What You Should Know About Solar Panels and Metal Roofing
Many property owners have made the switch to metal roofs because of their tremendous value and low lifetime cost of ownership. Metal roofs can stand up to the variable weather in the Midwest area and provide more reliability and peace of mind than traditional asphalt shingle roofs. They are also the ideal choice for homeowners and commercial property owners looking to take advantage of renewable energy devices like solar panels.
Solar energy can provide a consistent stream of energy using nothing but sunlight, acting as backup power for a home when the local grid experiences an outage or even sending excess power back into the local grid for energy savings or even payment from the local electrical utility company.
Homeowners considering upgrades to new metal roofs should also consider the potential benefits of investing in solar panels. While this combination upgrade typically entails an early investment, the long-term benefits are well worth the cost and can provide fantastic returns for many years to come.
Benefits of Metal Roofs
Metal roofs last much longer than typical asphalt shingle roofs and typically incur a fraction of the maintenance costs over their lifespans. While a traditional asphalt roof can last 20 to 25 years with expert installation, a well-built metal roof can last more than twice as long and require far fewer repairs during that time. The long-term cost of ownership savings will eclipse the initial higher investment compared to a new asphalt shingle roof.
Metal roofs also tend to offer energy savings to homeowners who decide to invest in them instead of asphalt shingle roofs. Some may assume that a metal roof will absorb more heat and therefore make it harder to cool a home during hot weather or become too cold for efficient heating during the winter. This is not true. In fact, most homeowners who invest in metal roofs start noticing lower utility bills after investing in their new roofs.
Some homeowners may prefer the classic aesthetic of an asphalt shingle roof over large vertical metal roof panels, but the design possibilities are more versatile than many might think when it comes to new metal roofs. Homeowners can choose from different shingle-style metal roofs including dimensional shingles, Spanish tiles, and even metal roof tiles that look like cedar shake.
Ultimately, metal roofs offer reliability, incredible value, design versatility, and long-term savings to which asphalt shingle roofs cannot compare. They are also ideal for solar panel installations, offering a stronger foundation for the brackets required to secure solar panels to the roof of a structure. Advantages of Installing Solar Panels
If you are looking for ways to reduce the energy costs of your home or commercial property, solar panels can be a fantastic investment. Available in different styles and configurations, solar panels offer property owners increased property value, consistent energy savings, and a host of other benefits worth consideration.
Solar panels absorb sunlight to provide energy to a structure, lowering the need for the structure to draw power from the local grid. It’s also possible to install solar batteries onto structures with solar panels to use as backup power in the event of a local grid outage.
Some homeowners who invest in solar panels coordinate with their local power companies to funnel excess energy back into the local grid, resulting in discounts on their energy bills. Homeowners that produce more electricity than they consume may even receive payments from their electric companies each month, a nice replacement for monthly electric bills.
Take Full Advantage of the Combination of a Metal Roof with Solar Panels
Many homeowners with traditional asphalt shingle roofs encounter several issues when it comes to solar panel installation. While they may still see tremendous savings on their energy bills, asphalt shingle roofs are susceptible to water damage. It’s also necessary to drill through the shingles into the roof bed to install solar panels on an asphalt shingle roof, increasing the chance for water to seep through the resulting holes and cause damage inside the roof.
Some property owners may also fail to notice water damage, moss growth, or other signs of an asphalt shingle roof in need of repair due to the solar panels blocking line of sight. Metal roofs are the ideal choice for any homeowner or commercial property owner looking to take advantage of solar power for several reasons:
Metal roofs are the ideal surface for solar panel installation. They offer stronger, more reliable support, and a professionally installed metal roof will likely outlive the solar panels installed on top of it.
Solar panels can maximize the cooling benefits of a metal roof. While a metal roof on its own will absorb sunlight without warming the interior of the structure, solar panels will take this a step further and turn that sunlight into energy for the structure.
Solar panels come in different styles, including photovoltaic panels and thin-film solar silicone sheets. While it’s possible to install photovoltaic solar panels on almost any type of roof, many property owners prefer the look and smaller profile of thin-film solar panels. Metal roofs are the ideal choice for thin-film solar panels, and many manufacturers of these panels design thin-film panels specifically for metal roof installation.
The combination of a metal roof with solar panels is an ecologically responsible choice for any property owner. Metal roof manufacturing uses mostly recycled materials and the entire metal roof is completely recyclable after it reaches the end of its lifespan. Solar panels cut down on fossil fuel consumption, resulting in a combination that any property owner can feel good about.
