Published on AE 868: Commercial Solar Electric Systems (https://www.e-education.psu.edu/ae868)

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PV System Safety

As we discussed earlier, PV systems consist of multiple mechanical and electrical components, and so safety practices and procedures are critical to reducing or eliminating installation errors, electrical hazards, or injury (or death) on job sites. We saw that NEC has guides for safety requirements for designing and installing PV systems such as voltage and current limits, OCPD and ground-fault devices, and disconnects.

Aside from the aforementioned regulations, this section describes safety practices and procedures that must be used to install PV systems. PV is an electrical system, and workers can get injured. Non-electrical hazards are usually caused by human error, due to carelessness or failure to adhere to safety requirements. Installers should be alerted to different non-electric hazards they may encounter on the installation site. Cuts, bumps, falls, and sprains can cause as much hazard and lost time as electrical shock and burn hazards.

Occupancy Safety and Health Administration (OSHA)

The Occupancy Safety and Health Administration (OSHA) creates a set of regulations that requires employers to provide a safe place for employees while reducing hazards. OSHA 29 CFR part 1926 applied to general construction practices includes several practices applicable to PV systems. OSHA 10 [1] is a recommended basic training for all workers.

In order for PV installers to reduce/eliminate their number of injuries, an awareness of potential hazards and a program where safety rules are frequently reviewed are required. This can be accomplished based on safety training series' offered to workers. Construction sites contain a number of risks that we will discuss in this section. Installers should know that these risks are continuously changing based on new materials and technologies, so regular updates on these topics are recommended.

Note:

There was a time when training was not available for workers to comply with safety regulations. One of the best, effective ways to convey the importance of complying with regulations is by illustrating real examples of incidents. For that reason, OSHA has put together a series of training videos to make training appealing to workers. Some of these videos on the following pages are directly related to PV installations and some are general examples of construction work related hazards. We encourage our solar professionals to watch all videos to get an idea about the importance of OSHA training and safety regulations in general.

Electrical Hazards

Common electrical accidents are classified as:

  • Direct injuries such as electric shocks, burns, or electrocution
  • Indirect injuries, such as traumatic injuries associated with falls after an electrical shock
  • Concussions
  • Eye damage

These injuries can occur when electric current flows through the human body. The injury can become critical depending on the amount of current, the path through the body, and the duration. It is difficult to estimate when current will flow or the severity of the injury that might occur because the resistivity of human skin varies from just under a few ohms to several hundred thousand ohms depending primarily on skin condition and moisture. DC current generated by PV systems can cause continuous arc, and if it travels through a part of the body, it may cause serious burns. Power conditioning units are hazards, as they generate high AC voltage that can cause injuries as well.

This OSHA prevention video (5:41) describes how to prevent deaths and injuries from employees' contact with overhead power lines while using ladders. Find more information on this topic on the OSHA website [2].

Electrocution/Work Safely with Ladders Near Power Lines. Transcript (opens in new tab) [3]
Credit: OSHA [4]

This OSHA prevention video (3:53) describes how to prevent deaths and injuries from contact with overhead power lines while using cranes. Find more information on this topic on the OSHA website [2].

Prevent Electrocutions: Work Safely with Cranes near Power Lines. Transcript (opens in new tab) [5]
Credit: OSHA [4]

Recommendations:

According to the OSHA website [6], Lockout/Tagout (LOTO) refers to "specific practices and procedures to safeguard employees from the unexpected energization or startup of machinery and equipment, or the release of hazardous energy during service or maintenance activities." This can be done by:

  • Lockout AC or DC power source disconnects using appropriate locks.
  • Labeling all deactivated circuits and equipment when they can be energized.

The following video (1:57) offers more information on this subject.

Electrical Panel Repair Results in Electrocution. Transcript (opens in new tab) [7]
Credit: OSHA [4]

Battery Hazards

Any system with batteries forms a potential hazard. Some areas of concern include:

  • Electrical Burns: Shorting the terminals of a typical battery that might be found in a PV system can cause high currents to flow for a few seconds. Severe burns and death can occur even though the voltage is low.
  • Acid Burns: Any battery acid can cause burns if it comes in contact with exposed skin or eyes.
  • Gas Explosion or Fire: Most batteries used in PV systems release gas as a result of the charging process. This gas may be flammable gas and can create a hazard.

