Alert: Photovoltaic systems
Learn about the suggested precautions when working with solar photovoltaic (PV) systems.
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The generation of electricity and heat from solar energy is a growing industry and various worker health and safety hazards exist in the construction (installation), operation and maintenance of solar energy equipment and systems. The purpose of this Alert is to raise awareness of these hazards.
In particular, the installation of solar photovoltaic (PV) systems (the conversion of solar energy to electricity) presents health and safety concerns for workers involved in the construction (installation), and maintenance of the systems as well as for other workers (i.e., emergency response or heating, ventilation and air conditioning (HVAC) maintenance workers) who work on or near these types of systems.
This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations, and should not be used as or considered legal advice. Health and safety inspectors apply the law based on the facts in the workplace.
Under the Occupational Health and Safety Act (OHSA) employers have a duty to ensure that workers and their supervisors are aware of any work hazards and hazards in the handling, use, and transport of any equipment (clause 25(2)(d)). Employers are also required to ensure that a worker has received training that is adequate to protect a worker’s health and safety while undertaking the work (clause 25(2)(a) of the OHSA). Depending on the specific hazards, this training may include, but is not limited to, some or all of the following elements:
- fundamentals of electrical hazards
- fall protection requirements and the use of fall protection equipment
- the safe handling, use, and transport of materials
- the safe use of ladders
- hazards and controls while working on sloped roofing
- hazards and controls while working at the edge of the roof
- hazards and controls while working around covered skylights and roof openings
- pre-installation checks, emergency plan, and first aid
Supervision must be provided to protect the health and safety of the worker (clause 25(2)(a) of the OHSA). When appointing a supervisor, employers must appoint a competent person (clause 25(2)(c) of the OHSA).
Clause 25(2)(h) of OHSA requires employers to take every precaution reasonable in the circumstances for the protection of a worker. Depending on the circumstances, it may be a reasonable precaution for an employer to establish written procedures to be followed when a worker is required to work on or near a PV system, including measures and procedures for evacuating the area where the PV systems are located in the event of an emergency.
There are sector-specific regulations that set out the requirements for work done in the sector. The sector-specific regulations are:
- R.R.O. 1990, Reg. 851 Regulation for Industrial Establishments
- O. Reg. 213/91 Regulation for Construction Projects
- R.R.O. Reg. 854 Regulation for Mines and Mining Plants
- O. Reg. 67/93 Regulation for Health Care and Residential Facilities
For some workplaces, such as farms, golf courses or schools, sector-specific regulations do not generally apply. At these workplaces, as with all workplaces covered by the OHSA, the employer has a duty to take every precaution reasonable in the circumstances for the protection of a worker (clause 25(2)(h)).
General safety considerations
The construction, installation and maintenance of solar panels and associated equipment can be dangerous if the hazards related to the work are not identified and any associated risks mitigated.
Some common hazards faced by workers include:
- electrical contact hazards
- fall hazards associated with working from heights
- slips, trips and falls
- exposure to hot or cold environments
- musculoskeletal disorder (MSD) injuries caused by poor lifting techniques
Each sector regulation under the OHSA sets out specific regulatory requirements to protect workers from workplace hazards. Constructors, employers, supervisors and workers, among others, have an obligation to know and comply with the regulations that apply to their workplace. Employers have a statutory duty to provide information, instruction and supervision to a worker to protect the health or safety of the worker (OHSA 25(2)(a)). Employers have a duty to ensure that workers or their supervisors are aware of any work hazards and hazards in the handling, use, and transport of any equipment (OHSA 25(2)(d)). Prior to beginning the work, the worker must have received adequate training in hazard recognition and controls to protect the worker’s health and safety.
Both electric shock and arc-flash blasts are potential hazards that workers must be protected from when working on PV systems.
There are normally two potential sources of electricity in solar PV systems:
- the solar module that produces direct current (DC) electricity (at any time they are exposed to light)
- the utility that supplies alternating current (AC) electricity
The DC electricity from the solar panels is fed to an inverter that converts it to AC electricity for use on location and any surplus is fed into the grid or into storage (batteries) if the system includes this provision. AC electricity is also supplied from the grid when the PV system/batteries are not providing enough power for on location use. Disconnecting the grid from the system at the main power breaker does not stop a PV system from producing electrical power in the presence of light. Even low light conditions can produce a voltage potential that can lead to a shock or arc-flash. If batteries are used to store electricity they should be viewed as a second source of DC power that has to be considered when work is performed on the system.
It is important to note that both AC and DC electricity present significant safety hazards and both must be addressed with appropriate safety precautions to protect workers.
