Everyday Solar Cooking

We’ll show you how to build a solar oven, so you can create savory meals while cooking without fuel.


| August/September 2015



Handmade Solar Ovens

A rhubarb pie and an apple tart are baked in two simple, handmade solar ovens.

By Philip Reynolds

Summer’s arrived and the heat is inescapable. You don’t want to turn on the stove to make dinner, which will heat up the house even more. If you’re like me and don’t have air conditioning — or if you’re energy conscious and keep the AC low — cooking indoors can be unbearable. Instead, why not use the source of all this heat to your advantage?

Solar radiation is the most prolific source of energy on our planet. About 84 billion kilowatt-hours of light reach Earth every day — more than four times our global energy consumption. The challenge is to efficiently harness this energy. Most people settle for gathering solar energy by eating vegetables from their gardens or catching its reflection with their cameras. Trap that energy in an insulated box with some food — then you’ll really be cookin’!

The functioning principles of a solar oven are simple: concentrate, convert, contain. Sunlight — or visible light — is concentrated by several reflective surfaces to pass through a glass lid into an insulated box. A pot of food you put inside the box will absorb the light and convert it into longer-wavelength infrared energy, or heat. The insulation will inhibit the heat from escaping, and the wavelengths will be too long to pass back through the glass lid. So, they’ll bounce around and heat up your food. Ever leave your car windows closed on a bright, warm day? Then you’ll recognize the basic principles of solar cooking.

How to Build a Solar Oven

Nearly 20 years ago, as I was helping a friend build his straw bale house (at which point he figured out I was into “weird stuff”), he mentioned that some people he knew were teaching a solar-oven-building workshop. I was intrigued, so I sent in my 50 bucks to attend. Three weeks later, I found myself on a homestead out in the Kentucky woods, looking at the piles of plywood, cardboard, tinfoil and glass that were to become solar ovens. The instructors, Mark and Andy, had just returned from a nonprofit-sponsored trip to Peru, where they taught people how to build and use solar cookers. Many of Peru’s mountain villages suffer from deforestation, so solar cooking offers a good alternative to cooking with wood.

That day, using only hand tools, I built my own “yard appliance.” This solar cooker requires only cheap materials and the design is so simple: square, with an inner box and an outer box separated by 1 or 2 inches of insulation, and a glass cover on the inner box to let in sunlight. Additionally, four reflectors are arrayed at obtuse angles to the glass to focus more light into the box and raise its internal temperature enough to make cooking possible. We used plywood for the outer box for rigidity and durability, and crumpled newspapers for insulation. A variety of materials can serve as insulation, including sawdust, chicken feathers or fiberglass batting. Insulation is key, because you want to trap heat in the box as effectively as possible to offset shading by clouds that will invariably show up to block the sun. In optimal conditions, the cookers we built can heat to 400 degrees Fahrenheit in about an hour, which is hot enough to cook anything from a casserole to biscuits. That’s a pretty good appliance for only a $50 investment. For me, the deal was even sweeter — I married Mark’s sister a few years later, and we’ve been solar cooking together ever since.

How to Use a Solar Oven

You can easily manage a solar cooker by keeping these elements in mind:

buhler
7/9/2017 4:17:05 PM

I'm not sure the new comment section is working by looking at what ellen smith submitted below.


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6/30/2017 6:04:01 AM


smith
6/30/2017 6:04:01 AM


smith
6/30/2017 5:37:06 AM


ellen575
8/17/2015 1:51:37 PM

I enjoyed my cardboard solar oven. Ended up using it quite a lot. Made it from leftover materials. My father laughed but stopped when I served the solar cooked chicken and later he saw the thermostat reach 400.


robert
8/15/2015 12:11:25 PM

Interesting article. I love the fact that people are out there trying to do things like this and succeeding. Tips that can be found online for cooking various foods with a conventional slow-cooker or crock pot might be relevant to cooking in a solar oven. Be aware that for meat and other foods, the temperature has to get up to 140 within a short time to avoid food poisoning.


ed
8/12/2015 2:37:28 PM

A great simple article






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