Solar panel installation methods on different commercial roof types

The use of solar energy in commercial buildings has grown 7% annually over the past decade, making it a top roofing trend. Installing solar panels is an effective way to reduce energy costs and prioritize sustainability initiatives. With many organizations considering installing solar panels on their buildings, it’s important to consider how different roof types require varied methods to ensure secure commercial solar panel installation.

If you’re in the process of planning a commercial solar panel project, or will be soon, discover the key factors to consider, such as when to use rail vs. rail-less mounting, the types of roofs that don’t allow for effective solar panel installation, and more.

What are different types of solar panel installation methods for commercial buildings?

Although there exists several types of solar panel installation methods for commercial buildings, there are two main solar panel installation methods: rail and rail-less mounting.

Rail mounting is typically used for installing solar panels on standing seam roofs. Rail mounting involves attaching metal rails to a roof and mounting solar panels onto these rails. By usng this method, you can avoid penetrating the roof structure by attaching the rails to the ridges of the roof panels. It is improtant to note though, that you are limited to using the ridges of roof panels but rather it can be installed in the roof valleys when preferred.

Rail mounting allows panels to be tilted to capture the most energy, making it optimal for flat roofs. However, this installation method may require additional work to avoid obstructions and other architectural elements.

Meanwhile, rail-less mounting attaches solar panels directly to the roof without the use of rails. In the mounting style, you can leverage roof ribs as rails for solar panels. Without the need for additional rails, rail-less mounting weighs less and enables better weight distribution.

Solar panels that are mounted using the rail-less method cannot be tilted, so this approach isn’t ideal for flat roofs as it’s important that the existing pitch allows for optimal energy capture.

When should rail vs. rail-less mounting be used?

Weight is a key factor to consider when selecting panels and mounting options. Rail-less mounting will weigh less and is ideal for commercial buildings where solar panels were not originally intended. It’s also important to consider the type of roof seam used — rail mounting is best for standing seam commercial roofs.

What else should be considered when deciding on a solar panel installation method?

Roof construction

Clay and slate tiles are not ideal for solar panels due to their fragility, which requires removal before installation and replacement afterward. As a result, solar panel installation on commercial roofs with clay or slate titles is very expensive.

Meanwhile, asphalt, metal, and tile shingles are optimal for solar panels as they aren’t as susceptible to damage during the installation process. Depending on the type of metal commercial roofing, it may be possible to avoid drilling holes entirely as the panel mounts can be clamped to the existing raised seams.

Available roof space

Roofs are an ideal location to install solar panels because of surface space and sun exposure. However, if there is limited space there could be issues fitting the system onto the roof. Continue reading to see how SFS, a screw manufacturer overcame this difficult factor at their large commercial building.

Roof age

If the existing roof will need replaced or repairs soon, it’s likely best to wait to install panels on the new roof to avoid paying for installation twice.

Roofs typically have a lifespan of around 25-30 years, so it may be better to replace or repair roofs older than 15 years before installing solar panels. Due to the weight of solar panels, it’s never recommended to install on damaged roofs.

However, if your commercial roof is less than 10 years old or in great condition you can move forward with installing panels.

Roof slope

Extremely steep roofs with a pitch greater than 40º are not ideal for solar panels. Too great of a pitch does not allow the panels to be installed at an efficient angle. Additionally, steep roofs complicate installation by making it challenging for installers to safely implement.

Meanwhile, flat roofs require specialized brackets or stands to tilt the panels to capture enough sunlight. Rail-less mounting does not allow for panel tilting, and should be avoided on flat roofs.

Inadequate sun exposure

Ideally, your roof should receive an average of 5-6 hours of direct sunlight daily. South-facing roofs are ideal for sunlight capture. To receive greater sun exposure, plan on either removing or extending over trees and other obstructions.

Be mindful of nearby tall buildings which could block sunlight from hitting the roof. Consider checking for upcoming construction projects or recently pulled permits nearby. If a new building will be constructed in the near future, this could impact your sun exposure.

Shadowmap is an easy tool to use to determine how much sunlight your location receives during the day.

SFS Project case study: Not enough roof space?

SFS, a fastener manufacturer, recently went through the process of considering all of the above factors for a solar system. The solar system was going to be creating energy for one of SFS's production plants, in Durant, Iowa, so the system was available roof space was an extremely important factor for them. With the plants roofs involving different ventilation systems and machinery used in the production process, SFS found it more practical to construct their solar system on the ground instead. Check out this video to learn more about this project.

FAQs about solar panel installation on different commercial roof types

Can solar panels be installed on a metal roof?

Yes. Solar panels can be installed on a metal roof. Certain types of commercial metal roofs make installation easier by removing the need for drilling and allowing panel installation on existing roof seams.

Can solar panels be installed on a flat roof?

Yes. Solar panels can be installed on a flat roof. However, when installing solar panels on a flat roof, you must use rail mounting to ensure the panels can be tilted to achieve necessary sun capture.

Can solar panels be installed on a tile roof?

Yes. Solar panels can be installed on a tile roof. The type of tiling will determine the installation process. Clay and slate tiles will need to be removed before installation as they are susceptible to damage and will not hold up to workers walking on them. This increases the time and costs of installation.

Asphalt tiles and tile shingles do not need to be removed prior to solar panel installation.

Can solar panels be installed on tar and gravel roofs?

Yes. Solar panels can be installed on tar and gravel roofs. However, most commercial tar and gravel roofs are flat. As a result, it’s critical to use rail mounting so panels may be tilted to capture enough sunlight.

How long does it take to install commercial solar panels?

Solar panel installation time depends on the type of installation method used. Rail mounted solar panels take longer to install as you must plan the layout, avoid obstructions, and assemble. Meanwhile, rail-less panels are pre-assembled and can be mounted quickly.

SFS wants to be your sustaibable partner

Sustainable action is part of SFS’s DNA. We believe that sustainability should always be considered and make efforts to reduce emissions while increasing our share of renewable electricity.

In addition to supporting your sustainability projects, we’re committed to progress in the environmental field through our internal practices. In 2022, we reduced our emissions by 48.4% and increased our share of renewable energy to 49.7%. We plan to reach 50% renewable energy by 2025.

We are to be your sustainable partner as you tackle your roofing projects. Whether you are replacing your roof to make solar possible, or you need roofing products for your next commercial build, SFS offers a variety of options and innovative solutions. Give the SFS team a call at 1-800-234-4533 to discuss the needs for your next roofing project.

About Serenah

After earning a Bachelors in Mechanical Engineering and spending countless hours on undergrad research, Serenah has been awarded for her experience and skills numerous times. She was given the opportunity to present her findings on topics like composite and bio composite materials at 10 different symposiums. SFS is proud to utilize her expertise in commercial construction and flat roof within their engineering team. Serenah is well researched and ready to answer your questions!