Rail vs. Rail-Free Solar Mounting Systems
Designing the perfect rooftop solar system involves many decisions beyond panel quantity and placement alone. For home and commercial photovoltaic (PV) systems, choosing the right solar mounting equipment can affect a project’s total costs, installation speed, and other important considerations.
In today’s evolving PV marketplace, there are two main categories of rooftop solar mounting systems: rail-based and rail-free. To help you understand how these technologies work and compare, this guide explores every detail of rail and rail-free mounting systems for rooftop solar panel installations.
Rooftop Solar Mounting System Basics
Before we break down the definitions and differences between rail vs. rail-free solar mounting systems, let’s first review some PV panel installation basics to put the technologies into perspective.
While many residential roofs are sloped at angles that allow solar modules to lay flat and harness direct sunlight, PV panels cannot be installed directly on roof surfaces. Instead, solar systems must be installed with a gap between the roof surface and the panels to allow airflow and prevent overheating.
Almost always, roof attachments for solar panels require some surface penetration to secure the system to a home or building safely. These penetrations are usually sealed to prevent potential leaks and water damage.
Rail-Based Mounting Systems for Solar Panel
In a rail-based solar mounting system, roof attachments support a “rail” or “rack” on which the PV panels are installed. Rails are placed horizontally on a roof, usually in pairs, supporting the top and bottom of several PV solar panels at once. While rail-based systems are the most traditional solar mounting materials, the technology continues to improve with PV market growth as today’s innovative manufacturers debut lighter, stronger, and easier-to-install hardware.
Pros
- The most cost-effective solution for typical rooftop solar installations.
- A low number of roof penetrations and mounting materials are required.
- Quick installation times for straightforward PV arrays.
Cons
- Inefficient for complex roofs without enough available space for uniform panel placement.
- Heavier rail systems may require additional rooftop hardware and structural support.
- Solar panel sharing racks must be installed at the same orientation and angle.
Rail-Free Mounting Systems for Solar Panels
Sometimes known as rack-less or rail-less technologies, rail-free solar mounting systems do not utilize a rack to support multiple PV panels at once. Instead, rail-free systems are designed piece-by-piece, with roof attachments, mounting materials, clamps, and support for each individual solar panel installed.
Pros
- Simplifies solar installations with greater design freedom and less rooftop labor
- Allows neighboring solar panels to be installed in landscape or portrait orientations
- Fewer components can lead to lower costs for hardware, shipping, and installation.
Cons
- More significant number of roof penetrations is required vs. rail-based systems
- Less options for the angle of installation rather than following the slope of the rooftop
- A steeper learning curve may be necessary during the installation.
Choosing Rail vs Rail-Free Mounting Systems
Every solar installation is different, and no one-size-fits-all answers exist for the best PV system components. While rail-based mounting systems may be an easier, tried-true method preferred by some solar companies, rail-free installations can deliver more value in the right set of circumstances. When choosing between rail and rail-free solar mounting systems, you can consider the following project factors to help determine the best solution.
Roof type: There are many types of solar mounting systems designed specifically for different roofing materials, such as asphalt shingles, metal, and tiles, which can affect your rail or rail-free racking choices. For instance, if you are installing solar panels on a metal roof, standing seams can act as the “rails,” minimizing the amount of mounting materials and equipment necessary.
Roof support: Some roofs, usually on older properties, may not be able to support the weight of a new solar energy system without additional building improvements. As rail-less systems are generally lighter than rail-based installations, choosing a rail-free design may enable you to reduce the amount of necessary structural improvements.
Roof complexity: Rail-based systems are the easiest and most cost-effective solar mounting option for simple pitched roofs with ample installation area. On the other hand, rail-less systems may make it easier to install more PV panels within a limited installation space, around obstructions, or on properties with complex rooflines.
Total costs: While rail-free solar designs require more roof attachments, rail-based systems can involve higher project costs for hardware, materials shipping, and installation labor. Depending on the project, total installation expenses may be lower for rail or rail-free racking systems. Therefore, pricing for both methods should be calculated to determine the most cost-effective solar mounting solution for every new project.
Property owner preferences: As not everything is an exact science, there are also several reasons why a property owner may want to install a rail vs rail-less solar mounting system due to personal preferences. For example, rail-less systems can be chosen for their aesthetics, just as rail-based installations may be preferred for those hoping to minimize roof penetrations.
Key Takeaways and Additional Resources
In short, both rail-based and rail-free solar mounting systems have advantages and disadvantages, though either technology can be an effective way to safely secure a PV installation onto roof attachments. Before finalizing a new solar energy system design, rail, and rail-free approaches should be considered to weigh all the pros, cons, and costs associated with each installation option.
Helping solar installers around the globe, SunModo manufactures high-quality rail-free and rail-based mounting technologies for every unique PV project. One tool assembly and Pop-On technology allows fast and worry-free installation on any roof types with SMR Rail System and a wide variety of Roof Attachments. Unlike any other rail-free system on the market, NanoRack solves the rail-free headaches of precise measuring and complex wire management.
With SunModo Design Tool, you can configure the best possible solar mounting solution for your next installation. Using the tool, you can test both rail and rail-less PV system designs to find the optimal solution at absolutely no cost. Try the tool or explore SunModo solar racking systems.
