The efficiency of a secondary optical element (SOE) is often questioned when a real high concentrating photovoltaic (HCPV) module is considered. Three years ago Opsun Technologies Inc. introduced a new type of SOE, which increased significantly the acceptance angle of the HCPV module close to the limits predicted theoretically (1). Indeed, introducing a SOE into a HCPV module enables the increase of its acceptance angle. Furthermore, the SOE homogenizes the concentrated sun light beam's profile, which leads to an improvement of the fill factor. However, the opposite input side of the SOE introduces an additional surface, causing optical losses due to Fresnel reflections. This issue added to the cost of the SOE, discards its benefic properties. Thus, eliminating or minimizing Fresnel reflection could transform the SOE into a powerful tool to boost significantly the efficiency of the HCPV module. Silicon dioxide (SiO_2) nanoparticles, obtained by sol-gel technique, were used to create an antireflective coating (ARC) for the use in a high concentrating photovoltaic (HCPV) device. These ARCs have shown a transmission increase from 92% up to 99% when deposited on glass substrates. The introduction of these same ARCs, with different optical paths, in the HCPV system has shown an overall power increase with strong dependence of the HCPV module performance (based on triple junction solar cells) upon the different ARC transmission spectra. In the present work we demonstrate a combination leading to almost 12% power increase in the HCPV. Indeed, a drastic peak power increase is observed here, due to the homogenization of the concentrated sun beam by the SOE and to the incorporation of a cost effective nanoparticle based anti-reflection coating (ARC) that eliminates the Fresnel reflections.
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