For solar installers most familiar with comp shingle or tile roofs, encountering a metal roof can be challenging. Besides just the many different types of metal, there are also different metal roofing systems. If the structure has a standing seam roof, solar installation is somewhat easier. Panel mounts clamp to the seam without penetrations. Trapezoidal and corrugated metal roofs, though, often require a direct attachment to the roofing structure. Flashing can’t be slid underneath, so waterproofing is especially important.
“The profile of a corrugated roof is not strong enough to support the mounting system, so the roof attachments are required to penetrate the roof material and attach to the structural member,” said Cody Norman, senior applications engineer with SnapNrack Solar Mounting Solutions.
To further complicate things, there are several variations of metal roofs. For example, sinusoidal corrugated roofing’s ridges and grooves are closer together, in a consistent wave-like pattern. Trapezoidal roofing has more flat space in between peaks. The type of metal roof will affect the type of solar mounting system needed for a successful install.
Each mounting manufacturer has a different design and way to attach to sinusoidal corrugated roofs.
SnapNrack’s Corrugated Straddle Block attaches to the roof at the peak of the corrugation. The fastener is positioned at the top of the ridge, out of the water channel. Still, SnapNrack suggests installers use a compatible adhesive sealant to ensure a waterproof connection.
S-5!’s CorruBracket and EcoFasten’s CorruSlide also span one ridge, but the CorruBracket attaches in the valleys, while the CorruSlide attaches more toward the bottom of the hump, not quite in the valley. (These are just a few examples. Many companies have multiple brackets or clamps with different installation techniques.)
Different still is Solar Connections’ Corrugated PowerMount which attaches at the top of two peaks. The mount’s two feet sit on two separate ridges. This two-peak attachment can be difficult because there is not a universal sinusoidal corrugation height.
“We see a lot of different heights between the ‘ribs’ of those corrugated panels, but we made our product so it could be used more as a universal option given the distance between those ribs,” said Chad Reilly, account executive for Solar Connections International.
EPDM gaskets are pre-assembled under each leg of the Corrugated PowerMount, and fasteners with EPDM washers provide a second, waterproof seal when attached through the metal roof.
Similarly, SunModo’s EZ Corrugated Metal Mount supports itself across two ridges with penetrations at the peaks of each.
For trapezoidal metal roofs, SnapNrack offers a specific solution with its Metal Roof Base. It attaches to the roofing structure in the flat surface between peaks. It is located in the flat section of the roofing panel, so an EPDM washer easily creates a weatherproof seal without requiring additional sealant.
Other companies, such as SunModo and S-5!, offer solutions that attach to the special trapezoidal ridge.
Once a metal mounting system is chosen, it’s time to jump on the roof. But that’s also not as easy as working on a comp shingle roof.
“There are some lighter gauge metals out in the market that are not as strong, so just check the roof structure before getting up on the roof to analyze and review where you’d like to layout your PV modules,” Reilly suggested. The roof’s lifetime and any corroded areas should also be gauged before putting on any extra weight.
Fall protection is also different on corrugated and trapezoidal metal roofs. With no standing seams to clamp a roof anchor, safety devices have to be direct-attached.
“The primary concern for installing on any pitched metal roof is fall protection, especially when those installers work primarily on comp shingle or tile roofs,” Norman said. “They should be using a fall protection anchor that is compatible with the roof type and does not create roof leaks once the anchor is removed.”
There may be more to think about when working on a metal roof, but a little extra attention and patience will ensure no roof type prevents the adoption of solar power.
Thomas Kimble says
Hi Shelly, I’m working on designing a solar system for my 28×24 log cabin off grid. It will have 12/12 pitch roof facing south, I’m thinking the 12/12 pitch roof is to step of angle, so I could put the solar panels on the porch roof that is 8′ long that is only a 3/12 pitch . Also considering maintenance of the panels would be easier on the porch roof instead of on the 12/12 pitch roof as would have to get a bucket truck to work on them if ever a problem. We are going to use metal roof that has those ridge lines that is spaced about 7″ apart. I think I seen a device type clamp that will fit over the ridge so that the bracket to the solar panel can attach to.
Joe Zhou says
We have a 100KW steel roof mounted project. The building has steel roof, and steel rafter structure. I wonder if we need to fasten the solar panels and aluminum rails to steel rafters, or only to steel roof? The building and roof are very new.
I’m finding it hard to find roof mounts for PBR metal roof profiles at 26gauge. Too thin for ridge mounts. Has to go into purlins. Yet with purlins having insulation underneath some of the fasteners that mount in the ridge come with spacers but those may not have correct spacing for compressed insulation. Mounting on the valley of the panels also isn’t ideal due to water vs the ridge. Seems like there is no ideal solution for PBR roofs. I’m running rails vertically not across the roof so that’s also different.
i have same problem – please let me know if you discover a solution
1- Can i install solar system om any metal roof or it or should the wind loads be taken into account for the metal surface?
2- What is the minimum space between the solar panel and the steel roof especially in hot countries.
Leslie Black says
Have 18 cables plus a #6 ground that needs to enter the metal roof into the utility room. 2″ conduit elbow is way too big a curve to be able to have the PV wires enter under the solar panels. 9″ high and panels are 5″ off of the roof. Is their a box or something to protect the wires from the sun and just drop into a straight pipe coming up out of the roof jack?
Fernando Pumarejo-Sproesser says
And what type or types of anchors (for fall protection) are recommended?
Kelly Pickerel says
Here’s one: https://www.solarpowerworldonline.com/2016/01/how-to-stay-safe-on-top-of-metal-roofs-when-installing-solar/
What Sealant do you recommend over any other for metal roofs?
Sonny Rivers says
Sashco “Through the Roof” Sealant works on metal and is great all around.
Charles Shields says
We (our Church) are in the early stages of our plans to build a recreational building about 96′ X 76′, and I am wondering how feasible it would be to install solar panels on our metal roof. This building will be positioned for maximum exposure to the sun. My plan is to have the roof pitched about 30 degrees with the long side exposed to the sun for most of the daylight hours. We are in NE Kentucky (Ashland) and are hoping some Gov incentives and Power Company incentives will pave the way. Your honest and experienced opinion would be appreciated.
Pastor Charles J. Shields
Shelly Higgins says
Feel free to contact me. We at S-5! are here to help you with solar, snow retention, utilities, or any type of attachment on metal roofs. I look forward to hearing from you.