SOLAR PANEL SAFETY AND CLEANING

by Diane M. Calabrese

What’s the watchword for solar panels?

Don’t get carried away.

Just because the panels get a proverbial “seal of approval” from advocates for green technology, it does not mean they are easier and safer to maintain. Cleaning solar panels requires the same due diligence as cleaning other surfaces.

Maybe more. And the U.S. Occupational Safety and Health Administration (OSHA.gov) has taken notice. Fall prevention, lockout/tagout procedures, and arc flash hazards are all on the list of solar-panel safety issues OSHA monitors.

“The top issue for solar cleaners is electrocution,” says Michael Draper, director of compliance and safety for Power Washers of North America (PWNA). “Most contractors don’t realize the risk when cleaning a solar panel that isn’t isolated.

“Many things can cause electrocution, including damaged panels, bad connectors, etc.,” continues Draper. “A thorough hazard analysis needs to be conducted before cleaning a solar array.”

Background for the hazard analysis includes both an understanding of the different types of photovoltaic (PV) surfaces and the expectations of OSHA. There’s no need to go it alone, thanks to groups that have stepped forward with educational material. PWNA is one of the groups.

“The PWNA has recognized that mobile contractors are adding solar panel cleaning to their offerings,” says Draper. “In response to this, the PWNA has produced Solar Cleaning Safe Practices as well as an online training course to educate contractors on the hazards associated with solar panel cleaning.”

One need not spend more than a few seconds in the online world to find alarming photos of individuals engaged in cleaning solar panels. Let’s put it this way: It is every bit as dangerous to lie/sit on a roof with a panel-cleaning brush in hand as it is to lie/sit on a roof with a wand in hand— perhaps more dangerous.

There’s a big difference between a solar panel and a roof shingle. Acknowledge it. What’s the most challenging aspect of cleaning solar panels? “Recognizing that it’s more than just another surface,” says Draper. “Solar panels—and on a larger scale solar farms—are actually PV power generators. And while solar cleaners and mobile contractors share some cleaning methods, the approach to cleaning is different.”

It’s true that choruses of praise and financial support (grants, subsidies, etc.) for solar panels seem to come from groups of all sorts (regulators, environmentalists, manufacturers, etc.). Yet a serious look at solar panels is just beginning.

Cleaning methods for solar panels are likely to become more clearly defined and regulated. “While unregulated today, it is highly likely that it will become more regulated through education and safety,” says Draper.

And although it’s not of immediate concern to solar cleaners, disposal of solar panels at the end of their lifespan (generously estimated at 25 years) concerns regulators. EPA estimates that by the end of 2030, the United States will have one million tons of solar panel waste.

Metals, such as lead and cadmium, used in some solar panels are deemed hazardous wastes. The current EPA position (December 2023) is that some solar panels fit into the hazardous waste category and others do not.

Methods for cleaning solar panels will continue to change as the types of PV surfaces change. Ongoing research and development aim to identify ways to prevent dirt accumulation on the panels, for instance.

The two common types of solar panels in use in the United States are silicon solar (at 95 percent) and thin-film solar. Silicon-solar panels have a crystalline silicon structure with metals embedded. Thin-film solar has a base (supporting) layer of glass, plastic, or metal that is overlaid with thin layers of semiconductor material (e.g., cadmium telluride).

Best practices in cleaning solar panels will emerge that are specific to the panel type and adhere to all safety protocols. Cleaning must be done. The idea held by some early advocates for solar panels regarding the way rainfall would keep panels clean has been demonstrated to be wishful thinking.

Studies by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) illustrate that rainfall alone cannot wash away soiling. Pollen coatings are especially vexing. Those who live in high-pollen areas know that pollen can make a car windshield opaque on some spring mornings. Pollen that coats solar panels reduces their performance.

NREL studies report performance of solar panels decreased by as much as 15 percent during peak pollen periods. Studies on pollen and dirt lead to one conclusion: To maintain optimal performance, panels must be clean.

Safety

Water, a soft and non-abrasive sponge, and a modest amount of liquid detergent (of the dish-washing intensity sort) are used to clean solar panels. Drying can be done with a chamois or squeegee, but to dry or not to dry is not a clear-cut best practice.

In residential areas, rooftops are where most solar panels are found. Thus, as noted in the first section, all OSHA regulations for working up high apply.

Here’s where it gets tricky. Some homeowners lease their solar panels. And some who lease sell excess power back to the grid owner.

On their solar farms and when working with individuals who lease solar panels, solar energy employers that connect to the grid must follow OSHA Standard 1919.269 (Electric Power Generation, Transmission and Distribution). Specific OSHA rules for panels not connected to the grid do not exist (yet), but workers are expected to be trained in hazards that they confront.

Some of the OSHA standards that apply to solar cleaners are those on falls, logout/tagout, crane and hoist safety, electrical, heat/cold stress, and personal protective equipment. One of the challenges for the contract cleaning industry is to determine which standards apply to cleaning solar panels.

For instance, installation of solar panels requires adherence to OSHA rules for the construction industry, while the applicable standard for cleaning solar panels is under maintenance in the general industry category. As such, installation (and removal) of solar panels requires guardrail and safety net systems as well as personal fall arrest systems.

Solar cleaners, however, are subjected to rules for general maintenance in general industry. If there is a fall hazard of more than four feet, a standard railing must be in place, or a personal fall arrest system or safety net must be used.

Solar panels are electricity generators. When they are connected to circuits or the grid, there is the potential to mix water and electricity. Power should not be flowing when washing is underway. Shut down solar panels before cleaning. Make certain they are shut down with logout/tagout. It is the first rule of working safely as a solar cleaner.

Arc flash, also known as arc fault, is a danger with solar panels that does not seem to get the attention it deserves. If a live solar panel system experiences any sort of breach, an electric current may jump from one conductive entity to another, leaping with a (fiery) flash and high heat. Serious injury to workers and damage to structures may result.

(Photos of panels and rooftops that have caught fire because of arc flash are easy to find. Look at them to get a reminder of just how potent a flash is and how much damage it can do.)

Top-notch solar panel systems have arc-flash detectors to alert owners of systems to breaches before they cause problems. But here’s the worrisome part: In some parts of the country, people install their own rooftop solar panels. Although some of the DIY installers may be experts, others are not. Contract cleaners should try to assess the integrity of a solar roof system before approaching it. Ask about the installer.

Solar panels can be as hot as 150°F in direct sunlight. Keep that in mind when doing a preliminary assessment prior to cleaning.

High surface temperature diminishes the performance of solar panels (up to 25 percent)—so much so that it serves as another reminder of how integrating power generated by solar energy into economic activity ought to invite a lot more debate about efficiency, waste, space limitations, safety, etc.

For now, however, the effort to increase the use of solar energy takes precedence over debate. For contract cleaners that means that there are going to be more and more panels requiring cleaning. How many more?

The Department of Energy (Energy.gov) has within it many entities focused on renewables. NREL was cited in the last section. There is also the Office of Efficiency and Renewable Energy (EERE), which in turn has a Solar Energy Technologies Office. (Take away from the many entities the fundamental piece of information that the push for solar is enormous.)

EERE is all about finding ways to deploy more solar panels safely and effectively. It works with innovators (through a project incubator system) seeking the optimal way to position panels—orientation, number, etc. The goal throughout is more panels.

An additional 3.3 million homes each year may get solar roof installations, according to NREL. Panels that will have to be cleaned.

Carry on, then, with care (and enthusiasm) CT