solar hot water system
How they workSolar 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.
Three types of solar collectors are used for residential applications:
There are two types of active solar water heating systems:
Passive solar water heating systems are typically less expensive than active ones, 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:
Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosiphon systems. Since an batch (integral-collector storage) system already stores hot water in addition to collecting solar heat, it may be packaged with a demand water heater for backup.
For more information about solar water heating system components, see the following:
Selecting a solar water heaterBefore you purchase and install a solar water heating system, you may want to do the following:
Installing and maintaining the systemThe proper installation of solar water heaters depends on many factors. These factors include solar resource, climate, local building code requirements, and safety issues; therefore, it's best to have a qualified, solar thermal systems contractor install your system.
After installation, properly
maintaining your system will keep it running smoothly. Passive systems
don't require much maintenance. For active systems, discuss the maintenance
requirements with your system provider, and consult the system's owner's
manual. Plumbing and other conventional water heating components require
the same maintenance as conventional systems. Glazing may need to be cleaned
in dry climates where rainwater doesn't provide a natural rinse.
When screening potential contractors for installation and/or maintenance, ask the following questions:
Improving energy efficiencyAfter your water heater is properly installed and maintained, try some additional energy-saving strategies to help lower your water heating bills, especially if you require a back-up system. Some energy-saving devices and systems are more cost-effective to install with the water heater.
Other water heater options
Seasonal water heating may be more suitable for temperate climates or for applications with seasonal use, such as cottages. In this case, a system based on batch collectors can be a viable alternative but the standard collectors are still used.
Solar systems can also provide hot water for a wide variety of commercial applications. These commercial systems should be designed by an engineer or expert and have a collector area of 10–100m2. Among many potential applications, the commonest are for: apartment buildings, senior citizen residences, hotels, car washes, restaurants, recreation centers, and hospitals.
Commercial solar hot water systems are basically the same as those used for homes, except that the thermal storage, heat exchanger, and piping are larger. The size of these components is basically proportional to the size of the collector array. The solar collectors are often used to preheat water and will have a back-up heater to ensure that hot water needs are met, even when there is no sunlight.
Related category• SOLAR ENERGY AND POWER
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