In principle, these systems are no different from Solar Home Systems (SHS). The only variation is the use of specially designed solar charge regulators with night light function. This function allows the regulator to recognize day and night by some preset algorithms as well site specific data. In its simplicity, the night light function commands the regulator to put the light on at night and off at dawn. However, some of these regulators have other programmable parameters that allow the manipulation of how the light behaves at night. For instance, a user could choose to put the light on for four hours from dusk and off thereafter and then on for three hours before dawn. Another possibility is to dim the light instead of completely putting it off. For more robustness some manufacturers design their regulators for the harshest outdoor conditions of use at IP68.