You can solar cook all year round with the right solar cooker. I added links to those cookers at the end of this article. My solar cooker is a poor design. I knew this the day I made it. I was just testing what the least amount of effort on my part would produce with stuff I already owned. My hurried effort produced a useful oven for the warm half of the year. In the winter, I would rather fill the house with the smell of baked goods.
By mid-November my box-style solar cooker was reaching only 150-175 F mostly due to the sun hanging low in the sky. I can cook fast cooking foods like baked potatoes and hard-boiled eggs, if I put them inside a lidded jar. The lidded jar traps heat and reaches up to 210 F when the oven is only 150 F.
Please learn from my poorly designed cooker and build a better one. Or if you are a busy homeschooling mommy like me, just forget about solar cooking between mid-October through mid-March.
Parallel to the ground vs. Parallel to the Sun. Although the Sun is closer to the Northern Hemisphere during the winter, the Earth is titled away from the sun by 23.5 degrees. This causes sunshine to come into my cooker at a steep angle. It has more shade than sunshine inside the cooker. This makes it take longer to reach cooking temperature (180 F). If I tilted my oven so that sunshine could shine straight inside, then the oven would work better. I don’t tilt it because it is shallow and also because I would have to make a stand to hold the food level inside the oven.
Reflectors. Days are shorter and so is available cooking time. If I added reflectors, then the sun would reflect off the reflector and into the cooker. This would add enough sunshine to raise it into cooking temperatures very quickly. I have avoided using reflectors because they catch wind like a kite and blow off. I hate when that happens. Hemet is a very windy place so I am will improve my oven in most ways, but I may still avoid reflectors.
Insulation. I only put one layer of cardboard and aluminum foil for insulation because it was fast. The whole cooker took only two hours to make. I didn’t expect that to be enough insulation for the cooker to hold heat long enough to cook, but wanted to test it out. Nearly everything I read on solar cooking came from a climate and latitude different from Hemet. Climate and latitude are important factors. Hemet is has an ideal climate and latitude for year round solar cooking.
I was planning to insulate the cooker with 1-2 inches of cardboard after testing it the first day. I was surprised that it held at 200-250 F. I could insulate more so less heat will leach out and probably still cook several food throughout the winter as long as they are in covered pots.
Exterior. The metal trash can came with my property. It was easy to clean and is meant to stay outside — unlike cardboard. I wanted to leave my solar oven outside year round because that is convenient. I made the cardboard box cooker to nest inside of the can so I could leave it outside. This is a fine solution for weather-proofing EXCEPT that metal conducts heat.
The summer is so hot that heat leaching isn’t enough to hamper cooking. Heat wants to move. In cold weather the warmth from inside the oven travels to the outside cold. The metal exterior works like a super highway. Having heat race out of the oven is big problem that can be solved by extra insulation. Because cardboard is not a good heat conductor, adding another inch or two would help. The ideal exterior is wood or another material does not conduct heat well.
Winter Solar Cooking Options:
Make A Solar Oven For $5 — Jun 19, 2011 Panel cookers can cook in the winter if its a clear sunny day with no wind.