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When you talk about using any kind of solar technology in rainy, grey western Washington, most people look at you blankly and ask, "Here?" In rainy, grey northern Europe, however, solar energy is the norm. Recently, even in the non-sunbelt states of the U.S., a revived interest in solar energy is growing, especially for heating hot water. Heating water uses a large portion of household energy. To discover more about solar hot water, I spoke to several people who have been using these systems for a number of years. I also toured my parents' new solar hot-water system while visiting them on Cape Cod. My mom says she feels good about using sunlight and not relying on the electric company.

Understanding the basic concepts of solar hot-water heating, its benefits and how it works may convince you to get started on your own system. Our family is planning to install a solar hot-water heating system in our home in 2007. Nationally and locally, there are many incentives to make solar water-heating more affordable. Installing a solar hot-water system reduces your home's energy footprint, uses clean energy from the sun and slows global climate change.

Saving Energy with Solar Hot-Water Heating
In the U.S., hot water is heated with oil, electricity, natural gas, propane or liquid petroleum gas (LPG). Electrical use alone creates 40 percent of global warming emissions and, according to Solar Washington, hot water consumes 19 percent of the typical home's energy budget. Conservation begins at the hot water tank thermostat: Turn it down to 110 degrees (see "Energy Savings Begin at Home" in Issue #13), insulate your hot water tank and pipes and use less hot water by installing low-flow devices and fixing leaks.

There is a progressive range of energy efficiency with various hot-water heaters. Tankless hot-water heaters are more energy efficient than standard hot-water heaters and serve as a great backup for solar hot-water systems. Using a tankless hot-water heater instead of a standard one reduces energy consumption by 45 - 60 percent. According to Solar Washington, a [conventional] electric hot-water heater consumes about $460 of electricity annually and has a lifetime of 5 - 15 years. A tankless gas hot-water heater consumes $154 in fuel annually, and is a lifetime appliance.

Using a solar hot-water system instead of a standard one reduces energy consumption by 70 - 90 percent. According to The Renewable Energy Resource Center in Vermont, "By installing a solar water heater, a family of four, who currently use an electric water heater and consume an average of 80 gallons of hot water per day, will prevent 3,400 pounds of greenhouse gas emissions each year. This represents a reduction in household greenhouse gas emissions of 20% or more for a typical household." This equates to reducing your driving by 4,250 miles per year at 25 mpg (or 34 tons of emissions prevented over 20 years).

Solar Hot-Water Heating in your Home
Getting started: To install a solar hot-water system, first decide if you want just solar hot water or if you also want to use solar energy to heat your home. To better understand solar methods, take a solar-energy home tour (see (www.ases.org). Solar homeowner Lindsey Close in Falmouth, Massachusetts, has six 4-x-8-foot solar collectors on her roof and uses one-fourth the natural gas of a person who has a conventionally heated house. She puts her house in the Green Buildings Open House tour each year. She says it's important for people to see how solar technology really works. Visit homes with the kind of systems you are interested in and can afford.

Once you've decided on the system type, evaluate how much sunshine your roof gets. Determine the sun's path across your roof around the time of the winter and summer solstices. Check the shading your house receives from trees and the angle of your roof. Look at solar maps (which show the amount of solar potential by season for different areas of the U.S.) and use the solar calculator (see sources) to estimate your costs and savings. Then, unless you are a reasonably expert plumber and electrician, consult a solar professional. Use the American Solar Energy Society (ASES) or SolarPro websites (see sources) to determine if the professional has been in business for a while, has received no complaints and is adequately insured. Or find referrals at home tours or from local renewable energy networks.

How it works: There are two main parts to a solar hot-water system: the solar collectors on the roof and the water storage tank. In colder climates, or if roof area is at a premium, evacuated tube collectors are used. Frequently, though, solar hot-water systems use flat plate collectors, which look like and are placed similarly to Photovoltaic (PV) panels used to generate electricity, but operate differently. Flat plate collectors have tubes with fluid in them (either water or nontoxic propylene glycol) and an absorber plate. The absorber plate is heated by the sun, which then heats the fluid in the collector. The heated fluid is then moved between the collectors and the storage tank, either by a pump or by gravity.

