Ventana{trade mark, serif} power train features and performance

Abstract

Most CPV systems are based on Fresnel lenses. Among these, LPI-patented Fresnel-Köhler (FK) concentrator outstands owing to performance and practical reasons. The Ventana TM power train is the first off-the-shelf commercial product based on the FK and comprises both the primary (POE) lenses (a 36-units 1×1 m 2 acrylic panel) and glass (or silica glass) secondary optics (SOE). This high concentration optical train (C g =1,024×, ~250mm optical depth) fits with 5×5 mm 2 (at least) solar cells. The optical train is the fruit of a 1-year development that has included design, modeling, prototyping and characterization, and through the process we had the opportunity to find out how well the actual performance correlates with models, but also learned practical aspects of a CPV system of this kind, some of which have very positive impact on system performance and reliability.

Development and characterization of an FK photovoltaic concentrator for maximum conversion efficiency

“…CPV modules below 30% efficiency (at T cell = 25ºC) are the norm, and therefore showing results well over 35% efficiency is of great relevance, especially when it has been obtained with practical devices, as the FK concentrator. The results shown in this work improve the 34.5% instantaneous corrected efficiency value (to be compared with the maximum 36.0% value obtained in Figure 7) we measured on February 14 th 2013 and recently reported at CPV-9 in Miyazaki [8], which was achieved with a still incomplete prototype.…”

Spectrally-resolved measurement of concentrated light distributions for Fresnel lens concentrators

“…Device A gives a spot with a gaussian profile whereas device B produces a spot with a much more uniform distribution. The absence of an SOE in the case of device A explains such optical behavior, whereas the 4FK optic is known to produce a highly uniform pattern [10,18]. This non-uniformity can be quantified through the maximum value of the normalized current density plot.…”

“…The POE-cell distance was set to 96mm from the POE, corresponding to an optimized power production at a lens temperature of 25°C. Device B is a PMMA 4FK lobe concentrator [18] corresponding to a fourfold two-stage optical concentrator. It combines a Fresnel lens POE and a refractive SOE, splitting the light into four Köhler channels.…”