One stone, two birds: Multifunctional composites for bifacial solar photovoltaic power generation with enhanced flame retardancy and smoke suppression

Solar photovoltaics (PV) convert sunlight into electricity, with bifacial systems capturing light on both sides to enhance efficiency. Incorporating materials with high reflectivity in the 300–1100 nm wavelength range can further boost this efficiency by redirecting unutilized light to the rear of bifacial PV modules. In this work, a multifunctional composite material was developed by incorporating nano titanium dioxide (TiO₂) and magnesium hydroxide (Mg(OH)₂) into a polyethylene (PE) matrix. This composite system exhibits high reflectivity in the 300–1100 nm range, with the addition of 10 phr nano TiO₂ and 150 phr Mg(OH)₂ increasing the reflectivity to 76.39 %, enhancing solar energy utilization. Additionally, the composite showed enhanced flame retardancy, with the limiting oxygen index rising from 17.8 % to 28.0 %, a UL-94 rating improvement from “No Rating” to V-0, and significantly reduced smoke density, approaching zero compared to the control. Its thermal conductivity of 1.13 W·m⁻¹·K⁻¹ makes it suitable for passive cooling applications in building facades and automotive interiors. These combined properties make the composite a promising candidate for enhancing efficiency and safety in bifacial PV systems.