A new method for measuring the solar energy produced by bifacial solar panels has been devised by researchers from the University of Ottawa (Canada) SUNLAB Centre for Research in Photonics and Arizona State University. The characterization method is intended to improve the performance measurement of these double-sided photovoltaic devices indoors by considering external effects of ground cover such as snow, grass and soil and provide accurate representation of solar panel performance outdoors.

The proposed scaled rear irradiance (SRI) method determines the rear-side irradiance by the spectral albedo of the ground. The approach was demonstrated using data from a bifacial horizontal single-axis tracked array located in Boulder, Colorado. The SRI approach provided illumination conditions that matched operating conditions for a given combination of ground cover and system design.

The analytical system was confirmed to capture efficiency differences under varied spectral albedo and to represent system-specific illumination levels through in-lab bifacial device measurements. The methodology described in Joule allows comparisons between existing and emerging bifacial technologies and is expected to enhance performance via ground cover-specific design optimization.