Solar Thermal Heat Utilisation - Renewable Energy: Technology, Economics and Environment - page 131

Other components. Thermal insulation made of standard insulation material (e.g.
polyurethane, glass fibre wool, mineral wool) belongs to the group of other com-
ponents. On the outside of the box, one inlet pipe for heat carrier charging and
one outlet pipe for heat carrier discharging are installed. Furthermore, the neces-
sary components to attach the collector are outside of the box. Often additional
components are offered for on-roof installed collectors that enable an on-roof
collector installation with a certain angle to the roof slope. In general, the energy
output is only marginally increased by doing so. For in-roof installed collectors,
sheet metals for plumbing are often delivered alongside. If the temperature needs
to be measured inside or outside of the collector, there are drill-holes or other
means available.
Installation. Collectors are mainly installed on pitched roofs; in this respect the
integration into the roofing or the on-roof installation, on top of the tiles, are
common technical solutions. Independent of the type of installation
− the static's of the roof have to carry the collector load (in-roof collectors are
often lighter than the tiles that are generally intended to the used),
− the coupling to the roof has to ensure that the collectors are not separated from
the roof (e.g. by wind) and
− the heat expansion of the collectors and pipes must not be obstructed.
Integration into the roof is less visible and cheaper than the on-roof installation. It
is preferably used for new buildings or larger collector arrays on already existing
roofs. Additionally, roofing costs are saved for the parts of the roof where the
collectors are installed. If retrofitted, collectors are often installed on top of the
roof tiles. This easier form of installation does not damage the roof cladding and
consequential damages of the building can be largely ruled out in the event of
collector leakages or damaged glazing
Installation of collectors on flat areas (e.g. on flat roofs, in gardens) facilitates
optimal adjustment and incline when compared to the installation on pitched
roofs. Mainly standardised frames are used to integrate the collector. Frames need
to be arranged so that shading is avoided. It can be useful to build the collectors
with a comparatively low incline (e.g. 20°). Because of the lower level of internal
shading, larger collector areas can be built on the same area. Furthermore, installa-
tion costs decrease with smaller frames and lower wind loads. The reduced output
of installation due to a flatter incline of the absorber area compared to the optimal
installation is insignificant for systems with low solar fractional savings.
Collector designs and practical applications. The different collector designs can
be differentiated according to the heat carrier and the way they absorb radiation.
According to this method, four basic collector designs can be identified:
− Non-concentrating swimming pool liquid-type collectors
− Non-concentrating glazed flat-plate liquid-type collectors
− Non-concentrating glazed air collectors,
− Radiation-concentrating liquid-type collectors and