Can You Install Solar Panels on Metal Roofs?
Solar panels are a great way to reduce your carbon footprint while also saving money on your energy bills.
However, are they compatible with your metal roof? It’s a common question for people who want to use solar energy but aren’t sure if they can make it work with a metal roof over their heads.
[toc]
Although solar panels can be installed on any type of roof, they are less common on metal roofs than on other types of roofs. This is primarily due to the widespread belief that metal roofs are incompatible with conventional solar mounting systems.
But this isn’t necessarily true. Solar panels can be safely mounted on a metal roof with the right solar mounting system and proper planning. In this post, we’ll look at how to mount solar panels on metal roofs, as well as the benefits and drawbacks of doing so.
Let’s get started!
I believe the question of whether solar panels can be installed on metal roofs stems primarily from two other questions.
- Are metal roofs compatible & safe with the installation of electrical equipment like solar panels?
- Is it possible to securely attach solar panels on metal roofs without causing roof damage?
So installation of solar panels on metal roofs comes down to electrical safety and installation feasibility.
The Electrical Safety of Solar Panels on Metal Roofs
Metal roofs are typically made of aluminum, steel, copper, and zinc alloys, all of which have high electrical conductivity. This means that any electrical equipment installed on the roof may come into contact with the roof, posing a short circuit risk.
Even if a piece of electrical equipment is properly installed and initially has no electrical contact with the roof, high winds and rain can cause the wiring to come into contact with the metal roof, resulting in a short circuit.
This is why many electrical equipment manufacturers explicitly state that their products should not be installed on metal roofs, or that additional insulating materials or methods must be used to ensure electrical safety.
Solar panels are no exception to this rule, and solar panel manufacturers may not warranty their products if they are installed on a metal roof. In most cases, the manufacturer will strictly require you to install the panels on a non-conductive surface like a tile or asphalt roof.
Or you will be required to use a non-conductive mount or flashing to ensure electrical safety.
Therefore, the best way to ensure that your solar panels are safe and compatible with a metal roof is to check the manufacturer’s installation manual for any conditions or restrictions.
There may be specific instructions, required additional parts, or materials for the safe installation of solar panels on your roof.
If you’re not sure, it’s best to contact the manufacturer, or your solar installer, to get clarification.
Assuming you have determined that your solar panels are compatible and safe to install on a metal roof, the next step is to make additional checks to ensure electrical safety.
Properly Ground The Metal Roof
Grounding metal roofing is an important safety measure and should not be skipped. To do this, you will need to attach a grounding rod to the metal roof and then connect it to an electrical ground.
This should be done by a qualified electrician, as it can be dangerous if not done properly. Failure to properly ground the roof could result in electrocution or damage to your home.
The grounding cable should be buried at least six feet deep in the ground and connected to a copper rod that is also buried in the ground. This will help to dissipate any electrical current that may occur and keep you and your family safe.
Ideally, the metal roof should be grounded before the solar panels are installed, but this may not always be possible.
If you have to do the grounding after the solar panels are installed, make sure you have switched off the solar inverter and all other electrical equipment before you start.
Install a Grounding Bolt
Install a grounding bolt on the side of the metal roof that is not covered by a solar panel. This will allow any electricity that does escape the system to be safely grounded.
Grounding bolts should be installed by a qualified electrician and should comply with all local electrical codes.
Install a Non-Conductive Barrier
Although grounding the metal roof and the solar array is a good way to increase electrical safety, it’s not the perfect solution by itself.
Because grounding suggests a safe path for electrical current to flow, however, the current may still find a way to flow if there is an accidental contact between the metal roof and the solar array.
Therefore, it is recommended to install a non-conductive barrier between the solar panels and the metal roof. This can be done by using an insulator such as foam, rubber, or neoprene. There are roof flushings made of various non-conductive materials that can be used for this purpose.
You can also use a non-conductive mounting system, or install the panels using anti-shock silicone caulking. Other forms of flashing may also be used, as long as they provide electrical insulation. The type of barrier to use will depend on the solar panel installation method and the manufacturer’s recommendations.
Use Bonding Straps
Bonding straps are another good way to increase electrical safety. Bonding straps serve as a connection between different metal parts of the system to ensure that electricity pursues a planned and safe path to the ground.
Using bonding straps eliminates the need of using additional non-conductive barriers or grounding lines by extending the grounding line to different parts of the system.
Ground Solar Panels
The solar panels themselves should be electrically isolated from the roof, which means they will not conduct electricity and pose a threat.
In order to ground the solar panels, you will need to use a grounding wire that is directly connected to a metal part of the solar panel frame and then to the ground.
Make sure that all wiring is done in accordance with the applicable electrical code and that the ground itself is properly insulated.
