Accelerating the simulation of annual bifacial illumination of real photovoltaic systems with ray tracing.

Accurate modeling of bifacial illumination is critical to improve the prediction of the energy yield of bifacial solar systems. Monte Carlo ray tracing is the most powerful tool to accomplish this task. In this work, we accelerate Monte Carlo ray tracing of large solar systems by nearly 90%. Our model achieves root-mean-square error values of 7.9% and 37.2% for the front and rear irradiance compared against single-axis tracking field reference data, respectively. The rear irradiance modeling error decreases to 18.9% if suspected snow periods are excluded. Crucially, our full system simulations show that surrounding ground surfaces affect the rear irradiance deep into the system. Therefore, unit system simulations cannot necessarily ignore the influence of the perimeter of large installations to accurately estimate annual yield. Large-scale simulations involving high-performance supercomputing were necessary to investigate these effects accurately, calibrate our simplified models, and validate our results against experimental measurements.

Impact of Pregrown SiOx on the Carrier Selectivity and Thermal Stability of Molybdenum-Oxide-Passivated Contact for Si Solar Cells.

Thin SiOx interlayers are often formed naturally during the deposition of transition metal oxides on silicon surfaces due to interfacial reaction. The SiOx layer, often only several atomic layers thick, becomes the interface between the Si and deposited metal oxide and can therefore influence the electrical properties and thermal stability of the deposited stack. This work explores the potential benefits of controlling the properties of the SiOx interlayer by the introduction of pregrown high-quality SiOx which also inhibits the formation of low-quality SiOx from the metal-oxide deposition process. This work demonstrates that a high-quality pregrown SiOx can reduce the interfacial reaction and results in a more stoichiometric MoOx with improved surface passivation and thermal stability linked to its lower Dit. Detailed experimental data on carrier selectivity, carrier transport efficiency, annealing stability up to 250 °C, and in-depth material analysis are presented.