Cooking without electricity - Sun Oven

Once you have a store of food, how are you going to cook it in an emergency? One option is a sun oven. I spent some time this week experimenting with the sun oven.
I used this recipe for Sweet and Sour Chicken from Wendy DeWitt.
Here's how the day went.It was a rather cool day in Southern Texas; 61° at noon.
8:30 am I set out the sun oven to "preheat"
9:30   The oven was 300°. I made a slight adjustment to better capture the sun.
10:30  345°  I put the rice and water in the oven in separate containers to heat.

11:05  300° in the oven. The water and rice were both 150° and I combined them.
11:50 300° oven. I put the chicken in the oven.
11:20 250° I made some adjustments to the oven to face the sun better.
12:00 260° Adjusted the oven
12:30 290°
1:20 260° wiped the condensation off the glass on the oven. Adjusted it to face the sun. Rice looked like it was   done.

 1:50 260° I think I put the sauce in now. I forgot to write it down.

2:40 200° (The sun had moved behind a tree in the yard. I moved the sun oven to a different spot.) Wiped the condensation. Shook the sauce.

3:15 150° The chicken was 200° and the rice was 180°. At this point, the backyard was very shaded and I didn't want to move the sun oven to chase the sun spots so I took everything out and we ate dinner very early. (and warmed it up in the microwave later)

What did I learn?
*Start early and prepare. I think the sauce would have thickened more if I had put it in earlier.
*The sun is definitely lower in the sky in the winter. I had to make more frequent adjustments of the oven to follow the sun across the sky. By 4 o'clock, they sun was too low in the sky to cook anymore.
*I think it might make a difference if the jars used to cook were darker. I don't know if the white rice reflected too much sun. Before the next experiment, I plan to paint the outsides of the jars black.