Installation is easy. While installing solar panels on a traditional asphalt shingle roof involves lots of drilling that may require additional flashing, water sealing, and more headaches when it comes time to repair or replace the roof, most metal roofs will last far longer than the solar panels attached to them.
Metal Roofs Offer Better Options
Metal roofs offer higher lifetime value than even the most well-made and professionally installed asphalt shingle roofs and adding solar panels to a metal roof is an environmentally friendly choice that offers tangible benefits to property owners in the your area. Homeowners and commercial property owners can enjoy energy bill savings, increased property value, and many other distinct benefits by choosing a combination of a metal roof with solar panels.
Installing Solar Panels on a Metal Roof
While basic human needs still include “shelter,” today’s housing options have evolved well past simple grass huts. Beyond mere shelter, homeowners look for well-built structures that provide value and longevity—and also keep them safe and dry.
Although many people may associate a metal roof with industrial or commercial structures, more homeowners are turning to metal roofs for reliable, long-term solutions. Shingle roofs are much cheaper to install than metal roofs, but the lifespan averages about 15 to 20 years.
With a longer lifespan of about 40-70 years, metal roofs are more expensive to install, but also require little maintenance. This makes them more affordable in the long term, and also appeals to those interested in sustainability.
Renewable home energy systems can also increase your sustainability, especially because solar panels are unlikely to outlive metal roofing. If you do plan to install solar panels on a metal roof—rather than asphalt or slate shingles—there are some key considerations to keep in mind.
How Metal Roofs Differ from Other Materials
Integrating photovoltaic systems with metal roofs can create confusion for some solar installers and roofers. While residential solar technology is becoming more common, the popularity of metal roofs has skyrocketed in recent years. As a result, a gap in knowledge may exist for some roofers between incorporating new roofing materials and installing solar systems.
Another important consideration for metal roofs is to make sure the installation team maintains your roof’s integrity to preserve its characteristic watertight qualities. While some kinds of metal roofs can use clamps to mount solar panels, other types will require specialized frames and mounts to retain the seal.
Understanding Different Types of Metal Roofs
In addition to the material itself, the way metal is formed into roofs differs greatly from more common roofs of slate or asphalt shingles. Three of the most common types of metal construction are corrugated, tile, and standing seam roofs. Each requires installers to use a different method for attaching photovoltaic panels, and each comes with a specific set of potential issues that could arise.
Corrugated metal has been around for centuries, but it’s become an increasingly common alternative to non-ferrous materials for economical roofing.
Corrugated metal is fabricated by shaping a flat sheet into a wave pattern, similar to the inside of a cardboard container. The depressions of each trough allow for adequate drainage, and the structure is much stronger than a simple flat metal sheet.
While they are extremely lightweight and cost-effective, these constructions are not meant for significant weight loads. As a result, mounting systems must spread the force of the panels over larger areas. The existing solutions for corrugated roofs include installing rails with several mounting points, as well as brackets that mount on at least two high points to distribute the load across the roof.
Standing Seam Roofs
Standing seam designs offer some of the most flexible options for installing solar panels. They are distinguished by a raised bar, or seam, every couple of feet, bordered by a drainage channel. This design offers two specific ways to mount panels:
- Thin-film panels can be installed directly and connected between the seams. This ensures minimal penetration of the roof and reduces the risk of potential leakage. However, this method also offers little flexibility in terms of angling the panels to capture the maximum amount of sunlight.
- Some mount designs can use the seams themselves as mounting points via brackets that clamp. This provides slightly more flexibility for angling but still limits the need for screws and anchors that could affect the integrity of the roof.
Metal Tile Roofs
Metal tiles are the third type of metal roof construction and, as the name implies, they create a checkerboard-like layout along the roof. There are also two methods for mounting solar panels to this type of material, but they require a bit more customization and planning than those for standing seams:
- Mounts that take the place of individual panels limit the need for drilling and using silicone or polymer sealants because they simply replace the tiles in the existing roof. Such mounts must be carefully designed to fit the measurements of tiled systems and may not always work with your specific materials.
- The same rail mounting system used for corrugated roofs can also be used for metal tile roofs. Be sure that the installation company has enough experience with these systems to ensure that they can properly seal the mounts themselves so there is no gap in the roof’s moisture barrier.
