 We all enjoy a hot shower after a long day. However, some of us are looking for more sustainable options for our old water heaters that use up lots of energy. Solar water heaters can be a cost effective way to generate hot water for your home. They can be used in any climate, and all they need for power is sun light, which is always free.
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't. Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.
There are three types of solar collectors in use today. Flat plate collectors are glazed collectors which are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors have a dark absorber plate, made of metal or polymer, without a cover. Integral collector-storage systems feature one or more black tanks or tubes in an insulated, glazed box. Water flows through all solar heaters in much the same way. Cold water first passes through the solar collector, which pre-heats the water. The water continues on to the conventional backup water heater, providing a reliable source of hot water. Solar collectors should be installed only in mild-freeze climates because the outdoor pipes could freeze in cooler climates. Evacuated-tube solar collectors feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and a metal absorber tube attached to a fin. These are more expensive and are used predominantly in commercial applications.
There are two types of active solar water heating systems that exist today. Direct circulation systems pump and circulate household water through the collectors and into the home. They work well in climates where it rarely freezes. Indirect circulation systems circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then is used in the home. They are popular in climates prone to freezing temperatures.
Passive solar water heating systems are typically less expensive than active systems, but they're usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems. Integral collector-storage passive systems work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs. Thermo-siphon systems circulate water based on the change in water density. Warm water is less dense and rises; cooler water is denser and sinks. The constant rising and sinking of the water forces a circulation pattern and water flows through the system. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.
These new systems are very eco-friendly. There are several options to choose from based on your geography and your wallet! A little research will go a long way toward making a better decision.
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