build a solar oven

The most significant aspect of my summer-long experiment with solar cooking was to realize on some level just how much energy is pumped out every day from the sun. It seems OBVIOUS that folks in, say California or Nevada should cook solarly, like everyday, but it seemed counter-intuitive that it might also work in the misty hills of Michigan. This is a VERY WORTHWHILE experiment to make even if it doesn’t work, because you learn about your place on the earth a little better.

I want to continue experimenting - most notably I want to cook some part of Thanksgiving dinner with the sun and I am also very curious as to how well the oven will perform during those extremely bright, snow covered days of winter - but I accomplished what I wanted so I’m crossing this one off.

Up to this point, I’ve only fiddled with the modified cone/parabola type cookers that are oh-so-sexy but that aren’t going to cut it, I bet, when winter sets in. I snagged a box from work that has nice, double-walled corrugated cardboard. It’s a big box, probably enough for one of the “Heaven’s Flame” designs I’ve seen. I’m a sucker as much for cool looking design as for designs that actually work—so much the better when I can have both!

Well, today I’m one for three. The pot with the rice tipped over late this morning and the one with the potatoes sprawled out mid-afternoon. The wind is the likely culprit, though I’d like to blame it on the Republicans somehow. The onions and garlic were great. They went into a blender along with a can of black beans to make a great dip which kept us going until it got cool enough to stoke up a grill.

Gotta break that rice curse before it ruins EVERYTHING. I’m convinced there’s enough power being generated by the sun. I guess I’m just going to have to do something resembling real work to tap it more reliably.

The puffy cheese eggs that we made yesterday were enough to convince Mib7 and myself to head to the store and actually BUY materials to make more solar cookers. We came away with two more windshield reflectors and another graniteware pot. Total cost: about $20.

Let me tell you a bit about the eggs though. Yesterday’s brunch was this delicious egg and cheese omelette. I’d almost call it a souffle because it puffed up light and airy. Just spray a pan with no-stick and add a mixture of 3 eggs, a half a cup of shredded cheese and a few tablespoons of milk. Sprinkle on some thyme or basil just to be fancy. We put it out in the sun about 10 AM and started gobbling about 1 PM. This allowed us to put another dish on to get started cooking with the afternoon heat.

Anyway today I’ve got that half-cooked pot out there to finish cooking, another pot of quartered onions and garlic and in the third pot, I’m trying rice again. I’ll get rice to work eventually.

I didn’t want to mention this until I had enough trials to convince myself but apparently there’s something about this solar cooker that makes bugs, especially those gloriously metallic munching machines known as Japanese Beetles, die. Every day there are at least a couple bugs belly up at the bottom of the cooker’s cone. Is the light attractive and the heat too intense? I have to say I enjoy finding a non-chemical means to decrease our Japanese Beetles population that doesn’t involve a crunch between the finger tips.

On that DEEELICIOUS image, let me note that today’s solar menu was more garlic mashed potatoes. Yum!

And one performance note: if you are going to leave the cooker unattended for, say, four of the prime cooking hours in the afternoon, try to make sure that it won’t be in TOTAL SHADE from the garage! D’oh! Potatoes still worked fine because they’d reached 160 degrees before we left on our excursion.

And when you put the parts together, they look something like this. Re-orient it toward the sun every couple hours or so, though I have to confess I’m not really the BEST at doing that. I think the design compensates pretty well for less than optimal direction-ing.

This is what we use for the simplest of cookers. Check out the next photo for what it looks like assembled.

And DON’T LAUGH. This is a pretty darned effective cooker. Remember we’re cooking here at a latitude of roughly 42 degree N, surrounded by lakes that like to turn into clouds during the muggy summertimes.

And what a meal it was: poached catfish and garlic mashed potatoes.

Since I’m a bit of a “fish-snob” - y’know, highly opinionated about that delicate range when fish is between raw and overcooked—I knew the real test of the cooker would be how it handled fish. So we jumped right in with catfish which is I think the hardest fish to cook. Other fish will be OK - OK for folks who aren’t fish-snobs of course—if they’re undercooked but underdone catfish is a chewy revolting nightmare.

We also pushed the envelope in the amount of food we cooked at one time. Three fillets of roughly .6 each for a total of 1.8 lbs of fish. We used the 9” Graniteware roaster and our tried and true “windshield reflector” cooker. The larder didn’t provide much flavorful liquid to use as poaching sauce so we emptied the last .5 cup of salsa from a jar. Come to find out, this concoction didn’t have enough salt for our tastes so when it came time to plate it up we scattered the fish with capers which were the perfect addition.

