Which System is Better for Mounting Solar: Rail or Rail-less?

By Evelyn Witterholt. 

For homeowners looking to mount solar on their metal roofs, it’s important to understand the pros and cons of rail and rail-less solar mounting systems. 

Solar panels and metal go hand in hand! The durability and sustainability of metal roofing pairs well with the energy efficiency of solar panels. With many home and building owners who have metal roofs wanting to maximize their investment in sustainability, it can be valuable for you to know the difference between rail and rail-less solar mounting systems.  

Rail and rail-less systems are the two main ways to attach solar modules to metal roofs. Rail systems are attached to the roof and the solar panels are attached securely onto the rails. Rail-less systems attach the solar modules directly to the metal roof. But to know which one is best for your roof, you must look at each type of mounting system more in-depth: 

Rail systems 

Rail mounting systems attach differently depending on which type of metal roof you have. For standing seam metal roofs, the rails are mounted onto the roof with non-penetrating clamps. Rails can be mounted on exposed-fastened roof types either with brackets on the roof panel’s rib or valley. The rail manufacturer is often equipped with an L-foot for a stronger mounting system. S-5! offers SolarFoot™ mounting systems for rails with L-foots and VersaGard™ for mounting without the need of an L-foot. for mounting without the need of an L-foot. 

Rail systems have long been the go-to mounting system of choice for solar panels. According to Solar Builder, customers who prefer this traditional system type do so because it involves an easier learning curve for contracting crews. Rails can also help you tilt solar arrays to get a better angle of the sun if the roof is flat. 

Depending on the type of metal roof, weight can have an impact on choosing a rail system. While newer metal roofs can handle the weight of a rail mounting system, older ones may not be able to. And since the components are so heavy, you may have to pay more in commercial freight charges. If there are any roof obstacles such as skylights, HVAC equipment, hips and/or valleys, the rails will need to be field cut to work around them which can be time-consuming for the contractors which costs you more money on labor. 

Rail-less systems 

The cool thing about rail-less mounting systems is that the components of the metal roofs become the rails. Seams on standing-seam roofs and exposed-fastened ribs or corrugations are used as the rails for the mounting system. The S-5! PVKIT®, a rail-less mounting system, is compatible with all of these metal roof types.  

Unlike rails, rail-less mounting systems adjust to obstacles much easier and can even fit smaller areas. They have lower added dead load and have 25% better load distribution than rail systems. There is a bit of a learning curve for roofing crews, but some systems come pre-assembled which can save time. Because they have fewer components, customers can save nearly 35% on material costs. However, rail-less systems cannot be tilted to capture a better angle of the sun. 

Whichever system is best for a metal roof all depends on the type of roof the solar panels are being mounted on, what obstacles the roof has on it and ultimately, whatever you prefer. Knowing the types of mounting systems can help you in making the best decision for your roof. 

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About Evelyn  

Evelyn works as a writer for RoofersCoffeeShop, MetalCoffeeShop and AskARoofer. When she isn’t writing about roofing, she’s either at the gym lifting weights or curled up on the couch watching a movie.