I thought you could not get a solar oven hot enough to boil to sterilize water, only a parabolic cooker can. Does yours boil?
Yes you can boil water in the SunFocus® or UGLI™. The water will read 212°, but only slow, steady and small bubbles will appear. Do not get confused thinking that seeing large, fast bubbles roiling over means the water is hotter than 212 degrees. It’s isn’t.