Most solar-powered attic fans run when their solar panel is producing power, so airflow typically drops after sunset. They are built to do the heaviest work during peak sun hours, which is also when attic temperatures are usually highest.
That said, some Solatube solar attic fan options are designed to extend ventilation beyond daylight hours. The Solatube ClimaSense Series is made to provide continuous ventilation even after the sun sets, helping maintain more consistent evening airflow. Carolina Skylights will recommend the right model based on your roof’s sun exposure, your attic ventilation setup, and whether overnight ventilation is a priority for your home.