BICON: High concentration PV using one-axis tracking and silicon concentrator cells

BICON is a two-stage concentrator system developed at Fraunhofer ISE which is one-axis tracked. The innovation of this one-axis tracked system is that it enables a high geometrical concentration of 300x in combination with a high optical efficiency (upto 78%) and a large acceptance angle of +/- 23 center dot 5 degrees all year through. For this, the system uses a parabolic mirror (40 center dot 4 x) and a three dimensional second stage consisting of compound parabolic concentrators (CPCs, 7 center dot 7x). For the concentrator concept and particularly for an easy cell integration, rear-line-contacted concentrator (RLCC) cells with a maximum efficiency of 25% were developed and a hybrid mounting concept for the RLCC cells is presented. The optical performance of different CPC materials was tested and is analysed in this paper. Finally, small modules consisting of six series interconnected RLCC cells and six CPCs were integrated into the concentrator system and tested outdoor. A BICON system efficiency of 16 center dot 2% was reached at around 800 W/m(2) direct irradiance under realistic outdoor conditions. Copyright (C) 2006 John Wiley & Sons, Ltd.