How to Choose Solar Water Heaters

As energy costs rise and people become more aware of the ecological impact of carbon emissions, solar water heaters are becoming increasingly popular. Solar heaters are a great starting point for anyone interested in solar power but intimidated by the installation costs.

Solar water heaters can be used in any climate and in any weather. Solar heaters are available in two basic designs: passive and active. A passive system consists of a solar collector and an insulated tank for storing the water. An active system consists of a solar collector, an insulated tank, circulating pumps, and controls. Most solar water heaters have a single tank with a backup heating method integrated into it (in case it is cloudy or raining) or else two tanks; one to heat the water, and one to store it.

Solar collectors for residential applications tend to fall into one of three categories: 1) Flat plate collectors contain a dark absorber layer under several layers of glass and have a thin box-like construction, 2) Integrated collector systems in which a glass tank or series of glass tubes heat the water and then send it to a conventional water heater tank for storage, and 3) Evacuated tube solar collectors in which a series of fin tubes exposed to the sun heats the water but are specially treated so that the heat can’t radiate back out before reaching a storage tank.

Passive solar heaters tend to be less expensive than active systems, but they are not as efficient and must be backed up by a secondary heat source in areas where the temperature falls below freezing on a regular basis. Biomass furnaces and burners (which use waste wood, industrial waste, weeds, and/or fast-growing non-lumber producing trees) are great back-up systems for solar water heaters. Combining biomass and solar is a very energy efficient and low-carbon way to provide year round hot water and heat for a home, and over the long haul it is a very cost effective solution.

Federal tax credits are once again available for 2009 and 2010 for solar water heaters and biomass stoves, so before you invest in either, go to www.energystar.gov and find out what you need to provide to get your tax credit at the end of the year. Some solar panels and solar water heaters are eligible for tax credit of up to 30% of the purchase price through 2016.

When choosing a solar water heater, think first about how much hot water your family needs and then about how much of it you can realistically expect to obtain from a solar heater. In parts of the country where the temperature does not frequently dip below freezing, a passive solar water heater may well provide more hot water than you need year round.

If you live in a part of the country that experiences harsh winters, you will almost certainly need to go with an active system and have a biomass boiler or tankless water heater for backup. Many active systems can be combined with a conventional water heater that you may already own. Check out the cost of systems available to you as well as any local ordinances and building codes, then ask yourself if installation is cost-effective in your case.

If you are an avid do-it-yourself handyman, you may find that even though an active system is beyond your means, a passive system is something you could rig yourself, saving you money on hot water heating for at least the portions of the year when the sun is hot.

Examine all your options, select one, and then take the plunge. You’ll be surprised at how much money you’ll save on gas or electricity, and what’s more, once you get a feeling for how solar works and get past the newness of it, you’ll almost certainly think of lots of great new applications in other parts of your life. Your solar water heater will be only the beginning.