>solar oven based on a thermal transfer medium which heats a cooking void indirectly
Isn't this kind of common?
See this for example: https://solarcooking.fandom.com/wiki/Auroville_Solar_Kitchen
Isn't this kind of common?
See this for example: https://solarcooking.fandom.com/wiki/Auroville_Solar_Kitchen
To my knowledge, it's not common. The Auroville Solar Kitchen is pretty much precisely what I had in mind, and it's the first I've heard of such a thing. I'd really like to see more specifics on what they're doing, though it looks as if there are a mix of ovens and steam tables offered.
The use of a fixed-position spherical mirror (rather than parabolic) solves the problem of a moving aim point ... a spherical mirror always has the same region of focus, even if it "smears" that focus a bit. Since what's beeing gathered is heat rather than image information, that loss of precision makes for a more robust structure (particularly given high winds, as noted).
Other options would be flat absorptive panels (sufficient for pre-heating a working fluid to much-less-than-boiling temperatures) or a parabolic or hemispheric trough type reflector which focuses on a pipe or channel running the length of the mirrors.
I'd like to see some more technical information (a quick DDG search does turn up some promising results), and it seems there are some more extensive documents and specs.