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In this paper, the main novelty is the proposal and performance analysis of a novel selectively filtered nanofluid spectrum semi-trough solar concentrated photovoltaic-thermal (SPVT) system. Experimental preparation and optical tests of Ag-CoSO4/water nanofluid are conducted. The selected nanofluid for the SPVT system has an average absorptance of 53.5% and an average transmittance of 46.5% in 250.0 ~ 2500.0 nm. The optical analysis results show that the optical efficiency of the SPVT system is 94.3% under the optical filtering condition. When the solar tracking error increases to 0.3°, the optical efficiency of the SPVT system can still be kept at 84.8%. This means that the SPVT system has relatively good adaptability on solar tracking error. The operation performance analysis results indicate that under the optical filtering condition, the electric power and photo-electric efficiency of the PV subsystem are 392.1 W and 30.9%, and the thermal efficiency of the SPVT system is 40.7%. Effects of four factors on the thermal performance of the SPVT system are evaluated, which are the inlet nanofluid flow velocity and temperature, environmental temperature and convection heat transfer coefficient between the nanofluid flow channel and air. The results show that the thermal performance of the SPVT system can be improved by properly increasing the inlet nanofluid flow velocity and environmental temperature or by reducing the inlet nanofluid temperature and convection heat transfer coefficient between the nanofluid flow channel and air. When the inlet nanofluid flow velocity increases from 0.002 m/s to 0.004 m/s, the thermal efficiency of the SPVT system increases from 40.9% to 50.7%, and with the inlet nanofluid temperature increased from 6.0°C to 14.0°C, the thermal efficiency decreases from 48.6% to 45.6%. The results of this paper can provide certain reference for research and development works of solar PVT systems in the future.
Wang et al. (Wed,) studied this question.