Efficiency enhancement of photovoltaic modules via full-spectrum utilization and waste heat recovery using liquid-state thermocells

The photovoltaic module (PVM) primarily captures photons near the semiconductor bandgap to generate photocurrent. However, low- and high-energy photons outside this range are largely wasted as heat, limiting efficiency to approximately 33% (Shockley–Queisser limit). To utilize the full solar spectrum, a spectrally selective absorber (SSA) and a liquid thermocell (LTC) are synergistically integrated with a PVM to form a novel hybrid system for the first time. The developed model improves upon previous work by including: (i) the PVM-to-LTC area ratio, (ii) iterative energy balance to determine LTC electrode temperatures, and (iii) key irreversible losses in both subsystems. Under AM1.5G conditions (1 kW m−2), the proposed hybrid system has a maximum conversion efficiency of 20.70% and a electric power density of 207.0 W m−2 when the PVM operates at 345 K. Compared to a standalone PVM, the hybrid system demonstrates a 7.64% improvement in both efficiency and power density, outperforming the PVM and solid-state thermoelectric generator hybrid technologies. Parametric studies reveal that lowering PVM and sink temperatures, narrowing LTC electrode spacing, and raising ambient temperature can significantly improve performance. This study provides a theoretical foundation for the optimal design and operation of PVM-LTC hybrid systems, offering valuable insights into solar full-spectrum utilization and waste heat recovery in PV applications.