Solar power's relevance in the U.S. continues to increase by almost every measurement. It was projected to account for 5% of electricity in 2022 and four times that by 2050, according to the U.S. Energy Information Association. Utility-scale solar is expected to grow at an even faster rate. The job outlook for solar photovoltaic (PV) installers through 2030 is one of the strongest measured by the Bureau of Labor Statistics.

However, this rapid growth and increased demand for installers highlights an important need. Workers entering the field as entry-level installers or from other skilled trades might not understand the nuances and risks of installing solar panels.

Will White is a Solar Application Specialist at Fluke Corporation. He's worked in the solar power industry in various roles since 2005 and has watched its rapid growth from the inside.

"When I started in the solar industry, I'll take operations and maintenance technicians as a good example, they would typically be the most experienced person on the installation crew, and you'd move them into service because they had that technical experience," he said. "Now, those operations and maintenance providers are so desperate for staff that they're hiring people off the street with no experience with solar at all. They might have some electrical or construction background, but not specifically with solar. And solar is a unique specialty within the electrical trades, and there's some specific knowledge that comes along with that, and there are some specific hazards that come along with it as well."

Working with DC Voltage

One of the noteworthy differences between solar power and, say, wiring a home is that solar power works with direct current (DC) voltage.

"Not many electricians who work in standard wiring are used to working with DC voltages, and the problem or the thing that you have to watch for with solar is that if there's sunlight hitting the modules, they are energized," White said. "There's no easy way to shut them off."

He noted that workers entering the solar industry from other backgrounds may need to learn to look for current flowing through a circuit they're working on before they open a fuse holder. If a fault is present and current is flowing through that circuit, opening that fuse holder could result in an arc.

"I've seen cases where an arc like that creates a cascading failure where you destroy an entire piece of equipment because you opened one fuse with current flowing through it," he said.

One of the most critical ways of reducing that hazard is to work with testing and measurement tools that are rated for the measurement category and voltage of the system. There are four categories expressed in Roman numerals, from Category I to Category IV, with the numbers increasing as you get closer to the power source, which requires more protection. Work on solar arrays is typically Category III.

The next thing to look at is the voltage rating within the category. The National Electrical Code sets the maximum voltage for solar PV systems on one- and two-family residential dwellings at 600 volts and for non-residential buildings (commercial, industrial, schools, etc.) at 1,000 volts. Ground-mounted utility-scale systems, however, don't have a voltage limit (with certain restrictions) and can reach 1,500 volts. There is currently limited testing equipment available rated for Class III/1,500 VDC.

White said that the usual outcome from using testing and measuring equipment that is not rated for the voltage is simply an "offline" or "OL" reading. However, if a transient voltage spike comes through the utility while using improperly rated measurement tools, there is a heightened safety risk to both the user and the equipment.

"There's a very limited selection at this point of testing and measurement equipment that's rated at that higher voltage, but it's really important," White said. "You can't use meters that aren't rated for the proper voltage, so having that equipment that has the proper category rating, the proper voltage rating is really critical."

The same expectation applies to analog tools. Using screwdrivers to land wires in a terminal, for example, calls for insulated screwdrivers that are also correctly rated for the voltage.

Other Safety Concerns

OSHA does not have regulations specific to working with solar PV systems. It's considered electrical work that is covered in many cases by the electric power generation, transmission and distribution standard 1910.269, and by 1926 which covers general construction.

Article 690 of the National Electrical Code, found in NFPA 70, addresses solar PV work. The code was updated for 2023 and includes some of the following requirements:

• Systems operating with at least 80 volts DC between any two conductors must have a listed PV arc-fault circuit interrupter, or components offering equal protection.
• PV system circuits on buildings must have a rapid shutdown feature to reduce the shock hazard for first responders.
• Systems also should have a means to disconnect it from all associated wiring systems.

For the full text of the codes and requirements, consult NFPA 70.

Solar PV installers have other safety considerations beyond using properly related equipment. Some of the primary concerns are:

• Falls from elevated heights
• Overhead power lines
• Struck by accidents caused by machines used on site
• Musculoskeletal injuries from lifting heavy panels or repetitive movements

"Those are the important things to know, and training is really essential when you're getting into the trade," White said.