In this interdisciplinary experimental study a new nanofluid-based optical filter (NFOF) was designed and tested for a photovoltaic/thermal (PV/T) hybrid system. To this end, Ag/ Cr2O3 nanoparticles (NPs) were synthesized with 5% concentration of Ag, then the obtained Ag/Cr2O3 NPs were suspended in glycerol (C3H8O3). The prepared nanofluid optical filter is outstanding and novel from some aspects: (i) the simple synthesis method of Ag/Cr2O3 NPs, (ii) bears desirable transmittance, (iii) high stability of nanoparticles in base fluid, (iv) low-cost production process, (v) acceptable overall energetic and exergetic efficiency. The intense solar irradiance occurs in the visible spectrum range where most solar systems are designed based on this range. Moreover, the highest spectral response of the silicon type solar cells can be achieved in wavelengths between 650 nm and 1075 nm (ideal window). Therefore, the prepared NFOF filters was designed to have maximum transmittance in wavelengths between 650 nm and 1075 nm for efficient photo-electrical conversion. Accordingly, they should have high absorbance in the wavelengths out of the said region (especially visible spectrum) for optimum photo-thermal conversion. The incident of spectra out of ideal window not only doesn't have any contribution to PV cell electricity generation, but also increases cell temperature which subsequently reduces its efficiency and longevity. For this purpose, NFOF was used as a selective thermal absorber that protects PV cell against unrequired spectra. Three different concentrations of Ag/Cr2O3 NPs were suspended in glycerol (10 ppm, 40 ppm, and 80 ppm). The performance of the hybrid PV/T system was checked by photothermal/electrical conversion efficiency, merit function, and overall exergy efficiency. The maximum photothermal energy conversion efficiency is 31.55% which is obtained by Ag/Cr2O3-glycerol (80 ppm) NFOF. Also, the highest value of photoelectric energy conversion is 13.25% which is obtained when there is no filter. Moreover, the Ag/Cr2O3-glycerol (40 ppm) NFOF caused the highest amount of overall energy efficiency (41%) and merit function (1.558). When E(λ)≠0, the highest and lowest overall exergy efficiency during 30 min testing was obtained by glycerol and Ag/Cr2O3-glycerol (80 ppm), while this is completely inverse when E(λ) = 0.