Validation of a Bifacial Simulation Software Against Measured Energy Yield From a Utility-Scale Vertical Fixed-Tilt Agrophotovoltaic Plant

This paper handles a validation study involving the open source bifacial photovoltaic (PV) simulation tool BifacialSimu. The tool is based on the existing python libraries pvlib, bifacial_radiance and pvfactors and offers to apply different simulation modes (view factor and ray tracing) for front and back side irradiance calculations. Measured PV energy yield (2021 and 2022) from a 4.1 MWp vertical fixed tilt agro-PV plant in Germany was used as reference data. In addition, onsite albedo measurements were conducted over a two month period in 2022. Over the measuring period, the albedo averages out to 0.19 and its daily characteristics are relatively coherent to the findings in literature. A recorded mowing cycle of the grass between the PV rows increases the median albedo by one percentage point. An overall yield comparison between BifacialSimu and the measured yield results in a mean deviation of -6.4 % in 2021 and -14.4 % in 2022 for the considered months. It can be said that BifacialSimu performs better at times when the share of diffuse irradiance is high, leading to more precise yield prediction in winter months. A similar assessment of PVsyst shows opposing behavior.