I have recently been doing quite a lot of experimenting with simple homemade collapsable solar ovens, the kind needed on a boat. They are so easy to make please dont buy one! here is the one I have been using http://www.allseasoncooker.com
I have been baking bread, cooking beans, rice, potatoes, just about everything you can make in any other oven. As mentioned above it needs to be pretty well aimed at the sun so you need to be on a pretty steady tack or in a very stable anchorage or mooring
. going ashore assures an easy time of it. You can cook up a ton for the next several days.
the best overall resource I have found is CooKit - Solar Cooking
everything you ever wanted to know can be found there. I have not made their style of oven yet but I am going to soon. I think it will be more forgiving of moving around a bit, and looks easier to make than the All Season cooker. I think the All Season oven gets hotter with a bit of tending to make sure it is aimed well. all in all, no matter what model you use, it is a great way to save cooking fuel
and have fresh bread on board! Good luck.
PS I did not have good luck with the model described in Sailing the Farm. I could never get it above about 120 degrees. OK for drying food
, but to cook i think you need the reflectors. I am currently building his water distiller though, so i hope it works better than his idea for the oven....