A novel photovoltaic/thermal (PV/T) solar collector based on a multi-functional nano-encapsulated phase-change material (nano-ePCM) dispersion

Overheating is a major problem encountered by photovoltaic (PV) cells that significantly deteriorates their performance and shortens their lifetime. For the first time, this study numerically investigated employing a nano-encapsulated phase-change material (nano-ePCM) dispersion in a double-pass photovoltaic/thermal (PV/T) solar collector, where the multi-functional nano-ePCM dispersion simultaneously operates as an optical filter, heat carrier, and storage medium. The water-dispersed nano-ePCM particles were made of silica shells and paraffin-based cores. The proposed system was optically, thermally, and electrically modeled and evaluated after rigorous validation against published results. The performance of the PV/T system was analyzed upon varying the PCM core material, flowrate, solar intensity, particle size and loading, and channel depth and length. In addition, the proposed system (SYS-1) was compared to two alternative configurations, where one was based on a cooling channel below the PV cells without an optical filtration channel (SYS-2), and the other was based on an optical filtration channel above the PV cells without a cooling channel (SYS-3). To investigate the optical filtration capabilities of the nano-ePCM dispersion, a performance metric known as the ‘spectral match’ (SM) was proposed. Results showed that all ePCM dispersions exhibited a SM > 70 % when the PCM cores were in their liquid phase and a SM > 30 % while in solid phase. As compared to SYS-2 and SYS-3, at the lowest investigated flowrate (0.0026 kg s⁻¹), the proposed PV/T system exhibited mean cell temperatures lower by 5 and 10°while offering relative thermal exergy enhancements of 66 and 208 %, respectively. This was attributed to allowing the PV cells to operate at temperatures substantially lower than the dispersion outlet temperature to achieve both high-grade thermal outputs and enhanced PV efficiencies. This study paves the way for novel PV/T collectors that employ smart, multi-functional fluids offering superior electrical and thermal performance.