Tile Talk: Steep-Slope Solar Applications

Identifying Key Elements For a Successful Solar Installation

by Richard K. Olson, president & technical director, Tile Roofing Industry Alliance

(Editor’s Note:  Richard K. Olson is president and technical director for the Tile Roofing Industry Alliance.  The association represents industry professionals involved in the manufacturing and installation of concrete and clay tile roofs in the United States and Canada, and works with national, state, and local building officials to develop installation techniques, codes, and standards for better roofing systems.  Olson can be reached at rolson@tileroofing.org.)

The requirement for the use of solar systems in roof applications is expanding as energy companies are shifting focus away from roof reflectivity for energy reduction.  This will require new resources to help integrate solar systems into steep-slope applications.  The roof cladding, solar manufacturers, and roofing contractors should all be brought into the discussions.  With most solar systems being installed by non-roofing professionals, we are seeing an increase in leaks or roof failure after the work has been completed.

Solar

         The solar panel industry continues to see evolution and changes in design for size, weight, mounting, and electrical connections.  The design professional will need to identify several key areas when calling out the use of solar panels.

Solar Panels

         The size and weight of the panel will need to be determined to allow for proper attachment for support to a load-bearing component designed for the attachment.  There are panels that will attach to racking systems, posts, and rails that each have specific installation requirements to meet the local building and electrical codes.  There are panels that will attach to trusses or the roof sheathing.  The proper call-out for size, location, and number of fasteners should be determined.  In the case of roofing tiles, we do not allow the supports to mount directly to the tile.

Electrical Collectors

         The solar manufacturer should be consulted to determine the requirement for the electrical wiring to the panels.  When the conduits are installed under the roof cladding, care must be taken to make sure that the cladding is not compromised for prevention of water intrusion.  Too often we are seeing the conduits raise the cladding or create improper point loading that can lead to leaks from failure to seat properly with adjacent materials, or from damage caused by foot traffic.  A licensed roofing contractor should be considered to work in collaboration with the solar installer to help prevent such issues. 

Mounting System

         When racks, rails, or other brackets are being installed, the design professional should provide call-out details for how they will be flashed, sealed, or caulked to prevent leaks in the roofing assembly.  For roofing tiles or other claddings with a space below the cladding, we require both a deck and top flashing when the fastening occurs at the deck level.  This will help keep the water on the top surface of the roof.  When caulking or other materials are being used, they should have formal code product approvals by the manufacturer for the use as a flashing for steep-slope applications.  In areas that experience wind or snow, the solar systems will need to provide proper installations that will meet the local building requirements.  In California that will include fire ratings, as roof assemblies are required to meet higher fire-performance standards.

         When solar is mounted directly to the roof deck, the height of the panels will need to be determined in relation to the roof system being used.  In the case of roofing tiles, the determination of profile and optional batten systems will change the height of the roof planes.  To keep the aesthetic and functionality for the panel systems, the design professional should evaluate any mounting systems for proper flashing, transitional, or wiring needs.

Location

         The location of the panels should be reviewed for determining access for installation and maintenance.  Consider areas that are ideal for heavy foot traffic, or close to roof access, to allow for safe and non-destructive operations of the solar systems and the roof cladding performance over time.  The consideration of landscape, such as trees, tall bushes, or other foliage, should be identified.  The ability to prevent shadowing and fire hazards from foliage is critical.

         Design professionals should review the options and installation requirements for any solar system being considered.  The manufacturer of the system can help provide resources and local code compliance data to allow you to make more detailed call-outs on your project plans.  These decisions will help reduce installation problems, increase the efficiencies of the project, and reduce the cost of the installation.  By working in collaboration with all of the roof components and solar manufacturer, you can achieve the optimum installation for a long service life of the roofing assembly.

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