Large-Scale Bifacial PV Test Field Performance Compared to Simulations Using Commercially Available Software, Research-Based and Open Source Tools

The aim of this work is to provide the photovoltaic (PV) community with a validation study of eight tools used to simulate bifacial PV performance. We simulate real 26 kWp bifacial p-PERC arrays located within a 420 kWp site located in Northern Europe (55.6°N, 12.1°E). The substructures investigated include horizontal single axis trackers (HSATs) and fixed tilt racks that have dimensions analogous to those found in utility-scale PV installations. Each bifacial system has a monofacial reference system with similar front side power. We use on-site solar radiation (global, diffuse and beam) and albedo measurements from spectrally flat class A sensors as inputs to the simulation tools, and compare modeled values to field measurements of string level DC power and rear plane of array irradiance. Our results show that state-ofthe-art bifacial performance models add ~0.5% uncertainty to the PV modeling chain. For the site investigated, 2D view factor fixed tilt simulations are within ±1 % of measured monthly bifacial gain. However, simulations of single axis tracker systems are less accurate, wherein 2D view factor and 3D ray tracing are within approximately 2% and 1% of measured bifacial gain, respectively.