In this video, I'll show you how I made my home-made solar oven that can reach up to 350 degrees Fahrenheit (or 176 Celcius). And that's in the Spring. In the Summer, I can probably get up to 400*F or more. The secret here is insulation. I also avoid using plastic, paint and other sealants like silicone, glue, or rubber (which is hard to build this without). Everything inside the box subjected to high heat is natural wood, aluminum, porcelain, and glass. That way I can avoid cancer causing chemicals and most importantly it doesn't alter the taste of the food.
Here are a few videos that I have cooked with this solar cooker:
Pork spare ribs: https://youtu.be/qSg7Wsl6ARc
Tenderize rib tips and cartilage: https://youtu.be/AlgtbQdOcAA