The metal roof, a perfect platform for solar PV
Today, building owners are adding grid-tied solar PV to augment the power required to run their facilities. The financial prospect makes sense, turning cash positive in three to seven years and providing power for decades thereafter.
With the increasing use of solar on commercial buildings, metal roofing has become a driver for roof type selection in many cases. Costco, FedEx, Whole Foods, Walmart, and others are using solar to power stores, offices, and distribution facilities. Apple Inc.’s widely acclaimed campus in California’s Silicon Valley boasts one of the largest roof-mounted solar arrays in the world at 7.4 MW—all of it installed over a SSMR.
According to a Berkeley study, the service life of solar PV is between 28 and 37 years, with an average of 32.5. Most alternative roofing systems expire long before the life of the PV system. This leads to costly disassembly of the PV array, re-roofing, and re-assembly. A SSMR provides an ideal platform and is the only commercial roof type featuring a service life that exceeds the solar PV system.
It is also easier and less expensive to mount solar to a metal roof than any other roof type. In most cases, this cost savings is even sufficient to offset the premium initial cost of a SSMR. Solar PV can be mounted to the standing seams of the roof with reliable tested and engineered mechanical attachment methods. Also note: building design for loading must account for the additional 2.0 to 2.5 psf collateral load presented by the PV array.
Designers should know something about roofing alternatives and service lives to bring added value to their clients. With the cost of solar decreasing over the last decade, federal and local incentives, as well as public policy mandates driving the popularity of solar, the numbers improve every year. When solar PV is incorporated in building design, the SSMR makes sense from a financial and ecological perspective.
Owner decisions: Service life and return on investment (ROI)
Metal roofing is known for its durability, environmental sustainability, variant styles, versatility, and material longevity. As a trusted roofing material for centuries, metal roofs are experiencing a surge in popularity because more and more owners and designers are realizing the maintenance and lifecycle costs are substantially lower than alternatives roofing materials. Among the many benefits of metal roofing is the ease of mounting rooftop ancillaries, which makes this roof type worthy of serious consideration for owners and designers within the investment discussions surrounding present and future building use and objectives. The attributes of today’s standing seam metal roof are especially poignant in this dynamic era when rooftop solar is a growing driver for building design—whether incorporated in the initial design phase or future-proofed for solar technology and other potential retrofits.
Rob Haddock, the inventor of non-penetrative metal roof attachment solutions, is an award-winning roof-forensics expert, author, lecturer, building envelope scientist, and former contractor. He has worked in various aspects of metal roofing for nearly five decades and is the recipient of the 2018 CSI Ben John Small Technical Writing Award. Haddock is a CSI Pikes Peak chapter member for more than 16 years.