Efficiency Limit of Photovoltaic/Thermal (Pv/T) and Thermodynamic Enhancement Methods Based on Non-Uniform Temperature Fields

Abstract

Due to structural limitations, such as metal gridlines, in crystalline silicon solar cells used in photovoltaic/thermal (PV/T) applications, their actual efficiency limit is notably below the Shockley–Queisser (S-Q) limit at the respective bandgap. Additionally, PV/T operation inevitably results in temperature non-uniformity, which substantially affects cell performance. In this study, we identified an optimized configuration between the non-uniform temperature field and cell structure, which enhanced efficiency. We proposed a loss analysis model that offered comprehensive theoretical insights for optimizing PV/T under non-uniform temperature fields. The findings indicated that, compared to a uniform temperature distribution, the actual efficiency limit increased by 0.333% with a non-uniform temperature field. Verification experiments further supported that this optimized non-uniform temperature configuration can potentially improve PV actual efficiency. Finally, the temperature field significantly influenced losses associated with carrier excitation, extraction and transport, with the balance between these losses determining the actual thermodynamic performance. This study identifies the fundamental factors influencing actual thermodynamic efficiency of PV/T in non-uniform temperature fields and provides a roadmap for realizing the full potential of PV/T.

Keywords: PV/T, actual efficiency limit, loss analysis model, non-uniform temperature field, carrier process