LAUSR

Abstract Nanofluids have been identified as one of the potential solar energy absorbing media to improve the performance of the photovoltaic-thermal (PV/T) system. Use of a nanofluid above the PV panel through optical filtration may improve the performance of PV/T systems. The aim of this study is to extend the current knowledge of the parameters affecting the optical behavior of water/silver nanofluid through analytical and experimental investigation. The effect of the optical path length and the concentration of the nanoparticles on the transmittance of water/Ag nanofluid were evaluated and an experimental correlation describing the relation was developed. The Rayleigh method was used to analytically evaluate the transmittance of nanofluid. Experiments were conducted at five concentrations of Ag from 0.0005 wt % to 0.05 wt % using a UV–vis spectrophotometer at path lengths of 2 mm, 5 mm, and 10 mm. Experimental results were used to develop a correlation on the transmittance of water/silver nanofluid with the concentrations and optical path length of nanofluid. The transmittance of water/Ag nanofluid depends on the optical path length and concentration of the nanoparticles. The transmittance is higher at shorter path lengths and low concentrations. The effects are most pronounced in the spectral range from 250 nm to 1400 nm. The performance of a PV/T system with optical filtration showed better overall performance than the standalone PV system at low concentration. The outcomes of this study are useful in understanding the effect of using an optical filtration layer in PV/T solar collectors in capturing more energy.