Get Help Installing Solar Panels on Your Metal Roof
Installing solar panels on a metal roof is a great way to provide long-lasting energy savings with systems that will endure as long as the roof itself. With so many design options available for mounting photovoltaic systems onto metal roofs, it’s important to work with trained experts to help you find the best fit for your home.
For the past four decades, in total, well over 2 billion square feet of metal roofing has been installed in the U.S. each year, and that number grows every year. Metal roofs are known for their durability, sustainability and versatility and are increasing in popularity in the solar marketplace.
Metal roofing is a natural choice for mounting solar PV as it provides an ideal platform and features a service life that actually exceeds the service life of a solar PV system.
In the commercial/industrial market sector, the field/lab study published by the Metal Construction Association indicates that the service life of (standing seam) coated steel is in the range of 70 years. Many alternative roofing systems will expire long before the life of the PV system. This leads to costly disassembly of the PV array, re-roofing and re-assembly.
The service life of solar PV is between 28 and 37 years with an average at 32.5 years, according to a recent Berkeley study. Aside from metal, there are no other roof types that measure up to that without requiring replacement. High-end tile may be the only exception, but it comes with a high price tag and is also much heavier (1.5 psf vs. 5 to 8). Mounting solar to tile is a bit complex and very tricky to do without breaking tiles so the cost is also much higher than mounting to metal.
Metal roofing is also the most sustainable roofing type (at a 72.8% recycle rate, steel is one of the most recycled construction materials available) and is conducive to lower solar installation costs, which is important to the buyer conscious of both environmental and economic energy efficiencies.
Ease of Installation
It is easier and less expensive to mount solar to a metal roof than any other roof type.
Solar PV can be mounted on the standing seams or ribs of the roof, which serve as the rails to which modules are attached with reliable mechanical attachment methods.
Metal roof solar mounting can offer fewer components, light-weight materials, better load distribution and provide a zero-penetration system for standing seam metal roofs, while preserving the warranty of the roof: no holes/no leaks.
S-5-PVKIT 2.0 Solar Attachment Solution
Once the decision is made to install solar, often a new roof is required. and more building owners are replacing their roofs with metal roofs because not only is a metal/solar roof system less expensive up front than other roof types, it leads to improvements in lifetime ROI of the system. The PV array and the roof should be regarded as a single asset.
When computing ROI within the solar profoma, inverter replacement is usually factored in at about year 15 – but what about the cost of roof replacement? The solar array has to be totally dismantled and then re-installed on the replacement roof. Often, even the initial cost of solar a metal roof is less expensive. Factor in roof replacement and the advantages become grossly magnified.
A number of exorbitant costs associated with completing a PV system re-roof for a traditional (non-metal) roof include:
- Remove modules
- Remove mounting racking system
- De-commission system during reroof
- Re-install PV system
- Re-commission potential
- Possibility of damaged components
- Potential for new wiring necessary
- System downtime
With metal, you can avoid roof replacement since a standing seam metal roof has a service life of 70 years. The roof will still be going strong long after the service life of the solar array has expired.
The Rise of Metal Roofing Solar
With the cost of solar decreasing significantly over the last decade, in addition to federal and local incentives as well as public policy mandates driving the popularity of solar, the breakeven and ROI improves every year – evident even more with solar on metal roofs because of its lower installation costs, so it makes even greater financial sense.
Metal is the most solar-friendly roof available and the PV contractor should know about it.
Metal roofing is attractive, durable, non-flammable and requires almost no maintenance. The “buy-it-cheap and fix-it-later” mentality has steadily diminished over the last few decades and more building owners are choosing metal than ever before.
Generation X is leading the charge to more durable construction materials and methods that reduce maintenance and have longer service lives. These facts are borne out by statistics clearly indicating that metal has a much larger share of replacement roofing than it does in new roofing within the residential market.
Solar contractors should know something about roofing alternatives and service lives in order to bring added value to their customers. The roof and the solar PV array should be evaluated as a single system. Advising the mounting of a solar array with a 30-year plus life on a TPO or asphalt shingle roof with a 15-year life is a bit like mounting a Ferrari engine on a Mini-Cooper chassis. Who would do that?
The S-5! Solution
S-5! Metal Roof Innovations, the leading authority on metal roof attachment technology, provides a simple, secure and economical method for attaching solar panels to any metal roof type.
