Next generation tools for accurate energy yield estimation of bifacial PV systems: Best practices, improvements and challenges

Bifacial photovoltaic technology is a promising, new approach to further reducing the Levelized Cost of Electricity of photovoltaic-generated electricity. However, designing and optimizing bifacial photovoltaic plants is a challenging task, which requires new modelling tools. This paper presents a physics-based energy yield simulation approach for bifacial photovoltaic systems, providing accurate yield prediction and insight into the operation of bifacial PV systems. Rear-side, inhomogeneous illumination is modelled using a CAD-assisted, GPU-accelerated ray-tracing-based approach, considering the influence of module build-up and layout, module frame, mounting structure and environment geometry. The non-uniform electrical-thermal operation with geometry-dependent convective and radiative cooling mechanisms and the resulting mismatch effect, which reduces module and system power output is modelled via interconnected electrical and thermal-equivalent circuits, where time-varying thermal resistors are used to model convective and radiative cooling. The combination of high-performance computing techniques, with advanced daylighting and circuit computing algorithms provides high accuracy at low computational costs, ensuring practical applicability to designing photovoltaic power generation system. The presented outdoor validation study confirms that our approach results in high accuracy, since the main mechanisms taking place during photovoltaic energy conversion are modelled on a physics basis. Additionally, physics-based modelling provides insight into the operation, the main loss contributions and mitigation strategies, applicable to bifacial PV systems.