Connection to the electrical utility grid
Before a PV system is connected to the grid or connected to the building distribution system(s), a Connection Authorization must be obtained from the Electrical Safety Authority (ESA) as required by rule 2-012 of the Ontario Electrical Safety Code (OESC) and the installation is subject to an inspection by an ESA inspector (rule 2-004 of OESC) to determine that system components meet appropriate standards and that the system is electrically safe to the requirements of the OESC. A properly installed, inspected and maintained PV system should present no electrical hazard to workers who are in close proximity to it or brush against it. A worker observing damaged PV equipment or exposed electrical conductors must immediately report this to his/her supervisor or employer (clause 28(1)(d) of OHSA) and stay a safe distance from the hazard.
Workers who are not authorized by the owner or operator of the PV system and who are not adequately trained on PV systems must not attempt to move, alter or maintain any PV system components. Doing so may damage system grounding/bonding and may place workers in danger.
Any work to be performed in or in the vicinity of PV solar systems should be thoroughly assessed to identify potential hazards and planned to deal with site specific conditions.
Important points to consider when working on PV systems
- All workers must be adequately trained on PV systems before they work on them (clause 25(2)(a) of the OHSA).
- Always follow the PV component/system manufacturer’s directions.
- Small amounts of sunlight can produce a voltage potential in a PV system that could result in electrocution or arc-flash injuries.
- A residential PV array can have up to 600 V of DC potential.
- Disconnect the DC switch before disconnecting or connecting a string of PV panels. This includes connecting or disconnecting ingress protection connectors (i.e., connectors that are finger safe where the electrical contacts of the wiring cannot be touched and result in an electrical shock).
- Each sector specific regulation requires Lockout and Tagging of electrical equipment before the work begins and while it continues under certain conditions. Those workplaces not covered by sector specific regulations should implement appropriate Lockout and Tagging procedures as a precaution reasonable in the circumstances for the protection of a worker (clause 25(2)(h) of the OHSA). Lockout and Tagging procedures should be in place before wiring is installed between the combiner boxes and the source (PV) disconnect at the inverter and before grid power is connected to the service meter.
Note: A surprise electrical shock delivered to a worker who is working at a height or on an elevated work surface could cause the worker to fall causing injury (e.g. from a roof or ladder).
Constructors and employers must ensure adequate fall protection systems (i.e. guardrail systems and fall arrest systems) are in place and used by workers at locations where photovoltaic systems are present or are being installed and workers may be exposed to a fall. They must also ensure that workers are properly trained and supervised in the safe use of fall protection components and access equipment.
Note: Skylights or unprotected holes in roof areas may present a fall hazard if they are not guarded.
Slips trips and falls
Constructors, employers and supervisors must ensure that workplaces are kept clear of conditions that could cause slips, trips and falls. In particular, they must take measures to:
- Treat slippery conditions created by weather or other sources,
- Clear obstructions in the work area and
- Ensure access routes to equipment such as HVAC units and equipment and anchor points used for window cleaning are free of obstruction.
Where ladders are to be used constructors/employers should conduct a site specific ladder risk assessment and address the hazards of working at heights prior to workers commencing work on the installation or maintenance of PV systems.
The “Ladder Use in Construction Guideline” has been prepared to assist constructors and employers with understanding their obligations under the OHSA and its regulations.
Improper lifting techniques by workers can result in musculoskeletal disorders (MSDs) such as injuries to muscles, tendons, nerves, spinal discs, etc. Therefore a risk assessment of the work with respect to the expected loads workers will handle and site characteristics should be performed in order to identify unsafe lifts.
Employers and supervisors are required to identify hazards associated with manually lifting loads including the weight and frequency of the load being lifted, the distance the load is lifted vertically and the distance the load is held from the body (OHSA, clause 25 (2)(h) and clause 25 (2)(d)). In addition, there must be adequate safety controls in place where lifting hazards exist and workers must be trained on how to safely lift loads (OHSA, clause 25(2)(d)).
Fire fighters guidance note #6-34 - issue: solar photovoltaic (PV) Systems – available in the section 21 manual
International Brotherhood of Electrical Workers (IBEW) construction council of Ontario
Oregon solar energy industries association (PDF) (a report by the OSEIA)
OSHA green job hazards (US Occupational Safety and Health Administration)
Specialized training including the hazards associated with installing a solar PV systems may be obtained from a variety of training providers including, but not limited to:
- Canadian Solar Industries Association (CanSIA)
- The Electrical Contractors Association of Ontario (ECAO)
- The International Brotherhood of Electrical Workers (IBEW)
- Ontario Solar Academy