Beyond the module model and into the array: Mismatch in series strings

Mismatch losses have the potential to significantly affect the performance of PV arrays, so it is important to model them as accurately as possible. There are many variables that affect mismatch in a system, and it is often not realistic for commercially-available tools to rigorously model the complex behavior of PV systems operating under non-uniform conditions. Though many tools have simplified methods for estimating mismatch loss, there are few general guidelines for how it should be characterized in PV systems. Various mismatch scenarios and resulting system-level power losses are modeled using a custom, comprehensive PV array simulation environment. Based on the results of these simulations, and the capabilities of current modeling tools, suggestions are made for accurate modeling of module mismatch, partial shading, and panel orientation differences in PV arrays. With improved understanding of mismatch-related PV system power loss, researchers and system designers will be better able to accurately assess and model its impact, enabling future PV research and maximizing the value of a diverse set of PV systems.