Annual Yield Comparison of Module Level Power Electronics and String Level PV Systems with Standard and Advanced Module Design

Abstract

This study focuses on the partial shade-mitigating effects related to the insertion of additional ideal bypass diodes in residential-scale photovoltaic (PV) systems. For this purpose, quantification of the resulting energy yield benefits is carried out in a representative residential environment. It is widely recognized that partial shading inflicts disproportional losses to the energy output of PV systems. Increased granularity levels in cell groups are perceived as a potentially promising measure to increase the shade-tolerance of photovoltaic devices. The past years, introduction of module level electronics promise to reduce further shading losses. The developed model includes a shading evaluation of the installation with means of 3D modeling, insertion of additional by pass diodes resulting in smaller cell groups, irradiance calculations, PV cell modelling and finally an empirical power conversion model. Results suggest that in the reference case of 3 by pass diodes the micro inverter system is performing the best under partial shading. By increasing the cell group granularity the string inverter systems seems to benefit due to the wide maximum power point voltage window.