Photovoltaic/thermal (PV/T) solar collectors employing phase-change nano-capsules as spectral filters: Coupled, decoupled, and partially-coupled configurations

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The ineffective utilization of solar radiation poses negative impacts on the performance of photovoltaic (PV) cells in terms of their efficiency and durability. For the first time, this study numerically introduces a comparative performance analysis between multiple PV/T configurations (thermally decoupled, coupled, and partially coupled) that employ nano-encapsulated phase-change material (nano-ePCM) dispersions. The dispersions act as multi-functional fluids that can optically filter incident radiation to fit the spectral response of Si PV cells, and serve as both heat carriers and storage media to effectively cool PV cells. The water-dispersed ePCM particles are made of silica shells and paraffin cores. The numerical model developed for the proposed configurations mainly comprises of three mathematical models (thermal, optical, and electrical) that are coupled together to simulate the performance of the novel systems. To ensure that the presented results are of high accuracy and credibility, the optical, electrical, and thermal models were rigorously validated against published data. Performance of the three PV/T configurations was comparatively analyzed upon varying the PCM core material, mass flowrate, channel depth, inlet and ambient temperatures, and wind speed. The utilized dispersion exhibited a 73.8% spectral match with Si PV cells, thus hinting at the effective spectral filtration capabilities of the designed fluid. When compared to similar PV/T configurations from different literatures, total exergy efficiency enhancements of 43.2%, 76.8%, and 2.6% were evident for the coupled, decoupled, and partially coupled systems, respectively. In addition, results have shown that the thermally decoupled system outperforms the coupled and partially coupled systems in terms of thermal performance but exhibits the poorest performance when superior electrical performance is desired.