Do all solar water heaters dissipate heat?
All solar and conventional water heaters do dissipate heat and in so doing cool down the water held in the storage tank. Most of the dissipated heat is lost through the insulation that surrounds the storage tank and the copper tubing (plumbers call this a “line set”) that runs from the solar panels to the solar tank. If energy is not added to the stored water eventually the water temperature will return to equal that of the surrounding air. When the sun is heating the solar collectors, most of the solar energy is transferred via the heat transfer fluid “propylene glycol” through the line set into the storage tank lower coils to heat the water. The balance is lost or dissipated back to the surrounding air. When the sun is not out, the solar collector cools to a temperature below that of the water in the storage tank and will not contribute to any heat dissipation because the pump system is automatically selected to the off position. After extended periods of hot and sunny weather and du
