9-Fold Fresnel-Köhler Concentrator for Increased Irradiance Uniformity on High Concentrations

Non-uniform irradiance patterns over Multi-Junction Cells (MJC) in Concentrator Photovoltaics (CPV) originate significant power losses, especially when there are different spectral irradiance distributions over the different junctions, and is likely that will have a larger impact in 4 and 5 junction cells. The spectral irradiance distributions are especially affected with thermal effects on Silicone-on-Glass (SoG) CPV systems. This work presents a new optical design, the 9-fold Fresnel Köhler concentrator (FK9), prepared to overcome these effects at high concentrations while maintaining a large acceptance angle (acceptance angle-concentration product-CAP-of 0.65), paving the way for a future generation of high efficiency CPV systems of 4 and 5 junction cells. A comparative study between FK9 and other concentrators for different concentrations and temperatures is presented, confirming its excellent spectral irradiation distribution in extreme conditions.