Mechanisms of nanofluid-mediated modulation of solar spectral transmittance and assessment of photovoltaic performance

In the context of the global energy transition and carbon-neutrality goals, nanofluids—with tunable optical properties—offer a promising route to enhance photovoltaic module performance. However, the multi-scale coupling from micro-mechanisms to macro-level performance remains underexplored. To investigate how nanofluid material, concentration, and particle size affect PV efficiency, we conduct experiments and modeling. SEM reveals the dispersibility, surface morphology, and agglomeration of nanoparticles (Al2O3, SiO2, CuO, SiC, TiO2, ZnO), and we quantify how material, concentration, and size influence spectral transmittance. Building on this micro-mechanistic basis, we measure and model solar-radiation transmittance versus concentration. Using the measured transmittance, we construct concentration–response models for PV conversion efficiency and for the efficiency difference; both decrease with increasing concentration, with SiO2 remaining relatively high and declining gently (>0.12), while SiC and CuO are the lowest (about 0.075). These models demonstrate high accuracy, highlighting the importance of concentration and particle size in PV performance. Estimates based on ten-year average irradiance data for 50 cities across five Chinese climate zones confirm that power generation decreases with higher concentration, and smaller particles outperform larger ones. These insights elucidate the role of nanoparticle micro-features in PV performance and provide a quantitative basis for material selection and regional nanofluid deployment.