Electrical–thermal trade-off in white solar cells with TiO2 particle scattering layers for building-integrated photovoltaics

White photovoltaic modules are attractive for building-integrated photovoltaics (BIPV) because they can improve architectural compatibility, whereas the strong visible-light scattering required for whitening inevitably reduces photovoltaic power generation. In this study, the coupled optical, electrical, and thermal effects of whitening were experimentally investigated using rutile TiO 2 particle scattering layers formed on glass substrates and placed over silicon heterojunction (SHJ) solar cells. TiO 2 particles with an average diameter of 508 nm were dispersed in an acrylic matrix and coated onto glass substrates with nominal TiO 2 volume fractions of 1–10 vol%. Increasing the TiO 2 loading increased visible reflectance and CIELAB lightness L*, while reducing optical transmission, short-circuit current, and maximum power output. The improvement in lightness became relatively small above approximately 5 vol%, indicating diminishing visual benefits at higher particle loadings. When referenced to bare glass at the same incidence angle, the relative electrical loss showed only a modest incidence-angle dependence over the investigated angular range. Under continuous 1-sun illumination, whitening substantially reduced the thermal response of the cell. At 10 vol% TiO 2 , the maximum output power decreased by 54.5% relative to the bare-glass reference, whereas the steady-state cell backside temperature decreased by 8.3 °C and the local backside heat flux decreased by 50.0%. These results quantitatively demonstrate an electrical–thermal trade-off in white photovoltaic structures and highlight the need to optimize scattering-layer design to balance architectural appearance, photovoltaic power generation, and backside thermal transport in BIPV applications.