Beyond 1 Sun: Evaluating the Efficiency of Perc and Topcon Silicon Devices Under Over-Irradiance Conditions
Abstract
Single-junction photovoltaic devices are nearing their efficiency limits, making second-order effects increasingly relevant. In high-sun regions such as Brazil, irradiance frequently exceeds 1 sun, yet device performance under these conditions remains insufficiently characterized. This work evaluates aged p-type PERC and n-type TOPCon minimodules using outdoor measurements on a single-axis tracker and controlled indoor tests. Prior to testing, all samples were subjected to 1000 hours of damp-heat aging following IEC 61215. The site’s irradiance distribution shows that more than one quarter of the total incident energy occurs at or above 1000 W/m². Both indoor and outdoor measurements reveal efficiency losses at elevated irradiance, primarily driven by series resistance effects. Under these conditions, the aged PERC samples in this work exhibit stronger degradation and more pronounced fill-factor reductions compared to the TOPCon samples. The TOPCon samples in this study maintain greater stability under increasing irradiance, which may be associated with differences in degradation pathways and series resistance evolution rather than intrinsic technology advantages alone. By combining irradiance-dependent performance with the local energy distribution, global weighted efficiencies indicate that the studied TOPCon samples adapted more effectively to high-irradiance conditions, translating this into higher operating efficiency. These results emphasize the need to characterize PV technologies beyond STC and highlight that minimizing series resistance—particularly after aging—is critical for optimizing performance in high-irradiance climates.
Keywords
PV Efficiency, Device Optimization, Irradiance Response, Over-Irradiance, Indoor Characterization, Outdoor Performance