I'm interested in hearing from someone who has tried it also. In my pipe dream outdoor kitchen I would have a permanent solar cooker on a heavy duty turn table to be able to adjust its orientation. I cook alot of one pot, slow cooker meals so i could probably make alot of use of one.
I cooked some sweet potatoes in it the other day and warmed up some left overs today. It's real simple to use and can heat up quickly to 300-350 in about 15 minutes (almost burnt myself first time I used it because I underestimated it). Naturally, cloud cover does really affect the temperature. When I was cooking the sweet potatoes, the temperature kept dropping because it was slightly overcast with some large clouds, but it still cooked them in about 30 minutes. They were super-moist and very tasty!
What if you had a solar cooking surface that was heated all day whether you used it or not. And should the time come that you want to cook a bit, you just wander over and start cooking. So your cooking surface is already hot and waiting patiently for you.
You could have a black cooking surface with all the reflective stuff pointing at it. That black surface would probably get super hot right around lunch time. And then when you put your cooking pot on it, you get lots of heat from below plus the heat from the current sun rays.
I've had some success with a DIY solar oven. All you need is: 1. A dutch oven, or camps stove with a lid. 2. An oven safe nylon baking bag (Reynolds makes em.) 3. One of those silver, reflective car windshield shades. 4. A couple inches of adhesive backed velcro.
Basically, attach some of the velcro to the top edge of the windshield shade to make it into shape that reflects light to a central point (a bowl, the corner of a cube, or a simple V shape.) Fill your stove with whatever goodies you'd like to cook, then place it in the baking bag, and place the baking bag in the center of the reflector. On a really bright sunny day, you could ideally bring the temperature of the stove up to 350* in about 15-20 minutes so you can pretty much cook anything you feel in it. Have fun!