Sizing your system: A typical solar hot-water system will provide about 60 - 70 percent of your family's hot water needs. Depending on your habits and the appliances in your household, hot water use varies tremendously — but most adults use approximately 20 gallons of hot water per day. Systems range from those designed for a small family with two 4-x-8-foot flat plate collectors and an 80-gallon tank to those designed for a larger family with four 4-x-8-foot collectors and a 120-gallon tank. Systems can be designed for other uses besides heating your water. My parents' system also heats their home in three ways: with a direct hydro-air fan that bypasses their heat pump, by using warm storage-tank water instead of cold well water for their heat pump and by providing radiant floor and wall heating. This small-family system includes two arrays of four 4-x-8-foot collectors each and a 1,550-gallon tank.

Orienting solar collectors: The solar collectors need to be oriented to absorb the most sun between 9 a.m. and 3 p.m. They should face south and minimize shading throughout the day to the extent possible. Both orientation and shading can be compensated for by adding more collectors. Depending on the angle of your roofline and where you live, the collectors can either be placed flat on the roof or raised at a 45 - 55-degree angle. The collector can absorb more sun at a raised angle in the northern states in wintertime. If you prefer having them flat on the roof for appearances, another collector can be added to compensate for the flat angle.

Backup systems: In the northern U.S., homes often don't get adequate sun during several winter months to heat enough water to 120 degrees. For these homes, a traditional hot-water heater is used as a backup. The backup system ensures the mix from the solar collectors and the traditional hot-water heater equals the right temperature. But even on a cloudy winter day in western Washington, there is enough sunlight to heat some water, which helps reduce the electric bill.

Economics of Solar Hot Water
Savings: Savings from a solar hot-water system depend on many factors, including the quantity of hot water used and the costs of local conventional hot-water fuels, such as oil. Households with higher hot-water use and energy costs will benefit the most. Solar hot-water systems save, on average, 60 - 70 percent of the annual water heating bills, or $100 - $500 per year.

Incentive programs: Initial costs can be offset by numerous federal, state and local incentive programs. Incentives come in the form of rebates, tax credits and loan assistance. Costs for a 2 - 4-person solar hot-water system are usually $4,000 - $6,000, depending on water quantity and selected components. After applying a federal tax credit of $2,000 (you may also be eligible for state incentives, like a waiver of sales tax on equipment and labor or a direct credit), the system cost ranges from $2,000 - $4,000. (Conventional water heaters cost $500 - $700, plus installation.) You can also apply for a low- or no-cost loan through a variety of sources.

Local utility payments may further decrease your costs. Because of the excellent quality and long lifespan of these products (20 - 30 years as compared to the

7 - 15 years of conventional water heaters), most systems pay back your investment 2 - 4 times over their lifetime. Although the initial investment is high compared to that required for standard hot-water heaters, solar systems can be cost effective because they convert the sun's energy very efficiently and can reduce, by up to 90 percent, the annual energy costs for hot water.

Calculating payback: Everyone wants to know how long the payback period is for installing alternative energy. Typical paybacks for solar hot water systems range between 4 and 15 years. But many benefits are neglected in payback estimates. First, the U.S. economy, unlike nearly all the rest of the world that has adopted Kyoto protocols, sets no monetary value on carbon emissions that cause global climate change. Neither do we apply a dollar value to our health. Finally, unlike most consumer products, any renewable energy system has a positive return on investment.

Harnessing Solar Energy
I spoke with homeowner Beverly Gori in Carver, Massachusetts, whose hot-water system has been in place for several seasons. She is thrilled about her array of six 4-x-10-foot collectors.
"We have tons of hot water — we don't even use the stove or the microwave [to heat water]. We wash our clothes in hot rather than warm water because we generate enough for six people."

According to ASES (see sources), "Enough sunlight falls on the earth's surface every minute to meet the world energy demand for an entire year." I am motivated to harness the sun's energy with a solar hot-water system. Using nature — sun, water, wind, waves and tides — to power our needs feels more in harmony with the earth. This feeling can't be assigned a dollar figure, but it makes solar hot water an excellent choice for our family.

Marian Wineman is an environmental consultant living in Seattle with her husband and seven-year-old daughter.

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