Performance Comparison Between Bifacial PERC and TOPCon on a South‐Facing Vertical Structure

ABSTRACT The aim of this study is to quantitatively compare the field performance of two bifacial photovoltaic (PV) technologies—Passivated Emitter and Rear Contact (PERC) and Tunnel Oxide Passivated Contact (TOPCon)—under real‐world rooftop conditions in winter in South Korea. PV module efficiency obtained under standard test conditions, such values can diverge significantly from actual field performance, directly impacting energy yield and the levelized cost of energy. This study employed a 20‐day rooftop field test on a south‐facing building to evaluate and compare the energy yield and electrical characteristics of PERC and TOPCon modules. TOPCon achieved an 8.16% higher energy yield than PERC, owing to its higher bifaciality coefficient (83.3% vs. 78.8%), better temperature coefficient of voltage, and lower rear‐side shading. TOPCon thus achieved 1.51% higher normalized open‐circuit voltage ( V oc ) and 7.40% higher normalized short‐circuit current ( I sc ). This study, the first to decompose the normalized V oc and I sc contributions under field conditions, confirms that device‐level innovations in cell architecture can substantially improve real‐world energy generation. These findings underscore the importance of optimizing module design based on field conditions rather than relying solely on laboratory benchmarks.