Recommendations:

  • Safety gloves and goggles should be worn when dealing with such hazards.
  • Keep all flames and equipment that could create a spark, such as a controller with relays, away from batteries.
  • The battery should be located in a well-ventilated area.

Falling Hazards

A fall is considered the primary cause of death in the construction industry. OSHA fall protection regulations apply to PV systems since PV systems can be installed in locations where climbing a ladder, working on roof, or use scaffolds is required.

A training on fall protection should be offered to workers on how to use fall protection systems and devices to avoid injuries that include:

  • Personal fall arrest systems (PFAS):
 Such as anchorages, lifelines, and body harnesses
  • Guardrails: For open-sided floors with top rail 39”-45” tall, mid rails, and lower rail at least 3 ½” high.
  • Safety nets
: Required for work sites 25’ and more above ground to catch falling workers and reduce fall-related injuries.
  • Stairways and ladders
: OSHA requires all elevations 19” and more to have stairways or ladders with certain regulations to meet safety requirements.
    • Ladder
      • Position ladder at an angle such that the horizontal distance from the top support to the foot of the ladder is 1/4 the working length of the ladder

      • Ladder rail extension: When using a portable ladder for access to an upper landing surface, the side rails must extend at least 3 feet above the upper landing surface—the ladder must be tied-off and a grab rail provided if the 3-foot extension cannot be achieved. 29CFR1926.1053(b)(1)

      • Face the ladder when going up or down when climbing a Ladder

      • Use at least one hand to grab the ladder when going up or down

      • Do not carry any object or load that could cause you to lose balance 

      • 29 CFR 1926 1053(b) (20), (21) and (22) [8]
  • Warning line systems: A barrier erected on a roof to warn employees that they are approaching an unprotected roof side or edge. They contain an area where roofing work may take place without fall protection systems 1926.500 (b)
  • Safety monitors: to warn workers when it appears they are unaware of a fall hazard or are acting in an unsafe manner. A safety monitor must be:
    • A competent person

    • At same level

    • Within sight

    • Able to communicate

    • Free from other responsibilities that could distract the monitoring


The following video (26:25) discusses OSHA's fall protection policies for residential construction.

OSHA's Fall Protection Policies for Residential Construction.
Credit: OSHA [4]

The following videos (3:21, 2:59, 3:06, 3:02, 3:03, and 3:10 respectively) cover various falls in construction.

Falls in Construction/Bridge Decking. Transcript (opens in new tab) [9]
Credit: OSHA [4]
Falls in Construction/Fixed Scaffolds. Transcript (opens in new tab) [10]
Credit: OSHA [4]
Falls in Construction/Floor Openings. Transcript (opens in new tab) [11]
Credit: OSHA [4]
Falls in Construction/Leading Edge Work. Transcript (opens in new tab) [12]
Credit: OSHA [4]
Falls in Construction/Reroofing. Transcript (opens in new tab) [13]
Credit: OSHA [4]
Falls in Construction/Skylight. Transcript (opens in new tab) [14]
Credit: OSHA [4]

Special Consideration

Different slopes for rooftop PV and fall protection

There are two types of slopes that exist on roofs and special attention should be taken:

  • Steep-slope roof = a roof having a slope greater than 4’ in 12’ (vertical to horizontal)

  • Low-slope roof = a roof having a slope less than or equal to 4’ in 12’ (vertical to horizontal)


Conveyors and hoists

Require emergency stop switches at the operator station or the motor

Scaffolding

At heights greater than 10 feet, the fall protection requirement for workers on scaffolds is different from the general construction requirement at 6 feet or greater. 29CFR1926.451(g)(1). See the following video (1:28) for more.

