An eight-inch screen is used for the majority of systems. Our installation technique requires folding at the bottom as well as overlapping a bit of screen onto the edge of the panels. This adds a bit to the necessary screen width.
Although it is becoming more and more commonly used, the six-inch screen is primarily limited to “low profile” PV racking. These are systems with a gap between the roof surface and the bottom edge of the panel frame of fewer than 4.5 inches.