The S-5-PVKIT 2.0 enables solar installers to “direct attach” PV modules to a metal roof’s structural seams or ribs, eliminating the need for a traditional rail mounting system. The PVKIT offers a lay-and-play experience for PV mounting technology, and its primary components come preassembled for use with S-5! clamps or brackets, providing easy and efficient installation for any metal roof type. This system offers impressive savings across several metrics by which PV mounting systems are measured.
The PVKIT both maximizes the surface area of the roof and reduces the collateral load on the roof. The non-penetration system does not compromise the roof integrity and eliminates the risk of voided roof manufacturer warranties – no holes/no damage.
S-5-PVKIT 2.0 Solar Attachment Solution
About Rob Haddock Rob Haddock, the inventor of metal roof attachment solutions, a former contractor, an award-winning roof-forensics expert, author, lecturer and building envelope scientist. He has worked in various aspects of metal roofing for nearly five decades.
The content opinions in this article are the author’s and do not necessarily represent the views of AltEnergyMag
In 1992, S-5! invented the very market space of manufactured roof attachment solutions. S-5!’s clamps and brackets are engineered for a variety of applications, including residential and commercial solar installations on exposed-fastened and standing seam metal roofing. The company has a portfolio of more than 5 GigaWatts of rooftop solar arrays, including many Fed-Ex and Walmart buildings; 700 Costco stores in eight countries; international airports; and corporate headquarters for Google, IBM, NATO, NREL and Apple. S-5! technologies are also affordable for domestic applications with more than 15,000 such solar installations in 50 countries.
Parallel Products Recycling Facility—Case Study
The EPC contractor recommended the S-5! PVKIT® — a direct-attach™ rail-less solar solution to provide a secure, economical and penetration-free method for attaching the solar modules to the metal roof.
CanDuit™ Clamp GRipperFix® Utility Mounting System
After many roof replacements, the city was ready for a new and better roof designed to last. They needed to support ±600 feet of rooftop conduit and piping, and wanted a roof that was solar-ready.
The Net Zero Home
Run solely on renewable energy sources, every aspect of the home’s design was calculated to conserve energy and capture as much of the sun’s energy for heat in the winter and cooling in the summer.
The relationship of PV and metal roofs: Mounting system installation
In the final entry of the three-part whitepaper series, S-5! and the Metal Construction Association take a look at the critical technical factors for solar PV systems specific to mounting on metal roofs and illustrates how long-term performance of roof-mounted solar PV systems can only be achieved through careful planning, design, procurement, installation and quality control.
S-5!’s PVKIT2.0 and Colorgard being installed on the Calcaire House
Image: The Solar Revolution
S-5!, a manufacturer of metal roof attachment solutions with non-penetrative solutions for attaching solar systems to metal roofs, has released a three-part series of white papers examining the relationship between solar and metal roofs with the Metal Construction Association (MCA).
In the first entry of this series, the two explored the advantages metal roofs inherently have in housing solar systems, from the perspective of asset lifespans and overall system lifetime costs, while the second entry focused on common types of mounting systems for metal roofs, and the associated risks, pros, and cons of each.
In the final entry S-5! and MCA bring together the previous conversations to take a comprehensive look at the critical technical factors for solar PV systems specific to mounting on metal roofs. authors from the two organizations illustrates how long-term performance of roof-mounted solar PV systems can only be achieved through careful planning, design, procurement, installation and quality control.
Of course, as was outlined in the first entry, the first consideration for installing a pv system on a metal roof should be to verify that the existing metal roof has a remaining roof life of at least 30 years. After that, calculations must be done to ensure that the roof and all components of the system can withstand and contribute to overall resilience in the face of wind, snow, seismic and collateral dead loads. Once those two steps have been completed, the hardware chosen for the installation must be thoroughly vetted for quality assurance and potential defects.
Hardware considerations and service life compatibility
First things first, all mounting system components for PV installations on metal roofs of all kinds must be certified to UL 2703, the UL Standard for Safety Mounting Systems, Mounting Devices, Clamping/Retention Devices, and Ground Lugs for Use with Flat-Plate Photovoltaic Modules and Panels.
According to the authors, metal roof mounting system components should be fabricated from corrosion-resistant metals with a service life expectancy at least equivalent to the roof itself.
