Yes, all Solatube® Daylighting Systems are designed with features that prevent water from entering the system. The round shape of the domes themselves prevent water from collecting on the surface.
In addition, the circular and seamless, one-piece design of the self-flashing systems allows rain runoff to naturally flow past the daylighting system. As a result, the flashing has no weak points that could separate and allow water to enter. However, an optional turret extension may be added to raise the dome above the roof deck where required.
For curb-mounted applications, the height of the curb would raise the dome sufficiently to avoid any rain runoff. The curb itself (made by others) would typically incorporate a water diverter (cricket) for sloped roof applications.