Which one is the tie rod of the photovoltaic bracket

Photovoltaic mounting systems (also called solar module racking) are used to fix on surfaces like roofs, building facades, or the ground. These mounting systems generally enable retrofitting of solar panels on roofs or as part of the structure of the building (called ). As the relative costs of solar photovoltaic (PV) modules has dropped, the costs of the racks have become. [pdf]
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