Investigations of Site-Specific, Long Term Average Albedo Determination for Accurate Bifacial System Energy Modeling

In recent years, bifacial modules have been attracting industry interest due to the potential for significant contributions to energy generation from the module rear side. Albedo is a critical parameter needed for modeling rear side irradiation, and accurate albedo values representing both longterm and evolving conditions are needed to quantify the impact of the additional energy generation for financing solar projects. In this paper, the authors identify multiple sources of long-term albedo data and compare to shorter term ground-based measurements in Utah and California. An evaluation of groundbased albedo measurement techniques is presented. Finally, we evaluate methods to reduce higher-frequency measured or longterm albedo data to monthly values commonly needed by industry-accepted software, such as PVsyst.