Natural illumination variations in light-dark cycles induce irreversible ion migration in perovskite solar cells, posing substantial challenges to their long-term outdoor operational stability. We addressed this issue by isolating defective octahedra at the perovskite surface using a vapor-deposited polydentate ligand. Surface octahedra isolation suppresses ion migration into the charge transport layer and reduces surface ionic defects, modulating the kinetics of ion migration during light-dark cycles. Our 785-square-centimeter industrial-scale perovskite solar modules achieved a power conversion efficiency (PCE) of 19.6%. Our modules demonstrated enhanced diurnal stability, retaining more than 97% of their initial PCE even after 101 light-dark cycles at 50 degrees C. Our perovskite modules maintained stable power output during 45 days of outdoor operation under severe summer conditions, exhibiting stability comparable with that of the reference silicon cell.