For conventional solar PV/T system, the photo-thermal and photo-electrical conversion processes are coupled. The spectral splitting PV/T system based on nanofluids can realize high solar utilization efficiency. In this paper, the solar spectral characteristics of Ag, CNT, CNT/Ag nanofluids with different concentrations were tested. Then, the thermal and electical performances of an experimental were measured and a thermal and electrical numerical model was established and validated. Finally, the initial energy performnace on the proposed system applied in Nanjing was analyzed based on the established model. The main results were: (1) Compared with independent Ag or CNT nanofluids, the spectral transmittance in the PV cell response range and the spectral absorbance in the rest range for CNT/Ag nanofluids were increased by 9.3% and 41.8%, respectively. (2) The filtration efficiency of CNT/Ag nanofluid spectral splitting filter reached its highest efficiency of 18.3% at 5 × 106 μg/m³. (3) The electrical and thermal efficiency of PV/T system were 8.2% and 45% in the experiment respectively. (4) When applied in Nanjing, compared with the independent Ag and CNT nanofluids, the thermal efficiency and electrical efficiency of the system based on CNT/Ag nanofluids were increased by 9.9% and 15%, 7.2% and 1.4%, respectively. •Excellent solar spectral performance of CNT/Ag mixed nanofluids.•Experimental and numerical investigation on a spectral splitting PV/T system.•High solar thermal, electrical and spectral splitting filter efficiency.