A novel comprehensive composite material for auxiliary solar photovoltaic double-sided power generation: Combining reflective cooling, flame retardant, and smoke suppressant properties

Solar energy is a sustainable and clean resource, and photovoltaic (PV) power generation enables its direct conversion into electricity. For the first time, polyvinyl chloride/Rutile titanium dioxide/magnesium hydroxide (PVC/R-TiO₂/Mg(OH)₂) composites have been reported to exhibit high solar reflectance in the 300–1100 nm waveband, high reflectance across the entire solar spectrum and good flame retardancy, and smoke-reducing properties. The optimized T5-M100 composite, containing 100 phr R-TiO₂ and 5 phr modified Mg(OH)₂, achieves a solar reflectance of 58.43 % across the full spectrum and 67.82 % within 300–1100 nm. A one-hour cooling test demonstrates a temperature reduction from 44.5°C to 28.0°C, confirming its effective reflective cooling performance. Additionally, flame retardancy and smoke suppression are improved, with the limiting oxygen index increasing from 27.2 % to 33.7 % and the smoke density rating decreasing from 78.8 % to 41.7 %. These results highlight the potential of PVC/R-TiO₂/Mg(OH)₂ composites as multifunctional materials for bifacial PV applications and passive cooling systems.