Ain't defending what I don't know, but noone was stumped. The engineering assumtions made were limiting and very likely not to be the case in a well engineered product. Output can definitely be higher than 300w if it isn't a flat sided featureless painted metal cube. There needs to be contact for electric interfacing if it is to replace batteries directly using common parts. Also, I'm sure high temp heat exchangers aren't usually flat painted metal surfaces.
In relation to Rossi stuff, they are INVISIBLE (tm) (patent pending)