High Vacuum Solar Collectors

A vacuum is a space from which most of the air, gas, or other material has been removed, or is not present, according to the Cambridge Dictionary. Simply put, it is a space which has almost no air. In typical flat plate solar collectors, most of the heat is lost through convection. Convection is how your oven heats food. A hot heating element in the oven heats the air surrounding it and the air is what heats your food, not the element. From a solar collector, convection is a loss of useful heat to the environment. In a flat panel collector, the hot surface loses heat by convection to the cold air around it.

This loss of heat means there is less to heat the hot water in your house. Because there is no air in the evacuated tube, there is no loss to the surrounding environment by convection. There are some minor losses due to radiation (see selective coating for more information). Flat plate collectors also lose heat to wind and snow. An evacuated tube collector can have snow on the tubes and the snow will not melt. Look at the following thermal image for how cold the evacuated tube collector actually stays.

• Selective Coating on Collector
• Solar Collector Automatic Limiting Device
• Solar Thermal Heat Pipe
• High Vacuum Solar Collectors
• Solar Collector Soda-Lime Glass
• Solar Collector Hermetic Vacuum Seal and Flexible Neck

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