Solenoid valves are activated by an electromagnet, controlled via the control unit of the irrigation system. This way, you can for example temporally controlling the irrigation. You can water your garden at night, without having to stand up. The humidity sensor or the rain sensor, the control unit receives a signal that sufficient water is available, and opens or solenoid valve closes automatically.
When selecting the solenoid valve, you should pay attention to choosing a reliable design that ensures a long life. As a rule, solenoid valves are installed in valve boxes.