Normally structures are made of MS and then galvanized with 80 microns of Zinc coating. The height of solar panels after mounting on such structures from roof surface remains 300 mm to 750 mm only. Sufficient only to allow cleaning roof below the panels from time to time. But it is possible to increase the height of structures to 2-3 mts also , giving enough room below the panels to create a workable space or do roof gardening below the panels, while the panels produce solar energy for your home/ industry. In some cases industries have used that space for storage of goods or staff canteen. In home people tend to use that space for roof gardening or creating an space for sitting.
Now a new trend is seen in chinese market for using FRP Solar Roof Top Structure. These are light weight , easy to mount and comparable in cost.