Passive Solar Hot Water - Free Energy

A thermosiphon solar collector system provides truly free energy. Unlike its active solar counterpart, passive solar energy uses neither pumps nor external input power. Passive solar collectors need nothing but energy absorbed from the sun to heat the water as well as to move that heat through the system. Once installed, a thermosiphon system will provide perpetually free hot water. During sunny periods the water in your collector is heated and pumped via the forces of convection to your storage tank, heat exchanger or indirect water heater, free of charge.

The laws of thermodynamics dictate that certain conditions exist to allow heat to flow properly throughout the system. If these mandatory conditions exist, convection will naturally cause a thermosiphon to occur within the closed-loop system. These physical requirements are as follows:

• The output of the collector must be above the level of the return.
• The hot water storage tank must be located above the collector.
• The output of the collector must be piped to the top of the storage tank or heat exchanger coil.
• The bottom of the tank or coil must return to the bottom of the collector.
• There must be a minimum of hydraulic resistance and heat traps.

Once these criteria are met, the system can function properly. Initially, as solar heat is introduced to the system, the water in the collector tubes becomes less dense, resulting in convection flow upwards toward the outlet of the collector. The heated water rises naturally to the storage tank or heat exchanger. This heated water enters the top of the tank and the cooler water at the bottom of the tank, being more dense, descends down the return pipe to the bottom of the solar collector. Providing there is a minimum of hydraulic resistance, such as sharp bends in the tubing; and the piping does not contain heat traps in the form of dips causing a negative pitch, then the heat will continue its cycle unimpeded.

As more people seek alternative sources of energy to reduce their heating bills or to be free of the grid completely, renewable sources of power such as solar are sought more frequently. The thermosiphon solar collector system satisfies this increasing demand by offering a method of heating potable water or providing a source of radiant heat that is completely free to operate!

Further information can be found at Renewable Options