This interesting hybrid solar oven was made by Art (ThornySahuaro on the Yahoo SolarCooking group.) What's interesting is that it both reflects light down onto the cooking pot but also up to the bottom. Reflecting to the bottom makes it possible to brew coffee and fry food while being a hybrid, it can still be used for baking. Thank you to Art for sharing this with everybody.
I call this solar oven a hybrid because it combines the high heat of a mirrored parabolic dish on the bottom with a more conventional box oven with a funnel reflector on top.
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My goal was to make an oven that would brew coffee and fry food but also be able to bake. I found that brewing coffee was difficult because the whole pot would boil but it wouldn't really percolate. I found that by taking a bright aluminum pot and painting just the bottom black it percolates quite well and will make coffee in about 45 minutes. When it's done I flip the lower reflector over and just let it set in the solar oven to stay hot.
I sized the oven to accept my large cast iron dutch oven and have had excellent results with several chickens and beef roasts. The heavy cast iron spreads the heat from the lower parabolic reflector so that food doesn't burn on the bottom. Bread and cakes go in their own separate pan inside the dutch oven and heat evenly. I have fried bacon and eggs in a regular frying pan but find that a cast iron frying pan heats more evenly.
How it's made
The top glass is a microwave oven tray. The bottom glass is a Pyrex pie pan.
The parabolic reflector is a Dish Network dish. It pivots to aim the focal point and allows it to be turned downward when not in use. The focal point is on the bottom of the cooking surface.
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The turntable base (photo below) has the rear hub from a front wheel drive car bolted to a couple of 2X4's in an X with a piece of 3/4 plywood for a table. The hub worked too well. The slightest breeze would spin it around so I ended up building a wooden brake to make it harder to turn.
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As the following photo shows, there is a big door in the back giving easy access to the oven. It can be pretty bright when you open the door but all I need to do is rotate the oven a few degrees when I open the door and the focal spot moves out of the way. I haven't found it to be a problem.
For insulation there is 1/2" foil faced foam board around the perimeter and inside the door. That keeps the outside of the metal wall and door from getting too hot to touch. The top and bottom are only single glass so I'm sure there is heat loss there.
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