Please refer to the Unirac Master List, pages 6 to 8 or pages 20 to 22, to determine the size you will need to use. Bottom clips are cheaper, but more difficult to install in large systems. The first step is a thorough site assessment. You need to gather data on the roof's structure, the local environment, and the specific solar panels being used. Think of it as. Balcony Solar Mounting System is a Solar Mounting System product installed on balcony railings, which can easily realize the construction of photovoltaic power plants on the balcony. The system is all bolted and fixed, eliminating the need for welding and drilling during installation. The unique. When placing an order, specify the mount model and the panel size (for example: UPM 10X "A", or SOP-Y "C"). Distance between purlins: 900mm. If laying panels flat to the roof click “Flat to Roof”. In this example choose. Install an array fl ush to a roof or other mounting surface with footings up to 48 inches apart.