The Sun supplies
us with an enormous daily energy potential that exceeds
primary energy consumption, by 80 times in Germany, 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 Water Heating
The use of solar energy to heat water results in
favorable 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 utilization for heating.
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.
How does a solar 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 minimize 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.
Elements of a solar heating system for hot water:
- Automatic solar controller
- Temperature sensor on collector
- Temperature sensor on storage tank
- Solar circulation pump
- Cold water inflow
- Hot water run-off
- Expansion tank
- Temperature sensor for additional heating
- Charging circuit- solar circulation pump
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.
Active environmental protection
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.
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 amortization (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.
Aren't solar 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 aluminum 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 payed 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 can make use
of an environmental bonus eight years long: up to 500
marks per year for a solar heating system.
The German Section of the International Solar Energy
Society (ISES) would be pleased to answer any further
questions on funding possibilities.
Text and illustrations used with permission
from the German Section of the International Solar Energy Society
(ISES)
Concise and comprehensible explanations of the basic
concepts in solar heating and photovoltaics can be found
in our Solar-Lexicon.
Reports on technology, business and
politics, as well as presentations on innovative systems
and products can be found in the Solar Magazine
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