And we accidentally tested another variable, namely how LITTLE time in the sun it takes to cook food. Our meal was out in the sun by roughly 9:30 this morning but we had to pull it out by 3:30 due to a rain storm. I can’t say that it was bright, clear sunshine the whole day either. We weren’t ready to eat that early so we took the whole roaster and wrapped it in a blanket to keep the heat in. We finally got around to eating roughly at 7:00, after a deep end-of-the-week nap. The internal temperatures were roughly 91 degrees Fahrenheit at 11:00 AM and at 3:30, it was about 130 degrees. When we ate, some 3 and a half hours after it had been taken out of the cooker, the fish was still 107 degrees, not blistering by any means but still warm enough to count as a “warm meal” especially in mid-July.

Basically, the fish was perfect. Of course it was moist because it was poached but most importantly it was cooked all the way through. I started eating with the thickest sections, the parts that are most likely to be rubbery and they flaked away with my fork. Perfect. As it ended up, our son skipped out on dinner so Mib7 and I ate ALL the catfish. Yum!

If any cheating happened it involved our side dish of garlic mashed potatoes. We cooked five little Yukon Gold potatoes with about a half dozen peeled cloves of garlic. We cooked them yesterday but succumbed to fast food for dinner so we didn’t eat them. Tonight we popped the potatoes and garlic into the microwave to heat them up, mashed them and devoured them. Again a little salt and pepper were needed. The potatoes are very moist and “creamy” even though we added no dairy products. Part of that has to be attributed to Yukon Golds which are a pretty nice potato but I’d bet something is being contributed by the cooking technique that keeps the moisture inside the cooking vessel in contrast to, say the dry heat of baking. (Ha, that almost sounded like I knew what I was talking about!)

I continue to be impressed by the efficiency of the “windshield reflector” cooker, so much so that I’m going to look for another reflector to make another one. I’m going to try to upload some photos just to prove how SIMPLE it is.

I still have to try - and succeed - at rice but there are many days left in summer.

I wanted to see if I could cook food in any meaningful way in the muggy climate of Michigan. So my summertime goal has been to be able to cook a couple cups of rice every day from June 21st til August 21st.

So far, I have had great success with everything EXCEPT rice! This includes a heavenly baked potato that I dropped in the cooker along with about a dozen peeled cloves of garlic that also roasted to perfection. I even got really brave one day and cooked boneless chicken thighs with a little salsa. I used a probe thermometer to check the internal temperature and it got to 170 degrees fahrenheit. (I’m saving the failed rice to use in an experimental batch of saki I’m planning later in the summer.)

If you are interested in this goal, check out the AMAZING resources at www.solarcooking.org. There are multiple designs, recipes and a living community of folks who do this every day.

My first design was made from a car windshield reflector. Basically roll one edge into a cone and fasten it with a “bull clip” paper clip. Put the tip of the cone in a bucket and put an inverted clear bowl in the center of the cone. This raises the cooking pot to the “focal point” of the reflector. For the cooking pot, I got an el cheapo “graniteware” double boiler for a couple bucks. It’s thin metal which conducts the heat well and the coating is a baked on black speckled enamel which makes it suck up that solar radiation. Internal tempteratures regularly get to 170 degree F and the amazing thing is that you can’t scorch food so you can just let is sit in the cooker until you want a nice hot meal sort of like a slow cooker. Since I couldn’t help but fiddle with it, I kept adjusting the cooker to point at the sun, though this design is supposed to refocus itself somehow.

The second style I made was a “cookit” style from the solarcooking.org website. I didn’t have carboard large enough so I scaled it smaller, ah, SIGNIFICANTLY smaller, nearly half which probably explains why it doesn’t work as well as the windsheild reflector design. But the Cookit looks so TOTALLY COOL. I want to make another one out of more durable materials, maybe even sheet aluminum and make it the right size.

The next model I want to build is the “box oven” style which are supposed to be even more efficient than the reflector types I’ve been playing with so far. These bring the promise of BAKING COOKIES and, this last thing is almost too good to imagine but the ability to can tomatoes. It’s always a drag to can and bake during the summer because we don’t have air conditioning for moral reasons. If I could make cookies let alone bread year-round I would be a very happy man!