A comparison of ray tracing and view factor simulations of locally resolved rear irradiance with the experimental values. (11th March 2020)

• Record Type: Journal Article
• Authors: Berrian, Djaber; Libal, Joris
• Is Part Of: Progress in photovoltaics. Volume 28:Number 6(2020)
• Page Start: 609
• Page End: 620
• Publication Date: 2020-03-11
• Subjects: albedo -- bifacial modules -- modeling -- prediction -- PV systems -- simulation -- ray tracing -- view factor; Solar cells -- Periodicals; Photovoltaic cells -- Periodicals; Solar power plants -- Periodicals; 621.31245
• DOI: 10.1002/pip.3261
• Languages: English
• ISSNs: 1062-7995

Abstract

Abstract: One of the prerequisites for a reliable energy yield prediction of bifacial photovoltaic (PV) systems is the capability of modeling the backside irradiance of those systems with high accuracy. Currently, the most important optical models used to quantify the reflected irradiance on the backside of a bifacial solar panel are view factor and ray tracing. The MoBiDiG simulation tool has been developed at ISC Konstanz uses the view factor (VF) concept to model the rear irradiance. In addition to the VF concept, ray tracing (RT) has been adopted to determine the backside irradiance of bifacial modules by using the open‐source tool bifacial_radiance that has been developed by the National Renewable Energy Laboratory (NREL). A customized monocrystalline silicon solar panel has been built in order to evaluate the accuracy of the existing optical models by locally resolved rear irradiance measurement. The performance of rear irradiance has been investigated along the rows of the customized PV module during sunny and cloudy days with typical back irradiance values of ≈ 50 and ≈ 150 W / m 2 . The comparison of measured and modeled data has been carried out on hourly, daily, and monthly basis, and the results show lower deviations for solar cells located in the center of the PV module than on the edge. Moreover, the concept of decisive solar cells has been introduced and applied to both measured and modeled data, solar cells located in the center rows were found to act as the most decisive solar cells. Finally, considering the installation configuration studied here, ie, bifacial mounting with low clearance height (below 0.2 m), both hourly RT and VF approaches are able to model long‐term cumulative irradiance received by decisive solar cells with a very high accuracy ranging from ± 0.5% to ± 2%. Abstract : A customized 60 cells solar panel has been built in order to evaluate the accuracy of the existing optical models for the backside irradiance of bifacial modules. The concept of decisive solar cells has been introduced and applied to both measured and modeled data. The results of validation using hourly ray tracing and quasi 3D view factor approaches are able to model long term cumulative irradiance seen by solar cells with a very high accuracy ranging from +/‐0.5% to +/‐3%.