The ability of festoon lights to remain illuminated throughout the night depends on how efficiently they charge during the day and their overall quality. Solar panels typically require approximately 4-8 hours to fully charge. Once charged, they can provide light for a duration of 6-12 hours, which is influenced by several factors including the duration and intensity of direct sunlight received during the day, the quality and efficiency of the solar panels, as well as the total light output of the LEDs.