Photocells, also known as photoresistors or light-dependent resistors , don’t necessarily require direct sunlight to function. These devices detect light levels and adjust accordingly, typically used to control outdoor lighting systems. While direct sunlight can certainly activate a photocell, they are designed to respond to varying levels of ambient light, including indirect sunlight, overcast conditions, or artificial lighting at night. As long as there is sufficient light falling on the photocell, it should be able to perform its intended function, whether it’s turning lights on at dusk or off at dawn.