Solar Sand Battery Evacuated Tube Implosion Solar Water Heater Thermal Storage 

Using Sand For Solar Thermal Heat Retention. Solar evacuated tubes are extremely efficient at transferring sunlight to heat. This heat is then transferred to the material inside. This video is for lower quality water heaters that may experience rain water infiltration from poor designs. This is also an efficient method for enhancing good designs enabling solar thermal storage. If you use heated water in the morning from a system like this, the standard fins may be a better option. The thermal storage does last several hours.