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Solar hot water systems - the three types
Heating water for your residential use is one of the most economical solar
energy applications available. Most people don't realize that heating water
is nearly as large a part of your electric bill as air conditioning/heating.
While payback of your initial cost varies with system, climate, and use; a payback
period of 4 to 7 years is typical with most systems continuing to provide savings
for 20 to 30 years.
While systems themselves are not terribly complex, new materials and subtle
design changes have steadily increased their performance efficiencies over the
last 20 years.
The Direct System
The direct solar hot water system is by far the most common system used in the
US. The collector panel is essentially an insulated box with a glass top, usually
mounted on your roof. Household water is circulated directly through the copper
tubing inside the box by a small pump. The tubes and additional copper fins
transfer the heat collected from the suns rays directly to the water. The heated
water is then stored in a slightly modified hot water heater tank, usually at
ground level. SDI has been a leading manufacturer of these systems for over
25 years.
The ICS System
Integral collector storage units actually serve as a preheater to your existing
electric/gas hot water system. The collector and water storage tank are actually
one in the same and mounted on the roof. Water is heated in this tank or large
tube style collector and replaces the water drawn from your conventional water
system as needed. This simple is extremely simple and durable.
The Indirect System
An indirect system is usually only proposed in climates subject to hard freezing
for extended periods. In design it is similar to a direct system except that
an antifreeze solution is heated in the collector in a closed loop system. The
heated antifreeze is passed through a heat exchanger to transfer its heat to
water stored in your conventional hot water tank.
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