One of the badges Katy wants to earn is Outdoor Cooking. There’s not a lot of places for outdoor cooking here in the ‘burbs so we thought we’d tackle a solar oven. To build a solar oven you take a box, cut a flap in the lid, line the whole inside with foil (shiny side up!) and cover the hole in the lid with plastic wrap. You can also put some black construction paper in the bottom of the box to help absorb heat.
So this is our solar oven:
When you’re cooking you prop the flap open so the sun can reflect down into the box. The plastic holds the heat in. Supposedly. We decided to try some slice and bake gingerbread cookies with the dough that’s been in the freezer since Christmas.
You’re supposed to let it pre-heat for about 30 minutes then allow twice as long as it would take in an oven. We skipped the pre-heating and just put the cookies in. We checked on it periodically and turned it when the inside had too much shade. Two hours later we had warm, soft cookie dough. The tops of some of the cookies might have been a little done, but that was it. I put an oven thermometer in and it only registered 150 degrees. Not nearly hot enough to make cookies! After consulting with some more experienced solar-oven cooks I decided that it seems to be best suited for melting stuff rather than actual cooking.
So we decided to try again. The gingerbread cookies were on Thursday. Today we decided to try smores. It was in the 90s on Thursday and our oven got to 150 degrees. It was over one hundred today and I wanted to see how hot the oven would get and how much hotter than just leaving something on the table. I put an outdoor thermometer on the deck table next to the solar oven and then put an oven thermometer inside the box to compare. The sun beating directly on the outdoor thermometer turned past 120 degrees where it maxed out. The oven thermometer read 160 degrees after about an hour. We set up the smores inside the oven. I then put the oven thermometer on the table where it registered about 140, 20 degrees cooler than the oven.
So we left those about 30 minutes and came back to check. The chocolate had melted but the marshmallows were barely warm.
But it was so hot today the chocolate would have melted anyway so I don’t see that the solar oven was any benefit at all. It seems like if it was going to work it would be best on a day like Thursday when it’s hot and sunny but not hot enough to melt chocolate or cheese on its own. I’ve heard you can cook hotdogs in them, too. But I never got the temperature over 160 degrees and that was on a really hot day. I guess if you’re camping in 100+ degree weather you might prefer a solar oven to building a fire, but you better start dinner right after lunch!
So I’m going to chalk this up as a failed experiment. However, if you really want to cook in a natural way you can build a solar oven from a wooden box lined with sheet metal and with a piece of glass over the hole. It will work as sheet metal conducts heat much better and the glass will really hold the heat in.
Next up is a box oven, which is heated with charcoal. I’ve never built one but I did use one on my camping training and it works very well.