Building integrated concentrating solar systems - Solar Energy Sciences and Engineering Applications - page 550

In order to answer the first question, it is necessary to see how multifunctional the
solar collector is. In Figures 17.1.2a and 17.1.2c the collector is acting as a shading
element, whilst in the other two cases (Figures 17.1.2b and 17.1.2d) it works as a
double skin roof or façade respectively. As can be seen, the solar system provides
additional positive functions to the building envelope. It is impossible from the pictures
to see the effects of the insulation or the structure on the building, both of which aspects
could also be satisfied by the solar technologies depending on the configuration used.
In this sense the cost-effectiveness ratio becomes better when compared to a scenario
in which a heat only benefit is gained.
The second question concerns the formal integration of the collector, where the
module's characteristics are essential. In the first configuration (Figure 17.1.2a) the
solar collectors are totally standard, placed on a specific structure to hold the systems
at the required angle for both illumination control and electrical production. In Fig-
ures 17.1.2b and c the collectors also have quite standard characteristics. By contrast,
in the another case the module's active area is divided into strips to allow partial light-
ening (Figure 17.1.2c). IEA SHCP Task 41, concerning the influence and characteristics
of the collectors in the appearance of the building, defines a set of key criteria for all
types of solar collectors: module shape and size, jointing, visible materials, surface
texture, colours, field size and position. When the collector's response to these aspects
is positive, the solar system's flexibility ensures a proper building integration from a
formal point of view.
Next, Figure 17.1.3 synthesizes the two questions posed above. As can be seen,
inside the house schematic a second column entitled “Constructive'' is defined. This
refers to the constructive properties of the solar collector: insulating properties, water-
proofing, resistance to impacts and wind/snow loads, etc. This point has not been
considered in the previous explanations due to as a building element, it is clear that
must fulfil all constraints as a constructive element in order to be architecturally
incorporated.
A summary of the requirements for building integration of solar thermal systems
are presented in Table 17.1.1.
17.1.2 Solar photovoltaic systems and building integration
requirements
In Table 17.1.2, several requirements for the building integration of non-concentrating
PVs are presented along with their advantages. For grid-connected PV systems, some
of their advantages are: they do not require additional land; the cost of the PV wall
or roof can be offset against the cost of the building element it replaces; power is
generated on site and thus replaces electricity that would otherwise be purchased at
commercial rates; and by connecting to the grid, the high cost of storage is avoided
and security of supply is ensured.
The way people deal with PVs in architecture differs from country to country
depending on factors such as the influence of the government on house building. How-
ever, in all cases of PV system integration into buildings there are some important issues
which should be taken into consideration (Table 17.1.2).
At this point it should be mentioned that the integration of PV systems in architec-
ture can be divided into five categories, based on the increasing extent of architectural