Building integrated concentrating solar systems - Solar Energy Sciences and Engineering Applications - page 568

Table 17.2.2 Concentrating systems which use aspheric/Puntual Fresnel Lenses (PFL) or Linear Fresnel
Lenses (LFL) as a primary concentrator (Chemisana, 2011)

Company or reference Actual status of the system PFL/LFL C 1 Cell type

Abengoa Solar (Chellini, 2007) Commercially available PFL 476X 3J 2

Green and Gold Energy Commercially available PFL 1370X 3J

(Green & Goldenergy, 2011)
Emcore (Emcore, 2012) Commercially available PFL 500X 3J

Whitfield Solar (Anstey, 2007) Commercially available PFL 70X c-Si 3

Photovoltaics International Stopped production in 2000 LFL 10X c-Si

(Kaminar, 1991; Bottenberg, 2000)
Entech Solar (O'Neill, 1990) Commercially available LFL 20X c-Si

Chemisana et al. Demonstration and LFL 30X c-Si

(Chemisana, 2011a,b) test installations

1 C: Geometric concentration ratio.
2 3J: triple-junction solar cell.
3 c-Si: monocristaline silicon solar cell.

Internacional) (Kaminar et al., 1991; Bottenberg et al., 2000) uses a one-axis tracker
and a PVT receiver. Recently, Entech Solar announced two new systems: TermaVolt TM
II (PVT) and SolarVolt TM II (PV). Both systems are based on the same technology but
use different receivers. Entech has resized the initial prototypes designed in the 1980s
into these two smaller, low-cost devices applicable for both ground and roof-mount
applications.
Linear Fresnel lenses have a number of attractive features when used for solar
concentration applications: they may be produced in large sizes; their aspect ratio
can be designed to be small, leading to a compact concentrating system; they may be
very thin, minimizing the cost of optical material and reducing the mechanical load
on the supporting structure; and they may be made of reliable and durable material
(Chemisana et al., 2009; Chemisana and Ibañez, 2010; Chemisana et al., 2011a,b).
The ability of linear Fresnel lenses to separate the beam from the diffuse solar radiation
makes them useful for illumination control in a building's interior space. The Fresnel
lenses are advantageous because they can combine within them both the concentrating
element and the optically transparent window. The use of Fresnel lenses as a transparent
covering material for lighting and energy control of internal spaces has attracted special
attention (Tripanagnostopoulos et al., 2007).
In addition to mentioning the general benefits of Fresnel lenses, some compar-
ison should be made between those which are image forming and those which are
anidolic. Image-forming Fresnel lenses for solar applications require high precision
tracking. Non-imaging lenses, often convex and arched in shape and designed for
medium concentration using one-axis tracking, have been devised as highly compet-
itive solar collectors. If the tracking requirements are minimized, the cost reduction
achieved by reduction of the PV cells' surface area outweighs the cost of the optical
elements (Leutz et al., 1999a; Leutz and Suzuki, 2001).
The concept of using a fixed concentrator with a tracking absorber has been men-
tioned in the past (Kritchman et al., 1979; 1981a; 1981b). It is based on a stationary
wide angle optical concentrator that, whatever the location of the sun, transmits the