Have you ever thought of making sunlight-controlled light bulbs? It sounds redundant, but it can automate anything when the sun is down without using a microcontroller. It has a photoresistor, or most commonly known as a light-dependent resistor(LDR), and a relay. This relay can be triggered on/off, depending on the surrounding luminosity. This relay module could hold up to 10A 250VAC and 10A 30VDC. The sensitivity or the luminosity level could be modified using the onboard potentiometer. There is no need for external devices like a microcontroller to make this module work.