Ground-Mount PV Racking Systems

Rack Your Brain No More

In commercial and residential applications, ground-mount PV systems provide the flexibility to install arrays in open spaces when available roof area is limited, obstructed or nonexistent. Ground-mount PV systems can range in size from a few kilowatts to multimegawatts and can be adapted to a variety of site conditions. They often allow for optimized designs, such as specifying the array’s optimal pitch and orientation to maximize kilowatt-hour production. Over the years, racking systems have evolved from off-the-shelf metal framing channels adapted and assembled in the field to engineered solutions, many of which do not require field modifications such as cutting, drilling and welding.

Pre-engineered ground-mount racking systems are typically made of anodized aluminum, steel or a combination of aluminum and steel components, generally assembled with hot-dipped galvanized or stainless steel hardware. Some racking systems are certified as conforming to the integrated grounding and bonding requirements of UL 2703, which approves ground-mount racking system components to serve as a grounding means for module frames—meaning there is no bare copper equipment-grounding conductor to purchase, install and manage. Several manufacturers are awaiting UL 2703 certification for their products, while others have not addressed the listing yet.

Given that ground-mount arrays often consist of long east-west rows of modules—and thus multiple support rails coupled together—certain manufacturers are beginning to provide provisions in rail splices for thermal expansion. Likewise, ground-mount racking systems are beginning to incorporate wire management features to help protect conductors while reducing the amount of time that installers spend securing and supporting the array wiring.

In addition, ground-mount racking systems can offer different foundations and installation approaches for addressing uneven terrain and various soil types and conditions. Where excavation is limited due to land use—such as installations on landfills, or areas where subterranean obstacles like underground utilities or shallow bedrock exist—foundations that do not require penetration, such as precast or cast-in-place concrete ballast blocks, may be necessary. Where excavation and digging are possible, installers can use concrete footings, driven piles, micropiles and helical screws to secure and support arrays. Depending on the racking system design and soil type, the plan may require either a single row or double rows of vertical support posts and associated anchorage points. Likewise, installation tolerances for the vertical support members differ among product offerings and are important to consider for complex or uneven sites where it may not be possible to install every post perfectly.

Given the number of ground-mount racking products available, module clamping and securing methods vary greatly. Some manufacturers have introduced clamping methods that do not require hardware, whereas others continue to rely upon the traditional top-down clamping style. It is always important to ensure that the products are compatible by reviewing the racking system’s method for securing modules and the installation requirements for the particular module used. Many ground-mount racking manufacturers have solutions for securing both framed modules and frameless laminates, but these methods may not be in compliance with a specific module manufacturer’s installation requirements.

In this article, we provide an overview of ground-mount racking systems that are available in North America from 34 manufacturers. As project size continues to increase along with the necessity to drive down installation costs, racking manufacturers, both old and new, continue to develop and refine their solutions for the industry. Integrators who have set foot in the various industry trade shows over the last few years have likely noticed the proliferation of racking manufacturers offering products in the US and Canadian markets. Our intent is to provide an objective overview of information related to key features, differentiators and intended applications for each manufacturer’s ground-mount racking product lines.

ADVANCED SOLAR PHOTONICS
Advanced Solar Photonics manufactures PV modules and racking systems for large commercial and utility-scale projects. Its SunRail ground-mount racking product is designed to American Society of Civil Engineers (ASCE) 7-10 and International Building Code (IBC) 2006 or 2009 standards. The racking system’s substructure is a single line of galvanized steel helical anchors. An east-west row of helical anchors can be installed on uneven terrain and in areas with limited access, and easily adjusted or removed. Several of the racking system’s upper components are preassembled at the factory to reduce in-field installation time. In addition to providing multiple UL-listed grounding options, the system incorporates cable channels and ducts for wire management. The company’s support team offers code-compliant designs for any locality. Geotechnical soil investigation and analysis services are also available.
Advanced Solar Photonics / 407.804.1000 / Lake Mary, FL / advancedsolarphotonics.com

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