Food & Drink

Green and hot: Solar cooking a delicious science

FRESNO, Calif. - It sounds so simple: Place food in a couple of pots, then open them hours later to find a hot meal. And you don't even have to turn on the stove.

That's what some converts to solar cooking are preaching and practicing. Maia Ballis of the Sun Mountain Environmental Center in Tollhouse, Calif., has treated family and friends to solar meals for about 20 years. Phil Erro, a solar-energy enthusiast, teaches solar-cooking classes several times a year at the Fresno, Calif., Adult School. Through the Fresno Rotary Club, Wilfred and Marie Pimentel have demonstrated solar cooking in various African countries.

Convenience isn't the only reason to cook with the sun's energy, they say.

In developing countries, where food often is heated over open fires, solar cooking can accomplish a lot more, the Pimentels say. When women no longer need to hunt for firewood, cooking is less of a chore. Deforestation is prevented. Respiratory illnesses from cooking smoke are eliminated.

And in First World countries such as the United States, solar cooking can reduce your energy bill.

"Here you are running air conditioning, and you're creating heat in the kitchen," Ballis says. Solar cooking "just makes so much sense once you get over the initial hurdles."

The central San Joaquin Valley's dry, sunny climate is an ideal fit for solar cooking. It works reliably between May and October, Erro says. He's also done it in December when the weather is right.

Ballis is more cautious; she recommends cooking only on days when the ambient temperature climbs above 80 degrees.

Knowing when to use solar cookers requires understanding the science behind them. They all reflect sunlight onto dark-colored pots, such as those made of black enamel, cast iron or dark Pyrex. The pots absorb the light, converting it into heat energy. Typically, a clear plastic bag or insulated box will trap the heat around the pot.

The amount of sunlight determines the heat of the pot. During the summer months, it's easier to for the cookers to catch sunlight.

"In the wintertime, the sun is at a much lower angle," Marie Pimentel says. Before cooking in the winter, "you've got to make sure you have at least three hours of sunshine."

No matter the season, she adds, it's best to catch the overhead sun between 10 a.m. and 2 p.m. To make sure the solar cooker catches the most sunlight, you may have to move it several times.

In addition to the amount of sunlight, other weather conditions affect solar cookers.

Box-shaped ones hold heat easily. Ballis uses a wooden box lined with aluminum foil. Sunlight comes in through the box's glass top; a panel covered in aluminum foil reflects the light onto the pot. This homemade cooker reaches temperatures of 150 to 225 degrees.

The Pimentels use the high-end Global Sun Oven, a $259 box cooker. Equipped with flaps that reflect sunlight into an insulated box, this oven can reach 350-400 degrees. (Go to for more information.)

The Global Sun Oven is best "if you're in a hurry," Wilfred Pimentel says. But be careful, he adds. It can burn food.

This cooker has another drawback. Only certain sizes of pots and pans fit in it.

"If they had made it slightly more rectangular than square, we could use cookie sheets," Marie Pimentel says. Smaller roasting pans will fit, but larger ones won't, she adds.

The CooKit, a popular alternative to box cookers, doesn't retain heat as easily. It's a piece of lightweight, reflective cardboard that folds neatly into a small package.

The inexpensive CooKit is the best option for solar-cooking novices, Erro says. For $47, you can buy a CooKit, black enamel pot and a solar cookbook. Go to for more information.

Taking one of Erro's classes might reduce the cost even more. Using the CooKit as a template, he teaches students to make their own solar cookers from cardboard, aluminum foil and glue. The lesson, plus cooking tips, costs $29, he says.


Call the Fresno Adult School at (559) 457-6000 for more information; the next class takes place Sept. 8.


Here's how the CooKit works: The dark-colored pot sits on top of one cardboard panel. Another panel curves like a parabola behind the pot. Sunlight hits the rear panel at various angles and is reflected onto the pot.

To retain heat, the pot is encased in a clear plastic bag, such as an oven bag for turkeys, Erro says. He also places the pot atop sticks to allow heat to circulate. With lots of sunlight, this cooker can reach 220 degrees.

Because the CooKit doesn't have an insulated container, it's not a good idea to use it on a windy day _ the wind will blow heat away from the cooker if it's not in a protected area.

Also, "if you have cloudiness at all, you don't want to solar cook," Erro says.

Don't worry too much about ambient temperatures, he adds. Food will cook about as quickly on an 80-degree day as it does on a 100-degree day.

Since the cooking temperature varies with the position of the sun, certain dishes will work better than others. Slow-cooker recipes are ideal, since they call for similar temperatures.

Other recipes need to be adapted. To make a custard, Marie Pimentel recommends using a ratio of "one egg to not quite a cup of milk. ... And don't leave it in there a long time."

While baking cinnamon rolls on a CooKit, she lets some of the moisture escape by inserting a bamboo skewer between the lid and the pot. She loosely ties the surrounding plastic bag. A flick of her finger removes any drops of water on the interior of the bag.

"I have to adjust the bag to allow humidity to vent," she says. "Otherwise, I'll end up with pretty soggy rolls."

