Solar water heating systems for homes have been around for some time. The increasing cost for energy, and growing concerns for the environment have motivated more and more homeowners to consider installing a solar water heating system. Advances in technology, which make the collectors much more efficient, have resulted in reduced cost of these systems. It also helps that, federal tax credits are available to help with some of the cost, provided your solar hot water system supplies 50% or more of the domestic hot water demand.
Two kinds of solar hot water heating systems are used for homes: open loop systems or closed loop systems. Open loop systems are installed in climates where temperatures stay above freezing and where the water is soft. In an open loop system, the incoming cold water is circulated through the solar collectors, and then stored in the solar hot water storage tank from where it goes to the water heater. In the closed loop system, a heat exchanger isolates the domestic water from the solar collector loop. The fluid running through the loop is usually a freeze-proof glycol solution. Because of the added heat exchanger and a bit more piping, the cost of a closed loop system is higher than that of a comparable open loop system.
Size and number of collectors depend on the type of collector you decide to use, for a given hot water requirement. Flat plate collectors and evacuated tube collectors are the two most frequently used types. Evacuated tube collectors have a higher efficiency than the flat plates, especially in colder or foggy weather and climates. It is generally ok to use flat plate collectors in sunny and warm climates, as long as your water is soft. The more expensive, but also more efficient, evacuated tube collectors are a better option in colder, cloudy or foggy regions.
You will need to keep your domestic water heater, or add one in your new home, even with the solar water heating system. It is a must to have this back-up full-sized water heater to ascertain that you have enoughsufficient hot water, even in the event of numerous days of overcast or snowy weather. A solar hot water storage tank is also installed, in addition to the standard water heater mentioned above. Consider the solar water heating system as a system that PRE-heats the incoming cold water on most days. It will be heated to the required temperature in the regular water heater. With a correctly designed system, enough hot water will be made in the solar collectors on sunny days to not require the regular water heater to be used. When you have several days of overcast weather however, that is when the regular water heater kicks in.
Where are you planning to install the solar collectors? I guesson the roof somewhere. The “somewhere” is critical. You have to make sure that the location you decide on receives enough direct sunlight, all year. Numerous tools are available online to help you determine this. Some of these tools are free. Be aware however, that some of these tools might not include the shading from trees. You can also contact a local solar heating system installer. Many will do a free analysis for you and they will include trees and tall buildings next door.
Now on to the roof itself. Will it need strengthening? How exactly will the collector support system be anchored to the roof? What about the pipe penetrations? What will be required to make sure that the roof is still totally waterproof after the solar system has been installed. Talk to a trusted contractor.
More things to investigate. Is there space in the basement or closet, next to the water heater, for the new solar storage tank, pump and possibly expansion tank (closed system only)? For initial planning purposes, you will need at least 2 1/2 times as much space as you use now for your water heater. More is better, so you will have easy access for maintenance.
Almost done. One more thing. The pipes. Where and how can you run them between the solar storage tank and the solar collectors on the roof? You have to find either two locations that can each accommodate a 1″ pipe with 1″ insulation, or put them next to each other in the same chase. Hint: closets or walls behind toilets, if the first floor powder room is below the second floor bathroom. Avoid having to build pipe enclosures in the living room or dining room. Expensive and not very nice looking, unless you are creative and hide the pipes behind a shelf.
That’s it. You have done a lot of the important up-front work. Hopefully you now know enough to be dangerous, can make educated decisions and ask the right questions about how to plan, design, purchase and install, or have installed, a solar water heating system for your home.
Don’t make the same mistakes others have made before you when they were designing and installing a solar hot water system. Get educated and learn how to plan and prepare for a successful system.
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