For copper roofs mounting system components should be brass or stainless-steel alloys, though anodized structural aluminum alloys may be used when brass alloys are not commercially available. Stainless steel fasteners or caps should be used when portions of those fasteners are exposed to the elements. For coated steel, aluminum, zinc, or stainless roofs, structural aluminum alloys and/or 300-series stainless steel should be used.
The most common and highest-recommended (by the authors, at least) style of metal roofs are standing seam metal roofs. Since these systems have few, if any, penetrative components, the same should apply for the solar installation. Solar PV mounting systems for standing seam roof installations must be mechanically attached to the panel seams only via seam clamps in order to preserve the roof’s design features and warranties.
Another metal roof style is the face-fastened metal roof, where the roof attaches directly to the structure by design vial long-life fasteners using coatings and/or metal alloys compatible with the roof material in terms of metallurgy and life expectancy. This type of system is protected from moisture intrusion by high-quality synthetic rubber seals and protected from UV exposure by the fastener head design. While fastening penetration in these roof types is unavoidable, the waterproofing diligence of mounting system components should be of equal or better quality than the roof construction itself.
The attachment style for these roofs also brings in the need for additional testing of the attachment components, which should be validated to ASTM E 2140, Standard Test Method for Water Penetration of Metal Roof Panel Systems by Static Water Pressure Head.
Additionally, the authors attest that stainless steel screws or caps should be used when portions of the fasteners are exposed to the elements.
For additional structural confidence, chosen systems and components must be proven by engineering calculations to withstand design loads mandated by the local building code. Proof of engineering by a duly registered design professional must be furnished to the client and the relevant authority having jurisdiction.
Mounting system attachments must be thoroughly tested for holding capacity by ISO 17025-certified independent labs and to industry-accepted protocols. Testing must be specific to the roof material, profile and brand of manufacture of the roof used on the project and be furnished to the client. This proof is ideally in the form of an accepted third-party listing or engineering evaluation, but the authors outline that it may also be a written report.
For even greater peace of mind when selecting components, the report outlines a series of questions that installers and customers should consider.
- How long has the supplier been providing engineered products for mounting solar PV systems onto metal roofs?
- What warranties are offered and for what terms of coverage? (See Figure 4) Note: It is not prudent to rely solely on a warranty.)
- Can the supplier’s track record be verified with customer testimonials and reference letters?
- Has the required product testing and engineering been performed to address the specific design considerations of the project?
- Does the roof manufacturer recommend these mounting system products?
- Do the company’s business practices and certifications comport with this document and will the company back this compliance with written verification?
- Are sales/marketing claims that substantiate the answers to these questions clear and verifiable?
The report recommends that, at minimum, the building and PV system owner should obtain a letter from the vendor stating that testing, manufacturing and product designs are in compliance with all provisions of this document along with obtaining the applicable lab load-test reports and job-specific structural engineering calculations that prove proper resistance of the PV mounting system to design loads.
While the components used and style of roof can be drastically different from metal roofs to other common materials, the report outlines that many of the best practices are the same as installing solar PV on any roof type, because every project must be engineered and designed to withstand the design forces and environmental conditions with certified components, regardless of roof.
However, metal roofs are unique enough to have their own installation considerations. Metal roofs will outlast the service life of a solar PV system, so it is critical that the mounting system and all attachments protect and maintain the durability of the roof. Equally important is the use of materials and assemblies that are thoroughly tested and certified, especially components in direct contact with the roof, so that the attachments do not compromise the integrity of the metal roof.
Regardless of the mounting system, the metal roof attachment should be mechanically compatible with the mounting system. Substituting, adding, or stacking components not tested as an assembly is generally a very bad idea. Of course, the attachment system must be the best fit for the specific metal roof regardless of roof style.
Finally, for an exposed fastened roof, the critical element is the integrity of the seal, since the attachment is designed to penetrate the roof.
Sealants and gaskets are necessary at both the bracket surface touching the roof and at the heads of all fasteners. A butyl sealant captured in a reservoir is generally the best way to seal brackets attaching to the pan of the roof panel, while a durable sealant strip is appropriate for brackets attaching above the pan, such as in the rib area. Ideally, these sealants and gaskets are integral to the component design and pre-installed by the manufacturer. This practice assures that inferior sealants are not locally sourced by the installer.
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Tim Sylvia was an editor at pv magazine USA. Tim covered project development, legal issues and renewable energy legislation, as well as contributed to the daily Morning Brief.