The ideas was hatched by Christopher, who had built ‘brea box’ solar heaters in the 70s.  And it’s very similar to a solar oven I had built in Peace Corps.  Place an old water tank - this one 30 gallons in size - inside an insulated box; place glass on top (and south-facing side); coat the box sides using aluminum foil; seal it all in and use the sun to heat your water each day. Simple! 

But we went to some extra steps to integrate it into our palapa roof above the toliet, where Ricardo and Isidro made a very strong foundation to support the weight - and raise the heater above any shadows.  When we’ve exhausted the 30 gallons - anyone who knows Americans knows how quickly we can exhaust a resource - there is an electric hot water hearer downstream that ‘kicks in; and heats the water.  Hot water will keep flowing through all day long and stay insulated all night long.

While plastering continues, roughly accomplishing one coat of plaster per dome per day. We’re moving quickly!!