Providing Residental Hot Water with Solar Hot Water Heaters

A popular emerging solar technology now allows a home to provide itself with free hot water heating through PV solar power. The sun warms water in an insulated storage tank through an open or closed loop system. During times when there is not enough sunlight, hot water is provided through the backup heating system.

Home Solar Hot Water Heaters
 
 

Open Loop Solar Hot Water Heating Systems

In an open-loop solar hot water system, water gets heated directly. This means that the water you are using is actually what gets heated. Flat-plate collector systems utilize radiator-type pipes or tubes that are mounted to take full advantage of the sun's solar rays. Set against a back plate designed to absorb and retain heat, the water in these tubes heats up quickly and is transferred via pump to an insulated hot water storage tank.

Intregral collector (ICS) or batch-collector solar hot water storage systems connect directly to a home's hot water system. During the nighttime or when photovoltaic solar energy is not being gathered, a bypass valve flips over to the home's conventional hot water heating system. The storage tanks are glazed and insulated to retain as much of the heat as possible, but it dissipates over time as it sits in the chamber.

Closed Loop Hot Water Solar Heating Systems

In climates that may experience freezing temperaturs, a closed loop solar water system may be needed so that pipes don't freeze or crack. In this case, water is mixed with antifreeze to create a non-freezing solution that will be pumped through tubing or pipes.

Alternative Home Energy

In the case of a closed loop solar heater, it's the solution that gets heated by solar power - not the household water itself. Instead, the water is heated by convection as it gets exposed to the warmer solution within the closed loop. This is usually done by a coil, which exposes as much surface area as possible to allow for maximum heat transfer. A circulator is used to move the solar-heated water/anti-freeze solution through the coil, and eventually the heated water is drained into a storage tank for home use. A solar controller determines when the circulator should run.

New progressive batch-type hot water systems exist in which the metal or copper tubes of a batch collector are interconnected with one another rather than separate. The end of each tube is connected to the next in a 'Z' shaped ladder, allowing for the heated water to transfer throughout the encapsulated collector to reach the output tube with the hottest water possible. This delivers higher temperature water, increasing the efficiency of the solar hot water system and allowing for cooler water to be heated more immediately as the hot water leaves the collector.

Passive Solar Water Heating Systems and Roof-Mounted Storage Units

Water can be solar heated through another method called a 'passive' system. These systems aren't nearly as energy efficient as the active systems mentioned above. But on the positive side of things, passive solar heating of water can be more durable and a lot more reliable too.

Roof mounted solar hot water is ideal for homes that don't have the space for a second hot water tank, whether it be inside or outside the residence. The solar arrays cleanly and silently capture the sun's heat and transfer it directly to the water in the tank. Because the tank is mounted above the entire rest of the home's plumbing, the resulting hot water can be gravity fed to wherever it needs to go. It's a simple, efficient method for heating water by the sun.

Another type of passive system involves what is known as a 'thermosyphon'. These systems take full advantage of the fact that, just like with air, warm water will rise as cooler water will sink. As the warm water rises it gets syphoned off into the hot water tank. The storage tank is actually installed above the solar collector to allow the heated water to rise into it. Thermosyphon systems can reliably heat water on sunny days, but are not as efficient as some other solar water heating methods.

Installation and Maintenance of Your Home Solar Hot Water System

Many plumbing contractors are now required to become certified in the installation of solar hot water units, especially in light of changes to building code requirements. Getting a certified solar water heating installer to set up your system is always your best bet. Once installed, regular maintenance on such a system appears to be minimal. Glazing may wear off of the solar components in some cases, depending upon the climate, but other than that the system should take care of itself. Electronic solar controllers maintain the hot water sensors and turn the circulatory and pumping systems off an on. Prevention against freezing may be necessary for open loop systems located in cold climates. But with just a little preventative maintenance, your solar hot water heater will operate in an energy efficient manner and should save you significant money when it comes to fuel oil or utility bills.


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