We purchased a SOS (Solar Oven Society) solar oven.  And of course had to try it out making cookies.  They were very good.  In the picture is a chocolate chip/peanutbutter chip cookie.  rolled out as one big cookie.  The temp in the picture is 280 degrees F.  We built our own solar oven a few years ago and it worked great.  But it was too big, heavy, and clumsy to take with us.  This has a plastic exterior and a special double layer plastic top.  The mirrors are alluminum and are not needed unless it is early morning/evening, or winter.  
The food cooks well, but does not get that browning affect. Browning reaction from the carmalization of sugar at about 325 degrees. (I teach a cooking course as well as science......not that different really).

The best thing we cooked, besides the breads, cakes, cookies, and chicken were the RIBS.  We would put on a dry rub and cooked them for 10 hours.  Temp was usually around 220-250.  This was in Canada in the winter!!!  Then we would put them on the BBQ for 2-4 minutes to finish them off with a little BBQ sauce.  Just amazing.  Cooking in their own juices.  They would just fall apart.  Unfortunately I never took a picture of the home made one.  It was when we were in between cameras.

This Friday we are cooking ribs....to go along with some fresh steamed blue crabs and some fresh sweet corn on the cob.   nice messy meal to be eaten out on the dock over looking the Chesapeake bay.  What life is all about.

Here is the new one with the cookies..