Building integrated concentrating solar systems - Solar Energy Sciences and Engineering Applications - page 578

thermal losses close to the FPTU, making it a promising solar system for domestic
water-heating applications.
Another possibility is the combination of stationary CPC collectors with multi-
ple absorber segments and several configurations such as tubular and flat-fin type
absorbers with pipe (Tripanagnostopoulos and Yianoulis, 1996). These types of solar
devices are appropriate for applications in the temperature range of 100-200 ◦ C.
At this point it should be mentioned that among the systems presented above,
only system 1, parabolic troughs (on a small-scale), has the potential to be actually
integrated into buildings (maximum level of BI). The other systems show a low level
of BI potential since they are merely placed or installed on the roof without replacing
elements of the roof.

17.2.5 Concentrating systems and building integration
requirements
Building integration is directly related with the concentration ratio C of a system.
Thereby, the evaluation of the BI potential of a device is based on its concentration.
In Table 17.2.4 the requirements for building integration of several concentrating
systems are given.

Table 17.2.4 Requirements for building integration of several concentrating solar systems (Chemisana,
2011).

Description of the Type of building Tracking

system integration requirements Restrictions/

High concentration: Flat roofs mainly Two-axis tracking Whole system movement.

C > 100x (mainly with high precision Control and management

point focus (tracking, cleaning, etc). High temperatures

Fresnel systems) management (case,

surrounding air, etc.)
Possible failures require
immediate actions due to the
very high fluxes effects

Medium Flat or inclined Two-axis tracking in Whole system movement

concentration: roofs some of the systems (if applicable)

10x < C < 100x Façades Single-axis tracking Maintenance, but much less

(parabolic troughs; for the whole restrictive than if high

Fresnel lenses or system concentration

mirrors) Single-axis tracking Possible effects derived from

for the receiver the high fluxes. These are

or for the closer to the restrictions of

concentrator high concentration systems

when C approaches 100x

Low concentration: All Do not require The same than conventional

C < 10x (V-trough, tracking → this solar panels

CPC, Fluorescent facilitates their BI

systems, holographic at any location of

systems, etc.) the building