Water calcs revisited

Eight square feet can produce one gallon of distilled water per day, says this dude in a video.

Let's see.  Assuming 100 watts of solar energy strikes every sq. ft. of surface, then that would be 800 watts times the number of hours of effective sunshine.  Let's say six hours.  Then we obtain 4800 watt hours per day, or 4.8 kilowatt hours in order to produce 1 gallon.  That compares with six in my own water experiment.   Since I didn't bother to get an energy rating on the stove I used, then I can conclude that my numbers may have been off a bit.

It seems to me that you can use this dude's idea of a water distiller.  I can use a glass top on a table, and fill the lower side with dirty water and collect the water from the glass.  He says it needs to be airtight.  I can buy that ( with a dollar ).

Incidentally, I think the ideas I obtained before are better than this.  I probably won't try this one.

Update:

Maybe I might try this one.  He goes into detail into how to build it.