Roof-mounted photovoltaic (PV) systems are an innovative and dynamic area within the roofing industry. New, affordable technology has emerged, allowing a wide spectrum of buildings to generate electricity from their previously inactive roof surfaces. However, with this technology come risks to roofing workers—some familiar, such as fall hazards, and some much less familiar but just as deadly, such as electrical shock and electrocution.
Occupational Safety and Health Administration (OSHA) regulations broadly cover some hazards involved with PV system installation and maintenance but provide little specific direction for safety issues presented by roof-mounted PV systems.
Regulatory background
OSHA regulations in 29 CFR 1926, "Safety and Health Regulations for Construction," apply to employees engaged in "construction work"—work performed under a contract for "construction, alteration and/or repair." OSHA general industry regulations located in 29 CFR 1910, "Occupational Safety and Health Standards," apply to other industries not including construction, agriculture or maritime segments.
OSHA defines "roofing work" primarily as the hoisting, storage, application and removal of roofing materials and equipment. This definition is important because construction industry regulations provide for unique fall-protection systems for roofing work on low-slope roofs. The distinction between construction work and general industry work also is significant for repair and maintenance work performed on roof-mounted PV systems.
Installation
For roofing work on low-slope roofs, 29 CFR 1926 provides for the use of a warning-line system in conjunction with a safety monitor (or guardrails, safety nets or personal fall-arrest systems [PFAs]). Based on this requirement, it is clear roofing workers installing a roof system on which a roof-mounted PV system later will be installed can use a warning-line system and safety monitor as a permissible fall-protection option. It also would be permissible to use a warning-line system and safety monitor for roofing workers performing flashing work to ensure proper waterproofing of structural supports for rack-mounted PV systems mounted on a roof system.
Roof-mounted PV systems that are directly adhered to an existing roof membrane typically are installed by roofing workers. Directly adhered PV components have similar attachment methods to many roofing materials, and the techniques, work methods and procedures to perform such installations support the conclusion that they fall under the definition of roofing work. In these instances, the PV modules become integral parts of the roof system. Using a warning-line system and safety monitor as fall protection during such installations appears to be a suitable and effective option under OSHA rules.
Using a warning-line system and safety monitor as a fall-protection option may be less suitable in instances where rack-mounted PV systems are installed over existing roof systems. This especially may be true when PV installers—rather than roofing workers—attach structural or support components for a PV system, as well as PV arrays and accessories, to a roof. It would be difficult to argue the work constituted roofing work in such an instance, and OSHA likely would require the workers to use guardrails, safety nets or PFAs rather than a warning-line system and safety monitor.
A somewhat stronger argument can be made that the work should be considered roofing work if the PV installation is performed as an integral part of and in conjunction with the roof system installation. This may be the case when structural or support components for a PV system are installed immediately after roofing materials are attached and flashings to the support components are completed. The phrasing of roofing work's definition that cites "roofing materials and equipment" would tend to support that argument.
Installing PV system components that cannot be distinguished as roofing materials and equipment also will require fall-protection options other than a warning-line system and safety monitor.
For example, electricians who connect a roof-mounted PV system's electrical components would need to use guardrails, saftey nets or PFAs.
Repair and maintenance
OSHA fall-protection requirements for repairing and maintaining a roof-mounted PV system also vary depending on whether workers are operating under general industry regulations or construction industry regulations.
For example, 29 CFR 1910 would require a building maintenance worker performing repair or maintenance on a roof-mounted PV system to use fall protection when exposed to fall hazards of 4 feet or higher. A warning-line system and safety monitor is not an option in general industry fall protection—standard railings or PFAs would be required to protect workers not operating under a contract for construction or repair.
In contrast, a roofing worker repairing flashing on support components of a PV system could use a warning-line system and safety monitor.
Design element recommendations
NRCA has developed a number of recommendations for building design elements to increase safety for construction, repair and maintenance personnel exposed to fall hazards on roofs, including those performing work related to PV system components. Some NRCA design recommendations include:
Additionally, access paths for rooftop PV systems should be included in the initial design phase. Access paths are required for service personnel and firefighting purposes. Additions to building code provisions are anticipated later this year to reflect specific requirements for firefighting access.
The California Department of Forestry and Fire Protection's Office of the State Fire Marshal has developed Solar Photovoltaic Installation Guideline—April 22, 2008, which recommends various design access elements to assist firefighting efforts on buildings with PV components in place. The guideline's commercial roof recommendations include:
Electrical hazards
PV system installations are governed by the National Fire Protection Association's NFPA 70: National Electrical Code.© Specifically, the code's Article 690, "Solar Photovoltaic Systems," applies to PV installations including roof-mounted PV systems. Licensed electricians are tasked with interpreting and implementing the code's requirements with regard to roof-mounted PV systems.
Roofing workers must be aware that once a PV module is exposed to sunlight, it will generate electricity that can pose a shock and electrocution hazard. Worker protection rules relating to electrical hazards are found in OSHA's 29 CFR 1926, Subpart K.
OSHA rules state: "No employer shall permit an employee to work in such proximity to any part of an electric power circuit that the employee could contact the electric power circuit in the course of work, unless the employee is protected against electric shock by deenergizing the circuit and grounding it or by guarding it effectively by insulation or other means."
In addition, OSHA requires hardhat protection where head injury from electrical shock and burns is possible. You are obligated to warn workers about where energized circuits are located, the hazards involved in contacting a circuit and protective measures that must be taken to prevent exposure to a circuit.
Some common hazards roofing workers must be aware of include:
Personal protective equipment (PPE) with electrical-resistant properties can be selected and used to minimize electrical contact hazards. Class G and E hardhats can withstand varying amounts of electrical energy for brief time periods. Electrically resistant gloves also are available with class ratings according to voltage resistance. Such gloves typically are worn under protective leather gloves to ensure the electrically resistant gloves' integrity, so flexibility may be limited. Electrically resistant gloves must be inspected regularly and tested for resistance as even minor cuts can destroy their protective capacity.
Although OSHA PPE rules cite a withdrawn footwear standard, electrically resistant performance characteristics for work boots and shoes are established in ASTM F2412-05, "Standard Test Methods for Foot Protection," and ASTM 2413-05, "Standard Specification for Performance Requirements for Foot Protection." Such boots typically are marked with the letters EH, for electrical hazard, signifying a rating for nonconductivity.
Learning from experience
Safety issues posed by roof-mounted PV systems continue to emerge as these systems become more popular and evolve. OSHA regulations may provide some broad direction regarding hazards presented by PV system installation and maintenance, but roofing contractors' experiences likely will serve as the most reliable sources for managing risks associated with PV systems.
Harry Dietz is NRCA's director of risk management.
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