Solar Shower Project

There will be a permaculture workshop here in August, and some of the participants will be camping on the grounds, so a recent project is a solar-heated basement shower for them. Here's the design: a large tank in an insulated box with a glass cover sits on top of three black 50-gallon drums filled with water (in the basement behind very large glass panels facing south). The idea is the sun heats the barrels and the tank that sits on top of them. As water runs through the tank it is solar heated for the shower.