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EarthSave promotes a shift toward a healthy plant-based diet.
Vol 19 No. 3
June 2008

Solar Cooking--the Sustainable Cooking Solution

By Lisa Rayner

Those of us who have chosen to become vegetarian or vegan already know that a plant-based diet is best for the environment. Over the last few years, rising concerns about the availability and price of energy and the growing effects of climate change have turned diet into a practical tool for change. Growing plants for food requires far less fossil fuel than does feeding grain to animals. Mainstream media sources like the New York Times are now reporting that eliminating the consumption of animal products saves more energy than driving a hybrid vehicle! We can take this concern a step further by considering how we cook our food.

What if there was a year-round method of cooking that was low cost, powered by sunlight, non-polluting, and easy to do even in college dorms, apartment balconies, workplaces and off-the-grid locations? There is: solar cooking.

A solar cooker uses passive solar principles to collect sunlight through glass or plastic glazing and transforms it into the heat of an oven using the greenhouse effect. Some solar cookers are similar to conventional ovens, reaching 350-450 F on a clear sunny day. Other solar cookers are most similar to using a slow cooker. Yet others are used like a gas or electric burner or stovetop grill. Solar cooking is possible as far north as Canada and Norway. If you have a sunny spot unobstructed by shade for at least three hours per day, you can solar cook. Some easy-to-cook foods, like grains and vegetables, can even be cooked in hazy or partly cloudy weather. There are many excellent commercial models available and free, do-it-yourself plans available.

I live in Flagstaff, Arizona at 7,000 feet. I have been a vegan for more than 20 years and a solar cook for more than 12 years. I use my solar cooker, a Global Sun OvenTM (see below), year-round on a south-facing balcony of my townhome. On sunny days, I use my solar oven to cook multiple foods one after the other. I might heat water for coffee or tea, cook a hot lunch, and simmer a pot of grain for dinner or a baked good for dessert. If I worked away from home, I would take a solar cooker to my place of work.

Solar cookers can be used to cook any kind of food. It is possible to do everything from simmering to poaching, steaming, sautéing, baking, toasting, pan frying, grilling, canning, water pasteurization, and even making ice (at night!). For many foods, solar cooking is my favorite cooking method because of its carefree nature. For example, I like to solar cook dry beans without having to worry about the beans drying out or burning. I solar cook everything from sautéed tofu, to barbecued seitan, homemade whole wheat bread, polenta (no stirring!), and steamed broccoli for very little effort on my part. The only requirement for successful solar cooking is the use of dark-colored pots and pans to absorb the sunlight. Shiny metal pots reflect light away from the food.

Whatever your climate and lifestyle needs, there is a solar cooker for you!

Solar box cookers, also known as solar ovens, are insulated boxes with a clear glazing on the sun-facing side. The glazing is often slanted to catch the maximum amount of sunlight. The inside may be black, to absorb heat, or reflective, to reflect sunlight onto the cooking pot. In addition, some designs have one or more exterior reflectors to focus additional sunlight into the oven chamber.

Hybrid electric box cookers have a single reflector and an electrical heating element with an adjustable thermostat to keep the temperature completely even in variably cloudy weather.

Panel cookers do away with the oven and reflect sunlight into a plastic cooking bag.

Parabolic reflectors look just like satellite dishes. The sunlight is intensely concentrated onto a single point where the pot, frying pan or grill pan is placed.

Each variety of solar cooker has advantages and drawbacks. Parabolic cookers reach very high temperatures (above 500 F) and can be used for simmering, grilling, frying and canning. However, they require frequent re-aiming to keep the concentrated beam of sunlight on the cooking pot. Multiple-reflector ovens work well anywhere, although in windy areas they must staked down. Some cookers are designed for inattentive or absentee cooking, most notably reflectorless ovens and single-reflector box cookers. Hybrid-electric cookers require access to an electrical outlet. Some cookers, such as homemade cardboard models, can’t be left out if rain is threatening. However, cardboard panel cookers are so small and lightweight they can be taken camping or backpacking. Some cookers are designed to be both windproof and waterproof. If you live north of the 40° parallel (Philadelphia, Pennsylvania; Denver, Colorado), choose a cooker with highly tilted glazing or a panel cooker with a nearly vertical back panel to capture low sunlight.

The cost of a solar cooker ranges from almost nothing, if you build one yourself out of cardboard and foil or scrap wood, to several hundred dollars, about the cost of a low-end electric or gas range. Visit the Solar Cooking Archive website, sponsored by the nonprofit Solar Cookers International, for build-it-yourself plans (www.solarcooking.org).

In the last decade, the number of commercial solar cookers has greatly expanded. Here are a few descriptions for several popular models. Prices include shipping:

Global Sun OvenTM: This multiple-reflector oven has four external reflectors and an adjustable back rod for tilting the oven directly at the sun in one-inch increments. It has a roomy 14” x 14” interior oven space. Temperatures reach 300-450 F. The panels fold over the glazing. A handle makes for easy portability. A purchase includes one three-liter graniteware roaster. $280. www.sunoven.com.

SOS SportTM: This is a windproof and waterproof reflectorless box cooker made out of recycled soda bottles. It has room for two cooking pots but has only two cooking positions: a 30-degree slant for overhead summer sun and a 60-degree slant for low-angle winter sun. Temperatures reach 325 F. A purchase includes two three-liter graniteware roasters and a reusable water pasteurization indicator. $150 plus $25 for the optional four-sided reflector. www.solarovens.org.

Tulsi-Hybrid Solar OvenTM: This model requires access to an electrical outlet. It has a single mirrored reflector and lots of floor space but less than seven inches of vertical interior height. The temperatures reaches 400 F. $300. www.sunbdcorp.com.

CooKitTM. This foiled cardboard panel cooker from Solar Cookers International costs $25 in the United States. The profits subsidize overseas distribution in Africa, Asia and Latin America. Plastic cooking bags are not included. www.solarcookers.org.

Solar Wall Oven™: Not yet available commercially, this unique design allows you to solar cook from inside your own kitchen! This oven is a reflectorless box cooker that is attached to the south wall of your home. The door goes through the wall. Plans are available at www.solarcooking.org.

Solar cooking times

Fast cooking foods: grains, oatmeal, polenta, small lentils, fruit, “above ground” vegetables (artichokes, corn, eggplant, green beans, leafy greens, peppers, tomatoes), small diced root vegetables, cubed tofu, tempeh and seitan, and reheating leftovers.

Moderate cooking foods: presoaked dried beans, large lentils, split peas, whole root vegetables, small loaves of bread, open face pies, and cookies.

Slow cooking foods: unsoaked dried beans, large loaves of bread, double crust pies, large winter squash, large pots of broth or stew, casseroles, and tofu roasts.

Solar cooking is an easy way to incorporate renewable energy into your life. Solar cooking is right for the planet, easy on your budget, and perfect for a vegetarian lifestyle.

EarthSave member Lisa Rayner is the author of The Sunny Side of Cooking: Solar cooking and other ecologically friendly cooking methods for the 21st century and Growing Food in the Southwest Mountains, a high-altitude permaculture guide for home gardeners. She is a writer and teacher of sustainable cooking and permaculture design in Flagstaff, Arizona. Lisa is known as a progressive political activist who rides her bicycle to meetings and events all over town. Visit her website at www.LisaRayner.com.