Compatible sustainability, durability, life span and long-term cost savings are a few of the reasons metal makes the perfect platform for photovoltaic arrays. Metal roofers and architects are increasingly recognizing the structural and economic benefits of this marriage … and the environmental and tax perks have proven to be powerful selling points.
Sustainability is the balance of trade between the built and natural environments and a solar metal roof is the most sustainable roof system. Metal roofs are 100 percent recyclable and the most recycled construction material is steel at 93.3 percent. Metal roofs are energy-efficient, meeting Energy Star requirements with high reflectance, and easily meet the recycle content for LEED credits. Unlike other roofing material, metal is impervious to UV degradation.
Likewise, at the end of their service life, crystalline silicone PV modules can be broken down and recycled. While solar panel manufacturers often provide a 25-year performance warranty, crystalline silicone systems have proven over time to offer a service life in excess of 30 years.
Because the expected service life of a new solar power system is 30-plus years, which is well beyond most conventional roofs that have a service life of only around 15 years, the roof will require replacement long before the solar system. That means incurring the high cost of teardown and disassembly of the solar system, tear-off and removal of the old roofing material (which will be dumped in a landfill), new roof replacement, and reinstallation of the solar system. Furthermore, by having to decommission the solar system while the conventional roof is replaced, out-of-pocket expenses are additionally increased by the loss of energy production during downtime.
Conversely, with the 40 to 60 year service life of a standing seam metal roof, your roof will long outlive your solar system, dramatically reducing the total life cycle cost of your solar roof. Actually, the total life cycle cost associated with putting solar on a metal roof is so much lower than on a conventional roof, the metal roof is essentially paid for through the realized savings.
Another important benefit of solar on metal is rooftop temperature stability. Because the raised solar panels cast shade on the metal roof, the rooftop temperature is reduced, thus substantially reducing your cooling costs. In Florida, where air conditioning costs represent 33 percent of the electrical consumption of the average home, reducing the temperature of the roof by 30 percent or more presents great savings for cooling the inside of the building.
When attached to a typical standing seam metal roof, the crystalline panels also create an air plenum, drawing air up under and back out through the array, keeping the modules cooler so that they are more efficient. While a conventional roof also has the air space and shading, the addition of photovoltaic panels can promote fungal growth on these roof materials. Research has shown that in humid climates, the shade provided by solar panels can stimulate rapid growth of fungus on membrane roofs. The zinc component in metal roofing material actually kills fungus, so fungus can’t grow on the metal roof.
Lastly, to support a solar system, a conventional roof may require a number of structural improvements. Even if the roof can support the weight of the crystalline system, there are still costly anchorage, racking and mounting systems that must be purchased and installed. Most of these racking and mounting systems
(as well as associated conduit for wiring and various other electrical hardware) necessitate putting hundreds, if not thousands, of holes in the roof; and the roof manufacturer will understandably consider those penetrations to be a violation of their warranty agreement. The labor cost alone for installation of the racking and mounting system can also be substantial.
With a standing seam metal roof, however, you can install the entire crystalline system without penetration, and at a huge savings in installation hardware and labor costs. A metal solar roof can have over 10,000 points of attachment and never void the roof warranty by penetrating the metal roof.
Colorado Springs, Colo.-based S-5! manufactures several non-penetrating solar attachment options for standing seam metal roofs. By far the most popular and innovative solution is the UL/ETL listed S-5-PV Kit that allows solar modules to be attached directly to standing seam metal roofs, foregoing the traditional rack and rail methods.
Indeed, a standing seam metal roof is the perfect platform for harvesting solar energy, offering: freedom from roof penetrations to preserve the roof manufacturer’s warranty; easy installation, which translates to great savings; the benefit of a cool roof with no fungal growth; and the strength, durability and longevity of a metal roof that will almost certainly outlive your solar system, providing the lowest possible overall cost.
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Gary Manlove is the business development manager at Metanna, Monument, Colo. To learn more, visit www.metanna.com.