Marie Pimentel also avoids delicate greens, which tend to turn gray and fall apart in the solar cooker. But root vegetables and eggplant, tomatoes, celery, onions and bell peppers work well.

And she never lets food sit overnight in a solar cooker.

Erro has his own tips. Generally, vegetables will take one-and-a-half hours to cook, he says. Pre-soaked grains require about two-and-a-half hours. Meat will need about three if its cut into chunks. Seafood also will take about three hours.

Ballis offers lots of recipes and solar-cooking techniques in her cookbook, "SunMt Herbal Cookery." (Go to for more information.) She recommends bringing rice to a boil on the stove top, then finishing it in the solar cooker. Or soaking beans overnight before cooking them.

The best aspect of solar cooking, she adds, is that food usually won't burn at such low temperatures.

"Because you don't have controls over the temperature," she says, "you just learn to check more often."



Makes 4 servings

1 pound free-range ground turkey

¼ cup taco seasoning

1 tablespoon balsamic vinegar

1 teaspoon liquid smoke

Olive oil

Place meat in a bowl. Add all seasonings to a well in the center of the meat, and mix well. Form a large loaf, and choose one of these two cooking methods:

Solar cook: Thinly coat the bottom of a black enamel pot (or other dark-colored pot) with olive oil. Add turkey loaf. Cover and place in solar oven until cooked through, about 2-3 hours. Serve over rice. If you want to reduce the cooking time, heat the bottom of the pot on a stove top until the meat sizzles, then transfer the pot to the solar oven.

Stove top: Heat a cast-iron skillet, add a little olive oil, then add the turkey loaf. Cover and cook over low heat until cooked through.

_"SunMt Herbal Cookery," by Maia Ballis (Sun Mountain Environmental-Multimedia Center, $22)



Makes about 2 servings as part of a larger meal

For the marinade:

2 tablespoons arrowroot powder or cornstarch

2 teaspoons ground oregano

2 teaspoons powdered basil

2 teaspoons garlic powder

1 teaspoon ground rosemary

1 teaspoon curry powder

1 teaspoon sea salt

¼ teaspoon powdered cloves

For the lamb:

8 ounces lamb, chops or stew cuts

2 tablespoons balsamic vinegar

1 red Bermuda onion, sliced

Olive oil

Green peas, for garnish

Make the marinade: Mix together all the seasonings, then put them in a zipper-lock plastic bag. Set aside.

Trim fat from meat, and cut it into bite-sized chunks. Place the lamb in a bowl, toss it in balsamic vinegar, and then add the lamb to the bag with seasonings.

Choose one of the following cooking methods:

Solar cooking: Thinly coat the bottom of a black enamel pot (or other dark-colored pot) with olive oil. Heat over medium-high on a stove top, then add onions and lamb, and sear all sides. Remove from heat, cover, and cook in a solar oven for 2-3 hours. Serve with rice garnished with peas.

Stove top: Heat a cast iron skillet, add olive oil, and then sear the lamb quickly for 3-4 minutes, turning to brown all sides. Add the onion, cover, and cook on low heat until tender. Serve with rice garnished with peas.

_"SunMt Herbal Cookery," by Maia Ballis (Sun Mountain Environ- mental-Multimedia Center, $22)



Makes 4 servings

2 Japanese eggplants, sliced thinly (or 1 regular eggplant, cubed)

Olive oil

1 large red Bermuda onion, peeled and chopped

4 cloves garlic, chopped

1 large green bell pepper, seeded and chopped

2 small zucchini, sliced

4 tomatoes, vertically sliced in wedges

Sea salt

In a cast-iron skillet, saute eggplant in a little olive oil. Add onion and garlic; cook, stirring, until the mixture is browned. Stir in remaining ingredients, then choose one of the following cooking methods:

Solar cook: Place the stew in a black enamel pot or another dark-colored pot with a lid. (You can use the cast-iron pot, but the cooking time will be longer.) Bring the stew to a simmer on the stove top, then finish cooking in a solar oven until soft, about 30-60 minutes depending on weather and the type of solar oven you're using.

Stove top: Add a splash of cold water and cover the cast-iron skillet to steam the vegetables. Simmer until the vegetables are cooked, adding more oil as needed.

Variations: To make a classic ratatouille, stir in the following during the last few minutes of cooking: ½ cup chopped fresh basil or ¼ cup dried basil.

To make Saul's Greek stew, mix together in a bowl: ½ cup plain yogurt, 2 ounces crumbled feta cheese, ½ cup chopped fresh dill weed (or ¼ cup dried dill weed or 1 tablespoon ground dill seed) and ¼ cup chopped fresh mint leaves (or 2 tablespoons dried mint). Remove the pot from heat and stir in the above ingredients. Let sit for at least 10 minutes before serving to blend flavors.

This stew works well with a variety of seasoning mixes. During the last few minutes of cooking, stir in 1-2 tablespoons of the following (or add to taste): Cajun spices, Jamaican spices, curry, chili blend or taco seasoning.