This article will help homeowners understand if their home’s roof type is suitable for solar panel mounting & installation. By learning about which roof materials work best for residential installation, you can determine if solar power is right for your home.
When considering solar panels for your home, the type of roof you have plays a significant role in determining system design and price. This is because some roofing materials require special racking systems and/or labor in order to effectively install panels safely while maintaining roof integrity. While there are very few roofs that cannot support the addition of solar panels, some roofs may be slightly more complex, with their own unique requirements.
Asphalt Shingle Roofs
Asphalt Shingle Roofs: Asphalt shingle roofs are the most common roof type in the United States, and they are also one of the easiest for solar installation. The process is fairly standard with most racking manufacturers offering simple and effective systems to aid the process. All residential solar installation companies will have experience installing panels on asphalt shingle roofs, making it the most straightforward and cost-effective option.
Metal Roofs
Metal Roofs: Metal roofs, such as those made of steel or aluminum, are light, extremely durable, and also fire resistant. Metal roofs and solar panels pair well together, as metal roofs can last up to 70 years, whereas asphalt composite shingles are expected to last just 16-20 years. Most solar panel installations are guaranteed to last 25-30 years, and are capable of generating electricity far beyond the guarantee. When it becomes time to invest in new panels, you can simply have the panels swapped out without having to mount brackets and rails. Because of this, metal roofs are arguably the best roof type for solar panels over the long-term. There are three types of metal roofs: standing seam, corrugated, and metal tile.
- Standing seam metal roofs: These are a great option for solar panel installation, as they do not require any holes to be drilled into the roof structure. A specialized non-penetrating racking system is used to mount the solar panels to the standing seam. Installers can simply clamp onto the elevated seam, avoiding the need to drill into the roof. With a lifespan of up to 50 years, standing seam metal roofs are incredibly durable, making them ideal for solar panel installations; as solar panels typically have a lifespan of 30 years.
- Corrugated metal roofs: This type of metal roof will require a specialized mounting system that uses S-5 penetrating brackets called straddle blocks. These blocks attach securely to the elevated roof ridges, leaving the lower valleys, where the rain collects, untouched and free from penetrations. The straddle block allows for the attachment of an L-foot directly to a structural point beneath the corrugated metal roof, without collapsing or crushing the metal ridge. Top-quality brackets have thick rubber gaskets, and are topped with commercial-grade silicone to ensure a watertight seal & maximum longevity. The straddle block mounting method is secure, and does not compromise the waterproofing or integrity of the corrugated metal roof in any way, when performed by a certified installer.
- Metal tile roofs: Metal tile roofs use non-penetrating metal tile mounts for solar panels. These mounts look like metal roof tiles and fit seamlessly over the existing tiles. They are relatively easy for professionals to install and can be matched to your roof's color and style. When installed correctly, they are water-resistant and durable.
Fall Protection for Installers on Corrugated Metal Roofs
If your roof is made of corrugated metal, it may pose an additional safety concern for the installer. Keep in mind that because corrugated metal roofs do not have standing seams, the installer may attach a safety anchor directly to the roof structure to prevent falls. Make sure that your installer is using a fall protection anchor that will not leak once it is removed after the work is complete.
Clay & Concrete Tile Roofs
Clay and Concrete Tile Roofs: Clay and concrete tile roofs are very common in warmer states due to their longevity and insulative properties. Installing solar on a clay or concrete tile roof is very similar to a metal tile roof. A tile replacement mount that matches the existing tiles is swapped into place and, if needed, painted to match. Clay and concrete tiles are more susceptible to cracking under weight, so installers must be cautious as they move around the roof.
Slate Roofs
Slate Roofs: Slate roofs are also fairly common in some areas. Installing solar on a slate tile roof is very similar to a clay or concrete tile roof. However, due to the fragility of slate, it is important to choose a qualified installer who has experience with slate roofs.
Flat Roofs
Flat Roofs: Flat roofs present a unique challenge for solar installations, as the solar panels must be tilt- mounted at an angle facing south for maximum sun exposure. There are both penetrative and non-penetrative (ballasted) racking options available for flat roofs. Ballasted systems will require an engineering review to determine whether the roof can withstand the added weight requirement that comes with the non-penetrative option.
There are two main ways to install residential solar panels on a flat roof:
1. Ballast Mounting for Flat Roofs
Ballast mounting is the most common way to install solar panels on flat roofs. It is a non-penetrating mounting system, which means that it does not require any holes to be drilled into the roof. Instead, the solar panels are secured in place using weighted ballast blocks.
To install a ballast mounting system, the installer will first need to determine the weight capacity of the roof. Once the weight capacity has been determined, the installer can select the appropriate ballast blocks. The ballast blocks will then be placed on the roof and the solar panels will be attached to the ballast blocks using mounting brackets.
2. Penetrating Mounting for Flat Roofs
Penetrating mounting is less common than ballast mounting, but it is sometimes necessary for flat roofs that cannot support the weight of a ballast mounting system. Penetrating mounting systems require holes to be drilled into the roof to secure the solar panels in place.
To install a penetrating mounting system, the installer will first need to mark the location of the holes on the roof. Once the holes have been marked, the installer will drill them using a special drill bit. The solar panels will then be attached to the roof using bolts and mounting brackets.
Which mounting system is best for your flat roof will depend on the specific characteristics of your roof, such as its weight capacity and type of roofing material.
Other Factors to Consider:
Beyond the type of roof material, there are a few other factors to consider when planning a solar installation, such as:
- Roof age: Older roofs may not be suitable for solar panel installation. If your roof is more than 20 years old, it’s important to have it inspected to make sure it is in good enough condition to support the weight of solar panels.
- Roof condition: If your roof has any leaks, damage, or other problems, it will need to be repaired before solar panels are installed.
- Roof orientation: The ideal roof orientation for solar panels is south-facing. However, east-facing and west-facing roofs can also be viable options, albeit with slightly reduced energy production.
- Roof shading: Shading from trees, buildings, or other structures can reduce the efficiency of solar panels. It is important to assess the amount of shading on your roof before making a decision about solar installation.
- Local building codes and regulations: It is important to use a reputable installer that is experienced with building code permitting in your area.
Conclusion:
If you are considering solar panels for your home, it is important to understand your roof type and the unique requirements associated with solar installation on that type of roof. By working with a certified solar installer, you can ensure that your solar system is installed safely and efficiently, and that it will provide you with the durability and energy savings you expect for decades to come.