This particular solar cooker design caught my eye, and I was wondering if anyone has used it.
The designer/inventor said that there was no need to use a plastic bag, as the reflector provides ample heating for a black cooking vessel.
Since an oven bag costs little, why would you NOT use it to help trap UV rays and provide air insulation?
In my own testing, with two identical panel cookers containing a pot of water, the poly bag variable was tested. The one without the bag reached 100F and the one with the bag reached 142F.
The reason I mention this, is that when you introduce a product that represents a paradigm shift, it's failure to succeed will forever taint the concept that has been introduced by the failed product.
It is an interesting cooker design.
Thanks again Brad for your always insightful and very useful knowledge with regards to all of these solar cooking questions and ideas that abound on the internet.