Using Seam Clamps to Support Solar Panels on Metal RoofingPosted on February 14, 2019 by Lynn Chesnut
The standing seam metal roof is a very popular roofing solution due to its durability, water-tightness, relative simplicity, and clean appearance. While the standing seam, which is created by forming two adjacent metal roof panels together, contributes to all of these traits, some people may not realize that it also simplifies the attachment of other items to the roof. The most common and effective means to attach anything to a standing seam metal roof is to use an ingenious piece of hardware known simply as a seam clamp.
These are engineered and fabricated small cubes of stainless steel or aluminum that are designed to be mechanically attached directly to the standing seams in a metal roof. They do that with a round-point set screw in the clamp that squeezes and dimples the standing seam for a true mechanical attachment. This approach is truly non-invasive since it does not penetrate or compromise the integrity of the metal in any way and therefore keeps all roofing warranties intact. Once secured onto the standing seam, then the seam clamp is the base for threaded bolts or screws that fit into specific locations on the clamp. From there, specific hardware can be secured to attach a variety of additional items. Specifically, seam clamps have been used for decades on metal roofing to secure accessory items such as snow retention systems, fall protection devices, HVAC equipment, lightning protection, satellite dishes, and even rooftop service walkways.
How do they work with solar panels?
One of the biggest current uses of seam clamps is for the connection of solar photovoltaic (PV) panels to a metal roof. On many roof-mounted PV systems, the use of rails or some similar component may be needed to support the PV panels. By using seam clamps with customized interface hardware designed to connect directly to the solar panels, the standing seams of the roof act as the rails. Eliminating the use of the rails and using the seam clamps means the installation is easier and the cost is reduced notably, both in terms of material and labor.
Solar systems are typically warranted 25 years for power production, but the real service life of the modules can be 40 years or more. Hence when mounting the PV system, the building designer or owner needs to be sure that the roof underneath it has a comparable life. Metal roofing is a very good match since it will last as long or longer than the PV panels. A roof with a shorter life will require removal of the PV to replace the roofing and then a reinstall of the PV at a high cost.
How many seam clamps are needed on a roof?
Some seam clamp manufacturers have independently tested their product in combination with literally every standing seam metal roofing system on all of the available metal gauges that are on the market. As such, very specific information can be provided on things like loading capability, wind uplift resistance, etc. for the seam clamps. With that information, combined with the roofing and solar panel information, an engineer can calculate the needed spacing and locations of seam clamps. Those calculations will take into account the specific design wind speed and wind uplift potential for the project location. It will also take into account the specifics of the building structure and the internal structure of the solar panels. In some cases, locations such as perimeters and corners of groups of solar panels (called an array) may require more frequent spacing while in the field of the array, the spacing may be less. Ultimately, the best location and spacing of seam clamps is determined and the proper quantity identified. It is worth noting that when engineered in this manner, the most common mode of failure is that the module itself fails under windy conditions, rather than seam clamp attachment.
What maintenance is needed on seam clamps?
Virtually no maintenance is required. All of the clamp designs are not friction connections, they are mechanical interlocks, so loosening is rarely, if ever, an issue. We have noted that the set screw dimples the standing seam and compresses it to make a mechanical interlock. In addition, locking head screws, bolts, and nuts all with serrations that are directional allow the hardware to be seated but not unscrew, thus holding everything permanently in place. Since all of the metal is either stainless steel or aluminum, there is no concern of rusting or corrosion.
To learn more specifically about seam clamps and how to use them to mount solar panels on a standing seam metal roof, visit the website of the leading manufacturer of seam clamps known as S-5! To learn more about standing seam metal roofing and metal buildings, contact your local Ceco representative.
Content for this article was provided by Rob Haddock, Founder and CEO of S-5!®