Solar Water Heater Systems
Try A Solar Water Heater
With a
solar
water heater, you'll get the hot water your household needs while saving
money and energy and reducing your dependence on coal-fired power.
After a year with their solar hot water heater, homeowners
Bob Allen and Lyle Rudensey say they’ll never go back to relying on a
conventional water heater. Even in gloomy, rainy Seattle, they are saving
money and energy by heating all of their water with the power of the sun.
“With a lack of leadership at the federal level, I feel it’s very important
that we all do what we can to reduce our dependence on fossil fuels and
reduce greenhouse gases,” says Lyle. “Solar hot water systems are a great
place to start. They’re not as expensive as solar photovoltaic, and they’ll
save you substantial amounts of energy and money.”
Looking at his household energy bills, Lyle notes that
it’s hard to quantify the exact dollar amount the new water heater has
saved, because he and Bob also installed energy-efficient appliances and a
solar photovoltaic system last year, as part of an overall strategy to
reduce their dependence on fossil fuels. Still, according to the American
Council for an Energy-Efficient Economy (ACEEE), water heating uses more
household energy than any activity other than heating and cooling, so
replacing your household’s water-heating energy with free power from the sun
will have a significant effect on your bottom line. With all their savings
combined, Lyle points out that his and Bob’s electric bills have dropped to
a low of $5.
“Plus, the water heater increased the value of the house,”
Bob adds. “And it’s a hedge against future energy cost increases.”
Bob and Lyle installed an “active” solar water heater with
“evacuated tube” collectors, which they say works great in the Pacific
Northwest, because the heater keeps working even on overcast days or when
temperatures are freezing outside.
“I can’t think of anything negative to say about it,” says
Lyle. “It never ceases to amaze me to see our solar hot water system still
pumping 80- to 100-degree water late into the evening on a day
when it isn’t even sunny.”
Active Versus Passive Heaters
When you select a solar water heater
for your home, you can choose between an active system (like Bob and
Lyle’s), or a passive system. ACTIVE
SYSTEMS use a pump to move water
through their heating system, and this requires a source of energy (often a
solar photovoltaic panel). PASSIVE
SYSTEMS use no pumps or electrical
components.
Because of their design, passive systems are the simpler
of the two. They work essentially like a garden hose left out in the sun,
except the container for the water is much, much larger. The sun directly
heats the water in a large, rooftop tank, which then flows down into your
plumbing system. If the water has not yet reached the temperature you’ve
selected on your thermostat, your conventional water heater will need to
kick in to finish the job. Passive systems are best suited for warm climates
where your rooftop storage tank is in no danger of freezing.
Because of their simplicity, passive systems are usually
cheaper and can last longer than active systems. The drawbacks are that they
can be less reliable, and require a heavy water tank, or collector, to be
mounted on your roof. (Depending on your roof’s design, this may require
structural support.)
An active system stores water in a tank inside your house,
and uses its pump to move either water or a “heat exchange” fluid through a
“collector” on your roof. Collectors are the components of your solar water
heating system it to heat your water. Used in freezing climates, the
heat-exchange fluid is a non-freezing liquid that carries the sun’s heat
from the roof to your tank, where it transfers the heat to your water. The
fluid re-circulates to the roof to be heated again, while the water flows on
to your tap. (This fluid is usually propylene glycol, which the FDA has
approved as an additive in food and medicine. However, it is a suspected
neuro- and respiratory toxin, according to the National Institute of
Occupational Health and Safety.)
Although active systems are more expensive but more
reliable than passive ones, you may still wish to keep your conventional
water heater for a back-up. In fact, in many areas, local building codes
require conventional back-ups, so be sure to check with your contractor or
local government. Active systems using the “heat exchange” method are best
for areas where freezing temperatures are likely.
Keep in mind that solar water heaters also work great for
your outdoor hot water needs, like pools and hottubs.
Two Types of Collectors
If you choose an active system, you’ll need to consider
two types of collectors:
1. FLAT-PLATE COLLECTORS:
These are metal boxes with glass or plastic covers (called glazings) on top
and a dark-colored “absorber plate” covering a system of pipes on the
bottom. Sunlight passes through the glazing and is collected by the absorber
plate, which converts the sunlight into heat that is passed on to the liquid
(either water or a heat-transfer fluid) in the system of pipes. The
advantage of this type of collector is the price—it’s cheaper than
evacuated-tube collectors.
2. EVACUATED-TUBE COLLECTORS:
Best visualized as a series of tiny, open-ended thermoses, these collectors
consist of individual glass vacuum tubes surrounding a secondary inner tube,
through which the liquid or heat-transfer fluid flows. The most efficient
(and most costly) collector, the evacuated-tube model works somewhat better
than the flat-plate model in cold climates.
Depending on the type of system you choose, a solar water
heater can cost from $2,000 to $6,000, and begins paying for itself right
away with your reduced energy bills. The amount you save will depend on many
factors, including how much hot water you use, your system’s performance,
sunlight in your area, and the local cost of conventional fuels, but the US
Department of Energy estimates than on average, your bill should decrease by
between 50 and 80 percent.
The Tax Incentives
A federal
incentive went into effect on January 1, 2006, making a solar water heater a
more affordable addition to your home than ever.
For any solar water heater placed in service between now and the end of
2007, you can receive a federal tax credit for 30 percent of the system’s
cost, with the maximum credit capped at $2,000. Be sure to save
documentation of all costs associated with the system’s installation
(including the labor of any installers, plumbers, or electricians you use),
and note that to claim the credit your system must be certified by the
Solar Rating Certification Corporation.
Also, to find additional state-level tax incentives,
including rebates, property tax credits, sales tax exemptions, and more,
visit the
Database of State Incentives for Renewable Energy.
Remember that no matter where you live or what your
climate, a solar water heater can be a great way to reduce our country’s
dependence on fossil fuels, and position you to not only start saving money
today, but to save a lot more money in the future as the cost of fuels like
natural gas and heating oil continue to rise.
“Some people might think that solar water heaters aren’t worth installing in
a climate like the Pacific Northwest, but that’s not true,” says Lyle.
“Germany gets about 70 percent as much sunlight
as Seattle does, and they are the biggest users of solar power in the world.
This is something everyone can do that really makes a huge difference.”
Resources:http://www.greenamericatoday.org
