By John D. McCann
Solar cookers are one of my favorite ways to cook as the energy used is from the sun, and that is free. However, you must have the sun, and it does take longer to cook than by conventional means.
There are various types of solar cookers that can be constructed by yourself, or that are available for purchase. I have divided them into solar box cookers, which are enclosed, and solar cookers that are open. I use both types and I find the box type is better when it is cold out as they are insulated and retain the heat better. If it is cold, and the wind is blowing, the open type cooker is affected by heat loss mechanisms such as convection, conduction, and radiation of the heat.
One of the easiest types of solar cookers to build yourself is a box oven made from a cardboard box (see photo below). You basically use a cardboard box inside another box, with room to insulate between the two using crumpled up newspaper. The inside box is covered with aluminum foil. A piece of glass or an oven bag is placed over a large hole cut in the lid to allow the sun in. Another piece of cardboard is covered on one side with aluminum foil and is attached to the top of the outside box, so that it can be tilted to reflect the sun into the top of the box. I have built them, and they work, but are not as effective as other types of cookers.
This is a simple solar oven made by Eldon Martin from two
cardboard boxes, one inside the other. Photo by Eldon Martin
My wife, Denise, and I wanted to build a substantial solar oven that would be effective and last for years. I had a piece of glass measuring 16 inches x 20 inches from an old picture frame. We felt this would be ideal for the top glass in a box type solar oven. We started with that and built a frame to hold it, using one inch square wood and 3/8 inch quarter round trim. It made a substantial lid.
We then designed an insulated box from 1/2" plywood and used Mylar material glued to the insulation for reflection on the inside. For the lid, we used another piece of 1/2" plywood with a piece of Plexiglas mirror, which was chosen so it wouldn't break. We insulated the bottom of the box and used a second plywood bottom painted with two coats of High Heat black paint, used for grills and wood stoves. A special arm was designed, that could be adjusted to hold the mirrored top at the correct angle to reflect the sun into the box. The results were very effective. For a complete article, and photo tutorial, on how we built this oven, check it out on our website HERE.
This is the solar oven that my wife and I built.
There is also the option of a solar cooker, which again is not enclosed. We purchased a commercial item called the "Hot Pot" solar cooker. The whole unit comes in a sturdy box with the reflector folded flat in the top of the box. The reflector is really unique and is made from a light metal material with a very shiny reflective material on the inside. It folds so the reflective material is protected when closed. The box, the "Hot Pot" came in, has a "box in a box" which holds a Pyrex glass bowl and lid with a black enameled insert.
This solar cooker is very easy to set-up. Simply open the reflector, which almost seems to spring open by itself, and set it down. You them place the black enameled insert in the Pyrex bowl and add the food you are going to cook. Place the bowl on the bottom of the reflector, add the lid, and let the sun do the work. We have cooked various types of food, as well as baked cake ,in the "Hot Pot" solar cooker with no problem. We liked this cooker so much we naturally ordered a second one. We now have "dual" solar cookers and can cook dinner in one while a cake is baking in the other. For a complete article and many more photos of the "Hot Pot" solar cooker, check our website HERE.
Another commercial product available is called the SunRocket™, which is basically a solar water heater and thermos. You simply fill the thermos with water, open the panels and place it in the sun. If the sun is high, you can lean it back on the provided bracket, which doubles as a carry handle. If the sun is low, you can use it standing straight up. Although it doesn't boil water, it definitely makes it hot enough for making coffee or tea, and can be used for heating wash water when the power is out. It's made from an evacuated glass tube made from Vycor glass (95% silica, high temperature and thermal shock resistant). The aluminum reflective panels are made of high-quality scratch and weather-resistant plastics. It also includes a pressure relief valve.
The directions indicate that the SunRocket™ can be used to sterilize water, but in order to do so, you must ensure that the water temperature is above 150 degrees F (65 degrees C) for more than 20 minutes. The problem with this is there is no means for you to determine what the temperature of the water is in the thermos
As you can see, there are many options for using the sun's energy for cooking. You can make your own cookers or buy commercially available devices. There are a plethora of plans for building different types of solar cookers and ovens on the internet. Some are fairly easy to construct, and some get rather complicated, but everybody should be able to construct some type. Do a little research and you should be able to find something that will work for your needs and skills.
This article has been an excerpt from my book "Practical Self-Reliance: Reducing Your Dependency On Others." If your are interested in self-reliance, check out my book at Survival Resources HERE or at Amazon HERE.
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Copyrighted 2014 by John D. McCann