Ten Ways I Use My Solar Oven

July 24, 2020

Several years ago when I moved into my little house heated only by a wood stove, I knew I needed a summer baking option, pronto.

Even if you don’t have a wood stove, summer cooking in sweltering North Carolina really heats up the house, and then it takes extra energy to cool it back off to a tolerable temperature. That’s energy I neither want to fork over money for, nor want to pay the ecological consequences of using. When we built the house, we planned from the beginning to move cooking outside for the hot months (April-October). This is an historical adaptation. Many houses in the South had outside summer kitchens before the advent of air conditioning.

Also, we felt the resilience factor of heating and cooking with home-grown wood was important. But the budget was too tight to make the house big enough to accommodate both a wood cook stove and a regular stove/oven, and we couldn’t really afford duplicate appliances anyway. So we have no regular electric or gas stove.

For summer stir fries and breakfast eggs, I currently cook on the patio on a dual-fuel Coleman that has been with me since I lived in my truck, long before I was married and saddled with these beautiful kids. It burns about 5 gallons of gasoline per year. I have my eyes on some very compelling rocket stove options to utilize small-diameter wood (which our land produces in near infinite quantity), but I haven’t yet done extensive testing.

But a camp stove only gets you so far. I also have a solar dehydrator for drying all the various products of the garden, and the sun oven gets me the rest of the way. It’s my go-to appliance for all these essential summer tasks:

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Beets and onions in my All-American Sun Oven

1. Roasting beets for yummy beet/apple/carrots salad with balsamic vinegar. This is a favorite for lunch recently, which is good because I have lots of beets.

2. Drying/sterilizing empty eggshells in preparation for crushing and feeding to our chickens, to replace oyster shells. They eat inexpensive 16% all-stock rather than spendy layer pellets. They’re able to forage some nutrition during most seasons, and this eggshell refeeding practice makes up the difference in calcium, especially when the weather gets dry and the bugs die off.

3. Deep-dish pizza!

4. Slow-cooked cabra verde and other favorite dinners.

5. Baking sourdough bread, soda bread, muffins and crackers from local wheat, and corn bread from our home-grown, home-ground blue corn. I must admit my muffins rarely turn out perfect, but everything else on this list I’ve got down. Our mill makes a whole-wheat flour from sprouted grain that is higher in nutrition than any flour I could get at the store. We have a little local co-op going to split the cost of shipping, so I’m actually saving money for a far better product when I factor in the processing premium on things like tortillas and bread. Of course, making these things from scratch takes time.

6. Rendering local pastured fat into lard. This is our primary cooking fat. It’s really cheap, $1.50/lb in bulk, because it’s a waste product; even lean pigs produce more fat than customers buy. Taking it off their hands helps my local pasture farmers stay in business, and gives us a source of high-vitamin nutrition. I’m also using it to make soap.

7. Speeding up the sun tea. We ferment kombucha, both a caffeinated black tea variety and a lower-caffeine hibiscus from home-grown Roselle. If I remember, I can set the tea out to steep in the morning. It will do its thing in the sun, and I can avoid heating water for it. If I forget, I can pop it in the sun oven whenever there’s a free spot and get the same effect much faster, and just as free.

8. Warming the milk for mesophilic cheese. Now that the spring kids have weaned and I’m making bigger batches of cheese, I’m pulling some of the milk from the cooler instead of just using it warm from the goat. It needs warming up.

9. Roasting bulk peanuts for home-made peanut butter. This not only saves me money, it reduces my waste stream (all those peanut butter containers) and allows me to control exactly what’s in our butter. I can avoid ingredients like added sugar and emulsifiers that are problematic from a health perspective, as well as those that are problematic from an environmental perspective, like palm oil.

10. Simmering beans to perfect tenderness and digestibility. Eating more plant-based is definitely easier on the earth, but it’s harder on the intestines unless the beans are slow-cooked.

With all these different uses, my sun oven is full all day, nearly every sunny day. It’s a big part of how we reduced our electricity use by 85%. I check it every time I walk past, which is about 20 times a day as I run around harvesting onions, cutting goat forage, chasing after children and working on our new culvert. It’s a perfect example of an appropriate technology: unquestionably very useful, and after the initial investment, operation is free both in a monetary sense and in an environmental sense.

