Modelling bifacial photovoltaic systems : Evaluating the albedo impact on bifacial PV systems based on case studies in Denver, USA and Västerås, Sweden

This study aims to develop a simulation and optimisation tool for bifacial photovoltaic (PV) modules based on the open-source code OptiCE and evaluate dynamic and static albedo impact on a bifacial PV system. Further, a review of the market price development of bifacial PVs' and an optimisation to maximise energy output was conducted. Two case studies with bifacial PV modules, a single-axis tracker in Denver, USA, and a vertical and a tilted system installed at a farm outside Västerås, Sweden, were analysed in this study. The results showed that an hourly dynamic albedo value could provide more accurate simulation results of the rear side irradiance for the bifacial single-axis tracker than a static albedo value. The developed model showed an R2 accuracy of 93% and 91% for the front and rear sides, respectively, when simulated with an hourly albedo value for the bifacial single-axis tracker system. The optimisation was based on weather data from 2020. The results showed that the tilted reference system could increase its energy output by 8.5% by adjusting its tilt from 30° to 54° and its azimuth angle from 0 to -39°. In contrast, the vertical system would increase its energy output by 2.1% by rotating the azimuth angle from -90° to -66°. Conclusions that could be drawn are that bifacial PV price has closed in on the high-performance monofacial PV price the last five years and may continue to decrease in the coming years. Further, it was concluded that detailed dynamic albedo values lead to more accurate simulations of the ground-reflected irradiance. The availability of measured albedo data at the location is essential when the ground-reflected irradiance stands for a significant share of the irradiance. It was determined that during 2020 the optimal configurations of a vertical and tilted bifacial PV system in Västerås would save 11 300 SEK by consuming self-produced electricity and earn 11 600 SEK from selling the surplus of electricity for the farm outside Västerås