Passive Solar Heating Hot Water Systems
Passive solar heating hot water services operate essentially the same as the active ones, except they have no pump or PV panel. They operate on the principle of cold water sinking due to it being heavier than hot water. This happens because hot water molecules move around more than cold ones and therefore take up more space. This makes hot water less dense than cold water. The cold water flows into the tube going to the heat collecting panels. As it heats it exands and pushes the water around it. Since the warmer water is less dense it is easier to push, and the now warming water forces the hotter water forwards through the tube, eventually returning to the tank hotter than when it left. These systems have less moving parts than the active systems and so require less maintenance. The tank must be located HIGHER than the heat collecting panels which can result in some installation issues depending on the way your home is built. Installing a heavy water tank high in your roof needs to be done professionally and may add substantially to the unit cost.
Passive systems also have backup burners or an electric element to ensure a ready supply of hot water. The burner or heating element will be inside the cylindrical water tank. The image above shows it on the outside just for ease of understanding. As with active systems, passive solar systems will significantly reduce your heating fuel bill. Passive systems are generally better suited to hotter climates, but check with your supplier about their suitability for your area. Return from Passive Solar Heating Hot Water to Home Heating OR return to the Green Planet home page for more Solar Power Facts.
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