Installing Rooftop Photovoltaic Systems (NRCA)

Position Paper: Installing Rooftop Photovoltaic Systems

This article was a Special Report delivered by the NRCA in February of 2010. Visit the original article at their website.

With growing demand for photovoltaic (PV) systems and an increasing use of rooftops as their natural home, the National Roofing Contractors Association (NRCA) and United Union of Roofers, Waterproofers and Allied Workers want to ensure these systems are properly installed, taking into account a number of crucial factors of which building owners, designers, installers and utility companies should be aware.

NRCA and the United Union of Roofers, Waterproofers and Allied Workers recommend rooftop PV system installation always involve a professional roofing contractor and, when necessary, a licensed electrician. The involvement of a licensed electrician is necessary to oversee the proper installation of a PV system’s electrical components, and, in most jurisdictions, there are requirements for licensed electricians to perform that function.

NRCA and the United Union of Roofers, Waterproofers and Allied Workers also recommend rooftop PV system installation only can be undertaken with the involvement of a professional roofing contractor employing skilled roofing workers for a number of reasons, including:

  • The roofing contractor will assess the roof’s condition. Installing an expensive PV system over an aged or faulty roof system will lead to unintended results.
  • The roofing contractor knows how to install new roof systems properly and safely to best accommodate rooftop PV systems.
  • The roofing contractor is aware of local building code requirements that pertain to the installation of the rooftop PV system. These requirements typically include provisions for wind resistance and fire resistance; simply installing a rooftop PV system over an existing roof system can lead to building code violations if not done properly.
  • The roofing contractor knows how to organize a roofing job site, properly load materials on the roof, and keep building occupants and passersby free from risk.
  • The roofing contractor is trained—and insured—for safety on the rooftop. Falls remain one of the primary sources of injury in the roofing industry. Workers who are not aware of best safety practices or Occupational Safety and Health Administration requirements not only put themselves in danger but also may be putting the building owner at risk.
  • Skilled roofing workers, including highly trained journeymen and apprentices, are proficient in the application of all roof systems. They understand PV technology and the types of PV applications used in roofing, have received extensive safety training and recognize the unique safety hazards associated with PV roof systems.
  • In addition, roofing workers are insured for worker’s compensation at a rate appropriate for work on rooftops. That is not likely to be the case for other tradesmen, and disputes easily can arise in the event of a claim.
  • Often, rooftop PV installations require penetration through the roof system. Roofing contractors understand how to properly secure equipment on rooftops, know how to apply flashing materials, and understand how attaching equipment to a roof system may affect its long-term watertightness.
  • Transporting material and equipment across a rooftop can damage the roof system. The roofing contractor understands proper methods to move material and equipment across the rooftop without causing damage.
  • Many roof systems carry warranties that are issued by the roofing contractor or the roof membrane or system manufacturer. All these warranties include provisions that make them void if alterations are made to the system (including any attachments) without the manufacturer’s prior approval.


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