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The Sun supplies us with an enormous daily energy
that exceeds primary energy consumption, by 80
times in Germany and probably the same in Ireland for example. This energy source is
virtually inexhaustible and is also at our disposal for the
next million years. Fossil fuels such as coal, natural gas,
or oil are, in contrast, limited. The next generations will
not be able to use them without restriction, so the sun
presents itself without a doubt as the energy of the future.
· Solar heating systems for
hot water
· How does a solar heating system work?
· Active environmental protection
· Aren't solar heating systems too
expensive?
Solar Water Heating
The use of solar energy to heat water results in
favourable basic requirements, since a household's
warm water use is roughly constant throughout the
year. Thus there is a larger conformity between
demand and the solar energy supply, than with the
utilisation for heating.
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Hot water demand and solar radiation
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You can cover 60 - 70% of the yearly domestic hot water
with solar energy and a properly dimensioned
system. In summertime 80-90% and in wintertime
15-20%. One
can use the available solar energy even better, when
washing machines and dishwashers with hot water
connections come into use, instead of traditional
appliances.
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Percent of monthly
solar coverage
(Annual Value: 65%)
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Solar heating systems for hot water distinguish
themselves with simple system technology which is,
however, technologically sophisticated. In the
meantime, there are a large number of solar
companies, which have many years of experience in
system planning and mounting. They offer a wide
palette of system concepts for a variety of needs.
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How does a solar
water heating system work?
The heart of a solar heating system is the
collector. A flat-plate solar collector, the most
prevalent collector form, is made up of a
selectively layered absorber that serves to absorb
the incoming solar radiation and transforms it into
heat. This absorber is embedded in a thermally
insulated box with a transparent cover (usually
glass) to minimise thermal loss.
A heat conducting liquid (usually a mixture of
water and non-environmentally damaging anti-freeze)
flows through the absorber and circulates between
the collector and the warm water storage tank.
Thermal solar energy systems will be brought into
operation through a solar automatic controller. As
soon as the temperature on the collector exceeds the
temperature in the storage tank by a few degrees,
the regulator switches on the solar circulation pump
and the heat conducting liquid transports the heat
received from the collector to the storage tank.
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The conventional heater guarantees, with the
charging circuit, that enough warm water will be
available even when the solar heating system
supplies little or no heat at all. Solar heating
systems can be integrated into buildings without a
problem. Thus, a modern solar heating system, with
at least twenty years life expectancy exceeds that
of a boiler, and ideally supplements conventional
heating technology.
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Active environmental protection
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With
the installation of a thermal solar heating system,
one is actively contributing to the lowering of
environmentally harmful CO² emissions. A solar
heating system has an unequivocally positive CO²
balance compared to conventional water heating
systems.
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CO² emissions
from heating systems producing
3,500 kWh/a (meets the warm water needs of a
four to five person household) and with a
solar
coverage percentage of 65%
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To avoid excessive CO² emissions, you should see to
it that no electric heating systems come into
operation. In contrast, the use of a solar heating
system combined with efficient energy technology (a
modern condensing boiler) with the lowest possible
energy consumption is environmentally ideal.
The period of energetic
amortisation (the time
until the solar heating system has produced as much
energy as was needed to manufacture the system) on a
thermal solar heating system is between half a year
and two and a half years. In comparison to that,
conventional systems never pay back energetically.
In order to make a certain amount of energy
available, they need an even larger amount of
primary energy.
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Are solar water heating systems too expensive?
The argument often put forward against the use of
solar heating systems is that they are not
economical. This often culminates in a flat out
rejection of renewable energy. But have you ever
asked yourself if the new aluminium wheel rims on
your car are economical? Or if the old oil central
heating boiler from the 70s still works
economically? Other than that, you cannot forget
that solar heating systems provide an important
contribution to the use of environmentally friendly
energy.
The inexpensive prices for conventional energy
sources conceal the real facts. The consequential
costs for environmental and health damages caused by
their use (the so-called "external costs")
are not included in their price and have to be paid for by the general public. You also have to
consider, that the price for conventional energy
sources will increase considerably in the near
future, due to these resources running short.
The sun, however, supplies its energy free of
charge. The relatively high initial investment at
first sight suggests that the systems are, in
general, very expensive. But from the time of
installation of the system on, there are no more
operating costs, except very low costs for
maintenance and pump electricity. Whoever invests in
a solar heating system is also investing in the
future. Other than that, there is the possibility to
lower the costs of a solar heating system by
claiming state or community funding. Since 1996,
homeowners in Germany will receive €125,- per m²
of solar collector installed.
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