Power optimizers that are available for North America (part numbers: Pxxx-2N and Pxxx-5N) must be grounded. When the power optimizer is mounted on a grounded structure, equipment grounding is done using the washers supplied with the optimizers (refer to the SolarEdge Installation Guide).
When the power optimizer is mounted on an un-grounded structure, such as a wooden structure, grounding terminals (kit part number: SE-GNDLUG5-100, 100 terminals in one kit) are used to create equipment grounding.