Scaffolding Collapse; Welder Falls. Transcript (opens in new tab [15])
Credit: US Department of Labor

Signal Persons

OSHA requires a signal person when:

  • Point of operation (load travel or load placement) is not in full view of operator

  • During crane travel, the direction of travel is obstructed 

  • The operator or person handling the load determines that it is needed because of site specific safety concern
s

Hand and power tools

Each power tool has its own set of requirements for use, and some come with safeguards. For most PV systems, workers will use electric power tools, air-filled tools, hydraulic tools, and tools that require liquids such as gasoline. Good understanding of the hazards associated with the power source will reduce the number of potential incidents and injuries.

Personal Protective Equipment (PPE)

Personal protective equipment (PPE) protects worker dangers, such as falling items, unsecured materials, and loud noises, that can cause injury. Examples of PPE include:

  • Safety glasses

  • Face shields for eye and face safety

  • Hard hats for head protection

  • Steel-toed safety shoes for foot protection

  • Armor for hands and arms, such as gloves

  • Hearing protection devices, such as earplugs or earmuffs


Other Hazards

Exposure to sun

PV systems are installed where the sun is brightest and no shade exists. Sunburn and dehydration due to extreme temperature may occur.

Insects, Snakes, and Other Vermin

Installers should pay attention to any of inhabitant in the site where the PV system will be installed. Serious injuries may occur due to neglect. The site may be treated against these hazards before the installation starts.

Cuts and Bumps

Most PV systems contain metal items with sharp edges and can cause injury if you are not careful. Installers should wear gloves when handling metal, particularly if you are drilling or sawing.

Falls, Sprains, and Strains

Many PV systems are installed in remote areas in rough terrain with different altitudes. Walking to and around the site, particularly carrying materials or test equipment, can result in falls and/or sprains. Installers should follow correct dress codes from head to toe.

The following videos (2:48 and 2:45, respectively) offer more on sprains and strains.

Sprains and Strains in Construction/Pulling Cables. Transcript (opens in new tab) [16]
Credit: US Department of Labor
Sprains and Strains in Construction/Laying Stone. Transcript (opens in new tab) [17]
Credit: US Department of Labor

Burns

Metal left exposed in the sun can reach high temperatures that can cause serious thermal burns. In addition, most stand-alone PV systems contain acid batteries that can create acid burn hazards. Chemical burns will occur if the acid makes contact with an unprotected part of the body. Safety glasses and gloves are recommended for installers.


Source URL: https://www.e-education.psu.edu/ae868/node/973

Links
[1] http://www.osha.com/courses/10-hour-construction.html
[2] http://www.osha.gov
[3] https://www.osha.gov/dts/vtools/construction/ladder_powerline_fnl_eng_web_transcript.html
[4] https://www.osha.gov/
[5] https://www.osha.gov/dts/vtools/construction/crane_powerline_fnl_eng_web_transcript.html
[6] https://www.osha.gov/dep/greenjobs/solar_loto.html
[7] https://www.osha.gov/video/shipyard_accidents/shipyard_accidents_video_transcript.html#v2_7
[8] https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10839
[9] https://www.osha.gov/dts/vtools/construction/falls_from_bridge_fnl_eng_web_transcript.html
[10] https://www.osha.gov/dts/vtools/construction/scaffolding_fnl_eng_web_transcript.html
[11] https://www.osha.gov/dts/vtools/construction/falls_floor_fnl_eng_web_transcript.html
[12] https://www.osha.gov/dts/vtools/construction/falls_leading_edge_fnl_eng_web_transcript.html
[13] https://www.osha.gov/dts/vtools/construction/reroofing_fnl_eng_web_transcript.html
[14] https://www.osha.gov/dts/vtools/construction/skylight_fnl_eng_web_transcript.html
[15] https://www.osha.gov/video/shipyard_accidents/shipyard_accidents_video_transcript.html#v1_6
[16] https://www.osha.gov/dts/vtools/construction/pullingcables_fnl_eng_web_transcript.html
[17] https://www.osha.gov/dts/vtools/construction/stone_laying_fnl_eng_web_transcript.html