If you were in a desert environment where the ambient temperature was in the mid-70s but you had enough sunlight to make a solar oven that could heat to 140 degrees then it seems like you could still let the environment do most of the work for you.
Even if you couldn’t get something like this efficient enough to work on solar power alone it could still be a practical device for certain situations where shipping in water is difficult. For example, an outpost or research station in a remote area that has no surface water.