So far, we have discussed the electrical safety concerns of installing solar panels on a metal roof. However, there are a few other points that are equally important.
The Feasibility of Installing Solar Panels on Metal Roofs
Installing solar panels on a metal roof is possible, but it’s not always easy. There are different types of metal roofs, and each one will typically require at least a little different installation approach.
Standing seam metal roofs
Standing seam metal roofs have raised seams that run vertically from the ridge of the roof down to its lower edge, with a gap between each seam for drainage purposes.
In most cases, standing seam metal roofs do not require any penetrations for installing solar panels because the panels can be mounted on the roof’s surface. However, you will need to use a non-conductive mounting system to avoid any potential electrical shorts.
Metal tile roofs
Metal tile roofs are made of smaller metal sheets, with each sheet covering an area that is similar to an individual tile. The tiles are then fitted together and attached to the roof as a single unit.
Installing solar panels on a metal tile roof is possible, but it’s not always easy because of the irregular surface. You will need to use tile replacement mount products in order to create a flat surface that will allow the solar panels to be safely installed.
Tile replacement mount products are roof tile-shaped and may be swapped out with your existing roof tiles. They not only simplify the installation procedure by providing a flat surface, but they will also protect your roof from any damage that may be otherwise caused by a traditional mounting system.
Corrugated metal roofs
Corrugated metal roofs are made of metal sheets that have been crimped in a wavy pattern. Installing solar panels on a corrugated metal roof can be difficult.
Because, unless the pattern of the corrugations is convenient enough to allow for the mounting of a clamp, you will need to drill holes to mount your solar panels.
In all types of metal roof installations on solar panels, it is better to use a railed system. Because using a railed system help minimize the number of holes that need to be drilled, and will also provide a more secure mounting system.
Other considerations of installing solar panels on a metal roof
Here are some other factors to consider when installing solar panels on a metal roof:
Water leaks
The main function of the roofing system is to protect the building from the elements and prevent water penetration which can damage our building. While no roofs are leakproof metal roofs may be more susceptible to water infiltration if their structural integrity is compromised.
Most solar installations on metal roofs require at least some roof drilling to install the rails that hold the panels in place. This can lead to leaks if the holes made on a metal roof are not properly sealed.
Therefore, if you plan to install solar panels on a metal roof it is critical to hire a professional solar installer or roofer who is familiar with the nuances of installing solar on metal roofs.
However, the best way to prevent leaks is not to drill holes in the roof at all. There are several mounting systems that allow you to install solar panels on a metal roof without having to drill holes in your roof. These mounting systems will provide a greater degree of protection from water infiltration.
Corrosion
One potential issue that arises when installing solar panels on a metal roof is corrosion of the solar panels. Because both a metal roof and the solar panels are metal, they can create a galvanic reaction that may cause the metal parts of the solar array to deteriorate.
To prevent this from happening, it’s important to use materials that are compatible with each other and to properly seal all seams and joints. Make sure that the roof and solar array don’t come into contact with each other at any time.
Also, make sure that any paint or coating used on the roof will not react with the solar panels. Dried paint or coatings can be scratched off, which will create an opportunity to stick to the different parts of the solar array creating a galvanic reaction.
If you live in an area with a high concentration of corrosive chemicals in the air (for example, saltwater or acid rain), you might need to apply additional materials and coatings on the roof and choose solar panels rated for that environment.
Oil Canning
Oil canning is a term used to describe the rippling effect on metal sheets that results from uneven internal stresses in the metal. If you install solar panels on a metal roof you will create additional stresses on the metal, which may aggravate the oil canning problem.
Also, having solar panels on a metal roof will likely require you to step on the roof, which is also adding to the stress on the metal sheets.
Oil canning can be prevented by using thicker metal sheets and a higher gauge of the material. Using a rib roller profile to break up the amount of flat space on a panel is another option.
Roof Load
Adding a solar array to your roof can add to the weight of the roof, and in some cases may be too much for the roof to handle. Most metal roofs are designed to withstand some heavy snowfall, but not for the additional weight of a solar array or regular foot traffic on them.
In order to install solar panels on a metal roof, you will need to have a structural engineer determine if the roof can support the additional weight of the solar array. If the roof cannot support the weight, you may need to reinforce the roof structure before installing solar panels.
Conclusion
It is entirely possible to install solar panels on a metal roof. However, because solar panels are electrical devices and metal roofs are conductive surfaces, additional precautions should be taken when installing solar panels on metal roofs.
Water infiltration, corrosion, oil canning, and increased roof load are all factors. In order to ensure a long-lasting and efficient solar array on a metal roof, some due diligence will be required.