This solar water heater is currently in everyday operation at a New Mexico commune. The copper tubing visible through the glass is brazed into the zig-zag pattern you see. The corrugated roofing behind the tubing is painted black (to help collect heat) and insulation-in turn-behind the roofing makes the unit more efficient. Note also the insulation (which is nothing but a wooden box filled with sawdust) around the storage tank on this homemade setup and around the water heater's connecting pipes. Holding tanks, particularly if they're outdoors and exposed to chilling winds, should always be protected this way. It's foolish to collect the sun's warmth and then just dissipate it to the atmosphere.
THE MOTHER EARTH NEWS EDITORS