First Attempt - Small Cardboard Box Solar Oven

by Steven
(Rockville, MD)

I've always been intrigued with the idea of cooking with solar energy (probably because I love to get anything free) so I decided to make a small solar box oven. I took the cardboard box from a Pizza Oven I got for Christmas. The box is 15 inches by 13.5 inches. I made a cardboard brace by gluing strips of cardboard and glued four of those on the bottom so that the inside cardboard box would be propped up. I filled the bottom with a layer of shredded paper, set the smaller cardboard box on top (it's about 12.5 inches by 10 inches) and then filled in the side gaps with more shredded paper.

I cut the sides of both boxes so the top lid would be at an angle to better capture the sun. I ordered a 12 x 12 inch piece of plexiglass for the lid, which I made by cutting out the middle of a piece of cardboard and then taping the plexiglass to it. I lined the inside of the solar oven with aluminum foil as well as the top flap which I would use as my reflector. I put a small metal grill on the bottom so the pot would be off of the cardboard.

To make sure my lid was on tight I used screws on the side of the lid to hold it in place securely.

I got to test my oven today, a beautiful sunny day about 80 degrees, low humidity here in Maryland (just north of Washington DC). I'm using a 3 quart graniteware pot which fits perfectly inside my oven. I chopped up some potatoes, onions, carrots, and celery and put that on the bottom of the pot. I lay two chicken thighs on top. Everything was seasoned with olive oil, salt, pepper, some sugar, garlic, thyme, and paprika.

I set the box out on my patio at 11:50 am and aligned it with the sun. I adjusted the alignment every half hour. It took about an hour to hit 200 degrees Fahrenheit. When I did a test with an empty box it only took 20 minutes to reach 200 degrees, but I guess having a pot of food inside makes a difference. I did not preheat the oven because I think if I took off the lid all the heat would escape out of my small oven.

So I started "timing" it when it hit 200 degrees which was about 12:50 pm. I let it go for three more hours until 3:50 pm. At that time, it was just above 250 degrees. I don't think it would go much higher that that.

The chicken was cooked perfectly! Completely cooked, soft, tender, and juicy! The vegetables were another story. They probably needed another 90 minutes or so in the sun. I just finished them off on my stove.

I think next time, if I were to cook root vegetables, I would cut them even smaller--into thin strips rather than chunks. OR, cook something like cabbage which should cook faster. But I think this little solar box oven has no problem cooking meat.


___________________________________________


Thank you for sharing this Steve, great narrative with great detail.

You are correct on the veggies, cutting them smaller does help to cook them more easily.

You had a good temperature for cooking with, great slow cooker temperature; you just probably needed a bit more time.
I think if you had left the whole thing cooking a couple of hours longer you would have had everything fully cooked and the veggies would have been tender. I even have to do the same with my commercial solar cookers to assure that the root veggies are fully cooked since these need more cook time even under normal cooking conditions.

Nice solar cooker!

Nathan
Admin.