“DIY Solar Water Heater. A Homemade “flat panel” COPPER COIL Solar Water Heater. Easy DIY. Full Instructions. Super hot temps (sustained at 165F+). Fast hot water. No electricity needed. Easily hooks up to standard water tap/garden hose. Reaches temps well over 150F (water pasteurization temp) so it works to clear/kill any pathogens (if a non-municipal source is used). It’s super portable so it’s good for camping/off-grid/emergency as well as everyday use.