Radiative properties of CuO-CoSO4 nanofluids and their performance in solar photovoltaic/thermal systems

The efficient utilization of solar energy can be achieved by coupling photovoltaic (PV) and photothermal (PT) technologies to harness the full spectrum of solar radiation. In this work, a new type of CuO-CoSO₄ nanofluid was proposed, and its performance in a photovoltaic/thermal (PV/T) system was studied. CuO-CoSO₄ nanofluids with different concentrations were prepared by two-step method, and their optical properties and stability were characterized. The experimental results show that the 50 mg/L CuO-CoSO₄ nanofluid has high transmittance in the ideal optical window of silicon cells (650–1040 nm), with an average transmittance of 67.58%, and higher absorptivity in the short waveband and infrared bands (280–650 nm and 1040–2500 nm), with an average absorptance of 68.52%, effectively realizing spectrum splitting. By establishing a performance analysis model for the nanofluid-based spectral splitting PV/T system, the electrical efficiency, thermal efficiency and total efficiency of the system at different concentrations were calculated, and the Merit function (MF) was introduced to comprehensively evaluate the system performance. The results show that the CuO-CoSO₄ nanofluid has the best spectral splitting performance when the CuO concentration is 50 mg/L. The system achieves an electrical efficiency of 14.46%, a thermal efficiency of 37.60%, and a system efficiency of 52.06%. The MF value reaches 1.2851, indicating a 28.51% improvement over traditional PV systems. This study provides a theoretical basis for the practical application and optimization of nanofluids in PV/T systems.

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