One of my customers built a
solar concentrator to break water down by high temps.
They could do it but separating the gasses was the bugger
that kept them from making a successful process...
"For
reference, this past year I’ve been charged
$4.90/gal and $1.15/lb at two different
local places to refill 20 and 30 lb portable
tanks."
That is like quoting the cost of electricity
based on what it costs at a DC fast charger.
Has more to do with delivery costs to move it
into your tank than it has to do with the cost
of propane which is like sub $2 a gal in MN
right now.