"How Long Does it Take to Cook with a Solar Oven?"

The short answer:  "It depends."


Let me explain.


It will depend on a number of factors:

1. What you are cooking
2. How bright the sun is
3. How well your cooker/oven is insulated
4. How large your reflective surfaces are

Among other things.

Notice I didn't say anything about what the outside temperature was.  Outside temperatures really have little effect on how well or how quickly food cooks.  The most important factor is how bright the sun is and how well you can collect the rays.  You can cook during the winter on sunny days.