Rooftop solar panels are installed with mounting systems either attached to the roof or ballasted with heavy blocks. Ballasted installations are used on flat roofs and require no penetration from the roof. For tilted or pitched roofs like asphalt, a small pilot hole is drilled into the truss of the roof frame. This pilot hole allows the mounting bracket to attach to the roof and the plate that holds the panel is flashed with the rest of the roof to prevent leaks. For metal roofs, clamps are used to hold the panels in place. In both cases, the panels and mounting system can withstand very high-powered wind loads and storms.