The stability, optical behavior optimization of Ag@SiO2 nanofluids and their application in spectral splitting photovoltaic/thermal receivers

Few studies focus on the stability and the optical characteristics optimization of the nanofluid filters for photovoltaic/thermal (PV/T) systems. In this work, a propylene glycol (PG) based nanofluid filter consisting of Ag@SiO2 nanoparticles was fabricated for both Si and GaAs solar cells and the stability was assessed. Results show that PG based Ag@SiO2 nanofluids retain their optical properties after subjecting to solar radiation, high temperature heating and ambient storage for 60 days. Further, an optimization routine based on Mie scattering theory and Lambert Beer law was proposed for selection of the best particle concentration and optical path distance of the nanofluid. The filtering efficiencies more than 43% and 35% are achieved for Si and GaAs solar cells, respectively. Finally, the filtering performance of nanofluids with the best nanofluid parameters was discussed in PV/T systems. The optimized nanofluids combined with Si cells achieve the value of merit function (MF) of 1.51 when Ag@SiO2/PG-DI nanofluid with particle concentration of 30 mg/L and optical path distance of 42 mm. It is higher than the value obtained in literature. For GaAs cells, the Ag@SiO2/PG-DI nanofluid filter with 23 mg/L particle concentration and 50 mm optical path distance produces the highest MF of 1.38.