-yourself-cheap” designs
is the “Heaven’s Flame” model developed by Joe Radabaugh,
which was published in
Backwoods Home Magazine.
With Joe’s permission, I’ve been handing out his instructions at my workshops. Click here to see the instructions laid up in four,