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Like all renewables, though, it has some drawbacks. First, it has an upfront cost that makes it inaccessible to lots of people, especially with the recent historic unemployment. Of course there are DIY plans for solar cooking implements of many types spattered all over the internet, and I hear some of them are quite good. When I bought mine I was at the end of building our house, and frankly I was completely DIY-ed out. Since cooking is an essential task I just wanted something that would work, and work well, and continue to work for many years. The All-American has certainly done that.

There’s also the upfront (or embodied) energy. The base of the unit is made out of plastic, plus there’s some metal, wood and glass. These are engineered products that come out of an industrial supply chain. The oven has a life expectancy, just like wind mill blades and solar panels, which means that someday it will become a disposal burden, and someday it will need replaced. There are currently no workable plans to build sun ovens, solar panels or wind turbines without fossil fuels. Mining equipment runs on diesel because diesel is the only form of energy we’ve currently got that has both the density and the flexibility to accomplish the task.

I’m not saying this problem is unsolvable. I strongly believe in the great power of human ingenuity. I’m saying it has to be solved and solved very quickly in order to run a modern society on renewables and prevent the arctic from burning, and I do not see it even being worked on right now.

Then there are the practical drawbacks. With a sun oven as our sole summer baking tool, there can be no such thing as midnight brownies on a whim. More thought and planning must go into all of these tasks, including the recognition that even on a good sunny day I am not going to accomplish more than any three of them at most, and usually just one or two. I must work around the sun and prioritize based on what we’re running out of.

And once in a while I just glare at the cloudy sky and shift my dinner plans from pizza to stir fry.

There’s also the fact that most of these tasks take longer in the sun oven than they would in a regular oven. This is not a big problem, unless the weather suddenly shifts and a sunny day unexpectedly becomes a cloudy one in the middle of baking. Without a reasonably accurate weather forecast, I think I would have a hard time telling whether I should set the sourdough to rise this morning or wait until tomorrow.

And, it works only as a slow cooker on days I’m not home. I can aim it where the sun will be at high noon and leave the beans all day, and they will be done when I get back, but I can’t bake bread on a day I’m mostly away. This would never have worked for me back when I had the midnight coffee shop job and the six a.m. substitute job. It’s a tool for life at a slower pace.

Taken in sum, these drawbacks definitely do not outweigh the usefulness of the sun oven. I can shift my habits to get excellent use from it, and do just about everything I need to do. I may get a little frustrated at inconvenient clouds sometimes, but mostly I can shrug about giving up the convenience of an electric oven.

But the drawbacks do illustrate the difficulty of running a modern society (which includes concepts such as “dinner time” and “just-in-time inventory”) on renewables, as they are currently deployed. Right now we need natural gas or coal plants, which can be ramped up or down at will, to make up the difference when the sky goes cloudy, or when everyone goes home after dark and turns on their stove. Unfortunately, the subsidy of renewables “going first” makes it financially difficult to keep operating the “filling in” facilities, especially as renewables make up a greater and greater portion of power generation.

We cannot currently store large amounts of energy from summer (when most of the solar wattage is produced) to winter (when more electricity is needed). Grid-scale battery tech is really exciting, but it is not here yet, and we shouldn’t forget that historically, lots of stuff that was “just around the corner” never actually arrived. Regardless, batteries will make renewable energy more expensive rather than less, and it’s looking like anything other than ever-cheaper and ever-more-abundant energy is fatal in the medium term to an economy based on growth (energy is cheap now because rising inequality means people can’t afford to buy, not because it’s cheap to produce).

Does this mean I think we shouldn’t work on renewables? That we should give up on cleaner energy, or fail to loudly celebrate its spread? Absolutely not!

I believe in them so much that I personally work with renewables every day of my life, with tools ranging from the sun oven to the laundry rack to the solar generator to the solar dehydrator to the solar shower to the pile of wood that will warm my house this winter. But the reality of energy on earth right now, at this fascinating moment when most of the cheap, easy oil is gone and most of the pollution sinks are full, means that we need to think hard about what we really want to do, and how to do it, and for how long.

If we work hard to greatly increase our efficiency (and also probably reduce our convenience somewhat), I think our civilization can build a really satisfying, comfortable life on renewable energy. It just may not look quite like the one we have right now.

Do you have a favorite solar tool? Tell me about it.

Kara Stiff

Kara Stiff

I have a BS in Sustainable Agriculture from the University of Maine, and I worked on sustainability issues in Native Alaskan communities through Cooperative Extension before moving to North Carolina. My goal with my writing and in my life is to inspire others to think critically about their choices in order to build communities that are happier, healthier and gentler on the planet.

Tags: appropriate technology, Renewable Energy, solar ovens