As the days get shorter and cooler and the trees lose their leaves, holiday lights and Christmas trees have started making their annual appearance. I’ve been getting in the spirit of the season in my own way—by roasting chestnuts in a solar oven.
Gathering around the solar cooker may not be as romantic as getting cozy in front of an open fire, but some traditions need to step aside in these climate-challenged times. And it turns out that sun-cooked chestnuts are deliciously succulent. I’ve been getting a variety of chestnuts called Colossal, grown down the street by Nevermore Farm, a community-supported agriculture farm I mentioned in a previous post.
I’ve written about solar ovens on this blog, in Good Green Kitchens, and other places, but didn’t get one of my own until this summer. My oven, a type known as a box cooker, is made by Sun Oven. There are other manufacturers and types, including smaller models perfect for taking camping or to the beach. Do-it-yourselfers can make solar cookers using inexpensive materials like cardboard boxes and aluminum foil; the Solar Cooking Archive Wiki has lots of ideas and plans.
My oven is basically a lightweight, insulated black box with a clear glass top. To cook, I place the oven outside, tilted so the glass top faces the sun. Mirrored reflectors surround the box, concentrating the sun’s heat inside the oven. On sunny days, my oven typically reaches about 300°F, and on particularly clear days it has gotten as high as 350°. To maintain that temperature, I need to reposition the oven now and then to make sure it’s pointed at the sun.
Some people treat their solar ovens like a slow cooker, leaving a pot of soup, stew or chili unattended in the oven all day. The oven won’t maintain the same high temperature as it does if you keep moving it to track the sun, but it will cook food gently at low heat.
The beauty of a solar oven is that I can cook without using fossil fuels or pumping CO2 or pollutants into the atmosphere. And as much as I like messing around in the kitchen, it’s just plain fun to cook outside. It makes cooking dinner feel more like playing hooky.
Solar ovens aren’t for every meal or everyone. While they can be used on sunny days any time of the year, they don’t work without sun, and to get the highest temperatures you need to use them during the midday hours, from 10 am to 2 pm. At other times or on days with heavy cloud cover, you’re back in the kitchen. Using a solar oven can also be tricky in urban areas; many city dwellers don’t have access to an outdoor space that gets good sun.
Food solar-cooks more quickly if placed in a lightweight black pot like the inexpensive GraniteWare pot shown in the photo above. For baking, dark pans and dark baking sheets work best because they absorb rather than reflect heat.
In the few months I’ve had my solar oven, I’ve made stews, soups and spaghetti sauce. I’ve also discovered that sun-cooked rice turns out great, as do sun-baked potatoes, sweet potatoes and winter squash. I love the solar oven for cooking dried beans. I’ll soak a pot of beans in water overnight, and in the morning I’ll put the pot outside in the solar oven and leave it there to slow cook. By the time the sun is low enough in the sky that it’s not producing much heat, the beans are soft and fragrant.
I’ve even used the oven to bake a pound cake. The one thing I probably won’t try again is cookies. My oven can hold a fairly deep pot but only one small baking sheet. Baking batch after batch, six cookies at a time, tried my patience.
Another reason I’m a big fan of the technology is that solar cookers are much more than just another eco-chic gadget. For years, a number of nonprofit groups have been working to get solar cookers into the homes of poor people around the world who live in places where sunshine is abundant but fuel is expensive and firewood scarce. Solar cooking is also much safer and healthier than cooking over an open fire, and solar cookers can even be used to pasteurize unsafe drinking water.
As the holidays approach, I’d like to plant a seed by suggesting that solar ovens make great gifts for eco-minded cooks. But if you and yours are up to your ears in stuff and don’t need yet another doodad, no matter how green, here’s an idea: consider donating to a group like Solar Cookers International, which spreads solar cooking technology and skills to those most in need.
Nondisclosure: I do not take kickbacks, free products or other swag, no matter how eco-luscious, from organizations I write about or manufacturers of products I recommend.