Module Racking and Mounting Systems for Pitched-Roof Applications
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When selecting array racking and mounting systems for pitched-roof applications, the optimal solution relies on many factors, including structural requirements, aesthetics, ease of installation, wire management and module grounding, roof clearances and compatibility with the desired module.
Mounting solutions and combinations provide varying clearances between the roof and the modules, which can impact aesthetics, cell temperatures and access beneath the array. Suitable roof attachment options vary based on the roofing material and the type of substructure under the array. Racking system features may include colors and finishes, preassembled components, universally sized module clamps, click-in-place hardware, telescoping rails, streamlined hardware sizes and types, and clampless and railless designs.
This article provides overviews of pitched-roof attachment and racking product lines and identifies key features to consider. Several racking systems have been tested for use with integrated bonding and grounding hardware per UL 467, or UL 2703, which specifically addresses PV racking systems, module clamps, module frames, and grounding and bonding components.
Rail-Based Mounting Systems
About a decade ago, the introduction of rail-based mounting systems that employ top-down module fastening resulted in a significant reduction in installation time for pitched-roof arrays. The availability of these systems roughly coincided with module manufacturers’ shift to quick-connect module leads that simplify array wiring and facilitate the use of top-down racking systems. Today, rail-based racking systems are used in most pitched-roof applications, and manufacturers are introducing increasingly refined products.
Conergy manufactures the SunTop IV mounting system for pitched-roof applications with a maximum slope of 60°. The extruded anodized-aluminum rail system works with both Conergy and third-party roof mounts. It is available in four rail sizes that allow for different spans based on the structural requirements and the attachment and roof type. The SunTop IV rail system incorporates a telescoping feature that allows adjustment of the rails to the required length while on the roof. All hardware connections utilize the patented Intelligent Nut, which requires a 6 mm Allen wrench only. The Sun-Top IV mounting system meets the International Building Code (IBC) 2009 and California Building Code (CBC) 2010 standards.
The CREOMOUNT racking system has a shared insertion rail design that eliminates the need for module clamps. Framed PV modules are positioned in insertion rails that typically run east-west across the roof. The shared insertion rail runs parallel between two module frames, so that two rows of modules require only three rails. Insertion rails are installed above and perpendicular to a base rail that runs north-south. The base rails allow the insertion rails to slide into position for portrait or landscape module orientation. Creotecc’s insertion rails do not need to be collocated with roof attachments. This allows fewer roof attachments to support multiple rows of modules, reducing parts and roof penetrations. The 20-foot module insertion rails come in five profiles and are available in mill or black anodized finish. The base rails are compatible with third-party attachment solutions, including nonpenetrating seam clamps for metal roofs. Creotecc offers roof attachments for composition shingle and tile roofs. The racking system is UL 2703 recognized; however, the clampless design currently requires the separate bonding of module frames.
DAETWYLER CLEAN ENERGY
Daetwyler Clean Energy produces the Secure-Top SS racking system for flush-mount applications. The module support rails span a maximum of 8 feet between roof attachments and connect to the proprietary angle bracket without hardware. The angle bracket provides additional clearance beneath the array and is compatible with most roof attachment devices such as nonpenetrating seam clamps, tile hooks or flashed composition and asphalt shingle mounts. Daetwyler’s module clips do not slide once installed in the module support rail, and they secure and ground the module frames when locked into place. The clips retain their ability to electrically bond the module frame to the rails if the modules are adjusted or relocated. The racking system meets listing requirements defined by UL 467. The multichannel rails accept a side-mounted wire-management bracket.