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7. Identification of key developments
Combining PVT with PV or thermal
collectors on a single roof or façade.
The thermal side of the covered PVT collector will
be used mostly for domestic hot water. Another
application is a so-called combi system, which
delivers a large part of the hot water demand and
a small part of the space heating demand. For both
applications, the required PVT area is limited by
the heat demand of the house. This is a big differ-
ence between thermal solar systems and grid con-
nected solar PV systems, since the PV area on a
building is only limited by the available roof and
facade area. To optimise a solar system it might
be necessary to combine PVT with standard PV
in a single plane. Therefore, roof-mounting tech-
niques have to be developed in which PVT and
PV can be combined in any ratio and in any shape.
In addition, the combination of PV and PVT
should also have an aesthetic appearance. There
are differences between the two that hamper an
aesthetic appearance. The PVT collector is
thicker than the PV module and (because of the
glass cover above the PV) the impression of shine
and colour is different. The simplest solution is
to develop PVT dummies. These have the same
appearance as PVT collectors but produce only
electricity. Of course PVT dummies are more
expensive than standard PV laminates, so this
is not the optimal solution. On the longer term,
aesthetically matched roofing systems for PV
and PVT should be developed. This can even be
a contrasting match in which the differences are
highlighted but are forming aesthetically a good
combination.
Finally, simulation tools have to be developed
for the dimensioning of solar systems in which
PV-modules, thermal collector modules and PVT
modules can be combined to fulfill the require-
ments of the building in the best way.
A similar problem appears when PVT air sys-
tems for space heating are extended to provid-
ing solar cooling as well. Since solar cooling
requires higher temperature levels than most
PVT air collectors will be able to provide, the
PVT collector array is often combined with an ar-
ray of conventional solar air collectors to boost the
temperature level. For the commercialisation of such
systems, it is important to develop standardised and
aesthetically matched roofing and façade systems
for PVT combined with solar thermal.
Design tools
Good design tools are essential for the appli-
cation of PVT systems. Design tools facilitate
the implementation of the PVT system in the
building development process. The design
tools have to range from rules of thumb and
spreadsheet based models to more sophisti-
cated models like a full physical simulation of
the yearly performance.
The whole range of design tools should be de-
veloped focusing on the target group which will
use the design tools.
· Dimensioning tools should be developed for
architects, in which they can easily dimen-
sion the PVT roof to fit in their building de-
sign. These tools should also have the possi-
bility to make a visualisation of the PVT roof
on the building.
· Sophisticated performance modeling tools
should be developed for engineering com-
panies, in order to make detailed calculations
of the PVT system yield. These tools can be
based upon the TRNSYS simulation model.
short term
R&D institutes,
· Develop rules of thumb and spreadsheet based models for standard PVT
PVT manufacturers,
modules (PVT liquid, flat-plate)
engineering companies,
· Develop dimensioning aids for the architects as well as a visualisation
architects
aid for standard PVT modules (PVT liquid, flat-plate)
· Develop a PVT module for the TRNSYS platform for standard PVT
modules (PVT liquid, flat-plate)
medium term R&D institutes
· System optimisation with full physical models.
PVT manufacturers,
· Develop PVT design tools for non-standard PVT modules
engineering companies, architects
(PVT concentrator, PVT air)
long term
R&D institutes, PVT manufacturers,
· System optimisation with full physical models for non-standard
engineering companies, architects
PVT modules.
Table 24. PVT design tool
development scheme.
Type
relevance
liquid glazed
···
liquid unglazed
···
air glazed
····
air unglazed
····
concentrator
·····
ventilated PV
·····
Type
relevance
liquid glazed
···
liquid unglazed
···
air glazed
···
air unglazed
···
concentrator
·
ventilated PV
····
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