An article published in Consumer Reports on Aug. 3, 2015 titled “Solar power is one way to meet Obama’s energy-saving challenge: What homeowners need to know about installing solar panels” highlights several important considerations for proper roof-mounted photovoltaic (PV) system installations. Although the article’s content is accurate, homeowners should have additional information to ensure that their roof systems will perform well throughout the life of their PV systems.
The article states: “Properly installed [solar] panels should not cause any damage to your roof. In fact, the panels tend to protect the roofing materials they cover by shielding them from precipitation, light and heat.” The key word here is “properly.” There are far too many installations where panels have been mounted only 2 inches or less above a roof because the installer believed this would “look better.” Many racking systems also are designed for low-profile installations for this same reason. Homeowners must be aware that when solar panels are installed too close to a roof surface, they can damage the roof by increasing the heat loads on roofing materials. Two inches or less above the roof system is too close.
Although panels provide some shading, they also absorb and concentrate solar energy. This energy can accumulate and raise ambient temperatures if the panel installation does not provide adequate space above the roof’s surface to allow for proper air flow. The resulting increased heat load can accelerate aging of roofing materials and cause significant performance problems for the most common roof underlayment materials. Further, panels installed too close to a roof surface can obstruct water drainage and promote accumulation of leaves, pine needles, dirt and debris, and snow and ice in cold weather climates. These conditions can permanently damage roofing materials and cause leaks.
NRCA publishes technical guidelines for roof-mounted PV systems. These guidelines recommend rack-mounted PV systems on steep-slope roof systems have a minimum of 5 inches of clearance between the roof’s surface and the lowest rack-framing members, and that highly heat-resistant roofing materials be used, including the primary roof covering and underlayment.
The article also correctly advises homeowners that a structural engineer and roofing professional assess the roof’s condition and structural capacities. It also provides limited references for state-by-state lists of contractors and solar installers. Although the article references NRCA for “roofer referrals,” homeowners should also be aware that roofing professionals may be the best contractor choice to provide proper roof-mounted PV system installations. Professional roofing contractors know how to assess a roof’s condition; they are most familiar with working safely on rooftops; they are best qualified to install rack mounting system penetrations and flashings; and they are most likely to carry the proper insurance coverages required for rooftop work. Many roofing contractors have qualified electricians on staff to perform the electrical work during rooftop PV installations.
Homeowners also should be aware of Roof Integrated Solar Energy™ (RISE™). RISE evaluates and certifies solar energy installers for knowledge about critical roof system construction and maintenance practices. RISE administrates the Certified Solar Roofing Professional™ (CSRP™) certification, providing the public with a tool to identify skilled rooftop solar energy professionals. The RISE website also provides a state-by-state list of professionals who perform rooftop PV installations. Visit www.riseprofessional.org for more information.