As part of a wider preparedness strategy, you goal should be find new and novel ways of doing things outside the normal trappings of your comfortable life. In the most extreme preparedness situations, you are going to be with out power and fuel (gas, diesel, wood) could be limited or useless...Or....In a long term survival siuation where you were completely prepared, you might want to ration your stored fuel in an efficient manner.
Sunovens hold some promise from what I have read. I know the dialogue concerning sunovens is controlled by the radical environmentalist, but as a student of the preparedness doctrine you should evaluate all options, even if the ideas come from people you think are crazier than you.
Sunovens could play a role in a permanent survival situation by reducing the need for electricity to purify water and other cooking chores. I doubt they would be of much use to the freedom fighter, the person in the midst of a temporary disturbance, or a person in an unstable situation. They require a time to build and use on a large scale, which if you were in a permanent stable survival situation you might just have to time to attempt such a project.
For my introduction I have chosen a simple model to build and test. Presently my resources are limited. I do not have a workshop to attempt to build a large one, so I have chosen a simple small sample to test.
I do not have a protractor so I am going to wing it from the picture. I also have no glue, so I will see how it works with the items I have (duct tape). I will build it, test it, and report.
Other sunoven links:
Principles of Solar Box Cooker Design
NOTE: There are much more efficient designs than the one I am building. I would think it wise to store large amounts of plans and directions in your future retreat, so that you will have a information store to use when you have the time.