This device itself will disconnect the load from the power source during the day and turn it on at night, an incandescent lamp can serve as a load, and such a device is called a twilight switch, a photorail or a light sensor.The basis of the device is a triac, I used BT136/600e.This is a 600 Volt triac, and the switching current is up to 4 amps.The control of the triac is carried out in phase pulsed using a dinistor
The resistance of the resistor R1 should be selected for the least heating.A triac with a 40W lamp does not heat up.