System‐Level Performance and Techno‐Economic Assessment of Rooftop Four‐Terminal Tandem Photovoltaic Systems With Module‐Level Power Electronics Under Partial Shading

Tandem photovoltaic (PV) modules represent a promising pathway toward next‐generation high‐efficiency PV systems, with four‐terminal (4T) architectures offering enhanced design flexibility and a practical route toward commercialization. However, the system‐level integration of 4T tandem modules and their performance under partial shading (PS) remain insufficiently understood. This work presents a system‐level evaluation of 4T tandem PV systems under a range of rooftop shading conditions, comparing conventional bypass‐diode (BPD) protection with module‐level power electronics (MLPE) architectures in terms of mismatch mitigation, annual energy yield, and economic viability. Physics‐based simulations using the PVMD Toolbox, combined with real weather data, are employed to evaluate multiple MLPE architectures, including module‐ and submodule‐level granularity as well as full‐power‐processing (FPP) and differential‐power‐processing (DPP) architectures. The analysis considers annual energy yield together with levelized cost of electricity (LCOE) and net present value (NPV). Results show that under no‐shading and low‐shading conditions, the additional conversion losses and costs associated with MLPE outweigh their benefits. In contrast, under moderate and high shading conditions, MLPE, particularly at the submodule level, effectively mitigates mismatch losses, increasing annual energy yield by up to 20% relative to conventional BPD architecture while achieving the lowest LCOE and highest NPV. These results provide quantitative design guidelines for selecting MLPE granularity and power‐processing strategies for practical 4T tandem PV systems and identify the operating conditions under which active power electronics become beneficial.