Fresnel Lens Characterization – Calibration and Automation

Abstract

Lens-based solar concentrators have been widely used to reduce the photovoltaic(PV) receiver area and increase the solar irradiance on the PV receiver. In our previous work an indoor Lens Characterization Unit (LCU) was developed to measure the focal length and irradiance patterns resulting from refracted lasers at the focal plane of large scale Fresnel lenses with unknown optical qualities. A new feature of a wirelessly controlled laser position x-y-scanner has been added to the system to improve the system automation. Spot size and the M2 factor of the power tunable laser source have been analyzed using Gaussian beam characterization for calibration of irradiance profile on the diffuser. An outdoor lens characterization solution based on the use of a photodiode based pyranometer and a two-axis focal area scanner has been developed to measure the normalized solar irradiance distribution of the focal area. Measurements performed on large scale Fresnel lenses in outdoor conditions demonstrated advantages in feasibility and accuracy comparing with the indoor solution.