Environmental Engineering Reference
In-Depth Information
gains of f orientation = 110% = 1.1. As a result, the required surface for fl at - plate col-
lectors is calculated as
0 6 2628
0 3 1000
.
kWh
A collector
=
48
.
m
2
.
.
kWh
m
1 1
.
2
The results of course depend heavily on the quality of the collectors and can vary
considerably. Some online tools are available to help with system design (see Web
tips ). Sophisticated computer programmes are necessary to improve the detailed
planning. Professional fi rms that specialize in this fi eld should also be able to
provide detailed system designs. In addition to determining the size of the collector
and the storage, their services include the design of other components such as
pumps, controllers and pipes.
http://www.valentin.de/onlineberechnung/
solarthermie
Online calculations for solar
thermal systems
http://desire.htw-berlin.de
6.4.2 Solar Thermal Heating as Support Heating
A large collector surface is needed if a solar thermal system is to provide support
heating in addition to domestic hot water. In contrast to the supply of hot water,
this option requires optimal building insulation to enable the sun to provide a larger
share of the heat requirement. Whereas hot water use is relatively constant through-
out the year, heating needs are concentrated in the winter months. However, the
yield from solar collectors is low in the winter. Therefore, solar thermal systems
that supply support heating are usually designed so that, in addition to hot water,
they can cover only a portion of the heating required during the transitional period
from March to October. In winter conventional heating systems essentially provide
the heating required (Figure 6.20 ).
The size of the collector surface and the storage also affect the degree of solar
coverage, and thus the proportion of heat covered by the sun. This also reduces the
share a conventional heating system provides. If a fossil system fi red with oil or gas
is used, then the carbon dioxide emissions drop in accordance with the size of the
solar system. However, a very large system also produces a higher surplus that
cannot be used. Therefore, as a rule, large systems are less economical than small
ones. So when it comes to design, one has to consider whether the priority is
maximum input from the sun or economic viability.
The following two design variants provide the basis for an outline design in Central
European climates:
Variant 1: Small system for good effi ciency
Collector surface with fl at - plate collectors: 0.8 m 2 per 10 m 2 living area
 
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